Experts Expose Flaws in Global Warming Extinction Predictions

Published March 1, 2004

A January 8 article in Nature magazine created a media sensation by predicting global warming will cause between 15 and 37 percent of the Earth’s species to go extinct by the middle of this century unless immediate and drastic action is taken.

But no sooner did the article gain the attention of the popular media than experts exposed its serious flaws.

The article, given extensive coverage in virtually every major newspaper in the country, claimed only a major shift in economic policy and a rapid implementation of new technologies would forestall a monumental die-off of species. After studying a sample of plants and animals around the globe, and then using computer programs to predict twenty-first century global warming, the authors claimed more than a million species will disappear by the year 2050.

Lead author Chris Thomas claimed the next few decades will see one of the worst mass extinctions since a meteor wiped out the dinosaurs 65 million years ago. “The midrange estimate is that 24 percent of plants and animals will be committed to extinction by 2050,” Thomas told the Washington Post. “We’re not talking about the occasional extinction–we’re talking about 1.25 million species. It’s a massive number.”

Massive Number of Problems

It did not take long, however, for Virginia state climatologist Patrick Michaels to identify major flaws in the study.

“There are a massive number of glaring problems” with the study, observed Michaels, who is a past president of the American Association of State Climatologists and was program chair for the Committee on Applied Climatology of the American Meteorological Society. “This is evidenced by the rapid turnaround for the manuscript, with acceptance in final form a mere five weeks after original submission. No one can clear revisions through 19 authors in that time unless there weren’t many revisions suggested, or, if there were, they were ignored by the journal’s editors in a rush to publication.”

Added Michaels, “acrimonious debates about what should or should not be published about global warming are the rule rather than the exception, simply because papers are being published–on many sides of the issue–that can be shredded after only a cursory review. Unfortunately, the debate may have started with Nature itself.

“In 1996, conveniently a day before the U.N. conference that gave birth to the Kyoto Protocol, Nature published a paper purporting to match observed temperature with computer models of disastrous warming. It used weather balloon data from 1963 through 1987. The actual record, however, extended (then) from 1958 through 1995, and when all the data were used, the troubling numbers disappeared.

“Since that famous incident, people have been very leery of what major scientific journals publish on global warming. The Thomas extinction paper only throws more fuel on an already roaring inferno.”

“You have to take the numbers with a grain of salt,” agreed Lewis Ziska, a scientist with the U.S. Agricultural Research Service.

The analysis was based on “a lot of steady state assumptions that lead it to the most pessimistic forecast,” added Daniel Botkin, a research professor for the department of ecology at the University of California at Santa Barbara.

Michaels pointed out many specific flaws with the article’s methodology and basic assumptions. Observed Michaels:

  • The article’s best-case scenario projects warming of 0.8º C in the next 50 years and produces an extinction of roughly 20 percent of the sampled species. According to Michaels, surface temperatures already have risen this amount in the past 100 years … but there is no evidence of massive climate-related extinctions.
  • Global climate models, in general, predict a warmer surface and an increased rate of rainfall. That scenario leads to expansion of global rainforests, where the greatest number and most diversity of species exist. Trading virtually lifeless polar ice sheets for expanding tropical rainforests creates a future climate with a general character that is more, not less, hospitable for biodiversity.
  • Temperatures have been bouncing up and down a lot more than 0.8ºC during the past several hundred thousand years. The Nature article’s published methodology implies there are large extinctions for each and every increment of change, whether the temperature goes up or down. Applying that method to all the temperature changes that have taken place would suggest just about every species on Earth should be extinct.

Stacking the Deck

“There are several reasons this claim should be laughed out of the court of public opinion,” observed Iain Murray, a senior fellow at the Competitive Enterprise Institute. Murray pointed out the Nature article assumed changes in climate would lead to shrinking habitats, which would result in catastrophic die-offs of species. However, “The Earth is not shrinking. The reduction of one area of habitat does not mean that it is replaced by void. Other habitats expand.

“And so far,” Murray continued, “all the evidence we have points not to desertification or other changes to less-hospitable climates because of global warming. Instead, the increase of carbon dioxide in the atmosphere seems to have led to a 6 percent increase in the amount of vegetation on the Earth. The Amazon rainforests accounted for 42 percent of the growth.

“To model only reductions in habitats and not expansions accounted for by global warming stacks the deck. The researchers created a model that dictated global warming will cause extinctions. Surprise, surprise! When they ran the model that’s exactly the result they got.”

Murray backed up his observations with some real-world examples. “The wholesale deforestation of the Eastern United States (prior to the twentieth century), for example, seems only to have caused the extinction of one species of bird. In Puerto Rico, the island’s loss of 99 percent of its forest cover caused the loss of 7 out of 60 species, but after the deforestation, the number of bird species on the island actually increased to 97. The species-area relationship (plotted as a linear function in 1859) seems to be a poor model on which to base extinction rates.”

“What is surprising,” summarized Michaels, “is that something with so many inconsistencies and unrealistic assumptions made it unscathed through the review process in such a prestigious journal as Nature. The politicization of scientific papers on global warming and the tendency of science journals to rush to judgment must end.”

James M. Taylor is managing editor of Environment & Climate News. His email address is [email protected].