The latest science, described in the World Bank report “Turn Down the Heat,” indicates that we are heading toward a 4° C warmer world, with catastrophic consequences in this century. While carbon dioxide (CO2) is still the No. 1 threat, there is another category of warming agent called short-lived climate pollutants (SLCPs). Mitigating these pollutants is a must if we want to avoid the 4° C warmer future.
The main SLCPs are black carbon, methane, tropospheric ozone, and hydrofluorocarbons. They are potentially responsible for more than one-third of the current warming. Because SLCPs have a much shorter lifetime in the air than CO2; reducing their emissions can create almost immediate reduction of global/regional warming, which is not possible by reducing CO2 emissions alone. According to one U.N. report, full implementation of 16 identified measures to mitigate SLCPs would reduce future global warming by about 0.5˚C.
In this blog, we will focus on one SLCP – black carbon. Black carbon is a primary component of particulate matter (PM), the major environmental cause of premature deaths globally. As a climate pollutant, black carbon’s global warming effects are multi-faceted. It can warm the atmosphere directly by absorbing radiation. When deposited on ice and snow, black carbon reduces their reflecting power and increases their melting rate. At the regional level, it also influences cloud formation and impacts regional circulation and rainfall patterns such as the monsoon in South Asia.