By Susanne Rust

Just as the federal government released its annual index of greenhouse gases, showing a steady increase over the past 21 years, the International Energy Agency warned that we are on the path to 11-degree warming if we don’t curb emissions now.

“Delaying action is a false economy: For every $1 of investment in cleaner technology that is avoided in the power sector before 2020, an additional $4.30 would be needed to be spent after 2020 to compensate for the increased emissions,” the authors of the energy agency report wrote in their 2011 World Energy Outlook.

Last week, the National Oceanic and Atmospheric Administration released its annual accounting of greenhouse gases in the atmosphere. The index showed a 29 percent increase over levels recorded in 1990, the agency’s baseline year, as established by the Kyoto protocol.

“The increasing amounts of long-lived greenhouse gases in our atmosphere indicate that climate change is an issue society will be dealing with for a long time,” said Jim Butler, director of the Global Monitoring Division of NOAA’s Earth System Research Laboratory in Boulder, Colo.

Butler says you have to think of this number not as a predictor, but more like a dial on an electric blanket. You know that if you turn the dial up, the blanket will get warmer. You may not feel the warmth immediately, but it will get warmer – just how warm, you don’t know.

One of the more striking findings in the agency’s report includes the increase in methane found in the atmosphere. The level of that gas has increased in the last four years, after holding steady for more than a decade. Methane is 25 times more potent than carbon dioxide as a greenhouse gas.

Butler said that increase is likely attributable to the thawing of permafrost and an increase of methane escaping from tropical areas.

“Climate warming has the potential to affect most aspects of society, including water supplies, agriculture, ecosystems and economies,” said Butler, who added that his agency will continue to monitor these gases “into the future to further understand the impacts on our planet.”

His warning was echoed by the International Energy Agency, which said “rising fossil energy use will lead to irreversible and potentially catastrophic climate change.”

Joe Romm, former assistant secretary in the U.S. Department of Energy and now editor of the blog Climate Progress, said the International Energy Agency “is one of the few organizations in the world with a sophisticated enough global energy model to do credible … projections of the cost of different emissions pathways and the costs of delaying efforts to achieve them.”

He said the key point of the report is that in the 2020s, “the world is going to be considerably more desperate than we are now. The evidence of human-caused climate change will be difficult for all but the most extreme deniers to ignore.”

He added that superstorms, like the one in Alaska last week, “will increasingly just be the normal weather – and we’ll start to see what really extreme weather is like.”

This post also appears at California Watch, a content partner of Climate Watch.