Global warming 'undeniable,' world report says

The past decade was the warmest on record and, as glaciers melt, severe storms batter cities and heat waves increase, more than 300 scientists have concluded that global warming is "undeniable."

A new report, published by the U.S. National Oceanic and Atmospheric Administration (NOAA) Thursday and compiled by investigators from 48 different countries including Canada, identified 10 climate indicators that are clearly linked to changing surface temperatures and they "all tell the same story."

"Glaciers and sea ice are melting, heavy rainfall is intensifying and heat waves are more common. . . . There is now evidence that more than 90 per cent of warming over the past 50 years has gone into our oceans," said Deke Arndt, co-editor of the report and manager of the NOAA Climate Monitoring Branch.

The study suggests continued warming will transform how societies currently function, as coastal cities, water supplies, agriculture and infrastructure will all be threatened.

"People have spent thousands of years building society for one climate and now a new one is being created — one that's warmer and more extreme," the report says.

Each of the past three decades has been hotter than the decade before. At the time, the 1980s was the hottest decade on record but in the 1990s, temperatures increased every year and the pattern continued into 2000.

The past decade was 0.6 C warmer than the 1960s, and 0.2 C warmer than the 1990s.

Temperatures were the hottest between 2000 and 2009 and the first six months of 2010 were the warmest on record, according to the NOAA.

"The temperature increase of one degree Fahrenheit over the past 50 years may seem small, but it has already altered our planet," Arndt said.

The study, the most extensive in a series of reports, examines global warming but does not investigate a cause or a solution. The scientists used global data from satellites, weather balloons, weather stations, ships, buoys and field surveys.

The 10 climate-change indicators pointing to global warming included declining Arctic sea-ice, glaciers and spring snow cover in the Northern Hemisphere, and rising air temperature over land, sea-surface temperature, air temperature over oceans, sea level, ocean heat, humidity and the temperature of the troposphere, the atmosphere closest to the earth's surface.

The scientists say the combination of factors was startling, as their "undeniable" conclusion became glaringly obvious.

The NOAA points to extreme weather conditions documented around the world in 2009. Flooding in Brazil killed 40 people and left 376,000 people homeless, three intense heat waves broke temperature records in Australia and the central north Pacific, near Hawaii, experienced tropical cyclones after years of calm.

The researchers say extreme weather events are unavoidable, but dangerous and erratic weather will be more frequent and more severe as global warming continues.