Global Warming Vs. Global Cooling Vs. Neither Vs. Both

In the l970s, glaciers in Switzerland were advancing, summer frosts were damaging crops in the upper U.S. Midwest, and some climatologists predicted a new Ice Age.

Now, some 20 years later, the worry is the opposite. Scientists who study climate say the planet has warmed an average of 1.1 degree Fahrenheit over the past hundred years, and dire prophesies of global warming have appeared in newspapers and on television. The blame is generally laid to people’s use of fossil fuels.

The latest wave of concern, earlier this fall, was based on reports of a draft version of a United Nations committee’s report. That report was said to predict significant warming in the decades ahead.

But, upon close examination, the underlying science does not support these interpretations. The U.N. report reveals no increase in knowledge about the role of human activity in climate change, does not proclaim the Earth’s climate to be at risk and inserts numerous caveats and qualifiers that most press accounts have ignored.

Scientist John Wallace, a lead author of another U.N.-National Oceanic and Atmospheric Administration study, puts the report in context: “It’s difficult to distinguish between the signature of greenhouse warming and the pattern of natural variability that we have identified.” Hence, it may be a decade before scientists can report with a high degree of certainty whether they have detected greenhouse warming caused by human activity.

Numerous other scientists agree. Climatologists do not adequately understand the myriad forces shaping the climate and controlling its puzzling shifts. No one knows, for example, why the highly accurate satellite logs of planetary temperatures show a slight cooling since this record began in 1979, or why the Arctic area has not experienced any warming.

Statistical models have not done much better. Results from early models did not match historical records. As the models have gotten better at replicating past climate changes, climate scientists have cut their projections of future warming - by as much as 30 percent.

Even these improved models cannot take into account how clouds might slow projected trends in warming. And nobody knows enough about how deep ocean currents, which play an important role in world climate, will function in absorbing increases in carbon dioxide.

So, although computer models are getting better at mimicking large-scale historical climate change with each passing decade, the U.S. Congress’ General Accounting Office still says that today’s models are too unreliable to estimate regional changes or to serve as a basis for billion-dollar policy decisions on the basis of today’s state of knowledge.

Nonetheless, many nations, including the United States, made major commitments to control emissions of greenhouse gases, primarily carbon dioxide (CO2), by signing the U.N. Framework Convention on Climate Change at the 1992 Earth Summit in Rio de Janeiro.

Even though estimates of future climate change have been reduced as new knowledge has accumulated, news reports continue to describe worst-case scenarios, making frequent reference to a “striking” retreat of mountain glaciers (but failing to mention the advance of others, including large ice sheets in Greenland and Antarctica). And they warn that “time is running out” for preventive action.

In fact, we are not running out of time. If anything, we should be taking more time before reaching costly policy decisions to control greenhouse gases. We don’t risk much - and can save billions of dollars - by learning before acting.

Two University of Michigan climate modelers have calculated that “the penalty is small for a 10-year delay in initiating a regime in which greenhouse-gas emissions are reduced.” Investing in new knowledge and technology provides a way to respond to potential climate change without imposing unnecessary economic burdens on the citizens of any country.

Americans should also know that only they and citizens of other industrialized countries are required under the U.N. agreement to make the economic sacrifices involved in curbing CO2 emissions. Developing countries, from giant China to tiny Nauru, would be free to emit as much CO2 as they like. That’s hardly the way to deal with what is promoted as a global problem, no matter what the correct level of concern turns out to be.

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