RE: GLOBAL WARMING

The Climate Debate Becomes Scientific, Finally.

By

Lee C. Gerhard

Principle Geologist

Kansas Geological Survey,  Lawrence, KS 66047

     After years of enduring one liners, bits of personal beliefs, philosophy, and political spin, the debate about whether people cause climate to change is finally turning scientific. Recently, the government scientific leader of people-caused climate change, James Hanson, published a new spin on the issue, arguing that the emissions from fossil fuels caused no climate change because of feedback from increased reflectivity. About the same time, a paper in Nature documented that carbon dioxide levels during the Cretaceous Period were over 2000 parts per million, and that "normal" might be about 500 ppm. The current level is about 360 ppm. These two papers disposed of the "highest levels of carbon dioxide in history" histrionics of some political persons, and carbon dioxide from people's use of fossil fuels as the cause of climate change. We now are able to talk about what the real climate changes are and what may cause them.

     There are some principles upon which all sides of the argument can agree. First, and foremost, the laws of physics apply equally to all sides. As I recently wrote to Sen. John McCain,

" The laws of physics apply to all of us equally. Therefore, the debate must be constrained by the laws of physics. Anthropogenic emissions of excess carbon dioxide must have some effect as a greenhouse gas. At the same time, the cooling of the lower troposphere coupled with warming of the earth's surface specifies that these emissions are not the driving force behind climate change…."

     This statement draws on the collected works of Richard Lindzen, M.I.T., who has argued, without detractors, that any human-induced greenhouse effect would be seen first in the lower troposphere, based on the physical principles. Since well-vetted satellite data shows that there has been no temperature change in the lower troposphere, then there can be no human climate effect. The recent Hanson paper shows that the effects of increased carbon dioxide from fossil fuels is entirely offset by the particulate reflections of solar energy. We have honored the laws of physics, without a human-induced climate change.

     The second principle, upon which almost all scientists who have reviewed the data would agree, there is some global warming taking place, starting at least by 1850. The changes in temperature of the earth are hard to measure, they take place in irregular sawtooth jumps and slower swoons, but the general trend for the last 150 or more years is upwards. Warming from the depths of the Little Ice Age probably started by 1600 or so.

     The third principle is one that geologists understand best. Climate varies all the time, at all scales, in both directions. There is no "normal" climate in earth's history. Geology is the only discipline that routinely works backwards in time to study real variability of processes. All studies of past climate demonstrate that climate varies naturally, over many scales, at all times.

     There are some other statements that are germane to the debate, but not everyone will subscribe to these. These statements are developed from the studies I and my colleagues have undertaken in the past decade, and reflect the current collective wisdom of this group.

1. Natural climate variability greatly exceeds any human-induced effect. We cite all the time-temperature curves published, detailing climate over the last 600 million years. While most would agree with the statement, the argument that current temperature changes are greater than natural variability persists, and we can only wait and see if this is true.

2. The earth's atmosphere/ocean system is exceedingly complex and has never been successfully modeled by any computer system. There are insufficient data and insufficient understanding of the complex interactions of the system to permit computer modeling without bias. Dr. Fred Singer made a valid point when he stated that "climate model exercises are not evidence." They are human intellectual concepts set to mathematical algorithms.

3. The ruling paradigm of environmental science currently is anthropocentric, that is, human activity is the dominant force in all environmental change. Most geologists reject this hypothesis, but it permeates the climate debate. Those of us who believe that natural dynamic systems' energy dwarfs human enterprise are not as vocal as our colleagues.

4. Climate drivers are numerous. Solar, orbital, and tectonic effects and their combined effects on the world oceans are the most likely major climate drivers. The geologic prognosis is that climate will episodically grow warmer for 200 years or longer, then become much colder. This cycle will likely continue until the next glacial age. We have been in this interglacial age for about as long as any preceding interglacial (10,000 years). Sea level is likely to rise towards previous post-glacial levels without any interference by humans.

5. Politics are way out in front of science on this issue because of the tremendous implications of dependence on fossil fuel imports for the United States and Europe, and the costs of maintaining those supplies. Further, all of the proposed human solutions to the proposed human-caused problem of climate change are additonal tax revenues to federal governments.

     If temperatures are going to get warmer, and there is little we can do to forestall that eventuality (and if it is natural event, there is nothing we can do), then we had better look at the natural episodic changes in climate and forecast what is going to happen. We have forecast up to several hundred years of warming is likely, based on statistical analysis of past events. The longer term prognosis is for the world to fall back into a prolonged cold spell, perhaps even another glacial age.

     There is little question that the earth will fall back in temperature along the way over the next several hundred years - temperature changes are well demonstrated to be episodic, with rapid warming and slower cooling. The most recent episode before now was the warming of the 1930's, followed by the 50 years of cooling. We do not understand the amplitude or the duration of cycles. It is as likely that the next cold snap will be hundreds of years in total duration as 50 years.

     The problem remains, then, how would we feed 10 billion people on a colder earth? I think this is a far more serious problem than continued warming. The Viking agricultural communities on Greenland starved to death when the Little Ice Age onset replaced the Medieval Climate Optimum. What will we do?

     (Author's note; some of the material upon which this essay is based will appear in the forthcoming book "Global Climate Change: Geologic Perspectives" published by the American Association of Petroleum Geologists. It should be on book shelves by mid-December.)

Submitted September 28, 2000