Regional Warming by Black Carbon and Tropospheric Ozone:A Review of Progresses and Research Challenges in China

Black carbon(BC)aerosol and tropospheric ozone(O3)are major air pollutants with short lifetimes of days to weeks in the atmosphere.These short-lived species have also made significant contributions to global warming since the preindustrial times(IPCC,2013).Reductions in short-lived BC and tropospheric O3 have been proposed as a complementary strategy to reductions in greenhouse gases.With the rapid economic development,concentrations of BC and tropospheric O3 are relatively high in China,and therefore quantifying their roles in regional climate change is especially important.This review summarizes the existing knowledge with regard to impacts of BC and tropospheric O3 on climate change in China and defines critical gaps needed to assess the climate benefits of emission control measures.Measured concentrations of BC and tropospheric O3,optical properties of BC,as well as the model estimates of radiative forcing by BC and tropospheric O3 are summarized.We also review regional and global modeling studies that have investigated climate change driven by BC and tropospheric O3 in China;predicted sign and magnitude of the responses in temperature and precipitation to BC/O3 forcing are presented.Based on the review of previous studies,research challenges pertaining to reductions in short-lived species to mitigate global warming are highlighted.