June 22, 2009


Letters to the Editor and other People Speak

Global warming: The science is not settled
by J. Winston Porter

J. Winston Porter is president of Environmental Strategies in Leesburg, Va., and was formerly an assistant administrator of the Environmental Protection Agency.

Will Rogers once quipped that it's "what we know that ain't so" that gets us in trouble. This might well apply to global warming , where the "science is settled" side is rapidly pushing massive plans in Congress to reduce carbon dioxide.

But the science is not settled. If it were, we would have great confidence in all these statements: 1) the world is getting warmer, 2) that's more bad than good, 3) humans are causing the warming, and 4) we know how to fix the problem.

If either of the first two statements is wrong, then warming is not a crisis. If either of the last two is not correct, we can't fix it. What are the chances that all four are true ?

To find out, we must multiply the four individual probabilities by each other. For example, if each statement has a 70 percent chance of being correct, the overall probability is just 24 percent that all are true.

Let's now look at these four issues.

The world is getting warmer. Complex and controversial computer models are used to predict future temperatures. But all we really "know" is based on actual measurements. The U.N. Intergovernmental Panel on Climate Change says the world has warmed about 0.8 degrees centigrade since 1880.

Early in this period, ocean temperatures were measured by dropping a bucket overboard and sticking a thermometer in it. Techniques evolved over time, leading to the use of satellites over the past 30 years.

Scientists have spent years massaging these data, but it's hard to compare buckets and satellites, particularly with such small temperature changes. To further complicate things, over the last decade, global temperatures have cooled. Also, it now seems that the hottest years of the last century were in the 1930s, not the 1990s, as we had been told earlier.

So, how confident are we of even measured temperatures, not to mention ones predicted by computer simulations of the entire world's climate ?

Warming is more bad than good. Any temperature changes, up or down, will have both positive and negative impacts. Extreme cold conditions lead to more deaths than hot ones. Warming conditions cause ocean levels to rise, but also allow forests and crops to grow faster. Effects can also be regional; there is some ice melting in the Arctic, but ice is increasing in the larger Antarctic.

Are we really sure that the world is at just the right temperature, and any increases will be catastrophic ?

Humans are causing the warming. Atmospheric carbon dioxide levels have increased over the last century or so. But water vapor still provides over 95 percent of greenhouse gas influences. So, how likely is it that the very small percent of carbon dioxide produced by humans is causing warming?

The IPCC's 2007 science report lists seven global warming indicators. For two of these indicators, it is said to be "likely" (at least 66 percent chance) that mankind is a contributor, and for the other five, human contributions are deemed "more likely than not" (at least 51 percent chance).

Hardly a ringing endorsement of human-caused global warming !

We know how to fix global warming. Congress and the administration think so, as they steam ahead with "cap and trade" or other costly schemes to control carbon dioxide.

Meanwhile, scientists are still studying fixes ranging from focusing more on other greenhouse gases to reducing deforestation to shooting particulates into the atmosphere to reflect sunlight. Others suggest that we simply adapt, if necessary, to possible warming impacts, such as slow increases in ocean water levels.

The bottom line: We don't know enough to spend megabucks on speculative solutions to what may be a nonproblem. Instead, let's move ahead on two common-sense fronts.

First, we should expand measures which make sense from several angles, including possible warming. Improved energy efficiencies, cleaner coal technologies and more nuclear power all make sense. Wind and solar can also play a role.

Second, we need serious scientific debate of the four issues I raised. But this time, let's listen carefully to both believers and skeptics. That's the way science is supposed to work.


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