Reducing soot emissions could slow melting of sea ice in the Arctic faster
Soot particles in the atmosphere are now emerging as the second most important, but previously overlooked, factor in global warming, according to an American Chemical Society (ACS) press release. Stanford University research scientist Mark Jacobson has told an ACS meeting that reducing soot emissions from diesel engines and other sources could slow melting of sea ice in the Arctic faster and more economically than any other quick fix.
Speaking at the 242nd National Meeting & Exposition of the American Chemical Society (ACS), Dr Jacobson cited concerns that continued melting of sea ice above the Arctic Circle will be a tipping point for the Earth’s climate, a point of no return. That is because the ice, which reflects sunlight and heat back into space, would give way to darker water that absorbs heat and exacerbates warming. And, he noted, there is no known way to make the sea refreeze in the short term.
While there has been concern at the effects of soot on global temperatures for some time, and particularly with respect its impact on Arctic ice melt, there has been a view in shipping industry circles that the science remains uncertain. Nevertheless the issue has started to be discussed at IMO though an International Chamber of Shipping spokesperson told World Bunkering that work on soot was still at an early stage.
Dr Jacobson has, however, calculated that controlling soot could reduce warming above parts of the Arctic Circle by almost 3 degrees Fahrenheit within 15 years. That would virtually erase all of the warming that has occurred in the Arctic during the last 100 years.
“No other measure could have such an immediate effect,” said Dr Jacobson. “Soot emissions are second only to carbon dioxide (CO2) in promoting global warming, but its effects have been underestimated in previous climate models. Consequently, soot’s effect on climate change has not been adequately addressed in national and international global warming legislation. Soot emissions account for about 17 percent of global warming, more than greenhouse gases like methane. Soot’s contribution, however, could be reduced by 90 percent in 5-10 years with aggressive national and international policies.”
Soot or “black carbon” consists of particles, nearly invisible on an individual basis, released in smoke from combustion of fossil fuels and biofuels. Major sources include exhaust from diesel cars, buses, trucks, ships, aircraft, agricultural machines, construction equipment and the wood/animal dung fires that hundreds of millions of people in developing countries use for used for cooking and heating. Black carbon particles become suspended in the atmosphere and absorb sunlight, just like a black t-shirt on a sunny day. The particles then radiate that heat back into the air around it. Black carbon also can absorb light reflected from Earth’s surface, which helps make it such a potent warming agent.
According to Dr Jacobson the good news is that decreasing soot could have a rapid effect. Unlike carbon dioxide, which remains in the atmosphere for years, soot disappears within a few weeks, so that there is no long-term reservoir with a continuing warming effect. And the technology for controlling black carbon, unlike that for controlling CO2, is already available at relatively modest cost.
Diesel particulate filters, for instance, can remove soot from car and truck exhaust. Government and other agencies also are trying to introduce low-soot cookstoves in developing countries. “Converting gasoline- and diesel-burning cars and trucks to electric or hydrogen vehicles and reducing emissions from diesel generators could have an immediate effect on warming,” said Dr Jacobson.
Source: World Bunkering
