As if the public debate about global warming wasn't complex enough, a new field in climate research is coming of age, grabbing media attention and spawning seemingly contradictory headlines.
The work, called attribution research, doesn't challenge the scientific consensus that climate change is happening. Instead, it strives to understand the regional effects of global warming by determining whether increased greenhouse gas levels did—or didn't—cause a particular weather event. But the findings can be confusing. For instance, scientists say that climate change made Hurricane Sandy worse, but that it had nothing to do with historic floods in Thailand. Warming probably didn't cause this year's severe winter storm, Nemo, but it may have supercharged it. It caused some droughts, but not others.
Adding to the confusion is a trend that worries some experts: People on both sides of the climate divide tend to promote only those attribution studies that support their beliefs. Whether a conscious decision or not, this selective use of research is further polarizing the national conversation on climate change, experts told InsideClimate News.
"When a new study comes out, it should be informing our understanding of the topic," said Gretchen Goldman, an analyst at the Union of Concerned Scientists who studies how research is used to inform policy decisions. "But the reverse is happening. People who have predetermined opinions about climate change are only searching for information that supports their views."
The treatment of two stories published by the Associated Press last month, less than a day apart, illustrates the trend.
The first, titled "Global Warming Didn't Cause Big U.S. Drought," was about a report by five federal agencies, led by the National Oceanic and Atmospheric Administration, which concluded that climate change didn't cause the 2012 drought. The second, "Greenhouse Gases Make High Temps Hotter in China," covered work by Chinese and Canadian researchers that found the highest temperatures in China have been made worse by global warming.
Both articles were written by Seth Borenstein, a respected science journalist. Both studies underwent a rigorous scientific process and peer review. Neither study challenges the consensus that the earth is warming because of human activities.
"Attribution research is about the details of climate change, not whether it is happening," said Martin Hoerling, a research meteorologist at NOAA and co-author of the drought study. "The warming of the planet is well founded in evidence. We aren't arguing otherwise."
However, in the days following the articles' publication, each side in the climate debate promoted the story that best fit their argument.
Global warming skeptics blogged and tweeted the drought findings as evidence that climate change isn't happening. The skeptic site Watts Up With That, run by meteorologist Anthony Watts, said the research "makes it pretty clear all the hype about last summer's drought was nothing but that: hype." Conservative blogger and skeptic Tory Aardvark wrote that "pesky natural variations are back and they always ruin a good warmist fear story."
Advocates of climate policy took a different approach: They largely ignored the study or drew attention to its flaws.
Joe Romm, a senior fellow at the Center for American Progress and editor of the site Climate Progress, wrote that the report is "needlessly confusing, scientifically problematic, and already leading to misleading headlines."
Bill McKibben's 350.org campaign, a grassroots group pushing for drastic emissions reductions, did not tweet about the drought research or mention it on its website, although McKibben said the omission wasn't a conscious one. "What goes up on [Twitter] isn't the subject of a lot of fevered and close debate," he wrote in an email.
The China story created a similar divide.
Environmental groups used it as an example of runaway global warming. Conservation International, a nonprofit environmental organization, tweeted "When people say greenhouse gases put our climate on steroids, this is what they mean." McKibben's group tweeted, "China beginning to feel heat from warmer planet," with a link to Borenstein’s story.
Watts Up With That and other climate skeptic sites largely stayed silent about the China research, though the skeptic site JunkScience said the findings were "based on ClimatePlayStation (i.e., modeling)."
Watts, editor of Watts Up With That, declined to comment for this story.
Just a handful of news organizations, including Time, Salon, and the Daily Climate, covered both research papers.