Mountain snow and glaciers store water and influence river systems. As the climate warms, changing snow and ice can affect when water becomes available, creating consequences far beyond the mountains themselves.
Black carbon is a dark particle produced by incomplete combustion. It is part of air pollution and can also warm the atmosphere and darken snow and ice, making it an unusually clear example of how environmental problems can connect.
Air pollution and climate change share sources and sometimes share pollutants, but they are different environmental problems. Good policy and good science recognise the overlap without confusing their causes, pathways or consequences.
Black carbon sits at an important intersection between air pollution and climate. It is produced by incomplete combustion, contributes to particulate pollution, absorbs solar energy in the atmosphere and can accelerate melting when deposited on snow and ice.
The snow, glaciers and frozen ground of the Tibetan Plateau and the wider Hindu Kush Himalayan region form part of a vast high-mountain water and climate system. Their rapid change is a regional environmental crisis with consequences extending far beyond the mountains themselves.
Snow and ice are naturally reflective. When light-absorbing particles such as black carbon deposit on their surfaces, reflectivity can fall and solar-energy absorption can increase, adding to melt pressure already driven by a warming climate.