Readers may already have seen the ABC News story ‘Big brown Asian cloud blamed for glacial melting.’ This story is based on a new paper published in the weekly journal Nature, also featured in the News and Views section.
The paper, which looks at the effect of the so-called Asian brown clouds (the aerosols formed by the burning of wood and fossil fuels), is published by a group of scientists from the University of California San Diego and the Nasa Langley Research Center. Up to now, it has been recognised that aerosols can cool the Earth’s surface by scattering the Sun’s rays (global dimming), which is the explanation often used in order to try and explain the global cooling during the 1940’s to the 1970’s, despite rising levels of atmospheric CO2. Researchers now say that they also have a significant warming effect on the atmosphere, dependent on the altitude.
According to the BBC:
“We found that atmospheric brown clouds enhanced lower atmospheric solar heating by about 50%. “[The pollution] contributes as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends,’ they suggested. ‘We propose that the combined warming trend of 0.25 Kelvin per decade may be sufficient to account for the observed retreat of the Himalayan glaciers.”
“The scientists said there remained a degree of uncertainty because, until now, estimates had largely been derived from computer models.”
Another problem for computer models on which the IPCC base there certainty about climate change.
This new paper adds to the concerns about the reported UK plan of burning more home grown wood in order to help reduce CO2 emissions.
There is also a concern that the Asian Brown Clouds are having a significant effect on the patterns of Australian rainfall via a climate ‘teleconnection.’
Professor Ramanathan concludes, “a huge proportion of the cloud comes from people burning wood and dung to cook their food, so if enough people converted to cleaner fuels, the cloud would quickly dissipate.”