Some prominent climate scientists, like NASA’s James Hansen, think the safe threshold for carbon dioxide in the atmosphere is no higher than 350 parts per million. Beyond this point, they say, we risk severe climatic consequences: melting ice caps and glaciers, rising seas, and a sharp increase in heat waves, droughts, crop failures and extreme weather events.
Of course, the world bid farewell to 350 p.p.m. more than 20 years ago and is cruising steadily toward 400 p.p.m.: last year, the Mauna Loa observatory in Hawaii observed carbon dioxide concentrations above 390 p.p.m for the first time ever. The last time carbon dioxide levels were this high was 15 million years ago, scientists suggest.
But even as many policymakers now view halting carbon dioxide levels at 450 p.p.m as an ambitious if perhaps unrealistic goal, one leading climate activist group continues to make returning carbon levels to 350 p.p.m. its raison d’être.
The group, called 350.org, staged an international climate change rally last October that Foreign Policy magazine called “the largest ever coordinated rally of any kind,” with more than 5,000 events in 181 countries.
Now the group is at it again, with a “global work party” scheduled for Sunday. Already, more than 7,000 events are scheduled in 188 countries, including a tree-planting outside Kabul, Afghanistan, and a solar-panel installation party at the University of Babylon in Iraq. (Alas, North Korea will not be hosting any tree-plantings.)
In the United States, more than 2,000 events are planned across 50 states; in New York City, community members will paint the roof of a Harlem high school white to reflect sunlight and save energy.
And just in case you were wondering, it is still all about getting the atmosphere concentration of carbon dioxide back to 350 parts per million.
“Three-fifty is the most important number in the world,” Bill McKibben, the environmentalist, author and founder of the group, said in an interview. “It’s the boundary condition for a workable planet.”
The success of the number 350 as an organizing principle seems to have taken even Mr. McKibben by surprise. “It should have been a very difficult number to organize people around,” he said. “It’s a little bit depressing, and it’s a pretty wonky data point.”
He compared the number to a bad cholesterol reading from a doctor. “If a doctor tells you that your cholesterol is too high, then you’re going to take action. It should be the same with the climate.”
Meanwhile, the international conference on climate change that opens in Cancún, Mexico, in late November is expected to generate little or no progress in advancing a global treaty to rein in greenhouse gas emissions, as our colleagues John Broder and Elisabeth Rosenthal report in Friday’s paper.
“There is no chance of completing a binding global treaty to reduce emissions of climate-altering gases, few if any heads of state are planning to attend, and there are no major new initiatives on the agenda,” they write.
Mr. McKibben contends that the currently dim prospects for progress on climate change are partly a result of a lack of coordinated grass-roots climate activism, something that his group and others are working to overcome.
“I don’t think anything of great substance is going to happen for the next two years,” he said. “We’ve got to spend the next two years building a movement big enough to matter.”
By JOHN COLLINS RUDOLF/NYT