At least half the years in the next decade will be warmer than the previous record year for global temperatures and next year could be the warmest to date, according to the Met Office.

The weather forecaster said there is a 50 per cent chance that the world average temperature in 2010 will be warmer than in 1998, which is the warmest on record in the Met Office’s 160 years of data.

This year is likely to be the fifth-warmest on record. The official announcement of this year’s global average temperature is being timed for maximum impact, to coincide with the UN summit on climate change in Copenhagen next month.

The Met Office’s Hadley Centre announced its predictions as a separate scientific analysis showed that previous estimates about the rate of temperature rise had been too low. The Potsdam Institute for Climate Impact Research said the planet could warm by 7C (10.8F). The increase would make large parts of the planet uninhabitable.

The institute said that emissions of carbon dioxide from fossil fuels, the main cause of global warming, were “tracking near the highest scenarios considered so far” by the Intergovernmental Panel on Climate Change. Emissions were nearly 40 per cent higher in 2008 than in 1990, the benchmark year for the Kyoto Protocol on cutting greenhouse gases.

The Met Office also predicted that temperatures could reach 7C above pre-industrial levels by 2100 if emissions carried on rising at the present rate of between 2 per cent and 3 per cent a year.

It said that global emissions would have to peak in 2016 and then fall at 4 per cent a year for decades if the world were to have a reasonable chance of limiting the increase to 2C.

The Earth’s temperature has risen by 0.75C over the past century and every year from 2001 has been in the top 11 warmest on record.

The Met Office’s predictions for rising temperatures over the next decade contradict those made by scientists at Kiel University in Germany, who have argued that the slight cooling trend in recent years will continue for several years because of natural cyclical factors outweighing the impact of greenhouse gases. The Met Office said yesterday that Kiel’s predictions were based on less comprehensive computer models that only included sea-surface temperatures. The Met Office’s models include temperatures below the sea’s surface.

The Met Office study concluded: “Projections suggest that the relative slowdown in [the warming] trend over the past decade is likely to end, with more rapid warming to resume from 2010 onwards.”

It said the chance of a new record next year was increased by the onset in May this year of El Niño, the warm phase of the natural fluctuation in the Earth’s climate system. This is warming the Pacific Ocean’s surface and raising global temperatures. The Met Office expects this warming influence to continue through the winter. Vicky Pope, head of climate change advice at the Met Office, said the latest climate science had reinforced its view that the increase in temperatures since the mid-20th century was “very likely due to man-made greenhouse gases”.

She said the Met Office was more than 90 per cent certain that human activities were to blame. She added: “In most other walks of life, if you said it was a 90 per cent chance people would say it was almost certain.”

The Met Office predictions are based partly on data from the University of East Anglia Climatic Research Unit, which has been criticised by sceptics who claimed that leaked e-mails suggested scientists had manipulated data. Ms Pope said there was no need to review data from the university. She said: “Some people are going to extraordinary lengths to try to discredit the global warming signal from observed datasets. If there really was a problem with the data it would be obvious to everybody.”

Meanwhile, a senior official in President Obama’s Administration said that Washington would announce in the “next several days” the provisional emissions reduction target that the US will offer at the Copenhagen summit.

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