NASA Podcasts

2009 Global Temperature Package: Year Tied as Second Hottest
01.28.10
 
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Narration: Laura Motel

Climate scientists at NASA’s Goddard Institute for Space Studies or GISS just released a new analysis of global average temperatures showing that 2009 was tied as the second warmest year ever recorded. And looking just at the southern hemisphere, 2009 even broke the record as the warmest year ever in this half of the world.

In fact 2009 was virtually tied with 5 other recent years in its position as second warmest on record, 1998, 2002, 2003, 2006, and 2007, and was only a fraction of a percent cooler than the warmest year, 2005.

Yet when looking at global temperatures over a longer timeframe, these scientists found a persistent warming trend over the past three decades, with the average global temperature increasing by roughly a third of a degree Fahrenheit per decade. This past decade, from 2000 to 2009, was the warmest yet.

And when looking back all the way to 1880, the year when precise temperature record keeping began, scientists observed about a one and a half degrees Fahrenheit rise in global temperatures.

[QUOTE: Jim Hansen] “There are already beginning to be effects of 1 or 2 degrees warming and if we get 5 or 10 degree warming several decades down stream there will be huge effects.”

GISS scientists came to these results after analyzing information from three sources, data from more than a thousand weather stations around the globe, satellite observations of sea surface temperature, and measurements from Antarctic research stations.

So what’s the cause of this long term warming trend? While there are several natural processes that can cause subtle climate warming or cooling, like variations in solar activity, fluctuations in ocean currents, and volcanic eruptions, climate scientists believe that rising levels of carbon dioxide and other greenhouse gasses are the dominant factor driving the rise.

[QUOTE: Jim Hansen] “If we want to limit climate change and keep it under an additional one degree Celsius or 2 degrees Fahrenheit, we would need to begin to decrease the CO2 emissions gradually so that by the end of the century CO2 stopped increasing.”

So while 2009’s temperature may not have been the global record breaker, it is in line with the long-term trend telling scientists that the planet is getting warmer.

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