Pollutants ward off global warming
Enviros: Well..okay then.
|Cutting air pollution could trigger a greater surge in global warming than previously thought, suggesting future rises in sea level and other environmental consequences have been underestimated, climate scientists report today. The warning comes after researchers investigated the effect of fine particles known as aerosols on climate change. Aerosols - particles smaller than one hundredth of a millimetre - are churned out from factory chimneys, from the burning of fossil fuels and forest fires, although sea salt and dust particles swept up by desert storms add to levels detected in the atmosphere. Because the particles are so light, they remain aloft for long periods, where they cool the Earth by reflecting radiation from the sun back out to space. Higher levels of aerosols lead to the formation of brighter clouds made up of smaller water droplets, which reflect still more of the sun's warming radiation. Cutting down on aerosols by improving air quality means that the Earth will in future be less shielded against the sun's rays. Writing in the journal Nature today, scientists at the Meteorological Office and the US government's National Oceanic and Atmospheric Administration report that climate models used to predict future global warming have badly underestimated the cooling effect of aerosols. "We found that aerosols actually have twice the cooling effect we thought," said Nicolas Bellouin, a climate modeller at the Met Office. The consequence is that as air quality improves and aerosol levels drop, future warming may be greater than we currently think." Dr Bellouin's study suggests that even by conservative estimates, climate models have got the impact of aerosols on the climate wildly wrong. "The discrepancy between the models and our observations is not good news," he said. ....Earlier this year, Peter Cox at the Centre for Ecology and Hydrology in Winfrith, Dorset, warned that if the cooling effect of aerosols turned out to be greater, it could trigger faster global warming. "It's quite a bizarre thing, because the last thing you want to suggest to people is that it would be a good idea to have dirty air, but as far as climate change is concerned, that's right. Everyone would be getting asthma, but the environment would be cooler. "That said, the direct effects of air quality, particularly in urban areas, are so important to human health, that it would be crazy to think of anything other than health damage," he said. If the Met Office calculations are right, they suggest the atmosphere's temperature is also more responsive to carbon dioxide than scientists believe. "If the cooling influence of aerosols is larger, it implies that the warming from the carbon dioxide must be larger than we think to match the warming we've seen in the past 100 years. "And if that's the case, future climate change will be more than we have expected with air quality improvements," he said.|