World average temperature rising

03:18, Jan 17 2013

The world's temperature will keep rising and it's 21st century activity that is boosting the thermometer, according to Nasa's Goddard Institute for Space Studies (GISS).

A visualisation released by GISS in New York, shows the average global temperature has risen about 0.8 degrees Celsius since 1880.

According to the new analysis, 2012 was one of the hottest on record with a worldwide average of 14.6C and also the ninth-warmest year since 1880 when record keeping began.

Last year's global average temperature was 14.4C. New Zealand, however, averaged 12.5C.

But the institute reports that each year after 2000 has been among the 14 warmest years ever and 2012 was the warmest La Nina year yet, which is unusual as La Nina weather patterns usually result in lower-than-average global temperatures.

GISS reports 2010 and 2005 ranked as the hottest years on record with the exception of 1998.

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Scientists said global temperatures had shown we were experiencing warmer temperatures than ever before.

"What matters is this decade is warmer than the last decade, and that decade was warmer than the decade before," GISS climatologist Gavin Schmidt said.

"The planet is warming. The reason it's warming is because we are pumping increasing amounts of carbon dioxide into the atmosphere."

The scientists said each future year would not necessarily be warmer than the year before, but with the increase in greenhouse gas, they expected each successive decade to be warmer than the previous decade.

GISS director James Hansen said people would notice the frequency of unusually warm extremes was increasing.

This year, record-breaking Australian temperatures prompted the Australian Bureau of Meteorology to add new colour codes representing 51C-54C to temperature maps.

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