Q&A With David Victor About Climate Change

Lucy Berman: Why are so many seemingly respectable people convinced that global warming is not a real problem? Are they are all just cranks or political hacks, or is there really something to debate?

A: It is hard to defend the position that nothing should be done about global warming. The evidence is just too overwhelming. But informed people disagree over the severity of the problem -- in part because nobody really knows how the buildup in greenhouse gases will affect the climate system, and especially because it is hard to assess how nature and humans will respond to a changing climate.  

Some people see humans, especially, as highly adaptive; that leads them to worry less about global warming. Others are more pessimistic. What really scares me about climate change are the unknown unknowns -- the possibility that the climate system will respond in radical ways and that nature will adapt poorly. The only way to reduce the odds of those extreme -- some people say "catastrophic" -- outcomes is to control the emissions that cause global warming in the first place. And if those efforts are tardy or fail, then geoengineering is a Plan B that is filled with troubles but better than nothing.  

Will Rafey: Can geoengineering ever be a reliable substitute for a transition to renewable, sustainable energy?

A: Per my reply to Lucy Berman, there is no simple substitute for controlling emissions. Renewable energy could be a large part of that effort -- and surely will be -- but it is not the only option. Much higher energy efficiency must play a role; nuclear power can play a major role (if, at the same time, there is attention to controlling the risk of weapons proliferation); advanced coal-fired power plants that safely store most of their pollution underground can also play a role. Geoengineering could be, at best, a Plan B. And if we don't invest to understand it and its flaws, it won't even be Plan B.

Michael Lamb: In the United States, we have made huge strides in improving the environment -- look back to videos of the 1970s -- yet certain people still blame us for the world's problems. Our manufacturing base has decreased, and environmental regulations have increased. Should we not tell the rest of the world that when they catch up to what we have done, we will join them in a worldwide group?

A: The United States -- and most other advanced countries -- has made big progress in solving the pollution problems that the public has cared about. We have made deep cuts in the emissions that cause smog and other local pollution -- though some places still lag, especially the big cities in the south such as Houston, Phoenix, and Los Angeles. We have sharply reduced pollution that causes acid rain. But the story is different for other pollutants, such as CO2 and other gases that cause global warming, which have risen sharply since the 1970s. Partly that is because we haven't cared enough about those pollution problems to spend real resources to solve them, and partly that is because it is hard to solve them -- CO2 is a nearly intrinsic byproduct of fossil-fuel combustion, and fossil fuels are the metabolism of modern economies. Our progress on local and regional pollution such as smog is laudable but not a reason to hold back efforts to control the pollution that causes global warming until other countries catch up. We really need to be in the lead. The United States, for example, emits about five times the CO2 per capita as China.  

Mark Miller: United Nations International Panel on Climate Change (IPCC) data -- for the Northern Hemisphere, at least -- demonstrates that temperatures have cycled from a Medieval Warm Period, through a Little Ice Age, and since the turn of the last century, appear to be returning to the temperatures prevalent prior to 1600. CO2 can at most absorb only eight percent of the infrared spectrum, ergo the heat, radiating back from the earth in response to incident solar radiation. Man is responsible for about three percent of the CO2 in the atmosphere. So, at most, man is responsible for 0.24 percent of heat capture from the sun. Water vapor -- clouds -- is responsible for most of the heat capture. Given the interchange of water between the oceans and the atmosphere without any input from man, it is obvious that man's influence on atmospheric temperature is negligible.