Clear and Present Danger: A Conversation With Nobel Laureate Steve Chu on the Risks of Climate Change

The Limits of Adaptation

When talking to colleagues and students about climate change, Dr. Chu hears a lot about the potential of adaptation. After all, human beings are pretty flexible, and we have a fairly long track record of shaping the natural world to our needs. Might we be right to think that we can deal with a few more hurricanes a year, or a few more hot days in the summer? We also know that the climate predictions come with uncertainties; couldn't the uncertainties mean the problem is less bad than we think?

This elicits quite a strong reaction from Dr. Chu. Adaptation is not, he says, a productive way to think about climate change. In terms of uncertainties, they go both ways: the chance of much worse effects increases as well. The new evidence we've discussed here tells us that the climate is far more sensitive than we originally thought, and changing faster than was initially predicted. He points to what scientists estimate as the "danger point" of greenhouse gases (GHG) over time, and demonstrates that it has been steadily dropping as scientists gather new information.

Today's carbon dioxide levels are at around 384 ppm, which combined with other GHG puts us at around 430 ppm CO₂e. Passing the 400 ppm mark places us in the middle of dangerous territory. Most experts, including Dr. Chu, now agree that if the CO₂e goes above 500 pmm we run a serious risk of setting off dangerous positive feedback mechanisms, where the Earth's response to a warming world would cause it to evolve in a way that would further increase warming.

It is true that much of the devastation caused by climate change will be felt in poorer, developing nations, particularly in the early stages. Developed countries have more resources, more resilient economies, and depend less on agriculture - the industry that will be hit the hardest. But those living in industrialized countries are facing not just inconvenience but major hardship of their own. According to Dr. Chu it is not outside the realm of possibility that climate change will cause not just a collapse in agriculture, but of our entire economic system.

Greenhouse gas levels on the scale we've discussed would cause drastic changes that are completely outside our realm of experience. Dr. Chu doesn't know how to make people understand: global warming doesn't just mean a shorter ski season; it means there will not be enough water to drink. The energy problem is not that gas prices are too high; it's that they're too low to provide enough incentive for innovation and change. Numerous biofeedback mechanisms exist that threaten us with the prospect of sudden, unpredictable and irreversible disasters. We are facing a profoundly altered world, one that will be greatly and permanently transformed if we choose to continue down our current path.

As for humanity's famous adaptability – it's really not a given. These changes are on a much bigger scale than anything we've seen before. The effects of global warming are right up there with the Ice Age in terms of their potential disruption to human society. At temperature changes of just 2-4°C – in the mid to low range of what is predicted – we will face the onset of irreversible melting of the Greenland Ice Sheet, as well as the collapse of part or all of the Amazon rainforest.

Warmer temperatures will enlarge the range of disease spreading animals and the bacteria, viruses and fungi they carry. Deadly diseases we currently think of as troubles of tropical areas – like malaria or Dengue fever – could become developed-world problems.

Moreover, climate change means that a large fraction of ecosystems will be unable to maintain their current form. We will see extensive species loss that threatens more than just the polar bears. Coral reefs, and their ability to support fish populations, will be decimated. Wetlands will dry up, and entire ecosystems will cease to function.

With an increase of just 2.5°C, bird habitat in the United States will be cut in half. Changes of 2.6-3.7°C will make 30-40% of mammals in South Africa endangered or extinct. Coral reefs provide habitat for 25% of all marine species and support up to 5% of global fishing. Warming ocean temperatures disrupt the balance of coral reefs, eventually causing their death. As reefs die off, they erode, putting the fish that depend on them - and the people who depend on the fish - at danger.[16]

At 1.6-3.6°C of temperature increase, 27% of the salmon runs in the western United States are in danger of disappearing. These populations are already under pressure - salmon fishing was suspended for many western North American rivers in the 2008 season.[17]

These are important changes; any one of them alone seems like a problem. Yet people don't seem to be able to grasp that global warming means facing all of them at once. A decline in fish populations might be tragic to environmentalists but merely annoying to first-world household cooks and restaurant-goers; a decline in fish population, coupled with declines in staple crops such as rice and wheat, and wedded to the collapse of agricultural centers like California's Central Valley mean global famine that may even spill into parts of the developed world, and will certainly create massive populations of desperate people within the developing world. These are the kinds of conditions, noted Dr. Chu, which create resource wars, revolutions, invasions, and terrorism.

There is more: a temperature increase of four or more degrees Celsius, which according to Dr. Chu is a significant possibility, would literally place us in an unfamiliar world. Here we face increasing risks of abrupt, large-scale shifts in the climate system like collapse of ocean circulation and the West Antarctic Ice Sheet. Heat waves like that experienced in 2003 in Europe, when 35,000 people died and agricultural losses reached US$15 billion, would become commonplace by the middle of the century.[18]

There will be serious risks requiring coastal protection in South East Asia, small islands in the Caribbean and the Pacific, and large coastal cities, such as Tokyo, Shanghai, Hong Kong, Mumbai, Calcutta, Karachi, Buenos Aires, St. Petersburg, New York, Miami, and London.[19] These cities would most likely be protected with sea walls and levies, leaving them exposed to problems like were seen in New Orleans after hurricane Katrina. What we should be imagining is a series of Katrina-scale events - occurring repeatedly, and spread across many of the world's greatest developed and developing cities.

According to Stern, without the construction of expensive flood defenses, major world cities would have to be abandoned.[20] As many as 300 million additional people will be flooded each year by 3 to 4°C of warming; that's comparable to the entire population of the United States, each year. Ultimately, permanent displacement means refugees: climate change could lead to 150-200 million environmental refugees by the middle of the century. Protecting ourselves against these events and recovering from their effects could cost 0.5-1% of world GDP by as early as 2050.[21]

Clearly, the disaster that we are facing is orders of magnitude different from anything we've experienced thus far, and adaptation should not be taken for granted. It would be hubris on a grand scale to think that a civilization experiencing these types of destructive forces would come out unscathed.

Climate change thus poses a different scale of problem. Past human success in bending nature to our will provides little guidance on how to adapt to changes on a scale never before seen in human history. In the face of potentially major changes to basic patterns of life on earth, efforts to avoid such changes, rather than adapt to them, are prudent.

Dr. Chu pointed out that many nations, while admittedly not his own, have already begun this process. Europe and Japan enjoy high standards of living and prosperous democracies, yet have emissions levels much lower than those of the United States. Japan, Germany, and the United Kingdom all get 1.8-1.9 times as much economic output per ton of carbon emissions. France does much better, at 2.8 times as much. Sweden leads the developed world, at 3.4 times as much output per ton of emissions. These are all prosperous, stable democratic societies; there is no reason to believe that the United States couldn't at least improve up to their level.[22]