For climate activists, '350' is a call to action

Weekend events in D.C. and worldwide

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As countries make final preparations to negotiate a new climate treaty in December at a U.N. climate change conference in Copenhagen, Denmark, activists from around the world are increasing the pressure on governments to commit to aggressive cuts in emissions of greenhouse gases that scientists say contribute to global climate change.

Saturday, one prominent group, 350.org, whose name refers to a target level of carbon dioxide in the atmosphere of 350 parts per million (ppm), will hold what it bills as the "largest day of global political action in history." Events are scheduled in the D.C. area and across the globe.

350.org has already made waves recently, so to speak. The group helped organize an Oct. 17 cabinet meeting held underwater by the president of the Maldives, Mohamed Nasheed, to highlight the threat climate change-induced sea-level rise poses to his low-lying island nation. This weekend, 350 divers plan to be in the Maldives' Male Lagoon to mark 350.org's "International Day of Climate Action."

The grassroots organization was co-founded by the environmentalist Bill McKibben, and takes its inspiration from studies published since the 2007 U.N. Intergovernmental Panel on Climate Change's Fourth Assessment Report showing that global emissions are outpacing most of the scenarios outlined by the U.N. panel, and that the climate system is more sensitive to the buildup of greenhouse gases than previously thought.

The most prominent scientific voice in favor of the 350 ppm target has been NASA climate scientist James Hansen, who first discussed it at a scientific conference in 2007. Hansen will take part in a 350.org rally in Rome on Sunday, in keeping with his increasingly activist-oriented role in recent years. Hansen and several colleagues published a paper last year that identified 350 ppm as the safe upper limit of carbon dioxide.

"If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm, but likely less than that," the paper stated. In April, a separate study from the Potsdam Institute for Climate Impact Research in Germany found that the 350 ppm target would have a 75 percent or greater chance of limiting global warming to less than two degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels.

The two-degree mark is significant, because the Group of Eight Industrialized countries and many others have formally committed to the goal of keeping climate change from exceeding that threshold.

"Very few people even knew of this number two years ago," said 350.org coordinator Jamie Henn in an e-mail conversation about the 350 ppm target. "So it's quite amazing to see so much support now, from scientists, over 95 countries, to millions of people around the world who will be participating in the October 24 day of action."

However, 350.org and Hansen's view of the severity and pace of climate change is not shared by all mainstream climate scientists. Many experts take a more moderate position that significant emissions reductions are needed, but that making the drastic changes necessary to get down to 350 ppm may not be necessary to avoid the most severe impacts of climate change.

In addition, the recent slowdown in the rate of warming has raised questions about how well computer models are capturing the way the climate system responds to greenhouse-gas emissions.

Henn points to recent extreme weather and climate events to bolster the need for the 350 target.

"We're at about 390 parts per million of C02 right now and people around the world are already feeling the impacts of climate change, from the children in Kenya who are forming a giant 350 in their parched fields this Saturday to the students who will be carrying 350 banners in the flooded streets of Manila," Henn said. "If we're already experiencing these impacts at 390, then it's clear that turning up the amount of C02 to 450 parts per million or beyond is the wrong decision."

The main D.C. area event on Saturday will be a rally starting in Malcolm X/Meridian Hill Park that has been organized by a coalition including the Hip Hop Caucus and Friends of the Earth. Click here for a full list of events being held locally and worldwide.

The 350.org climate action day comes several weeks after the "Friends of America" Labor Day rally in West Virginia, at which a petition against climate legislation was circulated.

Other noteworthy 350.org events in the works include a rally at McMurdo station in Antarctica, and a meeting on the Dead Sea between Israelis, Palestinians and Jordanians "to make the connection between peace and environment, highlighting the joint need to protect natural resources."

The views expressed here are the author's alone and do not represent any position of the Washington Post, its news staff or the Capital Weather Gang.