Eric Rasmusen’s Weblog

Pete Dupont has an excellent op-ed in the WSJ on global warming, with a coda about DDT and malaria.

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.”

… Half of the past century’s warming occurred before 1940, when the human population and its industrial base were far smaller than now.

To continue:

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….

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.

And then there’s the DDT coda:

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.

p.s. See Tim Lambert’s post, linked in the first comment below, for skepticism about many of Dupont’s claims. I did a little checking on the DDT one, and here’s what I came up with:

I should know better than to take a politician’s claims at face value. They are as suspect as the environmentalist claims.

A 1975 Time magazine article says that DDT did eradicate malaria in Ceylon, but that the island stopped using it, thinking the problem was licked, and malaria had returned by 1975. Another source says

The ban on DDT was considered the first major victory for the environmentalist movement in the U.S. The effect of the ban in other nations was less salutary, however. In Ceylon (now Sri Lanka) DDT spraying had reduced malaria cases from 2.8 million in 1948 to 17 in 1963. After spraying was stopped in 1964, malaria cases began to rise again and reached 2.5 million in 1969.33 The same pattern was repeated in many other tropical— and usually impoverished—regions of the world. In Zanzibar the prevalence of malaria among the populace dropped from 70 percent in 1958 to 5 percent in 1964. By 1984 it was back up to between 50 and 60 percent. The chief malaria expert for the U.S. Agency for International Development said that malaria would have been 98 percent eradicated had DDT continued to be used.34

Tim Lambert has a thorough
older post that tells the story better, with lots of linked sources and info on the unreliability of some sources.

What seems to be clear is that DDT eradicated malaria and that after Ceylon stopped using it— at times and for reasons variously reported—malaria came back. But Lambert says malathion worked just as well (if perhaps more expensively) and got rid of it again.

This entry was posted on Thursday, February 22nd, 2007 at 8:30 am and is filed under Global Warming, Science. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.