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If the Green Sahara Returned Tomorrow: How a Wetter North Africa Would Transform the Planet

During the African Humid Period (roughly 11,000- 5,000 years ago, with some definitions extending the onset earlier to ~14.5- 15 ka), enhanced monsoon rainfall greened the Sahara with lakes, rivers, and vegetation, while also supporting the growth and expansion of tropical glaciers on high East African peaks such as Kilimanjaro.

A return of African Humid Period (AHP)- like conditions today, much stronger West African monsoon rainfall, widespread greening of the Sahara and Sahel with savannah, grasslands, woodlands, expanded lakes (e.g., a revived Mega-Chad), and flowing rivers, would transform North and West Africa while producing significant regional and global climate teleconnections.

Scenic African savanna landscape with elephants, antelopes, a lake, mountains, and wind turbines at sunset — ***AI generated by Grok***

Ice- core evidence from Kilimanjaro’s Northern Ice Field shows basal ice dating to the early Holocene (~11.7–9- 10 ka BP). Comparison of oxygen- isotope records indicate glacier growth began early in the African Humid Period, with the ice fields expanding under the wetter conditions of that interval.

The same enhanced moisture that raised lake levels across northern and equatorial Africa (by tens to over 100 m in places) and expanded vegetation into the Sahara also increased snowfall accumulation on the high peaks, allowing ice to build up even though regional temperatures were generally warmer than in the preceding glacial period.

Tropical glaciers on Kilimanjaro (and nearby peaks such as Mount Kenya and the Rwenzori) are highly sensitive to precipitation and humidity in addition to temperature.

Higher moisture and cloud cover during the African Humid Period improved the mass balance enough for net growth and expansion relative to drier intervals. Moraine and exposure- age data also document early Holocene glacial features on these mountains.⁠

After the African Humid Period ended (around 5- 4 ka in many records), drier conditions returned, lake levels fell, the Sahara aridified, and the ice fields contracted.

The surviving ice on Kilimanjaro has continued to respond to later Holocene moisture and temperature fluctuations, but the modern rapid retreat is occurring under a different combination of reduced precipitation, increased sublimation, ablation, and warming. The continuous presence of ice since the early Holocene makes the current loss notable in that context.⁠

In short, the same orbital- driven strengthening of the African monsoon that created the “Green Sahara” also supplied the moisture that allowed Kilimanjaro’s (and other East African) tropical glaciers to grow during that interval.

Ancient rock art depicting three stylized human figures on a weathered sandstone surface — By Roland Unger, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22698492 WadiSuraSwimmers – African humid period – Wikipedia

The African Humid Period (AHP; roughly 14.5- 5.5 ka, peaking ~11- 5 ka) was primarily driven by orbital changes that strengthened and expanded the West African (and broader African) monsoon, amplified by positive feedback involving the land surface, vegetation, oceans, and other factors.

Primary Driver: Orbital (Milankovitch) Forcing

Earth’s orbital precession (the ~21,000- year “wobble” of its axis) is the dominant control. During the early- to- mid Holocene, precession aligned Northern Hemisphere summer with perihelion (Earth’s closest approach to the Sun). This boosted summer insolation over North Africa by ~7- 8% relative to today.⁠

Higher summer heating of the North African landmass (which has lower thermal inertia than the ocean) intensified the land- sea temperature and pressure contrast. This strengthened the summer monsoon, drew more moisture inland from the Atlantic (and to some extent other sources), and shifted the Intertropical Convergence Zone (ITCZ) and rain- belt farther north into the Sahel and Sahara.⁠

Precession paces North African humid periods over hundreds of thousands of years (and longer). Eccentricity modulates the amplitude of the precession signal, and high- latitude ice sheets can suppress humid periods during glacial times even at favorable precession phases. Obliquity (axial tilt) plays a secondary role.⁠

Amplifying Feedback

Orbital insolation changes alone are insufficient in climate models to produce the full observed greening, lake expansions (e.g., Mega- Chad), and rainfall increases.

Key positive feedback include:

Vegetation- albedo feedback: Expanding grasslands and shrubs lowered surface albedo (darker vegetation absorbs more sunlight), further heating the land, enhancing convection, and drawing in more moisture. Vegetation, soil-moisture, and surface- water (lakes and wetlands) feedback collectively amplified precipitation substantially.⁠
Ocean and atmospheric feedback: Changes in Atlantic sea- surface temperatures, moisture transport, and atmospheric circulation (including jets) reinforced the monsoon.
Other influences on timing: Strengthening of the Atlantic Meridional Overturning Circulation (AMOC) after deglacial meltwater events helped position the ITCZ northward and contributed to relatively abrupt onsets. Residual Northern Hemisphere ice sheets could delay the peak humidity. Greenhouse- gas increases played a minor direct role compared with insolation and ice- sheet effects.

The AHP began after the Last Glacial Maximum as insolation rose and ice sheets retreated, with relatively rapid transitions in many records once insolation crossed thresholds and feedbacks engaged.

It ended gradually overall as summer insolation declined, but with locally abrupt aridification in some areas (possibly involving vegetation and dust feedback or high- latitude cooling that weakened tropical circulation). The end was time- transgressive, occurring later at lower latitudes in some reconstructions.⁠

In summary, the AHP is a classic example of orbital pacing of monsoon strength, strongly modified by Earth- system feedback that turned a moderate insolation change into a dramatic regional climate shift, the “Green Sahara”. Similar humid periods recurred throughout the Quaternary (and earlier) under comparable orbital configurations.

Map of Africa showing vegetation and agricultural zones, including forestland, savanna, grassland, semi-desert, and extreme desert regions. — Africa Climate 7000bp – African humid period – Wikipedia

It would not be an exact replica of the mid- Holocene AHP, because today’s boundary conditions differ (higher CO₂, no residual ice sheets of the same scale, modern land use, and different orbital configuration), but model studies of “Green Sahara” scenarios and analogs provide strong guidance.

Local and Regional Impacts in Africa

Hydrology and landscape: Annual rainfall would rise dramatically across the present- day Sahara and Sahel (hundreds of mm/year in many areas, locally more). Large permanent or seasonal lakes, wetlands, and river systems would reappear or expand. Dust emissions from the Sahara (currently Earth’s largest source) would drop sharply due to vegetation cover and wetter soils.
Vegetation and ecosystems: Desert would shift to grassland and savannah, with some woodland in wetter zones. Biodiversity would change, expansion of flora and fauna adapted to wetter conditions, potential recovery of species whose ranges contracted after the AHP, but also losses or shifts for strict desert specialists. More standing water would likely increase disease vectors (e.g., mosquitoes).
Agriculture, water and society: Vast new potential for rain- fed farming, grazing, and water resources in currently marginal or uninhabitable areas. This could boost food security, support larger populations, and create economic opportunities in the Sahel and Sahara. However, existing infrastructure, cities, and farming systems (adapted to aridity) would face flooding, soil erosion, and the need for major adaptation. Land- use conflicts, migration into newly productive areas, and geopolitical tensions over water and territory are plausible. Projects like the Great Green Wall already explore partial, managed greening and show potential rainfall increases and local cooling, but a full natural AHP- scale shift would be far larger and less controlled.

Broader Climate and Remote Effects

Climate models of mid- Holocene Green Sahara conditions (and related experiments with prescribed vegetation and reduced dust) show that Sahara greening is not purely local:

Strengthened monsoon and lower albedo (darker vegetation absorbs more sunlight) enhance local heating and convection, further amplifying rainfall via positive feedbacks.
Reduced dust alters atmospheric radiation, cloud properties, and Atlantic sea-surface temperatures.
Teleconnections include shifts in the ITCZ and Walker circulation, influences on other monsoons, changes in ENSO variability (often reduced), and effects on tropical cyclone activity (some studies indicate fewer North Atlantic storms under greened Sahara conditions due to altered wind shear and moisture).
Remote drying is frequently simulated over parts of South America (including the Amazon) in Green Sahara experiments. Other possible effects include altered precipitation and temperatures in Europe, the Mediterranean, and parts of Asia, plus influences on high- latitude climate (e.g., Arctic responses in some solar-farm or greening analogs that mimic albedo and vegetation changes).

Dust reduction alone has climatic effects (more solar radiation reaching the surface, changes in ocean fertilization downstream). Combined vegetation and dust changes amplify monsoon strengthening beyond orbital forcing alone.

A true AHP return would require orbital precession driving substantially higher Northern Hemisphere summer insolation (as occurred ~11- 5 ka), which is not the case today. Anthropogenic warming may increase Sahel rainfall in some projections, but models do not generally produce a full Green Sahara under 21st- century scenarios.

Higher modern CO₂, different greenhouse-gas and aerosol backgrounds, and human land- use modifications would interact with any greening in complex ways, some amplifying, some damping.

In short, an AHP- like return would turn much of the Sahara into a productive, vegetated landscape with major benefits for water and agriculture in Africa, sharply cut global dust loading, and rearrange atmospheric circulation enough to affect weather and climate on other continents (notably potential drying in parts of South America).

The transition would bring large adaptation challenges, risks of conflict or displacement, and irreversible ecosystem shifts. Managed partial greening (e.g., via reforestation) is already under discussion precisely because of these powerful local and remote levers.

Panoramic view of a snow-covered glacier with steep ice cliffs beneath cloudy skies — KiliGlacier – African humid period – Wikipedia

Antarctic Sea Ice Collapse Triggers Abrupt Reversal in Key Southern Ocean Layer, Threatening Heat and Carbon Storage

New research from the University of Melbourne (with the Indian Institute of Science and University of Southampton), published in Nature Climate Change (October 2026), shows that the Antarctic Intermediate Water (AAIW), a vast, relatively fresh ocean layer spanning much of the Southern Hemisphere, has abruptly reversed long- term trends in salinity, density, and depth since around 2016, linked to major Antarctic sea ice loss.

Illustration depicting the collapse of Antarctic sea ice and its impact on the Southern Ocean, highlighting ocean layer reversal, with labels for fresh, warmer surface layer, denser, saltier deep water, and associated risks to heat and carbon storage. — ***AI generated by Grok***

New research from the University of Melbourne (with the Indian Institute of Science and University of Southampton), published in Nature Climate Change (October 2026), shows that the Antarctic Intermediate Water (AAIW), a vast, relatively fresh ocean layer spanning much of the Southern Hemisphere, has abruptly reversed long- term trends in salinity, density, and depth since around 2016, linked to major Antarctic sea ice loss.

What is the AAIW and why does it matter?

The AAIW is a layer typically found roughly 500- 1,500 meters (or more specifically ~700- 1,200 m in some descriptions) below the surface. It forms partly from Antarctic surface waters influenced by sea ice melt and spreads northward into the Atlantic, Indian, and Pacific Oceans.

It helps:

Store and redistribute heat, freshwater, and carbon.
Supply oxygen.
Support parts of the global ocean overturning circulation (a key climate regulator).⁠

The ocean absorbs over 90% of excess heat from human activities (mostly in the upper ocean) and a large share of CO₂ emissions, acting as a climate buffer.

The observed shift

Pre- 2016 (roughly 1990s and 2004- 2015): Antarctic summer sea ice melt supplied large volumes of freshwater (estimated at ~triple the Amazon River’s annual discharge, or ~17,400 gigatons in some accounts). This made the AAIW progressively fresher, lighter, and shallower.
2016- 2024: Record- low Antarctic sea ice sharply reduced this meltwater input (dropping toward roughly double the Amazon’s flow). The AAIW rapidly became saltier, denser, and deeper across multiple ocean basins. This is the first direct observational evidence of such a change, detected via Argo floats (thousands of robotic ocean profilers), satellite data, and other records.⁠

Researchers note the last comparable major switch in AAIW properties occurred at the end of the previous interglacial period (~130,000 years ago), when Antarctic ice was minimal, but that transition unfolded over thousands of years, not roughly a decade or two.

Implications for heat and carbon storage

A denser and weaker or altered AAIW could reduce the effectiveness of the density barrier (pycnocline) that limits vertical mixing, potentially allowing more excess heat to move into deeper ocean layers. Climate models may therefore be underestimating deep-ocean warming, regional sea- level rise, and longer- term surface temperature responses.⁠
Changes in how surface water is subducted could affect the ocean’s capacity to lock away atmospheric carbon, though the magnitude and timing remain uncertain.
As the altered water mass spreads north, it forms part of the upper limb of the global overturning circulation and could eventually influence systems like the Atlantic Meridional Overturning Circulation (AMOC), as well as Southern Hemisphere atmospheric circulation, storm tracks, rainfall, and weather patterns over years to decades. Effects could cascade more widely.⁠

The lead researchers (including Associate Professor Bishakhdatta Gayen and PhD student Kaushik Mishra) describe this as revealing a critical missing feedback and an urgent signal that the ocean is responding faster than previously appreciated.

Ongoing monitoring (especially Argo data) and improved climate model representation of these processes are highlighted as priorities, particularly while Antarctic sea ice remains at record lows.

In short, the findings raise important questions about whether current projections fully capture the ocean’s evolving role in heat and carbon storage under rapid polar change.

The study itself focuses on the observational reversal rather than detailed future projections or quantified environmental impacts.

A snowy mountain under a blue sky, with a foreground of ice and snow texture. — Sea ice off Victoria Land, Antarctica, with Mount Melbourne in the background. Credit: Alberto C Naveira Garabato

Antarctic Intermediate Water (AAIW) plays a key role in oceanic carbon storage and redistribution as part of the Southern Ocean’s contribution to the global carbon cycle.

AAIW forms in the polar Southern Ocean (primarily in the Polar Frontal Zone, between the Subantarctic and Polar Fronts). Surface waters there are influenced by sea-ice processes, winds, and mixing.

These waters exchange gases with the atmosphere, absorbing substantial amounts of CO₂ (both natural and anthropogenic) through air- sea gas exchange. Cold temperatures enhance CO₂ solubility, aiding uptake.

Once formed, AAIW is subducted (sunk) to intermediate depths, typically around 500–1,500 meters (often cited as ~700– 1,200 m), and spreads northward into the Atlantic, Indian, and Pacific Oceans as part of the upper limb of the global overturning circulation. This process isolates the absorbed carbon from the atmosphere for decades to centuries.

Specific contributions to carbon storage

Major anthropogenic CO₂ sink: Modern AAIW is a significant reservoir for anthropogenic carbon. Its associated carbon inventory has been estimated to exceed ~20 Pg C (petagrams of carbon).⁠
Redistribution and transport: AAIW acts as a lateral conduit, carrying carbon (along with nutrients and oxygen) from high-latitude Southern Ocean uptake regions to lower latitudes. This links Southern Ocean air- sea CO₂ exchange with biogeochemical processes in subtropical and tropical oceans.⁠
Physical and biological pumps: It participates in the solubility pump (temperature- and salinity- driven CO₂ uptake and isolation at depth) and supports aspects of the biological pump by transporting nutrients that fuel productivity elsewhere. Stratification and density structure associated with AAIW help regulate how effectively carbon is retained versus returned to the surface.
Broader Southern Ocean context: The Southern Ocean as a whole dominates global oceanic uptake of anthropogenic heat and carbon. AAIW (together with Subantarctic Mode Water) is central to the rate of water- mass formation and subduction that determines how much CO₂ is taken up and sequestered.

Relevance to recent changes

In the context of the recent research (the abrupt post- 2016 shift toward saltier, denser, and deeper AAIW due to reduced Antarctic sea- ice meltwater), scientists note that alterations to AAIW properties or the way surface water is carried into deeper layers could change how much carbon the ocean locks away.

The magnitude and timing of any such effect remain uncertain, but it raises questions about the future efficiency of this carbon storage pathway.⁠

In summary, AAIW functions as both a direct storage reservoir for absorbed atmospheric CO₂ at intermediate depths and a key transporter that redistributes carbon within the global ocean, helping moderate atmospheric CO₂ levels on multi- decadal to centennial timescales.

Its effectiveness depends on formation rates, surface conditions (temperature, salinity, ice melt), stratification, and circulation.

An expanse of icy water with numerous irregularly shaped ice floes floating on its surface, alongside a snowy edge. — Sea ice floes from a marine voyage. Credit: Alberto C Naveira Garabato

Reversal of Antarctic Intermediate Water trends triggered by sea ice decline

Abstract

Antarctic Intermediate Water (AAIW), a key component of the global overturning circulation and a major regulator of pycnocline structure, forms in the polar Southern Ocean, where sea-ice processes shape its properties. Sustained sea-ice expansion over several decades up to 2015 enhanced summertime meltwater input, stratifying the upper polar ocean and freshening AAIW. However, since 2016, repeated record sea-ice losses have reversed these trends. Using Argo-derived ocean observations supplemented by satellite and re-analysis datasets, we reveal that the abrupt post-2015 shift in sea-ice conditions is on course to alter hemispheric-wide water-mass properties. We estimate a net decline in sea-ice meltwater input of nearly 36 mSv per decade, relative to a pre-2016 increase of 14 mSv per decade. This unprecedented sea-ice loss has triggered densification and salinification of AAIW, whose core has salinified at $4.8 \times 10^{- 3} \pm 1.7 \times 10^{- 3}$ 4.8×10−3±1.7×10−3 g kg $^{- 1}$ −1 per decade. These changes signal that a hemispheric-scale reconfiguration of the pycnocline is underway.

Key points from the paper

Pre- 2016 trend: Decades of Antarctic sea- ice expansion increased summertime meltwater, which freshened and lightened AAIW while helping stratify the upper ocean.
Post- 2016 reversal: Record sea- ice losses sharply reduced meltwater input. This caused AAIW (and related Winter Water) to become saltier, denser, and deeper across the Southern Hemisphere.
Quantitative estimates:
- Net decline in sea- ice meltwater input: ~36 mSv per decade (vs. a prior increase of ~14 mSv per decade).
- AAIW core salinification rate: $4.8 \times 10^{- 3} \pm 1.7 \times 10^{- 3}$ per decade.
Methods: Primarily Argo float data (upper-ocean profiles), combined with satellite sea- ice observations, reanalysis products, and supporting datasets (e.g., EN4, IAP, CFC- 11 tracers).
Broader implication: The shift indicates an ongoing hemispheric- scale reconfiguration of the ocean’s pycnocline (the density gradient layer that regulates vertical mixing, heat, and carbon exchange).

Figures (titles)

Climatological state of Winter Water (WW) and AAIW
Evolution of Antarctic sea ice and northward transport of sea- ice meltwater
Evolution of WW and AAIW core salinity anomalies
Evolution of WW core density and depth
Evolution of AAIW core density and depth
Schematic of AAIW regime shift linked to changes in Antarctic sea-ice cover

Data and code

Data sources include RG- ARGO, IAP, EN4, NSIDC sea- ice products, GLORYS, SOSE, and others (full links in the paper).
Analysis code is available on GitHub: https://github.com/caskaus/AAIW_sea_ice_work.

The full text is behind a paywall (institutional access, Nature+, or purchase required). The abstract and supporting materials above capture the core findings. This is the primary research paper underlying the University of Melbourne press coverage discussed earlier.

Journal: Nature Climate Change, (2026)

DOI: 10.1038/s41558-026-02758-y

Provided: University of Melbourne

Published: 28 October 2026

Authors: Kaushik Mishra,
Bishakhdatta Gayen&
Alberto C. Naveira Garabato

Comparison of Antarctic sea ice trends before and after 2016, illustrating changes in Antarctic Intermediate Water (AAIW) characteristics and their impact on ocean dynamics. — Antarctic Intermediate Water shifted from freshening before 2016 to becoming saltier, denser and deeper afterward. Credit: Kaushik Mishra

No, New York Times, California’s Climate Has Always Been a Land of Flood, Drought, and Fire

The New York Times article “Latest Climate Report Warns of Major Upheaval to California Way of Life” by Soumya Karlamangla, claims California faces a future of bigger storms, more extreme floods, longer droughts, destructive wildfires, disappearing snowpack, and major disruption to everyday life because of climate change. This is highly misleading if not outright false.

It then warns of “more wildfires, bigger storms, longer droughts,” claiming California faces “major upheaval to long-established ways of life.”

Those are dramatic predictions. What the Times largely fails to provide is the historical context necessary to understand them.

A dramatic landscape showing a dry, cracked earth in the foreground, with a backdrop of mountains and dark, stormy skies. The image also depicts a wildfire burning in the distance, representing California's climate challenges. — ***AI generated by Meta***

From ClimateRealism

By Anthony Watts

Historic illustration depicting K Street in Sacramento during the 1862 flood, showing people in boats navigating through a flooded street lined with buildings.

The New York Times article “Latest Climate Report Warns of Major Upheaval to California Way of Life” by Soumya Karlamangla, claims California faces a future of bigger storms, more extreme floods, longer droughts, destructive wildfires, disappearing snowpack, and major disruption to everyday life because of climate change. This is highly misleading if not outright false. The historical and observational record shows that extreme storms, catastrophic floods, prolonged droughts, enormous wildfires, highly variable snowpack, and coastal erosion have always been defining features of California’s natural environment, while many of the Times’ most alarming claims are projections from climate models rather than observed trends.

The Times opens with a confident description of California’s future:

“Floods will become more widespread and extreme.”

It then warns of “more wildfires, bigger storms, longer droughts,” claiming California faces “major upheaval to long-established ways of life.”

Those are dramatic predictions. What the Times largely fails to provide is the historical context necessary to understand them.

California has always been a land of meteorological extremes. Its Mediterranean climate naturally produces long dry periods punctuated by episodes of tremendous precipitation. Atmospheric rivers carrying Pacific moisture into the state are not a recent creation of climate change. They are fundamental to California’s hydrology.

Perhaps the most obvious omission from the Times article is the Great Flood of 1861-1862.

Historical illustration of K Street in Sacramento during the 1862 flood, depicting boats navigating through submerged streets lined with buildings. — Image courtesy of US Geological Survey.

According to the United States Geological Survey’s history of California storms and floods, a succession of powerful storms battered California for weeks. Rivers overflowed, levees failed, Sacramento flooded, and enormous portions of the Central Valley disappeared beneath water. The USGS describes the event as remaining “unparalleled in its magnitude.”

The storm sequence lasted approximately 45 days. The Sacramento Valley became an inland sea. The flooding was so severe that California lost roughly one-third of its taxable land, and Governor Leland Stanford reportedly traveled by rowboat to his inauguration.

This happened in 1861 and 1862, when atmospheric carbon dioxide concentrations were far below today’s levels. Even that disaster wasn’t unprecedented.

The USGS ARkStorm project reports geological evidence of six megastorms larger than the 1861-1862 event during the past 1,800 years. The agency explicitly states that the Great Flood “is not a freak event,” and that there is no reason similar events will not happen again.

Another USGS review concludes that truly massive rainfall-driven California floods appear in the geological record roughly every 200 years.

That is rather important context when the New York Times tells readers that future extreme flooding represents a newly emerging climate threat.

The same applies to atmospheric rivers. The USGS calls them California’s primary storm mechanism and notes that just a few large atmospheric river events can determine whether a particular year is wet or dry. Researchers are studying sediment records precisely because the approximately 70-year instrumental record of atmospheric rivers is far too short to describe the full range of natural variability.

Climate change may alter the intensity of future atmospheric rivers. The USGS and climate-model studies project that possibility, and it should not be dismissed. But a projection of future change is not evidence that California historically lacked catastrophic atmospheric-river storms.

It plainly did not.

This is also why the Times’ presentation of flooding is so incomplete. Climate Realism has previously documented that major California flooding long predates modern warming, including the 1862 catastrophe and evidence of still larger prehistoric events.

More importantly, the observational precipitation record does not resemble the steadily worsening picture implied by the Times.

The National Oceanic and Atmospheric Administration’s California State Climate Summary shows enormous year-to-year variation in winter precipitation since the late 19th century. Its record of two-inch extreme precipitation events since 1930 likewise shows substantial variability rather than a simple upward march toward ever more extreme rainfall.

The Climate at a Glance California State Climate Summary, using NOAA data, similarly reports little overall change in California’s average annual precipitation since 1900 and no sustained increase in extreme precipitation events.

California’s drought history is equally inconvenient for the Times’ narrative.

NOAA’s reconstructed Palmer Drought Severity Index, seen in the figure below, extends California drought history back approximately 1,000 years using tree-ring and other proxy evidence. It shows repeated prolonged wet and dry periods centuries before industrialization.

Line graph showing the California Palmer Drought Severity Index over time from 1000 to 2000, with values ranging from -8 to 8. The graph features blue bars indicating wet periods and red bars indicating dry periods, along with a black trend line.

California does not alternate between drought and deluge because its climate has suddenly become unstable. Alternating between drought and deluge is normal for California’s climate.

Climate Realism recently made precisely this point in response to similar claims about Highway 1: California’s pattern of drought followed by heavy precipitation is not historically unusual. Massive swings between flooding and drought have occurred for as long as historical and paleoclimate records allow us to examine.

Wildfires deserve the same historical perspective.

The Times tells readers that several destructive fires have occurred during the past decade and presents them as evidence of the trends Californians are supposedly beginning to experience.

But “destructive” is not synonymous with “climatically unprecedented.” Put millions more people, homes, power lines, roads, businesses, and expensive property into fire-prone landscapes, and the economic consequences of fires can increase even without a corresponding increase in the underlying natural hazard.

Fire itself is not an aberration in California. It is an integral part of the landscape.

A peer-reviewed study in Forest Ecology and Management estimated that approximately 1.8 million hectares, about 4.4 million acres, burned annually in prehistoric California before 1800. The researchers concluded that California’s skies were probably smoky through much of the summer and fall long before modern industrial emissions.

California’s own Fish & Wildlife agencies acknowledge the same history, explaining that the state’s ecosystems evolved with fire and citing estimates of approximately 4.4 million acres burned annually before 1800 through lightning and Native American burning.

Climate at a Glance reports that modern California wildfire counts and acreage do not show the simple steadily increasing pattern often implied by climate coverage, while emphasizing the importance of vegetation management, ignition sources, and California’s naturally fire-adapted ecosystems.

None of this means temperature and moisture have no influence on fire behavior. Of course they do. It means that portraying California wildfire as some novel product of modern climate change requires ignoring thousands of years of California fire ecology.

Then there is snowpack. The Times states that Sierra Nevada snowpack is projected to decline 40 percent by midcentury and 60 percent by 2100.

Notice the operative word: projected.

NOAA’s State Climate Summary shows observed Donner Summit snow-water-equivalent record shows tremendous natural variability. April 1 snowpack has ranged from almost nothing to more than 80 inches of water equivalent during the observational period. Record-high values occurred in 1952 and 1983, while extremely low values occurred in 1963, 1988, 2014, and 2015.

The Fifth Climate Change Assessment cited by the Time does not measure California’s snowpack in 2050 or 2100. It cannot. Its future hydrology estimates are produced by feeding downscaled global climate model output into additional hydrological models. California’s own technical documentation describes precisely that modeling chain.

There is nothing illegitimate about using models to explore possible futures. Policymakers need scenarios for planning.

But scenarios are not observations, and newspapers should stop writing about modeled conditions decades from now as though they were measurements already taken.

The Times even acknowledges that the state assessment contains multiple scenarios based on different future greenhouse gas emissions levels, and quotes a state official saying, “The future is not predetermined.” Yet most of the article is written as though it is.

The same problem appears in the claim that as much as three-quarters of California’s beaches “could disappear” by 2100. Latest Climate Report Warns of … Again, “could.”

California’s coastline has been eroding, uplifting, subsiding, sliding, and rearranging itself for millennia. Local relative sea level also varies substantially because California is tectonically active. NOAA tide gauges presently show trends ranging from 5.08 mm per year at North Spit to minus 0.76 mm per year at Crescent City, where the land is rising faster than the ocean. Los Angeles’ long-term gauge shows approximately 1.07 mm per year, equivalent to about 0.35 feet per century if that linear trend continued unchanged.

That is considerably more complicated than “climate change will erase California’s beaches.”

Finally, the Times warns that California agriculture could suffer dramatically, including fruit-yield reductions and less irrigated acreage. Latest Climate Report Warns of … Yet actual agricultural data do not show California agriculture collapsing under recent warming. Climate at a Glance reports, for example, substantial long-term increases in almond production and yields and increased strawberry production.

Again, observations and projections are different things.

California has warmed. Additional warming can affect snow levels, heat extremes, ecosystems, and water management. Those are legitimate subjects for research and prudent planning. But that is a very different proposition from the New York Times’ portrayal of a state approaching some historically unfamiliar climatic upheaval.

California was experiencing catastrophic floods before automobiles existed. It endured megadroughts centuries before coal-fired power plants. Millions of acres burned annually before European settlement. Atmospheric rivers battered the coast long before anyone coined the term “climate change.” Beaches eroded, mountains shed landslides, Sierra snowpack swung wildly from year to year, and Californians learned to build reservoirs, aqueducts, levees, firebreaks, and flood-control systems because this has always been an extraordinarily variable and sometimes violent environment.

The lesson of California history is not that nature was once benign and humans somehow broke it. The lesson is that California has never been climatically benign.

The New York Times could have used California’s Fifth Climate Change Assessment to discuss sensible adaptation to a state naturally prone to flood, drought, fire, erosion, and enormous weather variability. Instead, it largely presents model projections as an approaching climate reckoning while giving readers almost none of the historical context needed to judge those projections.

California doesn’t need another climate horror story. It needs reporters willing to look backward at the data before confidently telling readers what catastrophe awaits them ahead.

New CMIP7 scenarios slash high-end warming projections as extreme pathways like SSP5-8.5 are retired

SSP5- 8.5 is still referenced in older studies and some risk assessments, but it is no longer treated as a plausible “business- as- usual” pathway and is being phased out of the core scenario set for the next IPCC assessment cycle.

CMIP7 “High” (H) scenario is now the highest emissions pathway retained for the next generation of climate modeling (CMIP7) that will feed into IPCC AR7.

Infographic comparing old extreme climate scenario SSP5-8.5 with new CMIP7 high scenario, highlighting drastic emission reductions and temperature projections from 2020 to 2100. — AI generated by Grok

SSP5- 8.5 is still referenced in older studies and some risk assessments, but it is no longer treated as a plausible “business- as- usual” pathway and is being phased out of the core scenario set for the next IPCC assessment cycle.

Current status (as of 2026)

In the IPCC AR6 (2021- 2023) and CMIP6 modeling, SSP5- 8.5 was the highest-emissions scenario (very high fossil-fuel development, ~8.5 W/m² radiative forcing by 2100). It produced the upper end of the temperature ranges often quoted (including the ~10- 12 °C Arctic warming figures).
By 2026, the ScenarioMIP group (responsible for scenarios used in CMIP and IPCC reports) has formally judged the high- end emissions levels of SSP5- 8.5 (and its predecessor RCP8.5) implausible. Reasons cited include:
- Rapid declines in renewable energy costs
- Emergence of climate policies
- Observed emission trends that are lower than the extreme pathways assumed in SSP5- 8.5

A key 2026 paper (van Vuuren et al.) and the new CMIP7 scenario framework drop or heavily de-emphasize SSP5- 8.5 and SSP3- 7.0 as central cases. The new “high” scenario is substantially lower in cumulative emissions.

How it is still used

Many published papers, impact studies, and some national climate assessments still cite results from SSP5- 8.5 because the CMIP6 model archive is the most complete available.
It continues to serve as a stress- test and low- probability upper- bound case for exploring high- end physical risks (e.g., extreme sea- level rise, ice- sheet response).
It is not considered a realistic projection of where current policies or even “no new policy” trajectories are heading. Current- policy estimates typically align closer to SSP2- 4.5 (roughly 2.5- 3 °C global warming by 2100).

Bottom line

SSP5- 8.5 remains in the scientific literature and is still occasionally used for sensitivity analysis, but the climate research community and the scenario developers preparing for IPCC AR7 no longer regard it as a credible central or likely high- end pathway. Newer scenario sets have a lower and narrower high-end range.

The current high- end projection (as of the 2026 CMIP7 / ScenarioMIP framework) is substantially lower than the old SSP5- 8.5.

Graph depicting projected climate scenarios on the left and associated emission scenarios on the right, illustrating temperature changes from 2000 to 2140. — Adapted from **van Vuuren et al., 2026**

CMIP7 “High” (H) scenario

This is now the highest emissions pathway retained for the next generation of climate modeling (CMIP7) that will feed into IPCC AR7:

Median global warming in 2100: ~3.3 °C above pre- industrial (1850–1900)
Likely range (approx. 5- 95%): 2.6- 4.4 °C
Cumulative CO₂ emissions (2024- 2100): ~3,820 GtCO₂ (roughly half of the old SSP5-8.5)
Annual CO₂ emissions in 2100: ~55 GtCO₂/yr (versus ~126 Gt in SSP5- 8.5)

It assumes a rollback or failure of current climate policies combined with development trends that still produce high (but no longer extreme) fossil- fuel use. It is explicitly described as an exploratory and high- end case rather than a “business- as- usual” or most- likely pathway.

Context and comparison

Scenario	Median warming 2100	Notes
Old SSP5-8.5 (CMIP6)	~4.4- 4.8 °C	Now considered implausible
CMIP7 High (H)	~3.3 °C	Current official high-end
CMIP7 Medium (current policies)	~2.9 °C	Closest to today’s trajectory
Current policy estimates (independent)	~2.6- 2.8 °C	Real- world tracking

Important caveats:

Climate- system uncertainties (especially climate sensitivity and carbon- cycle feedback) mean warming under the High scenario could still exceed 4 °C by 2100 in the upper part of the range.
Temperatures continue rising after 2100 under the High pathway.
Full Earth- system model runs of these new scenarios are still underway; the numbers above are primarily from simple climate model emulators (e.g., FaIR) constrained to AR6 assessments.

In short, the official high- end has been revised downward significantly, but it still implies substantial further warming and associated impacts if emissions remain high.

Multi-panel graph depicting trends in CO2, CH4, and SO2 emissions, effective radiative forcing, atmospheric CO2 concentration, and temperature projections over time from 1800 to 2500. — GMD – The Scenario Model Intercomparison Project for CMIP7 (ScenarioMIP-CMIP7)

CMIP7 Scenario Methodology (ScenarioMIP- CMIP7)

The new scenario framework for the Coupled Model Intercomparison Project Phase 7 (CMIP7) is detailed in van Vuuren et al. (2026), published in Geoscientific Model Development (doi: 10.5194/gmd-19-2627- 2026). It was developed by the Scenario Model Intercomparison Project (ScenarioMIP) team through multiple rounds of community consultation.

1. Overall Design Goals

Provide a limited, policy- relevant set of scenarios that span high- end climate risks, current- policy trajectories, and Paris- aligned low- emissions pathways.
Improve realism relative to CMIP6 by incorporating recent emission trends, renewable energy cost declines, and existing climate policies.
Support both physical climate science and impacts, adaptation, mitigation research.
Enable long- term studies (extensions to 2300- 2500) of irreversibility, sea-level rise commitment, and carbon-cycle dynamics.

2. Key Methodological Innovations

Emissions- driven (preferred) rather than concentration- driven
Most experiments are intended to be run by prescribing greenhouse- gas emissions directly to Earth System Models (ESMs). This allows interactive carbon- cycle feedback (land and ocean uptake, permafrost, etc.) to evolve, better capturing Earth- system uncertainty. (Concentration- driven runs remain an option for models that cannot run emission- driven.)
Updated socioeconomic foundations
Scenarios are built on revised Shared Socioeconomic Pathways (SSPs) and generated by multiple Integrated Assessment Models (IAMs): AIM, COFFEE, GCAM, IMAGE, MESSAGE-GLOBIOM-GAINS, REMIND-MAgPIE, and WITCH.
Harmonization to recent observations
Pathways are harmonized to observed emissions through ~2023. A common historical emissions dataset is compiled for all relevant species and IAM regions, then sectorally harmonized and spatially gridded for ESM input.
Seven marker scenarios (selected from ~90 candidates)
Long- term extensions
Stylized extensions beyond 2100 (to 2500) using rule- based methods (e.g., FLEX) to study multi- century responses.

3. Workflow Steps

Community design process and peer review (multiple iterations, 11 reviewers for the final paper).
Generation of candidate pathways by IAMs using updated SSPs.
Selection of 7 marker scenarios spanning the desired emissions/climate range.
Harmonization of historical + future emissions (all climatically relevant species).
Production of gridded emissions and land-use data.
Emulation with simple climate models (e.g., FaIR) for preliminary temperature outcomes.
Delivery of forcing datasets to ESM groups for full climate projections.
Use in downstream MIPs (ISIMIP, AerChemMIP, CDRMIP, etc.) and IPCC AR7.

4. Why the High End Was Lowered

The previous high- end (SSP5- 8.5) was judged implausible due to:

Observed emission trajectories tracking closer to middle- of-the- road pathways.
Faster- than- expected declines in renewable costs.
Existing climate policies already in place.

The new High scenario still explores substantial warming (median ~3.3 °C by 2100, range up to ~4.4 °C) but with roughly half the cumulative CO₂ of SSP5-8.5.

Primary Reference

van Vuuren, D. P., O’Neill, B. C., Tebaldi, C., et al. (2026). The Scenario Model Intercomparison Project for CMIP7 (ScenarioMIP- CMIP7). Geosci. Model Dev., 19, 2627–2656.
https://doi.org/10.5194/gmd-19-2627-2026

Official explainer: https://wcrp-cmip.org/explainer-scenarios-for-cmip7/

This framework prioritizes policy relevance, Earth- system realism (via emission- driven runs), and a narrower but still wide range of futures compared with CMIP6.

Is Climate Science Politicized? An Exchange

Kim Rogalin posted about the controversy over the (now removed) 4th edition of the Federal Judicial Center’s Reference Manual on Scientific Evidence from the National Academy of Sciences.

Bradley says his points about RCP 8.5 were never directly answered, and that Climategate should not be forgotten, quoting Andrew Dessler from 2009 calling the emails “embarrassing and a public-relations disaster for science.”

From Master Resource

By Robert Bradley Jr.

Kim Rogalin posted on social media (Facebook) about the controversy concerning the (now removed) Reference Manual on Scientific Evidence (fourth edition) of the National Academy of Sciences Federal Judicial Center (FJC). Her post (August 28, 2026) summarized a Federalist article, “After Climate Activism Scandal, 25 State AGs Push Feds to Suspend Grants to National Science Org,” where author Shown Fleetwood wrote:

The problem with that chapter centered on the fact it was not neutral or unbiased, as the science manual is supposed to be, but was written by activist lawyers and academics actively involved in climate lawsuits filed across the nation, plus plaintiffs, advisors, and climate experts participating in those trials. Being written by public advocates of climate lawsuits, while citing materials and using whole sections written by attorneys and academics testifying for the plaintiffs in those lawsuits, doesn’t just tiptoe along the line of the appearance of impropriety. It is flat-out improper and should have been sufficient by itself to disqualify the climate science document from inclusion in the FJC science manual….

The Academy did the right thing by removing the climate chapter from its website and formally investigating.

Jim Cooper Exchange

Enter Jim Cooper, Professor Emeritus at the University of Minnesota, who commented.

What BS. Members of National Academy of Sciences are elected based of quality of their scientific research not their political positions. Members are elected … in recognition of their distinguished and continuing achievements in original research. Membership is a widely accepted mark of excellence in science and is considered one of the highest honors that a scientist can receive. Current NAS membership totals approximately 2,700 members and 500 international members, of which approximately 200 have received Nobel prizes.” [NAS here]

I then engaged him as follows:

Bradley: Shame that climate science ruined the reputation of science in general. From Climategate to RCP 8.5.

Jim Cooper: No the shame is folks unwillingness to read the scientific literature . As retired scientist and Scientific Journal Editor, I know that the scientific evidence for Climate Change is robust and the quality of the research on par with other scientific fields. The exchange of personal opinions in a few emails did not affect the quality of the published research. I challenge you to prove otherwise using links to credible documentation.

Bradley: Are/were you part of the problem? Climategate was about real-time cheating for ‘the cause’ (and getting called out for it) and an admitted promise to attempt to skew peer review. Read the quotations! Secondly, what about all the journal articles based on RCP 8.5. Retraction? Climate models are not science….

Bradley: What about the busted paradigm of RCP 8.5-based peer-reviewed articles? Why did the profession turn the speculative (and now rejected) model scenario into a base case? Politicization or mass intellectual error?

Cooper: Again and again I will remind you and others that posts without links to credible domination for claims are noise. Links please, otherwise I will not respond.

Bradley: It is international news in the climate community that RCP 8.5 was formally rejected after a decade of primary use. It was the basis for literally thousands of published climate articles. Roger Pielke Jr. has covered this in detail. Are you following the debate? So again my question: “What about the busted paradigm of RCP 8.5-based peer-reviewed articles?” rogerpielkejr.substack.com/p/rcp85-is-officially-dead

Conclusion

My points were never directly answered by the self-anointed authority. If I had made the same case in a journal article, providing a link, what would Cooper have said? My guess is that he would state that it was not a quality journal. Such is the narrative that the experts do not want to disturb.

Climategate lives–and should never be forgotten. As a leading climate alarmist-qua-scientist, Andrew Dessler, stated back in 2009: “There is no doubt that these emails are embarrassing and a public-relations disaster for science.”

Jim Cooper Background

In a previous Facebook post concerning the Climate Change Reality Forum, Cooper wrote:

The goal of this site is: “The Climate change reality forum is an open Facebook group established to reach people with information that differs from the IPCC’s official position on this subject.” IPCC presents scientific research findings and the only valid debate must be with scientific research findings accompanied by full citation of sources not opinions. But I find that the latter predominant thus are not honest discussions of reality.

This led to more than one hundred comments, with Cooper responding to criticism by stating:

It’s your responsibility to prove your claims using data and/or previous published research findings. That’s part of critical thinking, and I repeat in science all statements and/or claims must be backed by citation of credible documentation. Please provide a link to paper where the figure appears….

How true–except when it comes to climate science and other politicized areas of scientific research.

Global Warming Is Making Days Longer by Speeding Up the Atmosphere

This is a Science X Dialog piece written by the lead author of the research. It closely follows (and largely reproduces) his earlier “Behind the Paper” post on the Springer Nature Research Communities site. It summarizes the findings of the March 2026 paper in npj Climate and Atmospheric Science.

There is a blog post by Susmit Subhransu Satpathy (PhD student researcher at the IBS Center for Climate Physics) on the Springer Nature Research Communities site. It discusses his team’s research paper published in npj Climate and Atmospheric Science.

A digital illustration of Earth surrounded by swirling energy patterns and flames, with arrows indicating movement toward a smaller celestial body in space. — AI generated by Grok

Atmospheric circulation not only drives weather and climate but also carries angular momentum. Shifts in winds or mass distribution allow the atmosphere to exchange momentum with the solid Earth, slightly changing the planet’s rotation rate (and thus the Abstract

Changes in the large-scale atmospheric circulation that regulate Earth’s climate can slow its rotation by increasing the Length of Day (LOD). Using large-ensemble simulations from three global climate models under the SSP3-7.0 scenario, we find that global warming-driven changes in Atmospheric Angular Momentum (AAM) propagate into measurable variations in LOD. These arise from modifications in both the mass and motion components of AAM. As the climate warms, expansion of the Hadley cell, intensification of subtropical jets, and weakening of tropical trade winds enhance the motion of the AAM, while a strengthened westward pressure gradient force associated with mountain torque and weakened surface friction torque indicate a reduced efficiency of momentum exchange with the solid Earth. Together, these processes accelerate the atmosphere and slow Earth’s rotation. By the late 21^st century, AAM-driven LOD increases reach 10–18% of the lunar tidal friction trend, highlighting anthropogenic climate change’s role in Earth’s rotational dynamics., or LOD).

Previous work had projected rising Atmospheric Angular Momentum (AAM) under warming, but the dynamical reasons were unclear. Using large- ensemble simulations from three global climate models under a high- emissions scenario, the team found a consistent picture:

The Hadley cell expands poleward
Subtropical jets intensify
Tropical trade winds weaken
Upper- level zonal winds strengthen

These well- known responses to warming systematically increase AAM. At the same time, momentum exchange between the atmosphere and solid Earth weakens (through changes in mountain and friction torques).

The result is a slightly faster -moving atmosphere and a slightly slower- rotating Earth.

By the end of the 21st century, the atmospheric contribution to LOD increase reaches about 10- 18% of the long- term lunar tidal friction trend. Although modest, the signal is systematic (externally forced by anthropogenic warming rather than internal variability) and arises from well- understood circulation changes.

The authors place this in context: tidal friction has long been the dominant long- term driver of rotational slowing, while core- mantle interactions dominate decadal- to- centennial variability. Atmospheric changes represent an additional, climate-driven component.

Climate change is reshaping the fundamental dynamical balance of the Earth system. The atmosphere, oceans, cryosphere, and solid Earth are tightly coupled, so changes in one can propagate into others in unexpected ways. Global warming influences Earth beyond the climate system itself.

Global map showing topography-weighted zonal pressure gradients with highlighted mountain ranges including the Rockies, Alps, Himalayas, and Andes. — The weakening of the momentum exchange between the solid Earth and atmosphere through changing mountain and friction torques. Credit: Susmit Subhransu Satpathy

Key research findings

The paper, Anthropogenic warming- driven atmospheric circulation shifts and angular momentum increase: influence on the Earth’s rotation (Satpathy, Franzke, Yuan, Maher, Park & Lee, 2026), shows that global warming alters atmospheric circulation in ways that increase Atmospheric Angular Momentum (AAM). This accelerates the atmosphere slightly and slows Earth’s rotation, lengthening the day (increasing Length of Day, or LOD).

Using large- ensemble simulations from three climate models (CESM2- LE, ACCESS- ESM- 1.5, and MIROC6) under the high- emissions SSP3- 7.0 scenario, the researchers found:

Circulation changes that boost AAM (especially its motion component):
- Poleward expansion of the Hadley cell
- Intensification of subtropical jets
- Weakening of tropical trade winds
- Strengthening of upper- level zonal winds
Weakened momentum exchange between the atmosphere and solid Earth (via changes in mountain and surface friction torques), so the Earth does not “keep up” as efficiently with the faster-moving atmosphere.

By the late 21st century, the AAM- driven LOD increase reaches about 10- 18% of the long- term lunar tidal friction trend (the dominant natural process that has been slowing Earth’s rotation for billions of years). The effect is subtle but systematic and externally forced by anthropogenic warming, not just internal variability.

Broader context

Earth’s rotation rate already fluctuates due to lunar tides, core- mantle interactions, post- glacial rebound, and mass redistribution (e.g., melting ice sheets increasing polar flattening and oblateness). This work isolates the atmospheric contribution as an additional climate- driven signal. Conservation of angular momentum means gains in atmospheric angular momentum are balanced by a corresponding slowing of the solid Earth’s spin.

The blog emphasizes that climate change reshapes fundamental dynamical balances across the Earth system (atmosphere, oceans, cryosphere, and solid Earth), producing effects that extend beyond temperature, precipitation, or extremes.

Diagram illustrating the Earth's axis of rotation and atmospheric angular momentum (AAM) changes, including graphs of Motion AAM anomaly, Mass AAM anomaly, Total AAM anomaly, and LOD AAM anomaly over time from 1850 to 2100, comparing different climate models. — The increasing trend of AAM with global warming. Credit: Susmit Subhransu Satpathy

Anthropogenic warming- driven atmospheric circulation shifts and angular momentum increase: influence on the Earth’s rotation

Changes in the large-scale atmospheric circulation that regulate Earth’s climate can slow its rotation by increasing the Length of Day (LOD).

Using large- ensemble simulations from three global climate models under the SSP3-7.0 scenario, the authors find that global warming- driven changes in Atmospheric Angular Momentum (AAM) propagate into measurable variations in LOD.

These arise from modifications in both the mass and motion components of AAM.

As the climate warms, expansion of the Hadley cell, intensification of subtropical jets, and weakening of tropical trade winds enhance the motion component of AAM, while a strengthened westward pressure gradient force associated with mountain torque and weakened surface friction torque indicate reduced efficiency of momentum exchange with the solid Earth.

Together, these processes accelerate the atmosphere and slow Earth’s rotation. By the late 21st century, AAM- driven LOD increases reach 10- 18% of the lunar tidal friction trend, highlighting anthropogenic climate change’s role in Earth’s rotational dynamics.

Key points from the paper

Background: Earth’s rotation rate (and thus LOD) varies due to core-mantle coupling, lunar tidal friction, post- glacial rebound, and mass redistribution (e.g., melting ice sheets increasing polar oblateness/J₂). AAM consists of a motion term (related to zonal winds) and a mass term (related to surface pressure distribution). Conservation of angular momentum means changes in AAM are balanced by opposite changes in the solid Earth’s spin.
Methods: Analysis of large- ensemble simulations under the high- emissions SSP3-7.0 scenario:
- CESM2- LE (100 members)
- ACCESS- ESM-1.5 (40 members)
- MIROC6 (50 members)
  These allow separation of externally forced signals from internal variability. Baseline period: 1850- 2014.
Main results:
- Both motion and mass components of AAM increase under warming (motion component dominates).
- Circulation changes driving higher motion AAM include poleward Hadley cell expansion, stronger subtropical jets, weaker tropical easterlies and trade winds, and stronger upper- level equatorial westerlies (including signs of equatorial upper- tropospheric super-rotation later in the century).
- Surface torques weaken, reducing momentum transfer from atmosphere to solid Earth.
- Rising AAM translates linearly into increasing LOD anomalies. By late 21st century the atmospheric contribution reaches ~10- 18% of the long- term lunar tidal friction trend (~2.4 ms/century). The magnitude is comparable to effects from ice- sheet melting and oblateness changes.
- Rough scaling: ~0.09- 0.11 ms of LOD lengthening per degree of global mean surface temperature rise.
Significance: The atmospheric signal is a systematic, externally forced response to anthropogenic warming. It demonstrates that climate change influences Earth’s rotational dynamics beyond the better- known effects of ice melt and mass redistribution.

The full article (including figures on AAM trends, Hadley cell expansion, torque changes, and LOD projections) is freely available as open access at the link above, with a PDF download option.

Journal information: npj Climate and Atmospheric Science, volume 9, Article number: 101 (2026)

DOI: 10.1038/s41612-026-01382-z

Published: 20 March 2026 | Open access

Authors:

Susmit Subhransu Satpathy¹˒², Christian L. E. Franzke¹˒², Naiming Yuan³˒⁴˒⁵, Nicola Maher⁶, Wonsun Park¹˒² & Sun-Seon Lee¹˒⁷¹ Center for Climate Physics, Institute for Basic Science (IBS), Busan, Republic of Korea
² Department of Carbon Neutrality and Climate Change, Pusan National University, Busan, Republic of Korea
³ School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, China
⁴ Key Laboratory of Tropical Atmosphere-Ocean System, Ministry of Education, Zhuhai, China
⁵ Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China
⁶ ARC Centre of Excellence for Weather of the 21st Century and Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia
⁷ Pusan National University, Busan, Republic of Korea

Corresponding authors: susmitsatpathy@pusan.ac.kr; christian.franzke@pusan.ac.kr

Abstract

“Antarctica’s Ice Loss Is Locked In This Century—Even at 1.5°C”

A new study concludes that Antarctica’s net ice loss this century is effectively locked in, even under the Paris Agreement’s ambitious 1.5°C warming limit, and that extra snowfall from a warmer atmosphere will not offset it enough to reverse the trend. This will add to global sea- level rise that threatens low- lying coastal areas.

A dramatic view of Antarctica featuring icebergs and glacial ice with a cloudy sky, accompanied by the text discussing the irreversible ice loss in the region. — AI generated by Grok

The article, by Yucheng Lin (City University of Hong Kong) and Robert Kopp (Rutgers University), was published in The Conversation on September 30, 2026. It summarizes their research in Nature Geoscience.

Key context

Antarctica holds enough ice to raise global sea level by about 58 meters (190 feet) if it all melted.
Roughly 1 billion people live in coastal areas, with about 100 million within 1 meter of current sea level and highly exposed to flooding.
Scientists have long disagreed on whether Antarctica will gain or lose mass this century, because warmer air holds more moisture (favoring more snowfall) while ocean warming melts ice shelves, speeds glacier flow, and drives ice loss.

How the study addressed uncertainty

Ice- sheet models involve a chain of assumptions (emissions → ocean/air warming around Antarctica → ice- shelf melting und or collapse → glacier sliding over bedrock). Different assumptions cascade into large differences in outcomes, and full simulations are computationally expensive.

The researchers trained a physics- informed machine- learning emulator on the large archive of Antarctic simulations from the Ice Sheet Model Intercomparison Project (ISMIP6). This allowed them to rapidly explore hundreds of thousands to millions of combinations of assumptions. They then filtered the results against satellite gravity data (GRACE) that has measured Antarctic mass changes since 2002. Only scenarios consistent with observed ice- sheet behavior were retained.

Main findings

The viable scenarios consistently show net ice loss from Antarctica this century, even if warming is limited to 1.5°C.
Extra snowfall does not compensate enough for dynamic losses driven by ocean warming and ice-shelf processes.
Greenhouse- gas emissions still matter: every avoided ton reduces the amount of Antarctic ice loss this century, with benefits that persist for centuries.
Under very high- emissions scenarios, cascading effects (rapid ocean warming → thinner and weaker ice shelves → faster glacier flow) could contribute up to ~25 cm (10 inches) of sea- level rise from Antarctica alone by 2100, enough to permanently flood the homes of more than 10 million people.
The three most important physical uncertainties for future projections are: how ice shelves respond to a warming ocean, how ice slides over bedrock, and how quickly the ocean and atmosphere around Antarctica warm.

Limitations and implications

The authors note that some processes (e.g., ice fracturing and calving and the evolution of subglacial rivers and lakes) are not fully represented in current models, so the emulator cannot capture them. These could alter the timing or magnitude of ice loss and the window for coastal adaptation.

The work provides a faster way to test assumption combinations and offers a clearer basis for the adaptation decisions already facing coastal communities worldwide. Sea- level rise is already driven by Greenland melt, mountain glaciers, and thermal expansion of seawater; Antarctica’s locked- in contribution adds to that total.

In short, the study reinforces that limiting emissions remains valuable for slowing the rate and ultimate amount of Antarctic contribution to sea- level rise, even though some ice loss this century appears unavoidable based on current observations and modeled physics.

Diagram illustrating the relationship between greenhouse gas emissions, global climate models, and their effects on global warming levels, sea-level change, and Antarctic ice sheet models. Includes graphics of factories emitting gases, a globe depicting climate patterns, and illustrations of ice dynamics. — What different types of models help scientists understand about ice melt, and how they are connected to help predict the Antarctic ice sheet’s future. On the left, how greenhouse gas emissions change the climate, including sea ice, ocean and atmospheric dynamics, which influence one another and levels of global warming. On the right, what goes into an ice sheet model, including ice shelf melt and collapse and how the ice slides. Every stage adds uncertainty. Credit: Yucheng Lin

ISMIP6 (Ice Sheet Model Intercomparison Project for CMIP6) is a coordinated multi- model effort that produced projections of 21st- century (and some longer- term) sea- level contributions from the Greenland and Antarctic ice sheets. It systematically samples uncertainties arising from climate forcing, ice- sheet model structure and physics, parameters, and ice- ocean interactions.

The Antarctic Ice Sheet (AIS) is the largest single source of uncertainty in future sea- level rise projections. Under high- emissions scenarios, ISMIP6 ensembles span roughly −5 to +43 cm sea- level equivalent (SLE) by 2100 (or −7.8 to +30 cm in core multi- model results relative to a control). Greenland contributions are more consistently positive and better constrained.

Main categories of uncertainty

ISMIP6 was designed to quantify uncertainty from:

Emissions scenarios (e.g., RCP2.6 vs. RCP8.5; later linked to CMIP6/SSPs).
Climate models (AOGCMs/ESMs from CMIP5/CMIP6 that supply atmospheric and oceanic forcing).
Ice- sheet models (structural differences across ~13+ international groups and models).
Parameters and parameterizations, especially for ice- ocean interactions (basal melt under ice shelves).
Ice- climate interactions (how models translate ocean thermal forcing into melt rates, grounding- line migration, etc.).

Quantified contributions to uncertainty (Antarctica)

Analyses of the ISMIP6 ensemble (focusing on additional dynamic mass loss driven by changing oceanic conditions) break down total uncertainty at 2100 approximately as follows:

Source of uncertainty	Share of total (AIS scale)	Notes / glacier-scale variation
Choice of ice- sheet model	~52%	Dominant overall. Ranges 14% (some ice streams) to 56% (Pine Island Glacier). Reflects differences in physics, resolution, sliding laws, calving, initial ice-shelf extent, and treatment of melt near the grounding line.
Ice- climate interaction	~22%	Includes melt parameterization choice/calibration and simulated ice- shelf geometries. Higher for sensitive glaciers (e.g., ~36- 39% for Institute Ice Stream and Thwaites).
Choice of climate model	~13% (rising over time)	Grows through the century. Highly variable by glacier (4% for Thwaites to 53% for Whillans Ice Stream).

Other important contributors include:

Ocean- induced basal melt rates and their calibration (often based on conditions outside ice-shelf cavities).
Initial ice- shelf extent (varies by a factor of ~2.5 across models).
Model spatial resolution and numerical treatment near the grounding line.
Basal sliding laws (e.g., Weertman, Coulomb, or hybrid) and related parameters.
Calving and ice- shelf collapse representations (ISMIP6 used idealized schemes; many models lack full hydrofracture or marine ice- cliff instability processes).

Key vulnerable glaciers identified include Thwaites and Pine Island (West Antarctica) plus Totten and Moscow University (East Antarctica), which show high sensitivity to ice-shelf basal melt.

Differences between Greenland and Antarctica

Greenland: Mass loss is more strongly driven by surface mass balance (atmospheric forcing). Model and climate uncertainties are substantial, but the sign is consistently positive. Ocean forcing plays a secondary role in the ISMIP6 design. One analysis attributes spreads of ~40 mm (ice-sheet model), ~36 mm (climate model), and ~19 mm (ocean forcing) under RCP8.5.

Antarctica: Competing effects of increased snowfall (atmospheric warming) versus ocean- driven dynamic loss creates sign uncertainty and weaker scenario dependence in many ensembles. Ocean forcing and ice-dynamics response dominate the spread.

Known limitations and gaps

Incomplete process representation: Many simulations omit or simplify ice fracturing and calving, subglacial hydrology/lakes/rivers, tidal water intrusion beyond the grounding line, and full marine ice- cliff instability (MICI). These can alter rates of ice discharge.

Underestimation of uncertainty: Some critiques note that the ensemble may under- sample parametric uncertainty or be biased low relative to recent observations of mass loss.

Computational constraints: Full exploration of all combinations is expensive, which is why later work (including machine- learning emulators trained on ISMIP6 archives) has been used to expand sampling, as in the recent study on locked- in Antarctic loss.

Forcing biases: Climate- model biases in polar ocean and atmosphere fields, and how melt rates are calibrated from them, remain major issues.

Longer projections (to 2300) show even larger spreads (e.g., −0.6 to +4.4 m under high emissions in some ensembles), with melt sensitivity and dynamic response factors explaining much of the variance.

How ISMIP6 addressed (and continues to inform) these issues

The protocol used “standard” experiments with prescribed melt parameterizations (sampling low/mid/high parameter values) and “open” experiments allowing groups to use their preferred schemes. Forcing came from a curated subset of CMIP models selected for polar skill. Results fed into IPCC assessments and subsequent studies that refine or extend the ensemble (e.g., more comprehensive sampling of melt sensitivity or climate- ice interactions).

In short, ISMIP6 showed that ice- sheet model structural differences and ice- ocean coupling are the leading sources of uncertainty for Antarctica, while climate forcing and surface processes matter more for Greenland. Reducing these uncertainties requires better observations of sub-shelf melt and grounding-line processes, improved basal sliding and calving physics, higher- resolution models, and tighter constraints from satellite mass- change records.

Map showing observations of Antarctic land ice mass changes from 2002 to 2025, with a blue graph indicating an average mass loss of -135 gigatons per year. The color gradient illustrates regions of ice mass change. — NASA’s Grace satellite has tracked ice mass loss over the years. Credit: NASA

The machine learning model referenced in the The Conversation article (and the underlying Nature Geoscience study by Yucheng Lin, Robert Kopp, and colleagues) is a physics- informed machine learning emulator trained on the large archive of Antarctic ice- sheet simulations from ISMIP6.

Purpose and design

Full ice- sheet models are computationally expensive, one simulation can take days on a supercomputer,so exploring every combination of physical assumptions (emissions scenarios, climate model forcings, basal sliding laws, ice-shelf melt parameterizations, etc.) is impractical. The emulator acts as a fast surrogate:

It learns the mapping from each simulation’s physical assumptions/inputs to its outcomes (primarily sea- level contribution or ice- mass change).
Once trained, it evaluates in a fraction of a second while retaining accuracy comparable to the original numerical models.
This enables running millions of combinations and filtering hundreds of thousands of possible futures against satellite gravity observations (GRACE/GRACE-FO mass-change data since 2002).

Only scenarios consistent with the observed ice- sheet behavior are retained. This “transient calibration” or bias- correction step is central to the study’s finding that net Antarctic ice loss this century is locked in even under low- warming pathways.

Key capabilities highlighted in the work

Systematic quantification of cascading uncertainties: It traces how each physical assumption propagates into spatiotemporally variable sea-level rise uncertainties.
Bias correction: By calibrating to the observed long- term Antarctic mass- loss rate (approximately 0.44 mm/yr sea- level equivalent, climate- variability corrected, 2002- 2021), the approach reduces projection uncertainty (by ~30- 42% in the 5th- 95th percentile range in related analyses) and increases median sea- level contributions relative to uncorrected ensembles.
Identification of dominant uncertainty drivers: AOGCM (climate model) selection, basal sliding laws, and ice- shelf basal melt parameterizations emerge as primary sources.
Scenario dependence and tail risks: Higher emissions produce greater mass loss (with high probability). Under very high- emissions pathways, the upper tail reaches ~25 cm of Antarctic contribution by 2100 in some bias- corrected results.

The preprint describing this work is titled “Bias-corrected Antarctic sea-level projections reveal greater impact of historical warming” (Lin et al.). It emphasizes that historical warming has already committed the Antarctic Ice Sheet to continued net mass loss through 2100 with high probability (P ≥ 0.92 even under aggressive mitigation such as SSP1-1.9), unlike some prior uncorrected ensembles that allowed for possible net gain.

Broader context of ML emulators for ice sheets

Similar techniques have been applied elsewhere in the ISMIP6 ecosystem and related research:

Neural networks, LSTMs, Gaussian processes, and graph convolutional networks have been used to emulate ISMIP6 ensembles, regional sea- level fingerprints (GRD effects), surface mass balance, or specific glaciers.
“Physics- informed” approaches incorporate physical constraints (mass conservation, flow laws, etc.) rather than treating the problem as a pure black-box regression, improving physical consistency and data efficiency.

In this study, the emulator’s speed and ability to perform large- scale sampling and observational constraint are what allowed the authors to conclude that extra snowfall will not reverse the locked- in ice loss and that emissions reductions still matter for limiting the rate and magnitude of Antarctic contributions to sea- level rise.

Committed Antarctic Ice Sheet mass loss by the end of the twenty-first century

The Antarctic Ice Sheet (AIS) is the largest source of uncertainty in sea- level rise projections. Uncertainties cascade through emissions scenarios, atmosphere– ocean general circulation models (AOGCMs), ice-sheet dynamics, and sea- level physics. Traditional intercomparison ensembles can be biased toward common modelling choices regardless of observational consistency.

This study uses a machine- learning emulation framework trained on ISMIP6 simulations to quantify how each individual physical assumption propagates into projection uncertainty. It also applies Bayesian calibration against satellite observations to reduce bias.

Key findings:

It is very likely (≥0.92 probability) that the AIS is committed to net mass loss by 2100, even under aggressive emissions- reduction scenarios.
Higher emissions drive greater Antarctic mass loss by 2100 (≥0.89 probability), elevating near- term coastal risks.
Under very high- emissions scenarios, cascading mechanisms consistent with satellite observations could produce up to 25.4 cm of sea- level rise by 2100 (95th percentile; median = 15.7 cm).
Managing these risks requires rapid emissions reductions plus better constraints on AOGCM selection, basal sliding laws, and ice- shelf melt parameterizations (the primary uncertainty drivers identified).

Core approach

The authors built a physics- informed machine-learning emulator on the ISMIP6 archive. This allowed them to:

Rapidly explore millions of combinations of modelling assumptions.
Systematically attribute uncertainty to specific choices (e.g., sliding laws ~21%, ice-shelf melt parameterizations ~20% of variance in raw simulations).
Perform Bayesian transient calibration against GRACE/GRACE-FO satellite mass-change observations (2002 onward).
Produce bias-corrected, probabilistic projections that better reflect historical performance.

They examined both raw and drift- corrected simulations and mapped how uncertainties cascade from global mean surface temperature → AOGCM choice → ice-sheet model features → regional sea-level fingerprints.

This is the peer- reviewed scientific paper underlying the The Conversation article by Yucheng Lin and Robert Kopp that started this discussion.

Title: Committed Antarctic Ice Sheet mass loss by the end of the twenty- first century

Journal information: Nature Geoscience

DOI: 10.1038/s41561-026-02102-1

Published: 30 September 2026

Provided: The Conversation

Authors: Yucheng Lin,
Xuebin Zhang,
Nicholas R. Golledge,
Robert E. Kopp,
John A. Church,
Yi Jin,
Chen Zhao &
Chris R. Stokes

Abstract

The Antarctic Ice Sheet is the largest source of uncertainty in sea-level rise projections, with uncertainties propagating through emissions scenarios, atmosphere–ocean general circulation models, ice-sheet dynamics and sea-level physics. In ice-sheet model intercomparison exercises, these uncertainties—typically attributed to intermodel differences—stem from modelling choices that may bias ensembles towards commonly adopted approaches regardless of observational consistency. Here we quantify how each individual physical assumption cascades into projection uncertainty using a machine-learning emulation framework, which also enables Bayesian calibration against satellite observations to reduce projection bias. Our results suggest it is very likely (≥0.92 probability) that the Antarctic Ice Sheet is committed to twenty-first-century mass loss, even under aggressive emissions-reduction scenarios. Higher emissions drive greater Antarctic mass loss by 2100 (≥0.89 probability), directly elevating near-term coastal risks. Under very high-emissions scenarios, we identify cascading mechanisms that could produce up to 25.4 cm of sea-level rise by 2100 (95th percentile; median = 15.7 cm) while remaining consistent with satellite observations. Effective management of these risks to densely populated coastal communities requires rapid emissions reductions and improved constraints on climate model selection, sliding laws and ice-shelf melt parameterizations.

Overlooked Lakes Amplify Northern Hemisphere Cooling Through Stronger Ice Albedo Effect

A recent study shows that seasonally ice- covered lakes in the Northern Hemisphere contribute disproportionately to cooling via a stronger cryosphere radiative effect (higher albedo) than surrounding land, an effect that has been underappreciated in climate models.

Terrestrial Cryosphere Radiative Effect (CrREₜ or terrestrial CrRE) is the cooling influence that snow and ice cover on land (and lakes) exert on Earth’s energy budget by reflecting incoming solar (shortwave) radiation back to space.

Published in Geophysical Research Letters on September 28, 2026), the paper by Cooley, Webb, Levenson, and Ryan quantifies lakes’ influence on the terrestrial Cryosphere Radiative Effect (CrREₜ), the cooling from high- albedo snow and ice reflecting sunlight.

Using 22 years of satellite data, the authors find:

Per unit area, lakes have a significantly higher CrREₜ than land (-14.4 vs. -8.2 W/m²).
Although lakes cover only about 3.7% of the study domain, they account for 6.3% of the total Northern Hemisphere CrREₜ.
Their contribution is larger still in late spring and in the Boreal Forest, where lakes can supply more than 25% of local CrREₜ.

Lakes’ stronger effect stems from two main factors: snow melts earlier on land (reducing land albedo sooner), while snow- and ice- covered lakes maintain a higher albedo increase relative to the surrounding landscape. The authors conclude that climate models should explicitly include lake CrREₜ processes, highlighting a previously understudied way lakes help moderate Northern Hemisphere temperatures.

This aligns with the Phys.org framing by Hannah Bird (a science journalist covering Earth and environmental topics for the site): “overlooked” lakes act as an under- recognized cooling influence through their ice and snow cover. The finding does not reverse overall warming trends but shows lakes amplify local and regional cooling relative to land via albedo, especially where seasonal ice is common.

Map showing lake contribution to carbon release factors (%) across North America and Eurasia. — Maps of lake contribution to cryosphere radiative effect (a) compared to nearby land (b) snow-off timing (c) and seasonal albedo contrast (d). Positive values indicate later snow-off timing and/or greater seasonal albedo contrast. Credit: Cooley et al, 2026.

Definition

It is the instantaneous effect of surface snow and ice on the top- of- atmosphere (or top-of-model) solar energy budget. In other words, it quantifies how much less solar radiation the Earth system absorbs because of the high albedo of snow and ice compared with a snow- and ice- free surface.

Negative values indicate a cooling effect (more sunlight reflected → less energy absorbed).
It is analogous to the well- known cloud radiative effect, but applied specifically to the cryosphere (the frozen parts of the Earth system).
Longwave (thermal infrared) effects are typically excluded; the metric focuses on shortwave reflection.

Key Influences

CrRE is shaped by more than just the presence of snow and ice:

Seasonal cycle of incoming solar radiation (insolation)
Cloud cover (which can mask the surface albedo effect)
Vegetation cover (which can hide snow)
Properties of the snow/ice itself and the underlying surface
Timing of snowmelt

Terrestrial vs. Broader CrRE

Terrestrial CrRE (CrREₜ) focuses on land and lakes (seasonal snow, lake ice, etc.). Ice sheets and glaciers are often treated separately (though snow on them may be included).
Full CrRE usually also includes marine contributions from sea ice.

Relevance in Recent Research

In the 2026 study by Cooley et al. (Geophysical Research Letters), the authors specifically examined the Northern Hemisphere terrestrial CrRE and showed that lakes have a disproportionately strong effect:

Lakes: about -14.4 W/m² (per unit area)
Land: about -8.2 W/m²
Even though lakes cover only ~3.7% of the domain, they contribute ~6.3% of the total Northern Hemisphere terrestrial CrRE (and >25% in parts of the Boreal Forest, especially in late spring).

This stronger lake contribution arises because snow tends to melt earlier on land, while snow- and ice-covered lakes maintain higher albedo for longer.

In short, terrestrial CrRE is a quantitative measure of how snow and ice on land (and lakes) help keep the planet cooler by boosting reflectivity. It is considered a more climate- relevant metric than simple snow or ice extent alone.

Diagram illustrating the interactions of solar radiation, infrared radiation, and their effects on ice production, ocean heat transport, and atmospheric circulation. Key components include clouds, surface albedo, ice shelf melting, and water vapor. — Major climate feedback operating in polar regions. Plus / minus signs mean that the feedback is positive / negative. Yellow and red arrows show solar shortwave and infrared radiation fluxes, respectively. Orange arrows show the flux exchanges between the different components of the climate system (ocean, atmosphere, ice) for several feedback. TOA refers to ‘top of the atmosphere’ [Credit: Fig 1 from Goosse et al. (2018)].
Cryospheric Sciences | Image of the Week – Climate feedbacks demystified in polar regions

Ice- albedo feedback is a powerful positive climate feedback loop in which melting ice and snow amplify warming.

How it works

High albedo of ice and snow
Fresh snow and ice are highly reflective (albedo typically 0.5- 0.9). They bounce a large fraction of incoming solar radiation back to space, helping keep the surface cool.
Warming causes melting
Rising temperatures (from greenhouse gases or other forcings) melt some of the ice or snow.
Lower albedo surfaces are exposed
- Over ocean: dark open water (albedo ~0.06) replaces bright sea ice.
- Over land: darker soil, rock, or vegetation replaces snow.
- On lakes: open water or thinner/darker ice replaces highly reflective snow-covered ice.
More solar energy is absorbed
The darker surface absorbs more sunlight, converting it into heat.
Further warming and melting
The extra heat raises local (and eventually regional) temperatures, causing even more ice and snow to melt. This reinforces the cycle.

Because each step strengthens the original change, it is called a positive feedback.

Why it matters

It is one of the main reasons the Arctic is warming roughly 2- 4 times faster than the global average (Arctic amplification).
It accelerates the loss of sea ice, glaciers, ice sheets, and seasonal snow cover.
It also operates on lakes: as lake ice shortens or becomes less reflective, lakes absorb more heat, which can further reduce ice cover the following season and influence local climate (as highlighted in recent studies of terrestrial cryosphere radiative effects).

Simple analogy

Imagine a white reflective tent on a sunny day (cool inside) versus a black tarp (hot inside). Melting ice is like gradually replacing the white tent with black material, the surface heats up faster and faster.

In short, ice- albedo feedback turns an initial warming into a self- reinforcing process that speeds up cryosphere loss and regional temperature rise.

Lakes Modify the Magnitude and Timing of the Northern Hemisphere Terrestrial Cryosphere Radiative Effect

Key Points (from the journal)

The study quantifies the contribution of lakes to the Northern Hemisphere terrestrial Cryosphere Radiative Effect (CrREₜ).
Lakes have a much stronger CrRE than nearby land, particularly in the Boreal Forest.
Lakes’ higher CrRE is caused by earlier snowmelt on land and lakes’ greater increase in albedo when snow- covered.

Abstract and Summary

Vast areas of Earth’s Northern Hemisphere are covered in lakes that form seasonal ice cover, yet their influence on the terrestrial Cryosphere Radiative Effect (CrREₜ) had not previously been quantified. Using 22 years of satellite data (roughly 2001- 2022), the authors constrain lakes’ contribution to CrREₜ.

Main findings:

Per unit area, lakes have a significantly higher CrREₜ than land (-14.4 vs. -8.2 W/m²).
Although lakes cover only 3.7% of the study domain, they contribute 6.3% of total Northern Hemisphere CrREₜ.
The lake contribution is even larger in late spring and in the Boreal Forest, where lakes can account for more than 25% of local CrREₜ.
The stronger lake effect results from (1) earlier snowmelt on land (which lowers land albedo sooner) and (2) lakes’ comparatively greater albedo increase while snow- or ice- covered.

The authors conclude that climate models should include lake CrREₜ processes and highlight this previously understudied cooling influence of lakes on Northern Hemisphere climate.

A related dataset (gridded results and time series) is available on Zenodo, associated with the submitted and accepted version of the paper.

This is the study underlying the Phys.org piece titled “Overlooked lakes may be helping to keep the Northern Hemisphere cool.” The paper is open access on the AGU site (Wiley Online Library).

Journal information: Geophysical Research Letters, Volume 53, Issue 18, 28 September 2026

DOI: 10.1029/2026gl124236

Authors: Sarah W. Cooley , Elizabeth E. Webb, Eric S. Levenson, Jonathan C. Ryan

Abstract

Vast areas of Earth’s Northern Hemisphere are covered in lakes that form seasonal ice cover, yet their influence on the terrestrial Cryosphere Radiative Effect (CrRE_t) has not previously been quantified. Here we use 22 years of satellite data to constrain the contribution of lakes to CrRE_t. We find that, per unit area, lakes have a significantly higher CrRE_t than land (−14.4 vs. −8.2 W/m²). Therefore, even though lakes cover 3.7% of our study domain, lakes contribute 6.3% of Northern Hemisphere CrRE_t. Lake contribution to CrRE_t is even greater in late spring as well as in the Boreal Forest where lakes can contribute more than 25% of CrRE_t. Lakes’ higher CrRE_t results from both earlier snowmelt on land and lakes’ comparatively greater increase in albedo while snow-covered. Overall, our analysis advocates for the inclusion of lake CrRE_t processes in climate models and highlights a previously understudied impact of lakes on climate.

“Implausible” Met Office UK Climate Projections Still Whipping up Unjustified Net Zero-Convenient Fear

A satirical illustration depicting a climate projection scenario for the UK in 2055, featuring exaggerated weather predictions. A scientist explains the projections while a worried politician signals alarm. The scene contrasts the alarming forecast with a calm, rainy British summer outside, highlighting skepticism about extreme climate forecasts.

Five months after the IPCC ruled that the infamous RCP8.5 doomsday climate scenario was “implausible”, the Met Office is still whipping up unjustified Net-Zero convenient fear, says Chris Morrison.

From The Daily Sceptic

By Chris Morrison

A weather presenter gestures while explaining a heat map of the UK, displaying high temperatures in various cities.

Five months after the IPCC ruled that the infamous RCP8.5 computer scenario responsible for most mainstream climate doomsday copy over the last 15 years was “implausible”, what news can I bring you of the Met Office’s UK Climate Projection 2018 report (UKCP18) that based its predictions on the now cancelled modelling nonsense? Good news: the Met Office immediately withdrew UKCP18 with a fulsome apology for all the harm caused. Everything from the compromised geography A level syllabus to numerous Net Zero rules and regulations that relied on its claims have been withdrawn pending future alteration. Sorry, I must have dropped off for a moment and started dreaming. Of course, the report has not been withdrawn; of course, no apology has been forthcoming, and of course, UKCP18 is still up to all its old tricks.

On June 23rd, the Met Office produced a weather forecast for 2055 showing how the summer temperature in England under a “plausible” computer model scenario could hit 45°C along with nine consecutive days where 40°C was recorded somewhere in the country. Not bad going in 30 years, given that the UK temperature ’record’ of 40.3°C produced on July 19th 2022 by the runway at RAF Coningsby was somewhat challenged in its veracity by the fact that Typhoon jets were attempting to land at the time. The claimed record was a 60-second 0.6°C spike and over a five-minute average – recommended by the World Meteorological Organisation to reduce ‘noise’ – the temperature fell below the magic, headline-grabbing 40°C.

Weather presenter discussing a forecast heatwave in the UK for the summer of 2056, with a map showing temperatures ranging from 21 to 45 degrees Celsius across various regions.

The Met Office did not specifically identify which “plausible” scenario it used but the figures were remarkably similar – in fact slightly hotter – than claims in UKCP18 that summer temperatures could rise by 5.1°C by 2070. Furthermore, Chief Scientist Professor Stephen Belcher, who called the illustration “scientifically plausible”, noted: “By using data from Met Office projections, we can glimpse into what an event like the 1976 summer would look like in the 2050s. It is a stark realisation to see the maximum temperature reach 45°C.”

The ‘maximum invented temperature’ would have been a more accurate statement, but such a reasonable scientific qualification was not made by Belcher, who is on record as stating that Net Zero will “stabilise” the climate.

The less charitable might suggest that the Met Office used implausible forecasts to whip up BS climate fearmongering during a glorious summer (albeit a tad inconvenient at times for those without the joys of air conditioning) in its relentless political drive to boost climate psychosis in the general population and promote the Net Zero fantasy.

Now take a look at this pack of panic-inducing poppycock published last June by Comic Cuts, or as it is sometimes called, the Guardian.

Headline about millions of homes in London, Essex, and Kent at risk of sinking due to the climate crisis, with a subheading discussing areas vulnerable to extreme weather and ground shrinkage.

The Guardian story was based on a report from the British Geological Survey (BGS), which is designed to help town planners, property developers and financial companies assess future climate risks. Maps of the UK are produced using geological information with the highest-resolution climate change data from the UK Centre for Ecology and Hydrology, “which is derived from and builds upon Met Office UKCP18 climate projections”. By 2070, the BGS noted that over four million homes could be affected by subsidence under the high-emission scenario RCP8.5. This pathway was the only one used by the Met Office in UKCP18 and its findings are highlighted in bold type in the report. Due to computer cost considerations, other lower emission scenarios were said to be statistically derived from RCP8.5.

Oh dear, the BGS published alarming subsidence conclusions in June using fanciful Met Office projection that had been stinking up the science joint since April’s ‘Implausible Day’. Did nobody see fit to tell the BGS before it published its geological garbage? Was Comic Cuts unaware that its story about housing foundations being dragged down beneath the soil was a load of climate-catastrophising conkers? Nevertheless, we must have sympathy and understanding for the Guardian at a difficult time. The Greenland ice sheet is in net balance this year so the newspaper cannot run its regular and ever popular ‘London houses beneath the waves’ routine.

Subsidence has always been a problem in the London area where old brick buildings sit on a heavy clay soil that shrinks and expands as water levels change. The BGS is supposed to give future guidance to help mitigate this problem. It might be better off in future making realistic projections based on accumulated evidence and observations, rather than raising fear based on duff computer modelled climate guesses.

Chris Morrison is the Daily Sceptic’s Environment Editor. Follow him on X.

OCTOBER PUBLICATION: new book by Chris Morrison with a foreword by Toby Young: IMPLAUSIBLE: How scientists, activist politicians and journalists invented a climate crisis, weaponised junk computer model findings and claimed a fake consensus to promote the collectivist Net Zero fantasy.

AMOC Collapse Would Be Catastrophic: And Ice- Age Records Show It’s Happened Before

Yeah, a full collapse of the Atlantic Meridional Overturning Circulation (AMOC) would produce severe, far- reaching climate disruptions that scientists widely describe as catastrophic for large regions, especially northwestern Europe, the U.S. East Coast, and monsoon-dependent areas in Africa, Asia, and South America.

The AMOC has switched states in the past, that is well- supported by paleoclimate records.

During the last glacial period (roughly 115,000- 11,700 years ago), the climate system exhibited repeated abrupt shifts closely linked to changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC). The two most prominent examples are Dansgaard-Oeschger (D-O) events and Heinrich events.

Illustration depicting the potential catastrophic collapse of the AMOC, with visual elements like ice, oceans, and geographic outlines showing past ice-age records. — AI generated by Grok

The AMOC is a major system of ocean currents (part of the broader thermohaline “conveyor belt”) that transports enormous amounts of heat northward in the Atlantic, on the order of 1 petawatt, far exceeding total human energy use. It helps keep northwestern Europe milder than other regions at similar latitudes. A collapse (or very strong weakening into a near-shutdown state) would sharply reduce this heat transport.

Main projected impacts

Cooling and weather extremes in Europe: Models show rapid cooling of several degrees to 5- 15°C (or locally more) in northwestern Europe over decades, with particularly harsh winters. Sea ice could expand southward (in some simulations toward the UK or Netherlands coasts). Summers might remain relatively warm due to ongoing greenhouse forcing, but year-round drier conditions, intensified droughts (especially in southern Europe), stronger winter storms, and wild temperature swings would severely damage agriculture, for example, one estimate reduces UK arable land from ~32% to ~7%.

Sea- level rise along the U.S. East Coast: Dynamic effects from the circulation change would add tens of centimeters to over half a meter (or more in places) of regional sea- level rise on top of global thermal expansion and ice melt, increasing coastal flooding risk.

Tropical and monsoon disruptions: A southward shift of the Intertropical Convergence Zone (ITCZ) would reduce rainfall in West Africa (potentially ~30%) and parts of India (~20%), disrupt Amazon seasonality (dry and wet seasons flipping in some models), and alter precipitation across other tropical regions. This threatens food systems for hundreds of millions of people.

Broader effects: Changes in storm tracks, marine ecosystems and fisheries (via altered nutrient upwelling and temperatures), Arctic sea- ice expansion, possible modest additional atmospheric CO₂ release from ocean carbon changes (with small net global warming after regional cooling offsets), and potential cascading stresses on other systems. Northern Hemisphere cooling would contrast with some Southern Hemisphere warming (a bipolar seesaw pattern seen in paleoclimate records).

These changes would unfold over decades to about a century once a tipping threshold is crossed, abrupt on human and societal timescales, though not instantaneous. Paleoclimate evidence (e.g., Dansgaard-Oeschger and Heinrich events) shows the AMOC has switched states in the past with major global repercussions, including large shifts in tropical rainfall.

Likelihood and uncertainty

A full collapse is not certain this century.

The IPCC AR6 assessed medium confidence that an abrupt collapse would not occur before 2100, while projecting overall weakening.

More recent studies are mixed: some identify early- warning signals (increasing variance/autocorrelation, freshwater- transport indicators, or “cold blob” patterns) suggesting the system is losing stability and could approach a tipping point this century under continued high emissions; constrained model ensembles project stronger weakening (~40- 50% by 2100 in some analyses) than the multi- model mean; other work finds resilience due to Southern Ocean upwelling, with collapse unlikely this century or reversible if forcing is reduced.

The risk is commonly framed as low- to-medium probability but very high impact. Weakening is already observed or inferred in various datasets, and continued high greenhouse- gas emissions plus Greenland meltwater increase the chance of further decline or eventual tipping. Reducing emissions lowers the risk.

In short, the statement is consistent with the scientific literature: a collapse would not freeze the planet as in fiction, but it would impose abrupt, multi- decadal regional climate shifts severe enough to strain agriculture, infrastructure, ecosystems, and societies across the North Atlantic sector and beyond. Monitoring improved early- warning systems, and mitigation remain the practical responses.

Map depicting ocean currents in the North Atlantic region, including the East Greenland Current, Polar Front, and North Atlantic Current, with Iceland and surrounding areas marked. — Arctic freshwater forcing of the Younger Dryas cold reversal | Nature

The AMOC has switched states in the past, that is well- supported by paleoclimate records.

During the last glacial period (roughly 115,000- 11,700 years ago), the climate system exhibited repeated abrupt shifts closely linked to changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC). The two most prominent examples are Dansgaard- Oeschger (D- O) events and Heinrich events.

Dansgaard- Oeschger events

These were rapid warmings recorded in Greenland ice cores, with temperature increases of about 5-16°C occurring over decades (sometimes as little as a decade), followed by more gradual cooling over centuries. They occurred repeatedly during marine isotope stages 2- 4 under intermediate glacial conditions.

Proxy evidence (including Pa/Th ratios and benthic δ¹³C in ocean sediments, plus ice- core isotopes) indicates that the warm phases (interstadials) corresponded to a relatively strong AMOC, with active deep-water formation in the Nordic Seas, while the cold phases (stadials) featured a weaker AMOC.

The shifts involved reorganization of atmospheric circulation, including northward movements of the Intertropical Convergence Zone (ITCZ) and associated rainfall belts during the warmings. Global effects appear in speleothem records (e.g., Asian and South American monsoons), European fluvial systems, and other archives, though the amplitude of change generally decreases with distance from the North Atlantic.

Heinrich events

These involved massive discharges of icebergs (primarily from the Laurentide Ice Sheet) into the North Atlantic, marked by distinct layers of ice- rafted debris (IRD) in sediment cores. They typically occurred during some of the longer, colder stadials that preceded certain D- O warmings.

The large freshwater input from melting icebergs is widely interpreted as having caused strong weakening or near- collapse of the AMOC by reducing surface density and suppressing deep convection. Consequences included:

Pronounced cooling across the North Atlantic and adjacent continents.
A bipolar “seesaw” pattern, with gradual warming in the Southern Hemisphere (visible in Antarctic ice cores).
Southward displacement of the ITCZ and rainfall belts, producing severe droughts or major hydroclimate anomalies across large parts of the northern tropics and subtropics (including Afro- Asian monsoon regions), while some southern tropical areas became wetter.

These tropical rainfall shifts are documented in a wide range of continental and marine proxies and occurred close in time (within dating uncertainties of hundreds of years) to the North Atlantic IRD layers. Similar AMOC reductions and associated climate impacts are also inferred for events such as Heinrich Stadial 1 and the Younger Dryas during the last deglaciation.

Overall significance

Together, these records demonstrate that the AMOC has existed in multiple states and can transition relatively rapidly between them, producing large regional- to- global climate repercussions, especially in heat transport, sea ice, and the position of tropical rain belts.

The glacial boundary conditions (large ice sheets, lower CO₂, different freshwater budgets) differ from today, so the exact thresholds and rates are not identical to modern projections. Nonetheless, the paleoclimate evidence establishes that AMOC state changes are a real mechanism capable of driving abrupt, widespread climate shifts, including major alterations in tropical rainfall patterns that affected monsoon systems on which large human populations now depend.

This past behavior is one reason climate scientists treat potential future AMOC weakening or collapse as a high- impact risk, even while the precise likelihood and timing under current anthropogenic forcing remain subjects of active research.

Tag: Climate models

Antarctic Sea Ice Collapse Triggers Abrupt Reversal in Key Southern Ocean Layer, Threatening Heat and Carbon Storage

What is the AAIW and why does it matter?

The observed shift

Implications for heat and carbon storage

Specific contributions to carbon storage

Relevance to recent changes

Abstract

Key points from the paper

Figures (titles)

Data and code

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No, New York Times, California’s Climate Has Always Been a Land of Flood, Drought, and Fire

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New CMIP7 scenarios slash high-end warming projections as extreme pathways like SSP5-8.5 are retired

Current status (as of 2026)

How it is still used

Bottom line

CMIP7 “High” (H) scenario

Context and comparison

1. Overall Design Goals

2. Key Methodological Innovations

3. Workflow Steps

4. Why the High End Was Lowered

Primary Reference

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Global Warming Is Making Days Longer by Speeding Up the Atmosphere

Abstract

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“Antarctica’s Ice Loss Is Locked In This Century—Even at 1.5°C”

Abstract

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Overlooked Lakes Amplify Northern Hemisphere Cooling Through Stronger Ice Albedo Effect

Abstract

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“Implausible” Met Office UK Climate Projections Still Whipping up Unjustified Net Zero-Convenient Fear

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AMOC Collapse Would Be Catastrophic: And Ice- Age Records Show It’s Happened Before

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