This year is set to be among the three warmest since records began in 1850 and caps a record-warm decade that is a new indication of man-made climate change, the United Nations said on December 02.
"The trend is of very significant warming," Michel Jarraud, head of the World Meteorological Organisation (WMO), told a news conference on the sidelines of a meeting of almost 200 nations in the Caribbean resort of Cancun trying to curb global warming.
He said 2010 so far was slightly warmer than both 1998 and 2005, the previous top two, but could slip if December is a cool month. The WMO said that land and sea surface temperatures so far in 2010 were 0.55 degree Celsius (1 F) above a 1961-1990 average of 14 degrees C (57.2 degrees F). The years 2001-10 were the warmest 10-year period, it said.
"There is a significant possibility that 2010 could be the warmest year," he said. A final ranking for 2010 is due to be published early in 2011. Asked if the data were new evidence that human emissions of greenhouse gases from burning fossil fuels were warming the climate, he said, "Short answer: yes."
The Cancun talks are trying to build on a nonbinding deal at the Copenhagen summit last year to limit overall temperature rises to 2 degrees C (3.6 degrees F). Curbs promised by emitters led by China and the United States are too little to reach the goal.
"It's becoming ever more clear that the current proposals are not enough to stay below 2 degrees," said Peter Wittoeck, head of the Belgian delegation in Cancun that holds the European Union presidency.
Cancun will seek a modest package of measures, including a new "green fund" to help channel aid to developing nations, a new mechanism to share clean technologies and to protect carbon-absorbing tropical forests.
The WMO said warming had been especially strong in Africa, parts of Asia and parts of the Arctic. Pakistan, hit by devastating floods, recorded a record temperature of 53.5 degrees C (128.30 F), the warmest in Asia since 1942.