This year is the seventh warmest since records began in 1850 with a trend to weather extremes and the impact of storms such as Typhoon Haiyan in the Philippines aggravated by rising sea levels, the World Meteorological Organization (WMO) said.
A build-up of manmade greenhouse gases in the atmosphere meant a warmer future was now inevitable, WMO Secretary-General Michel Jarraud said in a statement on the sidelines of UN climate talks among almost 200 nations in Warsaw.
The WMO, giving a provisional overview, said the first nine months of the year tied with the same period of 2003 as seventh warmest, with average global land and ocean surface temperatures 0.48°C (0.86°F) above the 1961-1990 average.
This year once again continues the underlying, long-term trend, towards higher temperatures caused by global warming, Jarraud said. The WMO said it was likely to end among the top 10 warmest years since records began in 1850.
Among extremes have been super typhoon Haiyan, one of the most intense storms in history that smashed into the Philippines last Friday. Other extremes this year have included record heat waves in Australia and floods from Sudan to Europe, the WMO said. Japan had its warmest summer on record.
Apparently bucking a warming trend, sea ice around Antarctica expanded to a record extent. But the WMO said: Wind patterns and ocean currents tend to isolate Antarctica from global weather patterns, keeping it cold.
In September, The United Nations' Intergovernmental Panel on Climate Change (IPCC) raised the probability that mankind was the main cause of warming since 1950 to at least 95% from 90 in a previous assessment in 2007.
It predicted impacts including more heat waves, downpours and rising sea levels.2010 was the warmest year on record, ahead of 2005 and 1998, the WMO said.
The IPCC said the pace of temperature rises at the Earth's surface has slowed slightly in recent years in what the panel called a hiatus that may be linked to big natural variations and factors such as the ocean absorbing more heat.
The WMO said that individual tropical cyclones, such as Haiyan, could not be directly attributed to the effects of climate change.
But higher sea levels are already making coastal populations more vulnerable to storm surges. We saw this with tragic consequences in the Philippines, Jarraud said. Seas have risen by about 20 cms (8 inches) in the past century.