A gradual increase of aerosol pollution in the Third Pole during the past four decades: Implication for regional climate change

• Published in: Environmental research 2023-12, Vol.238, p.117105-117105, Article 117105
• Main Authors: Sharma, B.R., Kuttippurath, J., Patel, V.K.
• Format: Article
• Language: English
• Subjects: Aerosol; aerosols; air; Black Carbon; Central Asia; climate change; dust; glaciers; ice; Middle East; organic carbon; pollution; Radiative Forcing; Regional Warming; satellites; South Asia; spring; sulfates; summer; Third Pole; water security; winter
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2023.117105

We analyse the long-term (1980–2020) changes in aerosols over the Third Pole (TP) and assess the changes in radiative forcing (RF) using satellite, ground-based and reanalysis data. The annual mean aerosol optical depth (AOD) varies from 0.06 to 0.24, with the highest values of around 0.2 in the north and southwest TP, which are dominated by dust from Taklimakan and Thar deserts, respectively. However, Organic Carbon (OC), Black Carbon (BC) and sulphate aerosols have significant contributions to the total AOD in the south and east TP. High amounts of dust are observed in spring and summer, but BC in winter. Trajectory analysis reveals that the air mass originated from East and South Asia carries BC and OC, whereas the air from South Asia, Central Asia and Middle East brings dust to TP. Significant positive trends in AOD is found in TP, with high values of about 0.002/yr in the eastern and southern TP. There is a gradual increase in BC and OC concentrations during 1980–2020, but the change from 2000 is phenomenal. The RF at the top of the atmosphere varies from -10 to 2 W/m2 in TP, and high positive RF of about 2 W/m2 is estimated in Pamir, Karakoram and Nyainquentanglha mountains, where the massive glacier mass exists. The RF has increased in much of TP during recent decades (2001–2020) with respect to previous decades (1981–2000), which can be due to the rise in BC and dust during the latter period. Therefore, the positive trend in BC and its associated change in RF can amplify the regional warming, and thus, the melting of glaciers or ice in TP. This is a great concern as it is directly connected to the water security of many South Asian countries. •High values of Aerosol Optical Depth and Black Carbon are observed in the southern Third Pole•Significant positive trends in Black Carbon over the southern and eastern TP, about 0.03 μg/m3/yr•High positive aerosol radiative forcing of about 0.5–2 W/m2 in the Third Pole during spring•Radiative forcing has increased in the Third Pole in recent decades (2001–2020)