Letters

From the February 1998 issue

(Page 2 of 5)

I enjoyed Dr. Benford's article very much. I continue to be optimistic that people will see science and technology as our friends and not the enemy. I am disheartened when so many scientists seem to believe that science is good, but applied science is the root of all evil.

I had some questions concerning various assertions I've heard regarding global warming. I've heard that if the atmosphere does increase in temperature, a greater amount of moisture will evaporate from the ocean surface. The presence of more water vapor increases the cloud cover over the oceans, thus increasing the Earth's albedo. As a result, the Earth's
atmospheric temperature is self-reg-ulating. Is this thinking correct?

I have also read that the CO₂ and other greenhouse gases released into the atmosphere are almost entirely a by-product of natural processes (e.g., volcanic eruptions) which almost completely eclipse human contributions. Is this so?

Greg Parsons
Cincinnati, OH

Benford suggests a series of Rube Goldberg "climate controls" to mitigate the
effects of greenhouse gases, despite the complete lack of scientific consensus that global warming is occurring, that it is an imminent threat, or that humans are
the cause. Benford speaks of a "consensus that the only way to counter global warming is by reducing emissions." No such consensus exists.

A recent Gallup poll of the Meteorological Society and the American Geophysical Society shows that 17 percent agreed with the proposition that human actions were causing global warming, while 83 percent disagreed. Only 13
percent of scientists responding to a Greenpeace survey believe catastrophic climate change will result from continuing current patterns of energy use. Recently more than 100 noted scientists, including the former president of the National Academy of Sciences, signed a letter declaring that costly actions to reduce greenhouse gases are not justified by the best available science.

The man who started the ruckus by telling Congress in 1988 he believed "with a high degree of confidence" that global warming had arrived, NASA's James Hansen, now thinks the net effect of recent atmospheric changes to be far too small to have much of an effect on temperature. Harvard's Brian Farrell has said bluntly: "There really isn't a case being made for the detection of greenhouse warming."

The facts are, as noted by Robert C. Balling, director of the Office of Climatology at Arizona State University, that the world has seen an increase in the level of carbon dioxide and other greenhouse gases from 305 parts per million in 1890 to 432 parts per million by 1990, a 42 percent increase. Yet during this period the planetary temperature rose a meager 0.45 degree Celsius.

The plot thickens when we observe that 0.4 degree of this increase occurred before World War II, while much of the rise in greenhouse gases occurred after this date. The timing of this modest warming is not consistent with the rise in greenhouse gases. The effect seems to precede the alleged cause.

In fact, as Dr. Balling notes, despite all the talk about global warming during the 1980s, the buildup of greenhouse gases from 1979 to 1994, and the anticipated 0.3 degree per decade warming, highly accurate satellite-based global temperature measurements not only show no warming but instead show very real cooling, a statistically significant cooling of 0.13 degree Celsius over this period.

Even if the Earth's temperature has
increased slightly, the increase is well within the natural range of known temperature variation over the past 15,000 years. Indeed, the Earth experienced greater warming between the 10th and 15th centuries, predating the Industrial Revolution.

A slight warming trend that occurs mostly in winter and at night (which many scientists consider the most probable scenario) would actually benefit mankind, producing milder winters and longer growing seasons. Carbon dioxide, rather than being a pollutant, makes forests and crops more abundant.

Benford claims that "systematic weather prediction has advanced more than tenfold in its assured time range" and that with "the latest systems, backed by heavy computer modeling, we will shrink uncertainties." Let's hope so. Current global warming predictions are based on computer models that cannot replicate what is already known about climate changes over the past 50 years.

One of Benford's goals is to increase the amount of sunlight reflected back into space. He'll have to reflect more than he figured. In the current issue of the journal Science, Richard Wilson, an atmospheric physicist from Columbia University's Center for Climate System Research, reports evidence that the sun has been gradually brightening over the past few decades, with total solar irradiance increasing over the past 19 years by about 0.036 percent per decade. If that continued over a century, it would be enough to bump global temperatures up by about 1 degree Fahrenheit or more.

Astrophysicist Sallie Baliunas of the Harvard Smithsonian Center for Astrophysics and colleagues have studied records going back 120 years and conclude that between 70 and 90 percent of global temperature shifts are sun-in-duced, not man-induced. It could just be that Benford, Clinton, and Gore have been standing out in that sun too long.