Warmest in 4,000 Years? Not So Fast!

Published March 18, 2013

The mainstream media is reporting in breathless fashion about a new paper claiming current temperatures are their warmest in 4,000 years. Already, however, objective scientists are reporting serious flaws in the paper. The media may wish to paint a picture of runaway global warming, but the science tells a completely different story.

Recently graduated Ph.D. student Shaun Marcott has published a paper claiming he compiled a proxy temperature reconstruction indicating current temperatures are their warmest in at least 4,000 years. Proxy temperature reconstructions require careful scrutiny because the proxies are not direct temperature measurements, but represent other data and factors that may or may not have a close correlation with past temperatures. Some proxies are better than others. Also, an agenda-driven researcher can easily cherry-pick certain anomalous proxies that support a predetermined conclusion while ignoring a much larger set of proxies that tell a different story.

Although objective scientists have had little time so far to dig into the meat of Marcott’s data, methods and conclusions, their initial observations are devastating. Don Easterbrook, geology professor emeritus at Western Washington University, has published two papers summarizing and documenting many of the already discovered flaws in Marcott’s reconstruction. Easterbrook reports that at least one more such paper is on the way, as he and other objective scientists find more and more flaws and areas of concern in Marcott’s reconstruction as they continue to analyze it.

Easterbrook points out that 80 percent of the data used by Marcott reflect oceanic data, not atmospheric temperatures. “Thus, they may reflect temperature changes from ocean upwelling, changes in ocean currents, or any one of a number of ocean variations not related to atmospheric climates,” Easterbrook writes. Given the opportunities for cherry-picking anomalous data to support a predetermined conclusion (such as objective scientists found regarding the discredited Michael Mann hockey stick), Marcott’s heavy dependence on oceanic rather than atmospheric proxies “in itself means that the Marcott et al. temperatures are not a reliable measure of changing atmospheric climate,” Easterbrook reports.

Easterbrook also notes that Marcott recycled Mann’s proxies to help compile the small portion of Marcott’s land-based proxies. Discredited proxies by any other name are still discredited proxies.

Perhaps most damaging, Easterbrook observes that many other published studies and data, including analysis of extremely reliable Greenland ice core data, completely contradict Marcott’s asserted proxy data.

When many temperature studies, including studies presented by the United Nations Intergovernmental Panel on Climate Change, indicate current global temperatures are cooler than the vast majority of the past 4,000 years, and then an outlier study with quickly identified serious flaws claims exactly the opposite, one would think the media would make note of the discrepancies. Unfortunately, the media has demonstrated little interest in doing so.

Read my full article explaining the flaws in the Marcott paper here at Forbes.com.