The air quality in the photo above might resemble Los Angeles, but the sea ice tells us this is the Arctic. The Intergovernmental Panel and Climate Change estimates that black carbon, also known as soot, is the second largest contributor to global warming after carbon dioxide. Control of black carbon, “particularly from fossil-fuel sources, is likely to be the fastest method of slowing global warming” in the immediate future, according to Dr. Mark Jacobson of Stanford University.
Reducing black carbon emissions could help keep the climate system from passing the tipping points for abrupt climate changes, including significant sea-level rise from the melting of Greenland. A new study by the Scripps Institution of Oceanography in San Diego found that black carbon pollution has raised the temperature by as much 0.6 °C over most of the Northern Hemisphere including the Arctic region.
“When soot is deposited over snow and sea ice, it darkens the snow and significantly enhances solar absorption by snow and ice,” the Scripps study said. “Recent studies suggest that this is one of the important contributors to the retreat of the Arctic sea ice.”
Significant reductions in carbon dioxide emissions are not likely anytime soon, but that does not mean there is nothing that can be done in the near future. One hope is a reduction in emissions of black carbon, also commonly known as soot. Black carbon often travels long distances, forming transcontinental plumes of brown clouds, such as those seen over in the Arctic in the photo.
“Substantial reductions in black carbon emissions could slow global warming measurably, and could buy at least some time to bring carbon dioxide emissions under control,” says Michael Levine, a lawyer for the environmental group Oceana.
Black carbon is the second strongest contribution to current global warming, after carbon dioxide. The deposition of black carbon darkens snow and ice surfaces, which increases their capacity to absorb heat.
“Airborne particles of black carbon heat the atmosphere by absorbing sunlight and heating the surrounding air, and if they settle on ice can accelerate melting,” Levine said. Until about the 1950s, North America and Western Europe were the major sources of black carbon emissions, but now developing nations in the tropics and East Asia are the major source regions, according to a recent study by the Scripps Institution of Oceanography.
“It is important to emphasize that BC reduction can only help delay and not prevent unprecedented climate changes due to CO2 emissions,” the Scripps study pointed out. Reductions of airborne black carbon would benefit public health by making the air cleaner. Black carbon particles are produced by a variety of combustion processes, including engines, industrial processes and forest or tundra fires.
Research from ancient sediment cores indicates that a warming climate could make the Arctic tundra more susceptible to fires, according to a 2008 study by Montana State University.
“Emissions in the Arctic are especially damaging because they accelerate ice loss during spring and summer, converting reflective ice surfaces into absorptive liquid surfaces that capture heat from the sun much more efficiently,” Levine said.
