A warm February in the Capital this year may not be directly attributed to changes in weather pattern, but a UN study released on Friday reaffirmed rising mercury across the globe.

The warming is likely to cause melting of ice-sheets, sea-level rise and extreme weather events like floods, droughts and cyclones.

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change said in its preliminary finding that 11 of the last 12 years rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850). The predictions about global warming and attendant climate change are not new. But the report now has strong evidence to say so and silences critics that climate change is just environmental mumbo-jumbo without the basis of science.

The report is sufficiently alarming for governments the world over to curtail industrial gases that cause global warming. It also shows that existing efforts, mainly those prescribed by the Kyoto Protocol to reduce emissions, may not be sufficient.

The Working Group report on physical sciences of climate change showed evidence that global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750. These emissions now far exceed pre-industrial values, which is determined from ice cores spanning thousands of years. The global increases in carbon dioxide concentration are due to fossil fuel use and vanishing forests that absorb carbon dioxide. Emissions of methane and nitrous oxide are primarily due to agriculture.

The atmospheric concentration of carbon dioxide in 2005 exceeds by far the natural range over the last 650,000 years.

Global warming has resulted in sea level rise from 18 cm during 1961-2003 to 31 cm during 1993-2003. Mountain glaciers and snow covers have declined in both hemispheres. Widespread decreases in glaciers and ice caps have contributed to sea level rise.

New data since the third assessment report show that losses from the ice sheets of Greenland and Antarctica have very likely contributed to sea level rise over 1993 to 2003. Flow speed has increased for some Greenland and Antarctic outlet glaciers, which drain ice from the interior of the ice sheets. The corresponding increased ice sheet mass loss has often followed thinning, reduction or loss of ice shelves or loss of floating glacier tongues, the report said.

Average Arctic temperatures have increased at almost twice the global average rate in the past 100 years. Satellite data since 1978 show that annual average Arctic sea ice extent has shrunk by 2.7 per cent per decade, with larger decreases in summer of about 7.4 per cent per decade. Temperatures at the top of the permafrost layer have generally increased since the 1980s in the Arctic.

The report predicts warmer and fewer cold days and nights, warmer and more frequent heat wave, heavy rainfall in some parts and droughts in many regions.

The region-wise analysis is yet to be made available, but India and the surrounding will be affected by warming expected at most high northern latitudes.