Over Asia, according to a new study in Nature reported in Scientific American, a high percentage of the local warming threatening Himalayan glaciers is the result of black carbon from cooking fires. It's so prevalent it shows up in NASA images taken from space. The Times of London ledes with the bad news:
They call it the Asian Brown Cloud. Anyone who has flown over South Asia has seen it – a vast blanket of smog that covers much of the region.
It is also what colours those sunsets at the Taj Mahal. Now a group of scientists has carried out the first detailed study of the phenomenon and arrived at a troubling conclusion.
They say that it is causing Himalayan glaciers to melt, with potentially devastating consequences for more than two billion people in India, China, Bangladesh and other downstream countries.
In a study published yesterday by Nature, the British journal, they say that black soot particles in the cloud are absorbing the Sun’s heat and pushing up temperatures at the same altitude as most Himalayan glaciers.
Scientists have already observed that two thirds of the 46,000 glaciers in the Himalayas are shrinking, leading to increasingly severe floods downstream and, eventually, to widespread drought. Greenhouse gases were previously thought to be the main cause of the problem, which threatens the sources of Asia’s nine main rivers – including the Indus, the Ganges and the Yangtze.
But the research team from the Scripps Institution of Oceanography in California says that the Asian Brown Cloud – made up of gases and suspended particles known as aerosols – is just as much to blame. “My one hope is that this finding will intensify the focus of Asian scientists and policy makers on the glacier issue,” Veerabhadran Ramanathan, who led the research, told The Times. “These glaciers are the source for major river systems, so at least two billion people are directly involved in this.”
The cloud is an enormous plume of smoke from factories, power plants and wood or dung fires that stretches across the Indian subcontinent, into SouthEast Asia.
But within that news, there is a potential for change. As Ramanathan told the Scientific American:
But the problem can be solved by swapping other fuels and methods for the wood in cooking fires. "The aerosol lifetime is two weeks," Ramanathan says. "If the world pays attention and puts resources to it, we will see an effect immediately. I'm talking weeks, at most a few months, not decades or centuries."
That contrasts with solutions for CO2 emissions, which will require much longer periods to show effects. Because the brown cloud appears to be at least as important, eliminating it could buy time to implement more far-reaching solutions before catastrophic glacial melt and other climate change impacts occur, Ramanathan argues.
Ramanathan and colleagues plan to demonstrate this on a small scale over the next few years in the Himalayas, over a 12-square-mile area in the foothills. "We want to create a black carbon hole," he says.
Here's the researcher with his drone aircraft, courtesy of Scripps: