Climate change: last decade 'warmest ever'
Updated on 28 July 2010
Scientists in 48 countries have concluded the past 10 years were the warmest on record, as a Met Office climate expert tells Science Correspondent Tom Clarke the decade on decade trend is "stonkingly obvious".
Global warming is "undeniable" and the past decade has been the warmest on record, according to the latest analysis by the world's leading climate scientists.
The "State of the Climate" report issued annually by the US National Oceanographic and Atmospheric Administration (NOAA), also suggests that despite a freezing winter for many, 2010 will be the warmest year ever recorded.
Click here to see: NOAA report
The report also collates, for the first time, parallel data sets on global warming trends from independent scientists that contradict criticisms raised by the "climategate" emails leak at the University of East Anglia.
In this year's report scientists at the Met Office Hadley Centre in Exeter copiled global data sets for 10 major indicators all linked to a warming climate. Analyses of things like sea temperature, snow and glacier melting, global humidity and the extent of arctic sea ice all point to a warming planet.
"When we follow decade-to-decade trends using different data sets and independent analyses from around the world, we see clear and unmistakable signs of a warming world," says Peter Stott, Head of Climate Monitoring and Attribution at the Met Office.
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A key criticism emerging from the leaked emails was that there were flaws in how scientists at UEA had compiled their data set of global land surface temperature.
The new comparisons by Stott and his team show that the UEA data sets is in almost complete agreement with two others produced by independent teams of researchers in the US For other global warming trends – for example global sea surface temperature – they compared seven different global data sets. All of them suggest that the world's oceans are getting slightly warmer.
Stott acknowledged that from year-to-year there can be big variations in things like sea-ice cover or global air temperatures that cannot be ascribed to global warming, but that the trend over the longer-term was clear. "If you look at variability from year-to-year it's a bit of a moot point," says Stott, "but if from decade to decade [the warming trend] is stonkingly obvious.
There are some measurements that appear to contradict evidence of a warming planet. The amount of sea ice around the Antarctic continent has remained about the same in recent years, despite annual losses of around 10 per cent from the Arctic ocean. However a closer look at wind patterns and the cooling effect of the ozone hole over the South Pole explain the sea ice phenomenon says Stott.
Click here: Tom Clarke sleeps in the Arctic snow
And not all of the measurements agree. The two existing data sets for land surface temperature held by US scientists suggest that 2010 is already the warmest on record. However, the controversial "HADCRUTEM3" data from the University of East Anglia indicates it is merely the second hottest year after the current record holder 2005.
The clear trends contained in the ten data sets presented today are "unequivocal," he says. "The evidence just continues to stack up and gets ever stronger."
