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.

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.

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.

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.

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

How it works

1. 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.
2. Warming causes melting
   Rising temperatures (from greenhouse gases or other forcings) melt some of the ice or snow.
3. 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.
4. More solar energy is absorbed
   The darker surface absorbs more sunlight, converting it into heat.
5. 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.