Britain's national weather service, the Met Office, says it has revised one of its forecasts for how much the world may warm in the next few years.

The forecast indicates the average temperature is likely to be 0.77 degrees above the long-term average by 2017, a revision from an earlier forecast suggesting a difference of 0.97 degrees.

Forecasters said the revised figure is the result of a new kind of computer model using different parameters, the BBC reported Tuesday.

If the forecast -- based on the average global temperature over the period 1971-2000 -- is accurate, they said, it would confirm the global average temperature has remained relatively static for about two decades.

The lack of increase in that period could be attributable to natural variability, forecasters said -- the cycles of changes in solar activity and the movements and temperatures of the oceans.

However, the Met Office said it stands by its longer-term projections calling for significant warming during the course of this century.