New study finds pollutants can slow global warming
A new study has found that certain pollutants in the atmosphere can offer localised protection against the effects of global warming.The research, led by Dr Peter Stott of the Met Office’s Hadley Centre for Climate Prediction, shows that particles from aerosols can shield the land from the worst effects of the sun.
Dr Stott told edie: “The aerosol particles have two main effects. Directly they scatter the sunlight, making the heat less intense below. Indirectly, they make clouds brighter. This means they reflect sunlight back into the atmosphere on a much greater scale, reducing the temperature below.”
However, he said the effect of the aerosols was short lived as they soon get ‘rained out’ of the clouds.
The study is one of the first to look into localised, continental patterns and signals of global warming. It found that of all the continents, Africa had the most obvious signs of global warming. Dr Stott told edie that the effects weren’t necessarily more extreme, just easier to see.
This is partially because Africa is less industrialised than other continents, and so produces less aerosol pollutants to help shield it. Also, as there are fewer pollutants in the air, there are fewer variables for the scientists to factor in.
Dr Stott said that Asia had the hardest results to measure. This is because of the presence of ‘black carbon’, or soot, in the atmosphere that absorbs sunlight and gains heat. This can distort the results as it can be hard to work out if temperature increases are caused by carbon dioxide, soot or other factors.
Researchers compared actual, recorded, temperature rises since the beginning of the last century with predictions made by computer models designed to forecast climate change from global warming.
It found that global warming is caused by man-made emissions of carbon dioxide, rather than natural phenomena, such as volcanoes, as some have suggested.
The study comes in the same week that Sir John Haughton, former head of the Met Office, called global warming a weapon of mass destruction. He said that global warming now kills more people than terrorism and branded Tony Blair and George Bush ‘cowards’ for doing nothing to prevent it.