Scientists meeting in France say 2002 was the second hottest year on record.
It continued a warming trend that has set records for the last five years. Only 1998 was warmer.
Antarctic temperatures are bucking the trend
The planet is now 0.6 Celsius warmer than in 1900, an increase that scientists attribute to human activity.
Researchers say even a fractional boost in average temperatures has significant consequences for the health of the planet.
The findings appear in The State Of The Climate, an annual report from the US National Oceanographic and Atmospheric Administration (Noaa), based on research from eight countries.
It was presented at the first joint meeting here of the leading European and American geoscience societies, the European Geophysical Society (EGS), the European Union of Geosciences (EUG) and the American Geophysical Union (AGU).
While the Earth warmed in 2002, the trend in Antarctica was toward cooler-than-average temperatures, a pattern consistent with global climate change, according to Dr Anne Waple of Noaa.
"The Antarctic is a very different beast," she said. "There is a great big land mass stuck at the South Pole and the circulation around that essentially cuts it off every winter. It has its own weather patterns."
The second half of 2002 saw a mild El Nino, the periodic weather phenomenon in the Pacific that disrupts climate patterns thousands of miles away.
Drought savaged people and livestock
While global rainfall was average overall, El Nino contributed to extreme drought in the US, comparable with the Great Dust Bowl of the 1930s, and in Canada, Australia, West Africa and India.
Droughts continued in parts of central America, and central Europe experienced near-record floods.
Tropical storm activity was below normal globally, and in India a failure of the monsoon rains led to the first all-India drought since 1987.
Scientists predict more frequent and extreme weather events because of climate change, but last year's droughts and floods cannot be tied definitively to it, said Dr Waple, as the climate record is not long enough.
"But we are operating in a world that is warmer than it was 100 years ago," she said. "Certainly that baseline climate change plays a role."
The meeting, the EGS-AGU-EUG Joint Assembly, heard details of research on the cause of Europe's catastrophic floods and the lessons learned from them.
Jiri Stehlik of the Czech Hydrometeorological Institute said an unusually sluggish low-pressure system that lingered over central Europe had brought two rounds of intensive rainfall within a week. The second overwhelmed swollen rivers and saturated soils.
Floods devastated central Europe
In Prague, where two rivers meet, the river discharge peaked at 5,200 cubic metres a second, making it a once-in-500-years flood that devastated the city and nearby villages.
"It was a very fast-happening flood," said Hans Wiesenegger, an Austrian hydrologist from Salzburg, where the river Salzach inundated the city.
"Within 18 hours, we had a peak discharge of 2,300 cubic metres a second. The average is 180 cubic metres."
Although flood forecasting was fairly accurate, scientists were unable to predict how the land and rivers would respond to the rain.
The 2002 floods are still considered rare events and attributed to natural cycles. Dr Waple said: "The flooding in central Europe was probably the most severe in 100 years or so.
"But if we were to see that sort of flooding next year and again in five or 10 years, then that is something that is clearly outside the bounds of natural variability."
Antarctic image courtesy of British Antarctic Survey