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.

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.

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.

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.

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

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.