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Cambridge University Science Magazine

Carbon dioxide levels in the atmosphere are well above the pre-industrial levels determined from ice cores spanning thousands of years. Emissions from the combustion of fossil fuels have increased by over 40% in the period from 1990 to 2008, but the most up-to-date measurements, published in Environmental Research Letters, show a decline during 2009.

Climatologists in Norway have developed a fast and efficient method for calculating global emissions by supplementing the Carbon Dioxide Information Analysis Center's data - released two or three years after the actual emissions occurred - with annual statistics from British Petroleum. They show that in 2009 CO2 emissions dropped by a global average of 1.3%. This coincided with a decline in global GDP (0.6-0.8%) resulting from the financial crisis that began in 2008. There were, however, considerable regional differences, with the USA and EU both decreasing emissions by 7% and China increasing by 9% above its GDP growth. There were also differences in the source of combustion; unlike oil and gas, there was no overall decline in emissions from coal.

The Intergovernmental Panel on Climate Change views CO2 and other greenhouse gas emissions as the very likely cause of the increased global average temperatures recorded during the last half-century. This warming looks set to continue, as without strong mitigation efforts or developments in technology a further 30-50% increase in emissions is expected in the next two decades.

Written by Robert Jones