Due to human activities, atmospheric greenhouse gas (GHG) concentrations have increased dramatically since around 1750, causing the climate to warm in the last few hundred years. The rate of global warming has accelerated in recent decades, with the global mean surface air temperature rising by 1.1 °C above the pre-industrial levels.Under the 2015 Paris Agreement, many countries agreed to cut greenhouse gas emissions with a view to ‘holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels’. Carbon neutrality is believed to be critical and urgently needed to meet the Paris Agreement’s warming target. Under the carbon neutrality pathway, key anthropogenic climate drivers including greenhouse gases, aerosols, and tropospheric ozone will change significantly across the globe.The individual and combined impacts of GHG, aerosol, and ozone changes on climate and weather extremes under the carbon neutrality pathway remained undiscovered.
On November 09, 2023, a studytitled “Aerosols overtake greenhouse gases causing a warmer climate and more weather extremes toward carbon neutrality”was published online in Nature Communications (https://doi.org/10.1038/s41467-023-42891-2). With the Community Earth System Model version 1 (CESM1), the authors found that the reductions in aerosols cause up to 1.0oC increases in surface air temperature over most land regions relative to 2020, significantly overtaking the impacts of greenhouse gases and tropospheric ozone. The findings reverse the knowledge that the changing greenhouse gases dominate the future climate changes as predicted in the medium forcing middle of the road pathway. Not only this, this study stressed that the significant decline in atmospheric aerosols negatively impacts global climate, exacerbating extreme weather occurrence (e.g., heatwaves, extreme precipitations) more than changes in greenhouse gases or the tropospheric ozone layer.
This study was primarily conducted by the research team of Atmospheric Environment and Climate Change (AECC) from Nanjing University of Information Science & Technology (NUIST). Associate Professor Pinya Wang from the AECC research team of the School of Environmental Science and Engineering (SESE) of NUIST is the first author. Professor Yang Yang is the corresponding author, and the coauthors include Professor Hong Liao from SESE of NUIST, Professor Ruby Leung from the Pacific Northwest National Laboratory (PNNL), Professor Jianping Tang and Dr. Daokai Xue from Nanjing University, and Dr. Lili Ren from Jiangsu Open University. The research was co-funded by the National Natural Science Foundation of China (42293323, 42105166, 41975159) and the National Key Research and Development Program of China (2020YFA0607803, 2019YFA0606800).
