The Earth's surface is continuing to get warmer as the atmospheric levels of greenhouse gases reach record highs, according to the annual briefing of the World Meteorological Organization (WMO).
Global temperatures in 2011 are currently the tenth highest on record and are higher than any previous year with a La Niña event, which has a relative cooling influence. The 13 warmest years have all occurred in the 15 years since 1997.
In addition, the extent of Arctic sea ice in 2011 was the second lowest on record, and its volume was the lowest.
The WMO's Statement on the Status of the Global Climate provides a global temperature assessment and a snapshot of weather and climate events around the world in 2011. It was released on Tuesday at the UN climate conference in Durban, South Africa.
"Our role is to provide the scientific knowledge to inform action by decision makers," said WMO secretary-general Michel Jarraud. "Our science is solid and it proves unequivocally that the world is warming and that this warming is due to human activities," he said.
"Concentrations of greenhouse gases in the atmosphere have reached new highs. They are very rapidly approaching levels consistent with a 2-2.4 degree Centigrade rise in average global temperatures which scientists believe could trigger far reaching and irreversible changes in our Earth, biosphere and oceans," he said.
The WMO’s provisional statement estimated the global combined sea surface and land surface air temperature for 2011 (January–October) at 0.41°C ± 0.11°C (0.74°F ± 0.20°F) above the 1961–1990 annual average of 14.00°C/57.2°F, according to the provisional statement. This is the tenth equal warmest year since the start of records in 1850.
The 2002-2011 period equals 2001-2010 as the warmest decade on record, 0.46°C above the long-term average.
Global climate in 2011 was heavily influenced by the strong La Niña event which developed in the tropical Pacific in the second half of 2010 and continued until May 2011. It was one of the strongest of the last 60 years and was closely associated with the drought in east Africa, islands in the central equatorial Pacific and the southern United States, and flooding in southern Africa, eastern Australia and southern Asia.
Strong La Niña years are typically 0.10 to 0.15°C cooler than the years preceding and following them. 2011’s global temperatures followed this pattern, being lower than those of 2010, but were still considerably warmer than the most recent moderate to strong La Niña years, 2008 (+0.36°C), 2000 (+0.27°C) and 1989 (+0.12°C). Weak La Niña conditions have redeveloped in recent weeks but have not yet approached the intensity of those in late 2010 and early 2011.
Surface air temperatures were above the long-term average in 2011 over most land areas of the world. The largest departures from average were over Russia, especially in northern Russia where January-October temperatures were about 4°C above average in places.
The seasonal Arctic sea ice minimum, reached on 9 September, was 4.33 million square kilometres. This was 35 per cent below the 1979-2000 average and only slightly more than the record low set in 2007.
Unlike the 2007 season, both the Northwest and Northeast Passages were ice-free for periods during the 2011 summer. Sea ice volume was even further below average and was estimated at a new record low of 4200 cubic kilometres, surpassing the record of 4580 cubic kilometres set in 2010.
The above-average temperatures in most northern polar regions coincided with the second-lowest Arctic sea ice minimum extent and the lowest sea ice volume on record.
Other freak weather events highlighted by the report, include:
• Severe drought, then flood, in east Africa
• Major floods in south-east Asia, Pakistan, Central and South America
• Deadliest flash flood with landslide in Brazil
• A year of extremes in the United States
• A dry start to the year in Europe and eastern China
• Another year of below-average tropical cyclone activity
In its annual briefing to the UN climate summit, the agency says 2011 is so far the 10th warmest year on record.
But continued warming was masked by cooling La Nina conditions, it adds.
However, this year is set to be the 11th warmest in a record spanning more than 150 years, according to climate scientists from the Met Office and the University of East Anglia.
The global average temperature from HadCRUT3 for January to October 2011 was 14.36°C, 0.36°C above the 1961-1990 long term average.
The latest figures from the HadCRUT3 record supports those already published by NOAA and NASA GISS which are all run independently.
2011's placing near the top of temperature datasets which go back to 1850 continues a long-term warming trend in global climate.
This has seen each successive decade since 1950 warmer than the last, with 2010 being one of the warmest individual years on record.
Peter Stott, head of Climate Monitoring and Attribution at the Met Office, said: "This year we have seen a very persistent and strong La Niña, which brings cooler water to the surface of the Pacific Ocean. This has a global impact on weather and temperatures, and is one of the key reasons why this year does not figure as highly as 2010 in the rankings.
"However, global temperature so far this year is likely higher than it was during the La Niña events in 2008 and 1999-2000 – indicating a continuing warming trend combined with natural variability."
Phil Jones, director of the troubled Climatic Research Unit at the University of East Anglia, said that due to natural variability we do not expect to see each year warmer than the last, but the long-term trend is clear.
"The HadCRUT3 record, supported by the other records, is one indicator amongst several which provide overwhelming evidence that the climate has warmed," he said.
"Independent researchers analysing long term trends of these indicators, have seen an increase in air, sea and land temperatures, rising sea-levels, and decreasing Arctic sea-ice, spring snow cover in the northern hemisphere and glacier extent."
Final figures for the whole of 2011 will be available in March 2012.
Commenting on the WMO figures, Friends of the Earth's executive director Andy Atkins said: "Many enjoyed this year's mild British autumn – but record temperatures are devastating news for people in poorer countries whose lives and livelihoods are under threat from catastrophic climate change.
"Greenhouse gas emissions are the problem - we need rich countries meeting now in Durban to commit to fast and legally-binding cuts in their emissions, and finance to help poor countries grow cleanly.
"Switching from fossil fuels to clean energy and energy saving could create new jobs in the UK and shield us from rising fuel bills – Ministers must take the lead for the sake of our planet and our pockets."
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