Every week, a new green initiative arrives at Stanford, from “meatless Mondays” to compact fluorescent light bulbs to Stanford commute club—all of which assume our normal activities damage the environment. Concerns about climate change as a consequence of human activity are particularly relevant now. People who challenge the global warming coalition face ridicule as ‘climate skeptics.’ But is the alleged science behind this issue so clear?
The linchpin of the argument behind anthropogenic climate change—the idea of man-made global warming—is the relationship between carbon dioxide levels and temperature. Typical climate history accounts depict global temperature averages vs. atmospheric carbon dioxide concentration over the last 600,000 years. The two variables appear perfectly correlated. Naturally, we conclude that changes in carbon dioxide drive temperature changes, as Al Gore indicated in An Inconvenient Truth.
But, wait . . . how do we know whether changes in carbon dioxide concentration affect temperature averages, or the reverse? Without further analysis, we don’t.
To address this issue, climate scientists have repeatedly studied periods over which carbon dioxide and temperature dramatically shift—namely, the beginnings and endings of Ice Ages. They have discovered global temperature increases eight hundred years before carbon dioxide concentrations rise, and temperature decreases eight hundred years before carbon dioxide concentrations fall. See papers from any of the following authors to investigate this claim: Petit (1999), Fischer (1999), Indermuhle (2000), Monnin (2001), Yokoyama (2000).
Figure 1 models the correlation between CO2 concentration and global temperature, as typically seen on a 600,000 year scale. Figure 2 represents a similar comparison but is a more useful depiction for understanding causal relationships, as it focuses in on a narrower time scale to portray the repeated lags between temperature changes and CO2 concentration changes.
Believers in man-made climate change tend to provide the 600,000 year diagram but rarely offer the same graph under a smaller time scale. Their portrayal distorts the relationship between temperature and CO2 concentration, hiding evidence to support the reverse conclusion: temperature trends drive CO2 levels. Reported accurately, the data invalidates anthropogenic climate change theory.
In addition to relying on the historical correlation of CO2 concentration and temperature, climate scientists frequently cite computer models as evidence for the causal role of carbon dioxide in the warming trend. The problem with this approach lies in the imprecise nature of climate models. Such models have multiple free parameters which researchers can adjust to skew predictions toward a desired result. It’s possible to aggressively tweak inputs to amplify the role of CO2 in temperature trends.
Models attributing CO2 levels to climate change have yielded miserable predictions over the last two decades, significantly overestimating warming effects. Furthermore, these models contradict solid evidence over the past 600,000 years, particularly most relevant studies of starts and ends of glacial periods. By contrast, models that do not emphasize carbon’s role in driving temperature change agree with historical data and predict warming trends as effectively or better.
Furthermore, when examining temperature change, we must ask: Compared to what? Global warming believers often cite temperature changes from the last 200–1,000 years to the present. But most any time within these centuries represents an abnormally low starting point with respect to the preceding millennia. The period from around 1200–1850 has been called the “Little Ice Age.” Our global temperature increase of about .7ºC in the last 150 years is positioned to overstate carbon effects without controlling for a “normal” starting point. On this topic, NASA Senior Research Scientist Leonard Weinstein’s 2009 article debunking the concept of CO2 feedback is particularly enlightening.
Another myth in the “science” of climate change is the claimed consensus. In response to the International Panel on Climate Control’s report (which was initiated and backed by the United Nations), independent scientists on the Non-Governmental International Panel on Climate Change created a comprehensive reply examining the errors in the IPCC’s report. This reply is called Climate Change Reconsidered, a document which garnered signatures from 31,478 American scientists supporting the statement: “There is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate.” There is not a consensus.
What does this mean for students? Any practice intended to reduce hydrocarbon fuel burning is a futile inconvenience. Email and poster bombardments encouraging students to live sustainably (with the goal of cutting CO2 emissions) are based on flawed reasoning. Stanford students are smart. They would never hassle themselves unnecessarily. Those who do change daily habits to cut carbon emissions merely subscribe to, and often propagate, popular faith.
We have grown up in a society in which the myth of man-made global warming is so thoroughly pervasive, doubt is heretical. But science proves human carbon dioxide emissions are not responsible for global warming. Understanding this fact, it is preposterous for us students to alter our lifestyles or sacrifice the wonderful benefits of technologies that rely on fossil fuels.