Climate Variation is the Norm, not the Exception

by William Yeatman on February 18, 2003

in Science

A new report by Dr. David Wojick, which reviews six major National Academy of Sciences studies published over the last five years, argues that a new understanding of climate change has emerged as scientists have grappled with the question of mans influence on the climate.

Wojick states, “The issues in the NAS reports and recent research are far more fundamental and clash with an underlying premise of much climate modeling over the past decade that climate over the past century and a half has been effectively constant and any changes are primarily because of mans activity.”

One of the NAS reports, Decade-to-Century-Scale Climate Variability and Change: A Science Strategy, published in 1998, effectively debunks that premise. “The evidence of natural variations in the climate system which was once assumed to be relatively stable clearly reveals that climate has changed, is changing, and will continue to do so with or without anthropogenic influences.”

The review goes on to quote several more passages from NAS studies, which simply do not offer any confirmation of the claims that the science is settled. The previously mentioned study also states, “Without a clear understanding of how climate has changed naturally in the past, and the mechanisms involved, our ability to interpret any future change will be significantly confounded and our ability to predict future change severely curtailed.”

Another NAS report, The Atmospheric Sciences: Entering the Twenty-First Century, also published in 1998, states, “Large gaps in our knowledge of interannual and decade-to-century natural variability hinder our ability to provide credible predictive skill or to distinguish the role of human activities from natural variability.” In 2001, the NAS admitted in a study titled, Climate Change Science: An Analysis of Some Key Questions, that “the observing system available today is a composite of observations that neither provide the information nor the continuity in the data needed to support measurements of climate variables.”

Far from being settled, the science is still in its infancy. The NASs Global Environment Change: Research Pathways for the Next Decade, published in 1999, argues that, “Climate research is only at the beginning of its learning curve, with dramatic findings appearing at an impressive rate. In this area even the most fundamental scientific issues are evolving rapidly.”

The NAS studies reveal, according to Wojick, that there has been a quiet revolution in climate science. “It seems that we have discovered or confirmed a number of natural mechanisms of climate change, at least ten in fact. These mechanisms provide alternative, competing explanations for global warming; alternative to, and competing with, the theory of human-induced warming. Also alternative to, and competing with, each other.

Each of these mechanisms can in theory explain all of the changes in 20th century climate. Human greenhouse gas emissions are therefore just one of many alternative hypotheses. In addition, the evidence for warming due to greenhouse gas emissions is no greater than for any of the other mechanisms” (Electricity Daily, February 3, 2003). As a result of this revolution, increases in our understanding about climate change have been paralleled by increases in the uncertainty about mans contribution, if indeed there is one.

The mechanisms include solar variation, emergence from the Little Ice Age, lunar energy variation, internal oscillations (such as El Nio), Milankovitch forcing (variations in the Earths orbit), ocean variation, biospheric variation, cryogenic variation (variations in the amount and distribution of ice), surface versus satellite temperature variation, and aerosol forcing mechanisms.

Wojick concludes that, “We do not know the extent of climate change in the past, we do not know why climate changes, and we must focus our research on this issue. Only then can we integrate the potential role of past increases in GHG [greenhouse gas] emissions into recent climate history, and only then can we begin to assess the outlook for future climate.”


Christopher Essex of the University of Western Ontario and Ross McKitrick of the University of Guelph, will give a Cooler Heads Coalition congressional and media briefing on their new book, Taken By Storm: the troubled science, policy, and politics of global warming, on Thursday, February 27, from 2:30 to 4:00 PM in Room 406 of the Senate Dirksen Office Building. Reservations are requested. To attend, please contact Myron Ebell at or (202) 331-2256. Include your name, telephone number, e-mail address, and institutional affiliation. Registered attendees will receive copies of the book, compliments of the Competitive Enterprise Institute.

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