using atmospheric data collected in india during covid-19 lockdowns in 2020 an international team of scientists has found that black carbon in india regulates dust loadings in the entire country the researchers also found that black carbon-dust-climate interactions caused the indian summer monsoon season to start later than usual during the 2020 lockdown black carbon in india modifies the atmospheric winds which determines dust transport from the middle east and the sahara and local dust emissions explained dr xiaohong liu professor in the department of atmospheric sciences at texas a&m university and a corresponding author of the research recently published in nature communications black carbon a type of aerosol from human activities was dramatically reduced in northern india in april-may 2020 during covid-19 lockdowns liu said surprisingly we found that dust which is a natural aerosol also reached a record low in india by analyzing the atmospheric data we found that the low dust level was caused by reduced atmospheric heating of black carbon during lockdowns which induced the easterly wind anomalies and thus reduced the dust transport from the middle east and the sahara we found that aerosol-climate interactions delayed the outbreak of the subsequent indian summer monsoon in 2020 dr zheng lu an associate research scientist in the department of atmospheric sciences at texas a&m university is also a co-first-author of this research india is a hotspot for air pollution and has heavy black carbon and dust levels the researchers explained atmospheric aerosols such as black carbon and dust can scatter and absorb incoming solar radiation thus heating the atmosphere and cooling the surface these changes can then further alter atmospheric circulation temperatures and precipitation black carbon is a strong absorber of solar radiation by heating the atmosphere it can induce vertical motion of the atmosphere and change temperature vertical profile thereby affecting atmospheric stability cloud amount and atmospheric circulation liu said aerosols in the indian atmosphere include carbon produced locally from incomplete combustion of fuels biomass-burning aerosols such as black carbon from crop residue burning and natural dust both local from the thar desert and transported from remote deserts such as the sahara and the middle east the accumulation of dust and black carbon in northern india acts as a heat pump liu explained and can reinforce rainfall during the pre-monsoon and summer monsoon seasons and black carbon and dust deposits on snow over the tibetan plateau and the himalayan region can accelerate snow melting however detecting the effects of black carbon and dust on the indian climate remains challenging due to climate feedbacks and natural climate variability thus the periods of covid-19 lockdowns in india gave scientists a window into previously unseen scenarios of indias climate inputs the precipitous reduction of air pollution during lockdowns provides a unique testbed for detecting the aerosol effects on weather and climate by comparing satellite and ground-based observations of meteorological states during lockdowns against those in the historical polluted period liu said our results of aerosol-climate interactions indicate co-benefits of future indian aerosol-reduction for air quality human health and climate change by leslie lee texas a&m college of geosciences