(Reuters/bdnews24.com) - Here are key findings on climate change from a February 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 a lot," 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 this century. That is a narrower and lower band than the 3.5 to 34.6 inch 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 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-metre) sea level increase. CHANGING OCEAN CURRENTS * The report predicts a gradual slowdown this century in ocean currents such as the one that carries warm water to northwest 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.