BY PETE DU PONT
Wednesday, February 21, 2007 12:01 a.m. EST
When Eric the Red led the Norwegian Vikings to Greenland in the late 900s, it was an ice-free farm country--grass for sheep and cattle, open water for fishing, a livable climate--so good a colony that by 1100 there were 3,000 people living there. Then came the Ice Age. By 1400, average temperatures had declined by 2.7 degrees Fahrenheit, the glaciers had crushed southward across the farmlands and harbors, and the Vikings did not survive.
Such global temperature fluctuations are not surprising, for looking back in history we see a regular pattern of warming and cooling. From 200 B.C. to A.D. 600 saw the Roman Warming period; from 600 to 900, the cold period of the Dark Ages; from 900 to 1300 was the Medieval warming period; and 1300 to 1850, the Little Ice Age.
During the 20th century the earth did indeed warm--by 1 degree Fahrenheit. But a look at the data shows that within the century temperatures varied with time: from 1900 to 1910 the world cooled; from 1910 to 1940 it warmed; from 1940 to the late 1970s it cooled again, and since then it has been warming. Today our climate is 1/20th of a degree Fahrenheit warmer than it was in 2001.
Many things are contributing to such global temperature changes. Solar radiation is one. Sunspot activity has reached a thousand-year high, according to European astronomy institutions. Solar radiation is reducing Mars's southern icecap, which has been shrinking for three summers despite the absence of SUVS and coal-fired electrical plants anywhere on the Red Planet. Back on Earth, a NASA study reports that solar radiation has increased in each of the past two decades, and environmental scholar Bjorn Lomborg, citing a 1997 atmosphere-ocean general circulation model, observes that "the increase in direct solar irradiation over the past 30 years is responsible for about 40 percent of the observed global warming."
Statistics suggest that while there has indeed been a slight warming in the past century, much of it was neither human-induced nor geographically uniform. Half of the past century's warming occurred before 1940, when the human population and its industrial base were far smaller than now. And while global temperatures are now slightly up, in some areas they are dramatically down. According to "Climate Change and Its Impacts," a study published last spring by the National Center for Policy Analysis, the ice mass in Greenland has grown, and "average summer temperatures at the summit of the Greenland ice sheet have decreased 4 degrees Fahrenheit per decade since the late 1980s." British environmental analyst Lord Christopher Monckton says that from 1993 through 2003 the Greenland ice sheet "grew an average extra thickness of 2 inches a year," and that in the past 30 years the mass of the Antarctic ice sheet has grown as well.
Earlier this month the U.N.'s Intergovernmental Panel on Climate Change released a summary of its fourth five-year report. Although the full report won't be out until May, the summary has reinvigorated the global warming discussion.
While global warming alarmism has become a daily American press feature, the IPCC, in its new report, is backtracking on its warming predictions. While Al Gore's "An Inconvenient Truth" warns of up to 20 feet of sea-level increase, the IPCC has halved its estimate of the rise in sea level by the end of this century, to 17 inches from 36. It has reduced its estimate of the impact of global greenhouse-gas emissions on global climate by more than one-third, because, it says, pollutant particles reflect sunlight back into space and this has a cooling effect.
The IPCC confirms its 2001 conclusion that global warming will have little effect on the number of typhoons or hurricanes the world will experience, but it does not note that there has been a steady decrease in the number of global hurricane days since 1970--from 600 to 400 days, according to Georgia Tech atmospheric scientist Peter Webster.
The IPCC does not explain why from 1940 to 1975, while carbon dioxide emissions were rising, global temperatures were falling, nor does it admit that its 2001 "hockey stick" graph showing a dramatic temperature increase beginning in 1970s had omitted the Little Ice Age and Medieval Warming temperature changes, apparently in order to make the new global warming increases appear more dramatic.
Sometimes the consequences of bad science can be serious. In a 2000 issue of Nature Medicine magazine, four international scientists observed that "in less than two decades, spraying of houses with DDT reduced Sri Lanka's malaria burden from 2.8 million cases and 7,000 deaths [in 1948] to 17 cases and no deaths" in 1963. Then came Rachel Carson's book "Silent Spring," invigorating environmentalism and leading to outright bans of DDT in some countries. When Sri Lanka ended the use of DDT in 1968, instead of 17 malaria cases it had 480,000.
Yet the Sierra Club in 1971 demanded "a ban, not just a curb," on the use of DDT "even in the tropical countries where DDT has kept malaria under control." International environmental controls were more important than the lives of human beings. For more than three decades this view prevailed, until the restrictions were finally lifted last September.
As we have seen since the beginning of time, and from the Vikings' experience in Greenland, our world experiences cyclical climate changes. America needs to understand clearly what is happening and why before we sign onto U.N. environmental agreements, shut down our industries and power plants, and limit our economic growth.
Mr. du Pont, a former governor of Delaware, is chairman of the Dallas-based National Center for Policy Analysis. His column appears once a month.
