The planet has warmed faster since the turn of the century than ever recorded, almost doubling the pace of sea-level increase and causing a 20-fold jump in heat-related deaths, the United Nations said.
The decade through 2010 was the warmest for both hemispheres and for land and sea, the UN's World Meteorological Organisation said Wednesday in an e-mailed report (pdf here) examining climate trends for the beginning of the millennium. Almost 94 per cent of countries logged their warmest 10 years on record, it said.
"The decadal rate of increase between 1991-2000 and 2001-2010 was unprecedented," WMO Secretary-General Michel Jarraud said in a statement. "Rising concentrations of heat-trapping greenhouse gases are changing our climate, with far-reaching implications for our environment and our oceans."
The report underlines the challenge the globe faces in containing temperature gains since industrialisation to the 2-degree Celsius (3.6 Fahrenheit) ceiling set by UN climate-treaty negotiators. The planet is on course to warm by 4 degrees by 2100 because emissions are still rising, the World Bank says.
Deaths from heatwaves surged to 136,000 in the 10-year period from fewer than 6,000 the previous decade, mainly a result of extreme temperatures in Europe in 2003 and in Russia in 2010, according to the WMO. A total of 511 disasters related to tropical cyclones killed 170,000 people and caused $US380 billion ($419 billion) of economic damage. Deaths from storms and floods fell.
"Given that climate change is expected to lead to more frequent and intense heatwaves, we need to be prepared," Jarraud said. "Despite the significant decrease in casualties due to severe storms and flooding, the WMO report highlighted an alarming impact on health and mortality rates caused by the European and Russian heatwaves."
The average global temperature for 2001-2010 was 14.47 degrees Celsius, according to the report. That's 0.21 degree warmer than 1991-2000 and 0.79 degree warmer than 1881-1890. The increase was recorded even without any "major El Nino" event during the decade, the WMO said. El Nino is a periodic warming of waters in the Pacific that pushes up global temperatures.
Sea levels rose at 3 millimeters (0.12 inch) a year, almost double the 20th-century rate of 1.6 millimeters a year.
Seas rise as warmer temperatures cause the water to expand and ice sheets in Greenland and Antarctica and alpine glaciers around the world melt. Record sea-ice melt in the Arctic Ocean doesn't raise seas because the ice already rests on the ocean.