The current cold weather gripping the UK does not undermine the fact the world is warming, experts said today.
Stephen Dorling, of the University of East Anglia's school of environmental sciences, said it was not surprising the cold period raised questions over climate change - but the snowy weather should not be used as evidence against it.
He said: "It's no surprise that people look out of their window at the snow and find it hard to rationalise what's going on with the longer term trend."
But he said it was wrong to focus on single events - whether they were cold snaps or heat waves - which were the product of natural variability.
Instead they should look at the underlying, longer term trends for the climate which were more "robust" evidence of the changes which are happening.
Dr Dorling said: "There is no doubt we will continue to have unusually warm and unusually cold Decembers and Januarys but it will be superimposed on what the background climate is doing."
He said the climate was similar to personal finance, where people could have good months and bad months in terms of their spending - for example being frugal in January after Christmas expenses - but if their salary was falling their bank account would be in trouble in the long run.
While individual and short term weather events could make the situation look better or worse, the background issue of climate warming caused by greenhouse gases was not going away.
The last decade was the warmest on record, with the last three each warmer than the previous 10 years, he said.
And more warming is already built in because of delays in the system - making it imperative urgent action is taken to prevent temperature rises breaching thresholds where the more dangerous impacts of climate change could occur.
The Met Office's Barry Gromett said December and January's cold weather was "within the bounds of natural variability" within a global trend of rising temperatures - in which 2009 is set to be the fifth warmest year on record.
Despite temperatures in December which were half the average for that month in the UK, the country experienced another warm year which was 0.6C above the long term average.
"Climate change is likely to give us milder and wetter winters - that's the general theme, but there's always opportunities within that to have colder years.
"If you look at the temperature graph for the UK or the world, it is a series of peaks and troughs and there's a lot of inter-annual variability within the climbing trend," he said.
And while the recent shift to an El Nino weather pattern in the Pacific will warm global temperatures overall, there were indications the system could have a cooling effect on Europe in the second part of its winter.
He added that it was not currently "universally cold" across the northern hemisphere, and while Siberia, the UK and parts of the US were very cold other areas including Alaska, Canada and the Mediterranean were warmer than usual.
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