In The Field

AAAS: Climate issue getting “more complicated”

A leader of the the Intergovernmental Panel on Climate Change told the meeting today that the world’s climate is likely to change much faster than predicted, leaving the world with two choices: start cutting carbon emissions earlier, or make the cuts deeper.

The comments came the morning after former U.S. Vice President Al Gore called on scientists at the meeting to help convey a sense of urgency about climate change to policy makers and the public.


“We are basically looking now at a future climate that is beyond anything we’ve considered seriously in climate model simulations,” said Chris Field, co-chair of the IPCC’s second working group and a professor at Stanford University and the Carnegie Institution for Science.

This is because the rate at which carbon is entering the atmosphere is increasing much faster than the IPPC modeled in its last report, issued in 2007. That report estimated that world temperatures could increase by between 1.1 to 6.4 degrees Celsius by 2100. But the surge in the use of coal to generate power in developing countries, combined with climate impacts on natural carbon sinks, such as oceans, forests and tundra, mean that future climate impacts will likely be more severe than the IPPC realized, Field said.

“We have higher emissions, and we have a less friendly natural system to picking up these higher emissions, and they both mean that looking forward, the challenge of stabilizing atmospheric carbon dioxide is getting more complicated than we thought it was before,” Field said.

Holly Gibbs, a researcher at Stanford University’s Woods Institute for the Environment, also showed data that attempts to help clarify one aspect of the climate debate. Two papers published last year suggested that clearing tropical forests to plant biofuel crops might actually worsen climate change, but that planting biofuels crops on “degraded” land – such as abandoned agricultural land – offers a net benefit to climate. Gibbs analyzed satellite images taken from 1980 to 2000 to try to answer the question of whether tropical crops are largely being planted on deforested or degraded land. She found that the majority of new crops were planted on freshly deforested rather than degraded land.

Gibbs said she could not tell from her data whether the new crops were planted for food or fuel. But she added, “What we know is that biofuell use is definitely fueling deforestation.” She said when biofuel prices increase, the amount of deforestation increases as well. She said she would personally estimate that between one-third to two-thirds of deforestation over the past couple of years has been due to the planting of biofuel crops.

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“If we run our cars on biofuels produced in the tropics, chances are good that we are effectively burning rainforests in our gas tanks,” Gibbs said.

Deforestation is a major issue in international negotiations on a successor agreement to replace the Kyoto Protocol, which is set to expire in 2012. Negotiators will meet formally again this December in Copenhagen. But despite the fact that climate is likely changing more rapidly than expected, and the fact that the next IPCC assessment will not be published until 2014, Field said it is difficult to envision any way to speed up the formal IPCC process.

“The feeling has always been that you can either make an assessment good or fast,” Field said. He said the IPPC is adding more special reports, such as one underway on renewable energy and a possible special report on climate extremes and adaptation. “I think we’ll see somewhere between two and five of these special reports in the next assessment cycle, but I don’t think the IPPC is going to deviate from its emphasis on quality and I don’t think we have any ideas on how to keep the quality and accelerate the timelines.”

Photo of land clearance for oil palm production in Ecuador provided by World Land Trust, via Science-AAAS.

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