Climate change 'undeniable', says government report
The last decade has been the warmest on record, and there's now conclusive evidence that the world is getting hotter, according to a major study from the NOAA.
The 2009 State of the Climate report is based on work by more than 300 scientists from 160 research groups in 48 countries.
It tracks 10 measurable planet-wide features used to gauge global temperature changes. Air temperature over land, sea-surface temperature, air temperature over oceans, sea level, ocean heat, humidity and tropospheric temperature are all rising; and Arctic sea ice, glaciers and spring snow cover in the Northern hemisphere are all declining.
"For the first time, and in a single compelling comparison, the analysis brings together multiple observational records from the top of the atmosphere to the depths of the ocean," said Dr Jane Lubchenco, undersecretary of commerce for oceans and atmosphere and NOAA administrator.
"The records come from many institutions worldwide. They use data collected from diverse sources, including satellites, weather balloons, weather stations, ships, buoys and field surveys. These independently produced lines of evidence all point to the same conclusion: our planet is warming."
While year-to-year changes in temperature often reflect natural climatic variations such as El Niño/La Niña events, the NOAA says the new report shows a consistent long-term trend.
The 1980s was the hottest decade on record - until the 1990s, when every year was warmer than the average of the previous decade. The 2000s were warmer still.
"Despite the variability caused by short-term changes, the analysis conducted for this report illustrates why we are so confident the world is warming," says Dr Peter Stott, head of Climate Monitoring and Attribution of the United Kingdom Met Office Hadley Centre.
"When we look at air temperature and other indicators of climate, we see highs and lows in the data from year to year because of natural variability. Understanding climate change requires looking at the longer-term record. When we follow decade-to-decade trends using multiple data sets and independent analyses from around the world, we see clear and unmistakable signs of a warming world."