WHY THE JURY IS STILL OUT ON THE CAUSES BEHIND GLOBAL WARMING, IN 500 WORDS OR LESS

A Western Heart is a great blog. Two days in a row I find posts there that I saw nowhere else. Today, I found this:

David Williams, an environmentalist and global warming acolyte, challenged Dr. David Wojick, a Virginia scientist and journalist who is a skeptic about manmade global warming, to make his case in 500 words. The Wojick response is below. Wojick, a civil engineer who has a doctorate in epistemology, once taught in the Carnegie Mellon University economics and society department, led by 1978 Nobel laureate in economics Herb Simon, who died in 2001, and who was cited for his work in the politics of science.

Wojick is an expert and consultant on the subject of how science and the understanding of science interact. He runs the Climatechangedebate.org web site

Whether or not humans are causing global warming is still an open question. In fact it is one of the greatest earth science research questions in history. Begun in 1990, the U.S. Global Change Research Program has spent about $40 billion looking for the human footprint in global warming. The jury is still out. The problem is that we now know that the earth warms and cools naturally, so how do we identify the human influence?

To begin with, the earth appears to have warmed over the last century or so, by one degree Fahrenheit. During this period atmospheric carbon dioxide levels rose steadily. CO2 is a greenhouse gas, so it seems natural to conclude that the CO2 rise caused the temperature rise. This seems simple enough but as soon as one looks closely this picture falls apart and the hard science begins.

For example, while the CO2 levels rose steadily, the global temperature actually went down for the middle third of the last century. Scientists predicted a coming ice age. This shows that rising CO2 levels do not necessarily cause rising temperatures. The CO2 went up but the temperature went down.Then too, it is now generally accepted that the temperature increase in the first third of the century was due to increased solar input, not increasing CO2. We now know that the sun varies over time. This shows that rising temperatures are not necessarily caused by rising CO2 levels. The temperature went up but not because of CO2.It is possible that the temperature rise of the last 25 years is due to rising CO2. However it has to be explained why the steady rise of CO2 over more than a century waited until the last 25 years to show up? Moreover, some parts of he earth are cooling, not warming. Others, especially parts of the Arctic, are warming very rapidly. This is inconsistent with being caused by the gradual CO2 rise.

We also know now that it may have been just as warm a thousand years ago, and maybe a lot warmer 5,000 years ago, when there was no CO2 increase.

Twenty-five years of research has taught us a lot about natural global warming, but this has only made the picture more complicated. In most cases we do not know why this natural warming occurs.

There are many theories and counter theories regarding all of these issues, and many more issues as well. The result is an incredibly complex and expensive program of scientific research.

Today there are three schools of scientific thought on global warming. The first holds that humans are causing the recent warming. The second is that most, if not all, of the warming is natural. The third school is the skeptics who say we really do not know what is happening, and will not know until we understand natural climate change. Among these schools there is a loud scientific debate. Whether humans are causing global warming is anybody's guess at this point.

Reliapundit adds: 500 truthful words. I hope the eco-nutsies are listening!