Matt Ridley: Global Warming Could Be Good

Monday’s excerpt from Steven Pinker’s The Better Angels of Our Nature argued that we shouldn’t fear global warming because even if it causes resource scarcity, people will not resort to violence over scarce resources. Today’s excerpt from Matt Ridley’s The Rational Optimist gives another reason why we shouldn’t fear global warming—extra warmth will be good for us.

The Rational Optimist was released in 2010

If only hypothetically, it is worth asking whether civilisation could survive climate change at the rate assumed by the consensus of scientists who comprise the Intergovernmental Panel on Climate Change (IPCC)–that is, that the earth will warm during this century by around 3° C…

Sea level is by far the most worrisome issue, because the current sea level is indeed the best of all possible sea levels: any change–up or down–will leave ports unusable. The IPCC forecasts that average sea level will rise by about 2-6 millimetres a year (or about a foot per century). At such rates, although coastal flooding will increase slightly in places (local rising of the land causes sea level to fall in many areas), some countries will continue to gain more land from siltation than they lose to erosion. The Greenland land-based ice cap will melt a bit around the edge–many Greenland glaciers retreated in the last few decades of the twentieth century–but even the highest estimates of Greenland’s melting are that it is currently losing mass at the rate of less than 1 per cent per century. It will be gone by AD 12,000….

As for fresh water, the evidence suggests, remarkably, that, other things being equal, warming will itself reduce the total population at risk from water shortage… On average rainfall will increase in a warmer world because of greater evaporation from the oceans, as it did in many previous warm episodes such as the Holocene (when the Arctic ocean may have been almost ice-free in summer), the Egyptian, Roman and medieval warm periods. The great droughts that changed history in western Asia happened, as theory predicts, in times of cooling: 8,200 years ago and 4,200 years ago especially. If you take the IPCC’s assumptions and count the people living in zones that will have more water versus zones that will have less water, it is clear that the net population at risk of water shortage by 2100 falls under all their scenarios….

Nor is there any evidence for the oft-repeated assertion that climate will be more volatile when wetter. Ice cores confirm that volatility of climate from year to year decreases markedly when the earth warms from an ice age. There will probably be some increase in the amount of rain that falls in the most extreme downpours, and perhaps more flooding as a result, but it is a sad truth that that the richer people are, the less likely they are to drown, so the warmer and richer the world, the better the outcome.

The same is true for storms. During the warming of the twentieth century there was no increase in either the number or the maximum speed of Atlantic hurricanes making landfall. Globally, tropical cyclone intensity hit a thirty-year low in 2008. The cost of the damage done by hurricanes has increased greatly, but that is because of the building and insuring of expensive coastal properties, not because of storm intensity or frequency. The global annual death rate from weather related disasters has declined by a remarkable 99 percent since the 1920s–from 242 per million in the 1920s to three per million in the 2000s. The killing power of hurricanes depends far more on wealth and weather forecasts than on wind speed. Category 5 Hurricane Dean struck the well-prepared Yucatan in 2007 and killed nobody. A similar storm struck impoverished and ill-prepared Burma the next year and killed 200,000. If they are freed to prosper, the future citizens of Burma will be able to afford protection, rescue and insurance by 2100.

In measuring health, note that globally the number of excess deaths during cold weather continues to exceed the number of excess deaths during heat waves by a large margin–by about five to one in most of Europe. Even the notorious one-off death rate in the European summer heat wave of 2003 failed to match the number of excess cold deaths recorded in Europe during most winters. Besides, once again, people will adapt, as they do today. People move happily from London to Hong Kong or Boston to Miami and do not die from heat, so why should they die if their home city gradually warms by a few degrees? (It already has, because of the urban heat island effect.)

What about malaria? Even distinguished scientists have been heard to claim that malaria will spread northwards and uphill in a warming world. But malaria was rampant in Europe, North America and even arctic Russia in the nineteenth century and early twentieth century, when the world was nearly a degree cooler than now. It disappeared, while the world was warming, because people kept their cattle in barns (providing mosquitoes with an alternative dining option), moved indoors at night behind closed windows, and to a lesser extent because swamps were drained and pesticides used. Today malaria is not limited by climate: there are lots of areas where it could rampage but does not…

Matt Ridley was awarded the Hayek Prize for the Rational Optimist in 2011

The global food supply will probably increase if temperature rises by up to 3° C. Not only will warmth improve yields from cold lands and the rainfall improve yields from some dry lands, but the increased carbon dioxide will itself enhance yields, especially in dry areas. Wheat, for example, grows 15-40 per cent faster in 600 parts per million of carbon dioxide than it does in 295 ppm. (Glasshouses often use air enriched in carbon dioxide to 1,000 ppm to enhance plant growth rates.) This effect, together with greater rainfall and new techniques, means less habitat will probably be lost to farming in a warmer world.

Indeed under the warmest scenario, much land could revert to wilderness, leaving only 5 percent of the world under the plough in 2100, compared with 11.6 per cent today, allowing more space for wilderness. The richest and warmest version of the future will have the least hunger, and will have ploughed the least extra land to feed itself. These calculations come not from barmy sceptics, but from the IPCC’s lead authors. And this is before taking into account the capacity of human societies to adapt to a changing climate

The Four Horsemen of the human apocalypse, which cause the most premature and avoidable death in poor countries, are and will be for many years the same: hunger, dirty water, indoor smoke and malaria, which kill respectively about seven, three, three, and two people per minute. If you want to do your fellow human beings good, spend your effort on combating those so that people can prosper, ready to meet climate challenges as they arrive.

 (Excerpted from pages 333-338)