The following was provided by Dr. William F. Downs, a Geochemist and friend. I’ve done a tiny bit of editing, and added a comment at the end. The timing is perfect as a contrast to  the review posted today.

There is little controversy over the fact that the temperature of Earth is currently rising and has been since the end of the “Little Ice Age” which lasted from about 1380 AD until circa 1780 AD.  Previously the climate experienced a warm period which was called the “Millennium Optimum” (c. 850 AD – 1300 AD) when I studied it during the 1960s.  It was considered “optimum” because the Vikings were able to expand into and develop farms in Greenland and grapes that had been planted in Britain by the Romans produced wine.  By the early 1300s, Greenland was no longer able to sustain agriculture and the Viking society in Greenland had collapsed.  There was another warming period termed the “Roman Warm Period” that existed in the first few centuries after the time of Christ.  The “Little Ice Age” was documented by Monks in Monasteries along the roads to Rome as Alpine Pilgrims on their way to Rome told their stories of glacial destruction of their Villages.

The temperatures and CO₂ contents of the atmosphere in the past are estimated by measuring the oxygen isotope ratios and concentrations of CO₂ released from ice cores collected from Vostok Glacier in Antarctica.  These data have been collected from ice that had formed during the last 100,000 years or so.  These data indicate that the current temperature level is lower than those experienced during the Millennial Warming Period.

The current estimates of climate change come from numerical simulations (models) of global climate trends.  If one is to develop a meaningful numerical simulation of a natural process, one must account for all of the properties that contribute to that process.  In the case of climate change, there are so many properties that are only incompletely understood that a meaningful model is probably beyond our current state of the science.  The design of many of the currently used models emphasize the CO₂ concentrations of the atmosphere and may very well be missing or minimizing other significant factors that contribute to the temperature of the globe – e.g., luminosity of the Sun, etc.  One of the essential steps in the development of a meaningful predictive model is the ability to predict the past.  If one cannot reproduce the measurements of climatic temperatures from the past, how can one place any faith in the predictions of the future?  The infamous “hockey stick” trend generated by Professor Mann at the University of Virginia (currently at Penn State) with co-authors Bradley and Hughes (1998) did not show either the “Little Ice Age” or the “Millennial Warming Period.”  In addition, the mathematics used to simulate the temperature trend was called into question by two Canadian statisticians (McIntyre & McKitrick, 2005).  A later comparison concluded that the Canadians were correct but that the outcome of the estimates would not have been changed.  I never quite agreed that we could use the wrong equations but come up with the correct answers.

My major criticism of the current numerical climate simulations is that in order to establish the size of the effect of any given factor, one must be able to simulate any change that would occur independent of that factor.  Not one of the current climatologists that have generated a climate temperature trend has generated a line that estimates the change in temperature if CO₂ concentrations had remained constant at the pre-Industrial Revolution level (~260 ppmv, parts per million by volume).  The current CO₂ concentration in the atmosphere is around 360 ppmv.  Recently, one of the U.N. climatologists predicted that if the CO₂ concentration reaches 400 ppmv it will be too late to prevent the temperature from rising more than 1°C.  I have a hard time believing that we are capable of measuring the mean global temperature to ±1°C.  Thus, I do not believe that current numerical simulations provide accurate estimates of the potential changes in global temperature.

There is a statement that is currently being used that 97% of the climate scientists believe that global warming is due to anthropogenic activities.  This datum does not reflect the views of many in the science community.  The question was asked of the attendees of the U.N. sponsored annual meeting of the Intergovernmental Panel on Climate Change.  It is hardly surprising that the scientists that make their living from predicting climate change believe in the hypothesis.  I would guess that a similar poll taken at a Right-to-Life rally would indicate that most of the attendees do not support abortion, but these data cannot be extrapolated to the general population.

We know that the climate of the earth changes.  There have been five or six major Ice Ages starting about 2.8 billion years before present.  The last one was the Holocene Ice Age that we are familiar with that had four expansions and contractions with the last one ending about 7,500 years ago. In North America these glacial periods have been named after the states whose sediments show the maximum extent of the glaciation – Nebraskan, Kansan, Illinoian, and Wisconsinan. A Serbian Astronomer, Milutin Milankovic, calculated the eccentricity of the Earth’s orbit, the axial tilt, the axial precession, the orbital inclination, etc. and predicted that the location of the Earth with relation to the Sun should produce changes in the climate in several cycles – 100,000 years, 40,000 years, and 20,000 years.  There is also a 400,000 year cycle.  These predictions fit very well with geological evidence.

One of the major problems with the concept of global warming is, if it is caused by Man, the potential remedies could be catastrophic to society.  If we were to stop using fossil fuels, our society must change drastically.  It is only a dream that solar and wind power can replace fossil fuels.  There are some political facts that are “inconvenient truths.”  The three major CO₂ producers are China, the U.S., and Europe, in that order.  China has recently agreed to consider curbing their fossil fuel use in the next few decades.  America has cut back significantly on the generation of CO₂, but will have a real problem going much farther.  The Europeans have had a real problem meeting their self-imposed goals.  Most of the developing world considers this to be a western problem and that the suggestion that they not develop a society that consumes large quantities of energy to be a plot to keep them poor.  Thus, politics will prevent much from happening on the curtailment of CO₂ generation.

This brings us to the point that we may be asking the wrong question.  Instead of focusing on the elimination of CO₂ releases from our activities, maybe we should be focusing on what actions we should take to be able to live in a warming world.

Comment from RF Alum:  Where is it written that the current temperature is the optimum temperature?  Perhaps people driven away from the coasts by rising water could settle and live comfortably in Greenland again (he typed cynically).