Global warming is projected to substantially weaken the South Asian summer monsoon’s remote influence on Mediterranean summer climate, according to a study by researchers at the Chinese Academy of Sciences’ Institute of Atmospheric Physics.

The paper, “Reduced Asian monsoon influence on Mediterranean summers in a warmer climate” (Nature Geoscience, published around 23 September 2026), was led by Hanzhao Yu, with corresponding author Tianjun Zhou and co-author Zhun Guo.

The Mediterranean’s hot, dry summers are strongly shaped by large- scale atmospheric subsidence (descending air) linked to the South Asian summer monsoon (SASM) via a well- known monsoon, desert teleconnection. Stronger monsoon heating tends to enhance this subsidence, suppressing clouds and rainfall over the Mediterranean.

Main findings (from large- ensemble simulations under a high- emission scenario)

• The interannual correlation between SASM heating and Mediterranean summer mid- level circulation/subsidence drops from an ensemble- mean value of about 0.41 (statistically significant, P < 0.001) in the late 20th- century climate to near zero by the end of the 21st century.
• The monsoon’s contribution to Mediterranean summer precipitation variability falls from ~14.2% explained variance to ~5.1%.
• In one large CESM1 ensemble (40 members), 39 members (~97.5%) showed weakened monsoon influence on Mediterranean subsidence, with explained variance of subsidence variability dropping from ~22% to under 3%.

Mechanisms

Two main dynamical changes drive the weakening:

1. Elevated monsoon convection (linked to increased tropospheric stability and a rising tropopause under warming) causes the monsoon- induced mid- tropospheric warm anomaly and zonal thermal structure to expand westward. This flattens isentropic surfaces and weakens the adiabatic descent over the Mediterranean.
2. Local dynamical feedbacks reduce the meridional wind anomalies that help transmit the monsoon signal westward.

The interannual coupling between SASM strength and Mediterranean summer circulation and rainfall is expected to largely disappear. This has consequences for predicting Mediterranean summer heatwaves, droughts, and wildfires, as monsoon conditions will become a much weaker precursor. Mediterranean precipitation variability will be controlled by other factors in a warmer climate.

The results come from large- ensemble climate model simulations, reanalysis data, CMIP6 models, and supporting theoretical and numerical experiments. They highlight how changing atmospheric dynamics under global warming can reshape major climate teleconnections.

The South Asian summer monsoon (SASM) and Mediterranean summer climate are linked by a well-established large- scale atmospheric teleconnection known as the “monsoon- desert mechanism.”

Intense convective rainfall and associated diabatic (latent heat) heating over South Asia and the Tibetan Plateau during the SASM (roughly June- September) generate westward- propagating Rossby waves (often described as a Gill- type response). These waves interact with the mid- latitude westerlies and produce:

• Large- scale subsidence (descending air) over the eastern and central Mediterranean (and parts of the Middle East and North Africa).
• Strengthened mid- tropospheric anticyclonic circulation and the northerly Etesian winds.
• Suppression of clouds and rainfall, reinforcing the region’s characteristically hot, dry summers.

Stronger SASM years tend to enhance this subsidence, leading to drier and sometimes hotter conditions over parts of the Mediterranean. Weaker monsoon years have the opposite effect. This link operates on interannual timescales and contributes meaningfully to Mediterranean summer climate variability (including precipitation, circulation, evaporation, heatwave and drought risk).

Classic foundational work includes Rodwell & Hoskins (1996, 2001). Later observational and modeling studies (e.g., Tyrlis et al., Cherchi et al. 2014, Rizou et al. 2015) have confirmed and refined the mechanism using reanalyses and CMIP models.

Large- ensemble simulations (e.g., CESM1) show an ensemble-mean correlation of ~0.41 between SASM heating and Mediterranean summer mid- level circulation/subsidence (P < 0.001). The monsoon explains roughly 14% of Mediterranean summer land precipitation variability (and higher fractions, ~22%, of subsidence variability in some ensembles).

A 2026 Nature Geoscience study (Yu, Zhou & Guo, Chinese Academy of Sciences) using CESM1 large ensembles, CMIP6 models, reanalyses, and linear baroclinic model experiments under a high- emission scenario finds that this teleconnection weakens substantially:

• Correlation between SASM and Mediterranean summer circulation drops from ~0.41 to near zero by the late 21st century.
• Explained variance of Mediterranean summer precipitation falls from ~14.2% to ~5.1%.
• Nearly all ensemble members (e.g., 39/40 in CESM1) show the weakening.

Broader implications

• Mediterranean summer heatwaves, droughts, and wildfires are already a major climate-change hotspot. Loss of the monsoon teleconnection means year- to- year predictability that currently draws on SASM conditions will diminish; other drivers (local factors, mid- latitude teleconnections such as the summer North Atlantic Oscillation, etc.) will become relatively more important.
• Mean-state changes (e.g., overall drying or circulation shifts) may still occur, but the interannual coupling itself is projected to fade.
• The finding underscores how warming can reshape remote climate teleconnections through changes in atmospheric dynamics and vertical structure, not only through thermodynamic effects.

In short, the SASM currently exerts a remote “steering” influence that helps maintain and modulate the dry Mediterranean summer. Under strong warming this influence is expected to largely disappear, altering both the variability and the predictability of the region’s summer climate.

Reduced Asian monsoon influence on Mediterranean summers in a warmer climate

The Mediterranean’s summer climate is strongly influenced by large-scale subsidence linked to the South Asian summer monsoon (SASM). Using large- ensemble simulations under a high- emission scenario, the study shows that this teleconnection weakens substantially under global warming:

• Ensemble- mean correlation between SASM and Mediterranean summer circulation falls from 0.41 (P < 0.001) to near zero.
• Mechanism: westward expansion of the monsoon- induced zonal thermal structure (tied to elevated monsoon convection) and reduction in meridional wind anomalies via local dynamical feedback.
• Result: monsoon-related Mediterranean summer precipitation variability drops (explained variance from 14.2% to 5.1%).

Global warming is projected to weaken the interannual coupling between the SASM and Mediterranean summer climate by altering atmospheric dynamics.

Main figures (titles)

1. Projected changes in SASM- related mid- level circulation over the Central- Eastern Mediterranean (CEM).
2. Future change of SASM- related CCF (cross- equatorial flow / circulation component) and its decomposition.
3. Westward expansion of zonal thermal structure and the role of the monsoon heating profile.
4. Reduction in SASM- related meridional wind and underlying mechanism.
5. Weakened control of SASM on Mediterranean summer land precipitation.

Data and code availability

• ERA5 reanalysis (single- level and pressure- level).
• CESM1 Large Ensemble simulations.
• CMIP6 models.
• LBM experiment output, analysis and visualization scripts (NCL 6.6.2 and Python 3.11.6): available on Zenodo https://doi.org/10.5281/zenodo.21500988.
  Source data are provided with the paper.

The paper includes extensive supporting analyses validating the diabatic heating index for SASM strength, observed relationships in ERA5, temporal evolution of the response, consistency across CMIP6 models, roles of elevated heating and thermal structure, LBM sensitivity experiments to heat- source height, and links between circulation and precipitation changes.

Note: The full article text is behind a paywall and subscription. The above is drawn from the publicly available abstract, author information, figure captions, data/code statements, and extended- data descriptions on the Nature page. For the complete methods, results, and discussion, institutional access or purchase is required.

Journal information: Nature Geoscience (2026), published 23 September 2026

DOI: 10.1038/s41561-026-02091-1

Provided: Chinese Academy of Sciences

Authors: Hanzhao Yu  (余晗召),
Tianjun Zhou  (周天军)&
Zhun Guo  (郭准)

Contributions: T.Z. conceived and designed the study (with support from H.Y.). H.Y. performed the analysis, drafted the paper, and ran the linear baroclinic model (LBM) simulations. T.Z. and Z.G. provided comments and revisions. All authors contributed to interpretation.

Funding: National Natural Science Foundation of China (grants 42588201, 42575166, 42175164).

Abstract

The Mediterranean is highly vulnerable to summer heatwaves and wildfires, with its climate strongly influenced by large-scale subsidence linked to the South Asian summer monsoon. However, how this Mediterranean–monsoon teleconnection will respond to global warming remains poorly understood. Here we investigate the future evolution of the South Asian summer monsoon’s remote influence on Mediterranean summer climate under global warming using large ensemble simulations under a high-emission scenario. The monsoon influence on Mediterranean summer circulation weakens substantially under global warming, with the ensemble mean of correlation coefficient decreasing from 0.41 (P < 0.001) to near zero. This weakening results from the westward expansion of the monsoon-induced zonal thermal structure associated with elevated monsoon convection and a reduction in meridional wind anomalies through local dynamical feedbacks. The weakened monsoon-induced subsidence response further reduces the monsoon-related Mediterranean summer precipitation variability, with explained variance decreasing from 14.2% to 5.1%. Our results suggest that global warming will weaken the interannual coupling between the South Asian summer monsoon and Mediterranean summer climate, emphasizing the role of changing atmospheric dynamics in reshaping large-scale climate teleconnections.