http://www.the-american-interest.com/2014/12/10/hot-stuff-cold-logic/
Hot Stuff, Cold Logic
RICHARD TOL
Politically correct climate change orthodoxy has completely destroyed our ability to think rationally about the environment.
Climate change is sometimes called humanity’s biggest problem. Ban Ki-moon, Christine Lagarde, and John Kerry have all said as much recently. The mainstream Western media often discuss climate change in catastrophic, or even apocalyptic, terms. Indeed, if you take newspaper headlines seriously, the Fifth Assessment Report of Working Group II of the Intergovernmental Panel on Climate Change came accompanied by the Four Horsemen of the Apocalypse; predictions of famine, pestilence, war, and death proliferated hither and yon. Conversely, when, on November 11, 2014, the United States and China inked an agreement on climate whose actual consequences are at best liable to be indistinct, banner headlines broke out, as though messianic times were nigh.
Assuming it falls somewhat short of the Four Horsemen of the Apocalypse, how serious will the impact of climate change be really? How much do we know about these impacts? What are the implications for policy?
It’s helpful to recall here that climate change means a lot more than just different temperatures. It means more or less rain, snow, wind, and clouds in various places. It means different outcomes for plants, whether direct or, since plants compete for resources, indirect. It means changes for the animals that eat those plants. And this includes changes for everything that hitches a ride on those plants and animals, and hence changes for all sorts of pathogens. Nature, agriculture, forestry, and health will all be different in the future. The seas will rise as water expands and glacial ice melts, affecting coastlines and everyone and everything that resides there. Water supplies will be affected by changing rainfall patterns, but water demand will also be altered by changing temperatures. Energy demands will change, too; there may be less need to heat houses in winter and perhaps greater need to cool them in summer. Traffic, transport, building, recreation, and tourism, too, will all feel the impact of a changing climate.
For some, the mere fact of these impacts is reason enough for governments, businesses, and individuals to exert themselves to reduce greenhouse gases to minimize the change. That is strange logic, however. Change, after all, can be for the better or the worse, and at any rate it is inevitable; there has never been a lengthy period of climate stasis.
Just as there is no logical or scientific basis for thinking that climate change is new, there is no self-evident reason to assume that the climate of the past is “better” than the climate of the future. With just as little logic, we might assume that women’s rights, health care, or education were necessarily better in the past. Any such judgment also contradicts Hume’s Law and, perhaps worse, is grounded in a fallacious appeal to nature understood in a very slanted way. There is no prima facie reason to assume that any given past climate was better than the prospective one. The climate of the 21st century may well be unprecedented in the history of human civilization; the number of people living in countries with free and fair elections is unprecedented, too. So what? “Unprecedented” is not a synonym for “bad.”
Others argue that the impacts of climate change are largely unknown but may be catastrophic. The precautionary principle thus enjoins that we should work hard, if not do our utmost, to avoid even the slim possibility of catastrophe. This logic works fine for one-sided risks: We ban carcinogenic material in toys because we do not want our kids to get cancer. Safe materials are only slightly more expensive, and there is no likely or even imaginable “upside” to children having cancer. Climate policy, on the other hand, is about balancing risks, and there are risks to climate policies as well as risks caused by climate change. Sharp increases in energy prices have caused devastating economic recessions in the past, for example. Cheap energy fueled the industrial revolution, and lack of access to reliable energy is one factor holding back economic growth in most developing countries. In the short run, we rely on fossil fuels to keep us warm and keep the lights on, to grow our food, and to purify our drinking water. So there is a cost to human well-being in constraining fossil fuel use.
What this means is that, instead of assuming the worst, we should study the impacts of climate change and seek to balance them against the negative effects of climate policy. This is what climatologists and economists actually have done for years, but their efforts have been overshadowed by the hysteria of the Greens and the Left, and the more subtle lobbying of companies yearning for renewables subsidies and other government hand-outs. It is especially important to maintain an objective attitude toward the tradeoff between possible dangers and the costs of policy, because estimating the impacts of climate change has proven to be remarkably hard. Past climate change is not much of a guide. The climate supposedly changed much less over the previous century than it is projected to do over the current one, but global mean surface air temperature has barely moved over the past two decades—and this is the period with the best data, in which almost all climate change impact studies have been done.
Besides, the faint signal of past climate change is drowned out by all the other things that have changed. If one tries to study the impacts of climate change on crops, for example, one must factor in the impact of new seeds, fertilizers, pesticides, and a host of other confounding variables such as air pollution and atmospheric deposition of nutrients. If one is interested in commercial agriculture, one needs to consider subsidies and international trade. If one studies the impacts of climate change on health, one needs to control for progress in medical technology, different diets, changes in work and leisure, aging, migration, and so on and so forth. If one studies the impacts of sea-level rise, one needs to cope with subsidence and tectonic movements, changing land use, shifting priorities in coastal zone management, eutrophication, and more besides. The same is true for all past climate change impacts: Many things are changing, often much faster than the climate, and in ways that confound all unifactoral explanations potentially relevant to policy.
