Sept 24 (Reuters) - Here are key findings on climate change from a Feb. 2 report by the U.N. Intergovernmental Panel on Climate Change, which groups 2,500 researchers from more than 130 nations.

EVIDENCE OF HUMAN CAUSES

* "Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (human) greenhouse gas concentrations," it says. The IPCC says "very likely" means at least a 90 percent probability.

* "The level of confidence that humans are causing global warming has increased allot," report author Peter Stott said.

TEMPERATURE INCREASES

* It is very likely that extremes such as heat waves and heavy rains will become more frequent.

* "For the first time we have a best estimate of what we can achieve if we keep emissions levels lower," said report chair Susan Solomon.

* The report does not include possible warming from methane, a potent greenhouse gas, escaping from melting permafrost.

* Warming is expected to be greatest over land and at high northern latitudes, and least over the Southern Ocean and North Atlantic.

SEA LEVEL RISES

* The report cites six models with core projections of sea level rises ranging from 7.2 to 23.6 inches (18 to 59 cm) this century. That is a narrower and lower band than the 3.5 to 34.6 inch (9 to 88 cm) gain forecast in 2001.

* If the Greenland ice sheet melts proportionally to the temperature increases, then sea levels would rise by up to 31.6 inches (79 cm) this century.

* Some models show an ice-free Arctic in summer by 2100, meaning that sea ice floating in the water disappears, but not ice resting on Greenland.

* If the Greenland ice sheet melted completely, that would lead to a 23.1-foot (7 meter) sea level increase.

CHANGING OCEAN CURRENTS

* The report predicts a gradual slow-down this century in ocean currents such as the one which carries warm water to north-west Europe.

* "It's very unlikely there will be an abrupt breakdown in ocean currents in the 21st century," said Jurgen Willebrand, the report's author with special expertise in ocean effects.

HURRICANES

* The report says it is "more likely than not" that a trend of increasing intense tropical cyclones and hurricanes has a human cause.

* It predicts such tropical cyclones will become more intense in the future.

* "There may not be an increase in number, there may be a redistribution to more intense events -- which is what has been observed in the Atlantic since 1970," Stott said.

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