"Global warming: our best guess is likely wrong," declared the headline of a press release from Rice University in Texas last week. The release, concerning a study on an abrupt climate event that occurred about 55.5 million years ago, stated further, "Unknown processes account for much of warming in ancient hot spell."
The attention-grabbing headline strongly implied that the consensus view of climate scientists -- that increasing amounts of greenhouse gases in the atmosphere are the main culprit for the planet's warming trend -- is wrong. In fact, the study says no such thing. Rather, it reaches opposite and narrower conclusions: that greenhouse-gas emissions could lead to other climate feedbacks that may warm the climate more significantly than previously thought.
Not surprisingly, the press release led to numerous misinterpretations of the study by climate change skeptics and the mainstream media alike. Overall, the episode offers a case study of how not to publicize a climate change study.
Keep reading for more on the misleading nature of Rice University's press release...
First, let's consider what the study in question actually found.
The study -- appearing in the journal Nature Geoscience and by researchers from the University of Hawaii at Manoa, the University of California at Santa Cruz and Rice University -- examined the mechanisms behind the so-called "Paleocene-Eocene Thermal Maximum," also known as the "PETM." The PETM was an approximately 10,000-year period of rapid and significant warming, during which the climate warmed by up to 13 degrees Fahrenheit.
The authors of the study used records of ancient climate contained in ocean sediment cores, as well as a computer model of the carbon cycle to determine how much of the ancient warming may have been caused by increased amounts of carbon dioxide, which is the main greenhouse gas scientists are concerned with today, and how much was due to other, largely unknown factors.
What they found was surprising: increases in carbon dioxide alone could only have caused less than half of the ancient warming that is thought to have taken place during the PETM, a conclusion which the researchers called "an enigma." This could mean that other positive climate feedbacks kicked in to further boost temperatures. "The origin of the additional warming is unknown at present," the study states.
The authors speculated, as other researchers have before them, that the increase in carbon dioxide levels and related warming temperatures set in motion other warming mechanisms in the climate system. Methane, a more potent but less abundant greenhouse gas than carbon dioxide, is the chief suspect in this hypothesis. Large amounts of methane are stored in solid deposits in the deep ocean as well as in Arctic permafrost.
As David J. Beerling of the University of Sheffield in the U.K. wrote in a commentary accompanying the study, "The upshot of the study... is that forecasts of future warming could be severely underestimating the extent of the problem that lies in store for humanity as greenhouse gases accumulate in the atmosphere."
The study itself concluded, "... our results imply a fundamental gap in our understanding of the amplitude of global warming associated with large and abrupt climate perturbations," and that "this gap needs to be filled to confidently predict future climate change."
The involvement of unknown positive feedbacks during ancient times and their potential role in modern warming was absent from Rice University's press release and several related media reports. Instead, the stories focused on the notion that climate models don't accurately represent the links between carbon dioxide and warming temperatures. This angle, which is not supported by the study itself, played right into the hands of climate change skeptics.
Marc Morano of the climate skeptic site climatedepot.com characterized the study with a blaring headline: "Study shakes foundation of climate theory! Reveals UN models 'fundamentally wrong' - Blames 'Unknown Processes' -- not CO2 for ancient global warming." Apparently, Morano read only the press release and not the study and its related commentary. He quoted Rice's release about seven times in his story.
USA Today also ran a story that was a regurgitation of the press release, and failed to note the study's implication that future warming could be worse than currently projected because other climate feedbacks, which are not yet well understood, could kick in. USA Today weather editor Doyle Rice wrote, "Could the best climate models -- the ones used to predict global warming -- all be wrong? Maybe so, says a new study published online today in the journal Nature Geoscience."
Reuters, however, provided a more complete account of the study and its implications, quoting co-author Richard Zeebe of the University of Hawaii as saying, "If this additional warming which we do not really understand, was caused as a response to the CO2 warming, then there is a chance that also a future warming could be more intense than people anticipate right now." Zeebe stated that human emissions of carbon dioxide could exceed the swift pace of the PETM event.
The nonprofit Union of Concerned Scientists published a short analysis on its Web site to counter what it saw as misinformation spread by the press release, skeptic Web sites and the media. The study "provides evidence that current climate models are underestimating the amount of warming that an increase in atmospheric carbon dioxide can cause. In other words, the potential consequences of global warming are likely worse than what scientists are predicting," UCS stated.
It is doubtful that Rice purposely intended for the media to miss a key implication of the study's results, and for the study to be featured on climate skeptic Web sites as evidence of why climate change fears are unfounded. Nevertheless, the release wound up doing a disservice to the university's own researcher, whose quotes in the media clearly indicated that the study showed more reason for concern about a changing climate, not less.