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.
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.