The world is getting hotter, with 2011 one of the warmest years on record, and increasing temperatures are expected to amplify floods, droughts and other extreme weather patterns around the planet, said a U.N. report released on Tuesday.
The World Meteorological Organisation, part of the United Nations, said the warmest 13 years of average global temperatures have all occurred in the 15 years since 1997.
That has contributed to extreme weather conditions that increase the intensity of droughts and heavy precipitation across the world, it said.
Our science is solid and it proves unequivocally that the world is warming and that this warming is due to human activities, WMO Deputy Secretary-General Jerry Lengoasa told reporters in Durban.
This year, the global climate was influenced heavily by the strong La Nina -- a phenomenon usually linked to extreme weather in Asia-Pacific, South America and Africa, but which developed unexpectedly in the tropical Pacific in the second half of 2010.
One of the strongest such events in 60 years, it was closely associated with the drought in east Africa, islands in the central equatorial Pacific and the United States, as well as severe flooding in other parts of the world.
The report was released to coincide with the start of U.N. climate talks this week in the South African coastal city of Durban aimed at reaching cuts in gas emissions to head off what scientists see as a global ecological disaster caused by climate change.
Prospects for a meaningful agreement appear bleak with major emitters the United States and China unwilling to take on binding cuts until the other does first, major players Japan, Canada and Russia unwilling to extend commitments that expire next year and the European Union looking at 2015 as a deadline for reaching a new, global deal.
The report said the build-up of greenhouse gasses has depleted sea ice caps and put the world at a tipping point of irreversible changes in ecosystems caused by global warming.
Concentrations of greenhouse gases in the atmosphere have reached new highs, WMO Secretary-General Michel Jarraud said separately in a statement.
They are very rapidly approaching levels consistent with a 2-2.4 degree Centigrade rise in average global temperatures which scientists believe could trigger far reaching and irreversible changes in our Earth, biosphere and oceans.
Russia experienced the largest variation from average, with the northern parts of the country seeing January to October temperatures about 4 degrees higher in several places, it said.
U.N. scientists said in a separate report this month an increase in heat waves is almost certain, while heavier rainfall, more floods, stronger cyclones, landslides and more intense droughts are likely across the globe this century as the Earth's climate warms.
The Organisation for Economic Cooperation and Development said global average temperatures could rise by 3-6 degrees Celsius by the end of the century if governments failed to contain emissions, bringing unprecedented destruction as glaciers melt and sea levels rise and small island states are erased from existence.
(Additional reporting by Tom Miles in Geneva, reporting by Jon Herskovitz, Editing by Maria Golovnina)