Around world, thermometers point to 2010 being hottest year yet

It may be snowing hard in Britain, but 2010 is on course to be the hottest year ever recorded for the world, figures released by the World Meteorological Organisation (WMO) indicated yesterday.

Global average temperatures recorded up to the end of October show that in two of the three data sets used, which are American, 2010 has been clearly the hottest year ever, while in the third set, which is British, it is running equal with the previous hottest year on record, 1998.

It is possible the position might change when the final figures for November and December have been factored in, although analysis has already shown that November temperatures for the world were running at "near record levels", the WMO said.

Releasing the figures at the UN Climate Conference in Cancun, Mexico, the WMO said the global combined sea surface and land surface air temperature for 2010 (January-October) "is currently estimated at 0.55C (0.99F) above the 1961-1990 annual average of 14C (57.2F)".

It added: "At present, 2010's nominal value is the highest on record, just ahead of 1998 (January-October anomaly 0.53C) and 2005 (0.52C)."

The WMO's official judgement is cautious, saying merely that "the year 2010 is almost certain to rank in the top three warmest years since the beginning of instrumental climate records in 1850."

However, even if this year's final position is not beyond doubt, it is already certain that the past decade is the hottest 10-year period in the instrumental record. "Over the 10 years from 2001 to 2010, global temperatures have averaged 0.46°C above the 1961-90 average, 0.03°C above the 2000-09 mean, and the highest value yet recorded for a 10-year period," the WMO said.

Michael Jarraud, the WMO's director-general, said the fact that the last decade had been the hottest ever was an indicator of a man-made impact on the global climate. "Based on climate models, it cannot be explained unless you take human emissions of greenhouse gases into account," he said.

Professor Phil Jones of the Climatic Research Unit at the University of East Anglia, which in conjunction with the Met Office Hadley Centre runs the British data set used in compiling the records, agreed. "The warmth of 2010 doesn't indicate in itself a man-made impact on climate, but the warmth of the decade 2001-2010 does," he said. "When looking for evidence of man-made climate effects we should be looking at the decadal timescale. The 2000s were warmer than the 1990s, which were warmer than the 1980s and so on back to the 1960s."

While Britain has been relatively cool in 2010 – our coolest year since 1996, along with a number of northern European countries – in many other parts of the world, temperatures have been abnormally high, and national records have been broken.

The highest of all, the WMO said, was at Mohenjo-Daro, the site of an ancient city in the Indus Valley in Pakistan, where on 26 May the mercury reached 53.5C or 128.3F. This was the fourth highest temperature ever recorded. The only higher recorded figures have been at Al'Aziziyah in Libya (57.8C or 136.3F, in 1922), Death Valley in California (56.7C or 134.1F, in 1913) and Tirat Zvi in Israel (53.9C or 129F, in 1942).

In Russia, the unprecedented heatwave of July and August is thought to have resulted in about 11,000 excess deaths in Moscow alone, where July mean temperatures were 7.6C above normal, making it the city's hottest month on record by more than 2C.

"These are just not temperatures we expect in Moscow," Mr Jarraud said. "Despite the fact that people in Europe may have felt it was colder than usual, globally it was warmer, and you have to focus on the global picture to draw a conclusion."