Fifty thousand Earth scientists call for climate action, but is anyone listening?

The American Geophysical Union, representing some 50,000 scientists and students in 137 countries, has staked out significant new ground on the issue of climate change. The question is, have they gone far enough?

At a press conference in Washington, DC on 24 January, they released a terse statement saying that “Earth’s climate is now clearly out of balance and is warming,” that many facets of the climate system “are now changing at rates and in patterns that are not natural,” and that these changes are best explained by increased levels of greenhouse gases and aerosols generated by human activity.

They were equally clear about probable impacts—reduced agricultural productivity worldwide, widespread loss of biodiversity, and, if warming greater than two degrees Celsius continues over centuries, melting ice sheets leading to a sea level rise of several meters.

“The scale of change we’re seeing is something modern society has never seen,” said Michael Prather, who chaired the AGU committee and was also lead author of the 2007 Intergovernmental Panel on Climate Change report.

Nor did the group rule out the possibility of “surprises that may cause more dramatic disruptions than anticipated.”

Unlike the Bush administration, which has steadfastly resisted international efforts to set specific targets for greenhouse gas emissions, the AGU was not afraid to lay out numbers. “If this two degrees Celsius warming is to be avoided,” they write, “then our net annual emissions of carbon dioxide must be reduced by more than 50 percent within this century.”

When I asked the AGU panel to explain the statement that Earth’s climate is out of balance, Prather said it meant that the climate is no longer cycling slowly within a fixed range. “It’s not a balanced system,” he said. “We’re starting to slide.”

Does that mean that we’re sliding toward an irreversible tipping point? Prather would only say, “We’re moving.” He would not say if that meant “crossing a single critical threshold” or “death by 1000 knives.”

In either case, the panel agreed, concerted, coordinated, and targeted international action is needed.

“If you don’t start on a trajectory downward [for greenhouse gas emissions], you won’t be able to stabilize climate change,” said Prather. “We have to turn it over and bring it down. What we’re really looking for are much larger reductions, greater than 50 percent, by the end of the century.”

Given the clarity and urgency with which the AGU presented the case for urgent action, I was disappointed by their lack of a specific action plan, even for their own organization. “It’s our responsibility to go out and talk,” said Prather, and of course to provide society with the best science possible. But individual members need to decide just what they want to do.

AGU president Tim Killeen also emphasized education, outreach and greater interaction with policy makers, but cautioned that the AGU is determined to stay within its scientific role and not be drawn into “debilitating political controversies”.

Clearly, the AGU deserves kudos for stating the science clearly and for issuing yet another strong wake-up call to citizens and policy makers worldwide.

Still, given the powerful economic and political interests who are fighting any caps or cuts in greenhouse gas emissions, much less 50 percent reductions, I suspect that the AGU is overestimating the impact of good science, education, and outreach alone. After all, energy producers, smokestack industries, automakers and other great producers of greenhouse gasses are not shy about exerting all the political influence they can muster or buy.

To the extent that the AGU and its members take their own work and warnings seriously, and want those warnings to lead to real change, they are going to have to venture out of their comfort zone and into that unfamiliar and risky political arena both farther and faster than they might like.

Robert Adler

for the institute