New figures from the U.N. weather agency Monday showed that the three biggest heat-trapping greenhouse gases in the atmosphere not only reached record levels last year but also were increasing at an ever-faster rate.
"The growth rate is increasing every decade," said Jim Butler, director of the U.S. National Oceanic and Atmospheric Administration's Global Monitoring Division. "That's kind of scary."
Scientists can't say exactly what levels of greenhouse gases are safe, but some fear a continued rise in global temperatures will lead to irreversible melting of some of the world's ice sheets and a several-foot rise in sea levels over the centuries.
The findings from the U.N. World Meteorological Organization are consistent with other grim reports issued recently. This month, figures from the U.S. Department of Energy showed that global carbon dioxide emissions in 2010 jumped by the highest one-year amount ever.
The WMO found that total carbon dioxide levels in 2010 hit 389 parts per million, up from 280 parts per million in 1750, before the start of the Industrial Revolution. Levels increased 1.5 ppm per year in the 1990s and 2.0 per year in the first decade of this century, and are now rising at a rate of 2.3 per year. The top two other greenhouse gases — methane and nitrous oxide — are also soaring.
The U.N. agency cited fossil fuel-burning, loss of forests that absorb CO2, and use of fertilizer as the main culprits.
Since 1990 — a year that international climate negotiators have set as a benchmark for emissions — the total heat-trapping force from all the major greenhouse gases has increased by 29 percent, according to NOAA.
The rise is happening despite the 1997 Kyoto agreement to cut emissions. Europe, Russia and Japan have about reached their targets under the treaty. But China, the United States and India are increasing emissions. The treaty didn't require emission cuts from China and India. The United States pulled out of the treaty in 2001.