Science & Tech

Holdren talks back to skeptics of global warming

4 min read

‘Disruption and its impacts have grown more … than anyone expected a few years ago’

“Global warming is a misnomer,” said John P. Holdren, speaking Tuesday night (Nov. 6) at the John F. Kennedy Jr. Forum at the Kennedy School. “It implies something gradual, uniform, and benign. What we’re experiencing is none of these.”

Holdren, the Teresa and John Heinz Professor of Environmental Policy at the Kennedy School and director of the program in science, technology, and public policy at the Belfer Center for Science and International Affairs, went on to outline the current and likely future effects of global warming, as well as its anthropogenic — or man-made — nature.

“The disruption and its impacts have grown more widely than anyone ever expected a few years ago,” Holdren contended. To fix the problem, he said, society has only three options: mitigation, adaptation, and suffering. “We’re already doing some of each, and will do more of all three.”

Climate change affects the availability of water, agricultural production, the formation and dispersion of air pollutants, the geography of disease, natural disasters, and much more. For those who may still be skeptical that global warming is happening, or that it is caused by human intervention, Holdren said, “There is good reason to put on the brakes before we go over the cliff. If you’re driving over a cliff, you’re not going to listen to people who say, ‘Listen, it’s foggy and you don’t know where the cliff is.’”

Holdren had plenty of evidence to rebut skepticism, discussing studies that showed the steady rise in annual mean temperatures since 1880, when records were first kept; the current geographic distribution of heating, which indicates that it’s concentrated in the far north of the globe; and changes in monsoon patterns, evaporation, precipitation, and sea level. Permafrost is thawing, he pointed out; arctic summer sea ice is disappearing; surface melting on Greenland is expanding; and sea level is rising.

“These changes,” Holdren said, “are already causing harm.” Major flooding is up virtually everywhere in the world, he said. Wildfires are also increasing — in the United States, fourfold in the past 30 years — which adds to the carbon dioxide in the atmosphere, creating what Holdren called a vicious circle. The power of tropical storms has increased almost in lockstep with the increased temperature of the sea surface, which is also acidifying the oceans, threatening coral reefs and any creature that makes its shell out of calcium carbonate. The World Health Organization estimates that, by 2000, climate change was already causing 150,000 premature deaths a year, and, Holdren said, “bigger disruption is coming.”

Only three options will allow us to “manage the unavoidable and avoid the unmanageable,” he added. The first is mitigation — taking measures to reduce the pace and magnitude of the changes caused by human activities. Current possibilities for mitigation include reducing greenhouse gases and soot emissions from the energy sector, reducing deforestation, and modifying agricultural practices to build up carbon in the soil. Also, said Holdren, in the future “we might get desperate enough to use technology to ‘scrub’ greenhouse gases from the atmosphere” or to try “geoengineering” by, for example, injecting reflecting particles into orbit to deflect some of the sun’s heat.

Mitigation alone won’t work, however, because, Holdren said, climate change is already occurring and can’t be stopped quickly.

The second option for minimizing the damage is adaptation, or reducing the adverse impacts on human well-being that climate change will cause. Though adaptation gets costlier and less effective as climate change grows, many of its possibilities — including changing crop patterns, developing heat- and drought-resistant crop varieties, strengthening public health measures against tropical diseases, and building new water projects for flood control and drought management — are “win-win.”

Unfortunately, if we don’t take sufficient steps quickly for mitigation and adaptation, the result will be more suffering around the world.

“The problem is each of these approaches has limitations and liabilities,” Holdren said. “There is no panacea. Maybe we’ll end up doing all of it, but we need a portfolio of choices.” The next most important steps, he added, are to accelerate “win-win” mitigation and adaptation measures, integrating them with current development plans; to put a price on greenhouse gas emissions so the marketplace can work to find the cheapest reductions; to expand international cooperation; and to sharply increase investments in energy-technology research and development.

Holdren’s most important message, perhaps, was that the United States must spearhead this effort, going from being a “laggard in climate policy to being a leader.” Once that happens, he said, the rest of the world will follow suit.