Chemke et al. (2026) Logarithmic CO2 warming reverses North Atlantic winter atmospheric circulation changes

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2026
• Date: 2026-01-09
• Authors: Rei Chemke, Ivan Mitevski
• DOI: 10.1038/s41612-025-01314-3

Research Groups

• Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
• Department of Geosciences, Princeton University, Princeton, NJ, USA

Short Summary

This study reveals that under continued carbon dioxide (CO2) emissions beyond 2100, the projected intensification of the North Atlantic winter storm track and jet stream reverses, returning towards their 20th-century states. This reversal is attributed to the logarithmic relationship between CO2 concentration and temperature, which leads to a reduced meridional temperature gradient at high CO2 levels.

Objective

• To investigate whether the projected intensification of the North Atlantic winter atmospheric circulation (storm track and jet stream) will persist, accelerate, or undergo non-monotonic changes under ongoing warming beyond 2100.
• To identify potential reversals or abrupt changes in atmospheric circulation and their implications for climate-change mitigation and adaptation strategies.

Study Configuration

• Spatial Scale: North Atlantic region (90°W – 30°E and 40°N – 60°N for CMIP6 runs; 20°W – 50°E for CESM abrupt runs), with regional impacts over eastern North America and the North Atlantic.
• Temporal Scale:
  • CMIP6 simulations: Historical (through 2014) and Shared Socioeconomic Pathways 5-8.5 (SSP5-8.5) (through 2300). Analysis focuses on the 21st to 23rd centuries.
  • CESM abrupt runs: 150-year simulations for 2x to 8x preindustrial CO2 levels, with the last 50 years used for analysis.
  • Specific periods for comparison: 1990-2010, 2140-2160, and 2280-2299.

Methodology and Data

• Models used:
  • Coupled Model Intercomparison Program Phase 6 (CMIP6) models: CanESM5, EC-Earth3-Veg, IPSL-CM6A-LR, MRI-ESM2-0.
  • Community Earth System Model (CESM) version 1.2.
• Data sources:
  • Daily and monthly wind, temperature, and specific humidity output from CMIP6 historical and SSP5-8.5 simulations.
  • Abrupt CO2 runs from CESM (2x, 3x, 4x, 5x, 6x, 7x, 8x preindustrial CO2 levels).
  • Circulation indices: Vertically integrated eddy kinetic energy (EKE) for storm track (calculated using a Butterworth bandpass filter of 2.5-6 days), and tropospheric (between 300 hPa and 1000 hPa) averaged zonal wind for the jet stream.
  • Eddy heat and moisture flux convergence.
  • Normal mode instability analysis of quasigeostrophic equations to calculate eddy growth rate.
  • Emergent constraint analysis to link meridional temperature gradient and jet stream evolution.

Main Results

• Under the SSP5-8.5 scenario, the North Atlantic winter storm track and jet stream intensify through the mid-22nd century (2140-2160), with the storm track increasing by approximately 14% and the jet stream by approximately 7% relative to 1990-2010 values.
• Beyond the mid-22nd century, despite continued CO2 increase, this intensification reverses, with both the storm track and jet stream weakening and almost fully recovering towards their 20th-century states by the end of the 23rd century (2280-2299). By this period, the storm track shows only a ~3% increase and the jet stream a ~0.2% increase relative to 1990-2010.
• This reversal is a regional feature of the North Atlantic and does not significantly alter the position of the flow.
• Regional climate impacts also reverse: initial warming and wetting at higher mid-latitudes and cooling and drying at lower mid-latitudes (eastern North America and North Atlantic) by the mid-22nd century are reversed by the end of the 23rd century.
• The underlying mechanism for this non-monotonic behavior is the logarithmic relationship between CO2 concentration and temperature. At lower CO2 levels (up to 4x preindustrial), enhanced warming in the upper tropical troposphere relative to higher latitudes intensifies the meridional temperature gradient, strengthening circulation. At higher CO2 levels (above 4x preindustrial), this warming pattern at low latitudes weakens considerably due to the logarithmic CO2-temperature relationship, reducing the meridional temperature gradient and consequently weakening the circulation.
• Emergent constraint analysis confirms that a logarithmic relationship between CO2 and the upper tropospheric temperature at low latitudes is crucial for capturing the observed reversibility of the jet stream.

Contributions

• Provides the first comprehensive analysis of North Atlantic atmospheric circulation changes beyond the 21st century, revealing a significant non-monotonic reversal in storm track and jet stream intensity.
• Identifies the logarithmic relationship between CO2 concentration and temperature, specifically its impact on the meridional temperature gradient, as the key physical mechanism driving this reversal.
• Highlights that non-monotonic changes are not limited to thermodynamic variables but also extend to large-scale atmospheric flow, challenging existing assumptions in climate projections.
• Offers critical insights for climate change mitigation policies, emphasizing the importance of the pace of CO2 emissions and the urgency of early intervention to avoid prolonged exposure to intensified circulation impacts.

Funding

• Israeli Science Foundation (Grant 407/25)
• Willner Family Leadership Institute for the Weizmann Institute of Science
• Zuckerman STEM Leadership Program
• Harry Hess postdoctoral fellowship from Princeton Geosciences

Citation

@article{Chemke2026Logarithmic,
  author = {Chemke, Rei and Mitevski, Ivan},
  title = {Logarithmic CO2 warming reverses North Atlantic winter atmospheric circulation changes},
  journal = {npj Climate and Atmospheric Science},
  year = {2026},
  doi = {10.1038/s41612-025-01314-3},
  url = {https://doi.org/10.1038/s41612-025-01314-3}
}