A leading climate scientist argues that overbroad claims by some researchers—coupled with overblown reporting in the media—can undermine the public's understanding of climate issues. Gavin Schmidt, a NASA climate modeler, author and PM editorial advisor, concurs with the consensus view that the planet's temperature is rising due largely to human activity. But, he says, many news stories prematurely attribute local or regional phenomena to climate change. This can lead to the dissemination of vague, out-of-context or flat-wrong information to the public.
"People think that if there's a trend, it has to be connected to this bigger trend," he says. "You often get this kind of jumping the gun." Sometimes researchers are citing a potential connection to global warming to get noticed, he says, and sometimes journalists are focusing on that connection to make the story more compelling. "There's a bit of a backlash amid people who have a brain," says Schmidt. "It's akin to [the media's reporting on] medical studies. It adds to people's confusion."
Here are 5 studies Schmidt points to that made unfulfilled promises, used loose, questionable climate connections to sensationalize a story or predicted events that never came to be.
The Study: In a study released to the public last month and set to be published in the Journal of Geophysical Research in August, a team of American scientists found by gathering wind-speed data across the country that average and peak wind speeds in the Midwest and the East had decreased since the 1970s.
The Fallout: Though the authors acknowledged their study was preliminary, they raised an intriguing possibility—that if dying wind were a true trend, global warming could be the cause. The reasoning was that warming in polar regions, brought on by climate change, would shrink the temperature difference between the poles and the equator, as well as the pressure difference. This would mean that winds would die down, and wind-power generation would be harmed by the very thing its proponents are trying to combat.
The Truth: Despite the delicious irony, Schmidt says, it's far too early to say that the dying wind is even a trend, much less one caused by climate change. Windiness is a complex phenomena with different causes in different places, he says, and is not one that can be measured by a singular cause on a global scale. Winds can change in one area, but if they do, expect to see changes in phenomena related to wind, like temperature gradients, as well. The data don't bear that out, he says, and his climate models don't predict wind changes over the North American continent caused by global warming.
The Study: The thermohaline circulation is crucial to the Earth's climate, acting like a conveyor belt carrying warm water into the North Atlantic and moderating the climate of North America and Europe. Many studies, however, have suggested that freshwater from melting sea ice might have the potential to shut down that circulation. A 2005 study showed a steep slowdown of the circulation between 1957 and 2004.
The Fallout: The idea that thermohaline circulation could come to an end, pushing the planet into a new ice age, exploded into popular culture after it showed up in movies like The Day After Tomorrow (2004) and Al Gore's documentary, An Inconvenient Truth (2006).
The Truth: Schmidt says that what looked like a full-blown trend of the circulation weakening can be explained in part by studies showing that the circulation can vary its strength over many timescales, making it hard to see a real trend in the noise. That doesn't mean that circulation could never be changed, Schmidt says, but the possibility was blown out of proportion. "The Gulf Stream shutting down is such a powerful meme," he says.
The Study: In early 2006, a study in Nature published surprising results that plants were giving off trace amounts of methane.
The Fallout: We know that methane is a far more powerful greenhouse gas than carbon dioxide, so the suggestion that it comes from plants led to a blizzard of headlines suggesting that trees could be contributing to global warming.
The Truth: The researchers balked after the media coverage of their study broke. The scientists said they were widely misinterpreted when it was reported that plants contribute to global warming. Rather, if plants do give off methane, they've been doing it since long before humans were on the scene and their emissions aren't connected to today's anthropogenic climate change. Schmidt says the findings were controversial among scientists from the beginning, because plants had never been known as methane emitters. "Subsequent work has dialed down the magnitude of this new effect tremendously," he says.
The Study: A catastrophic rise in sea level is one of the worst consequences that some climate scientists predict for a warmer world. A study in Science in 2006 noted that temperatures by the end of the 21st century could be comparable to those 130,000 years ago, when global sea levels were about 20 feet higher.
The Fallout: Unsurprisingly, given the implications of the sea level rise, this study was sensationalized with headlines like "London Underwater by 2100 as Antarctica Crumbles into the Sea." In his world tour, Al Gore also picked up the statistic, which led to much backlash both among scientists trying to get the science corrected and among climate skeptics.
The Truth: There's a big gap between saying something is possible and predicting that it will occur, Schmidt says, and the authors didn't predict that climate change would turn London into Atlantis by 2100. As Science's editors said in the same issue, past climate changes should be taken into account when trying to predict future climate change, but they won't be exactly the same. When media and others used the study as a predictive measure‹to say the sea will rise 20 feet in less than 100 years, Schmidt says, that "was a pretty egregious mess-up."
The Study: In 2007, scientists found the oldest authenticated DNA ever, gathered from 400,000-year-old tree and insect samples entombed in the bottom of a Greenland glacier. About half a million years ago, the study concluded, Greenland was a pretty warm place.
The Fallout: When the study came out, Schmidt says, about many people responded to the DNA find itself. But the others keyed onto one sentence in the press release, in which the lead author suggested that the finding meant the Greenland ice sheet was more stable than scientists had previously thought. Because these seeds and DNA specimens were found in the ice sheet, the ice must have been intact for at least a half-million years and survived the warm period 130,000 years ago. This could mean that Greenland is more stable than scientists thought and in less danger from current warming.
The Truth: Schmidt isn't impressed with the claim. The fact that Greenland was hot so recently (geologically speaking) shows that the ice isn't that stable at all, and the latest satellite evidence contradicts the stability claim and shows that Greenland is steadily losing mass.