- The Washington Times - Sunday, February 22, 2004

Proponents of policies to control human-induced global warming cite science as the basis for their claims and proposals. There is only one problem — as much as they claim otherwise, there is no scientific consensus for their theories.

Here’s a quick refresher. Science pursues knowledge through testing, observation and the systematization of facts, principles and methods. Progress is made when a hypothesis is proposed to explain or understand certain phenomena, and which is then tested against reality. A particular hypothesis is considered superior to others when, through testing, it is shown to have more explanatory power than competing theories and when other scientists can reproduce the results.

The theory humans are causing global warming does not work this way, however. No matter what the climate phenomenon, if it can in some way be presented as unusual by global warming alarmists, it is argued to be “further evidence of global warming,” even if it contradicts earlier “evidence” pointed to by the same people.

Here is a recent example. In late January, newspapers in England reported a study indicating ongoing global warming may plunge the world into the next ice age. This is not the first study that has predicted a great freeze. Indeed, some scientists were warning of the coming ice age as early as the 1970s. The main difference is that those early predictions were based on supposed evidence the Earth was undergoing a significant cooling trend since the 1940s and that a naturally occurring ice age was overdue.

Will global warming cause a new ice age? I don’t know, and neither does anyone else. Other than the fact the Earth has warmed about 1 degree Fahrenheit since the 1870s and that atmospheric concentrations of various naturally occurring and artificial greenhouse gasses are significantly higher now than in the recent past, there is very little consensus concerning causes of the Earth’s current warming trend or the consequences if it continues.

This is the problem with trying to forge appropriate policy responses to possible threats posed by future climate change — for what scenario do we plan?

In the realm of climate change research, different models looking at the same phenomenon using the same principles of atmospheric physics often produce dramatically varied results. Thus some scientists warn we can expect the polar ice sheets to melt, which would dramatically raise sea levels. Other scientists, as with the recent report, predict the coming of the next ice age with rapidly falling sea levels.

Still other scientists who examine the recent study predicting a “warming” induced ice age argue that, rather than a new ice age, the world’s climate will “flicker” between colder and warmer states for decades at a time. The latter scenario could be called “same as it ever was,” since it is precisely what has happened during the 150 years since science began to systematically measure weather and climate trends.

It is not just predictions of the future effects of climate change that are confusing and inconsistent. For example, in the past year studies have argued the current warming trend is caused by increasing greenhouse gasses; naturally occurring fluctuations in the solar cycle; changes in global agriculture via rapid expansion of water storage reservoirs and the widespread use of large-scale irrigation; the rapid expansion of cities and urban development; increased air pollution; deforestation; and various combinations of all the above.

What about the impacts of the current warming trend? This too is inconclusive. For example, some scientists have blamed global warming for declining snow cover on Mount Kilimanjaro. Critics of this research, however, have noted that the temperature records on Kilimanjaro show no warming. The decline in snow cover, they argue, is due to deforestation lower on the mountain that has negatively affected the moisture higher up the mountain. Similarly, researchers cannot reach a consensus on whether Antarctica is warming or cooling and whether its ice sheets are thickening or collapsing.

The only thing clear concerning the many purported effects of the Earth’s warmer climate is that, because they contradict each other, human-caused global warming cannot be causing all of them simultaneously and it may not be responsible for any.

H. Sterling Burnett is senior fellow at the National Center for Policy Analysis.