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climate scientists at nasa's goddard

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institute of space studies or gis just

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released a new analysis of global

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average temperatures showing that 2009

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was tied as the second warmest year ever

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recorded

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and looking just at the southern

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hemisphere 2009 even broke the record as

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the warmest year ever in this half of

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the world

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in fact 2009 was virtually tied with

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five other recent years in its position

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as second warmest on record 1998 2002

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2003 2006 and 2007 and it was only a

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fraction of a percent cooler than the

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warmest year 2005.

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yet when looking at global temperatures

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over a longer time frame these

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scientists found a persistent warming

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trend over the past three decades with

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the average global temperature

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increasing by roughly a third of a

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degree fahrenheit per decade this past

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decade from 2000 to 2009 was the warmest

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yet

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and when looking back all the way to

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1880 the year when precise temperature

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record keeping began scientists observed

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about a one and a half degree fahrenheit

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rise in global temperature

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there are already beginning to be

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effects of one or two degrees warming

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and if we get

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five or ten degrees warming

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several decades downstream there will be

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huge effects

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gis scientists came to these results

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after analyzing information from three

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sources

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data from more than a thousand weather

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stations around the globe satellite

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observations of sea surface temperature

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and measurements from antarctic research

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stations

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so what's the cause of this long-term

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warming trend

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while there are several natural

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processes that can cause subtle climate

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warming or cooling like variations in

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solar activity fluctuations in ocean

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currents and volcanic eruptions climate

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scientists believe that the rising

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levels of carbon dioxide and other

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greenhouse gases are the dominant factor

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driving the rise

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if we want to limit climate change and

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keep it

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under

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an additional 1 degree celsius or two

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degrees fahrenheit

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we would need to begin to decrease the

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co2 emissions

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gradually

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so that by the end of the century co2

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stopped increasing

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so while 2009's temperature may not have

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been the global record-breaker it is in

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line with the long-term trend telling