The first three months of this year were the warmest globally since records began in 1860 and probably for 1,000 years, the Daily Telegraph quoted British scientists as saying.
Geoff Jenkins, director of the Meteorological Office's Hadley Center, said the record on land and sea was consistent with computer predictions of the effects of man-made global warming.
The three months were about 0.71 Celsius warmer than the average for 1961 to 1990, itself the warmest period for 1,000 years according to ice-core analysis, he added.
The global record came in the wake of observed changes in the British climate since 1900: a lengthening of the growing season for plants by one month in central England, a temperature increase of one Celsius degree, and a 10-centimeter sea level rise.
Scientists, who compiled different scenarios for high, medium and low emissions of greenhouse gases, predicted that the average temperature of Britain could rise 2 to 3.5 Celsius degrees by 2080. A cooling of the British climate over the next 100 years because of changes to the Gulf Stream is now considered unlikely.