Are Americans losing interest in global warming? Hardly.

A study of Google Trends data finds that English-speakers' rate of Googling climate-change-related phrases steadily declined since 2007. But according to polls, Americans are more, not less, worried about global warming.

Have media-fueled events like "Climategate" made people less concerned about global warming? A pair of researchers have set out to answer this question by studying what people are Googling, and found a trend that has generated its own flurry of media confusion.

Since 2007, they found, English speakers have been Googling the terms "global warming" and "climate change" a bit less each year. And two erstwhile media kerfuffles – the hacking of climate scientists' emails at the University of East Anglia, which became known as "Climategate," and an irregularity in an intergovernmental study of the Himalayan glacier melt rate – have caused temporary spikes in searches for "global warming hoax."  But the slow decline of climate-related Google searches has ridden out those disturbances, its angle unchanged.

"We document here a strong decline in public attention to climate change since 2007," conclude the authors, in a May 20 article in Environmental Research Letters.

This conclusion, however, seems to conflict with survey-based polling data about what actually worries people. According to Ed Maibach, director of George Mason University's Center for Climate Change Communication (CCCC), Americans' concern with global warming has risen steadily since 2009. Asked questions like, "How worried are you about global warming?" Americans' self-reported levels of worry have risen, not fallen. Last October, 53 percent of Americans said they were "somewhat" or "very worried" about global warming.

Why the disconnect? For one thing, surveys tend to assess specific feelings and opinions, while Google searches reflect all kinds of activities – including homework assignments, research, and the settling of bets.

"I don't see a decrease in Google searching and an increase in public concern as being discrepant," says Dr. Maibach. "One possible reason driving the decline in searches, is that more people feel that they have enough information to have made up their minds."

The CCCC's most recent semesterly polling data corroborate this, by pointing to a shrinking number of global-warming "undecideds."  Between April and October 2013, the number of people who believed global warming is real remained steady, at 63 percent, while the number who did not believe in global warming swung upward by 7 percentage points. By October, only 14 percent of Americans said they "don't know."

These shifts tend to be driven largely by news coverage, says Maibach, and his colleagues' recent research indicates that "public concern about climate change is particularly sensitive to the cues of political actors. So, when our politicians are talking about it, it tends to be covered in the news. And when those politicians are speaking about it skeptical terms, it tends to drive public concern downward."

Maibach says that news coverage of climate change has plummeted since 2007, alongside Google searches. Yet despite its centrality in driving opinions, concern has risen. Why?

"Our data suggests that Mother Nature has been teaching the American people about climate change through extreme weather over the past few years. And that much of the news media focus in the past several years has been on the relationship between climate change and extreme weather," he says. "People are learning through their first-hand, lived personal experience." Unlike abstract, statistical information, experiences like these serve as "instantaneous, effortless" drivers of thought.

Why did the researchers who used Google Trends data arrive at a conclusion that so squarely contradicts Maibach's numbers?

It turns out they used methodology from a British study that may not apply to Americans at all, to infer cultural "interest" from Google search data.

"Google Trends is considered a robust and valid indicator for tracking interest, attention, and public opinion over time," they write. "Importantly, Google Trends data have been validated for the term 'global warming' relative to independent longitudinal polling data," they continue, citing the work of Oxford University postdoctoral researcher Jonathan Mellon.  

But Mellon's work established that Google Trend searches for the term "global warming," made in the UK, rise and fall alongside the proportion of Brits who voice environmental concerns when asked, "what is the most important problem facing your country?" During moments when more people in the UK cite global warming, climate change, or the environment as their top concern, he found, more people were Googling "global warming."

But that analysis works in part because a significant chunk of Brits actually list the environment as the most important problem, whereas very few Americans respond the same way. The fewer than 10 percent of Americans who cite the environment as their top concern, says Mellon, are not enough to validate the significance of fluctuating Google Trends in the US – let alone across the English-speaking world.

Global warming is a secondary or tertiary concern for a vast majority of Americans, if it is a concern at all. And Mellon's tests of validity say nothing about how secondary concerns interact with Google trends.

Without knowing such an association exists, a surge or ebb in Google searches could indicate many things, other than support or concern for an idea.

In the 2012 Republican primaries, "Google searches for Ron Paul outstripped those of any other candidate despite the fact that he failed to win a single primary contest," Mellon pointed out in a 2013 article on where and when Google Trends can be used to gauge an issue's importance to people.

Google Trends has opened up a wide avenue for learning what people have been researching across time and space – and unlike telephone polling, it costs nothing. "I think overall this paper is a step in the right direction in terms of how people are using Google Trends," Mellon told the Monitor.

But, he says, "If [Google Trends and survey data] are not showing the same pattern, you've got to take the survey data over the Google Trends data."  With Google data, "you don't know who the searchers are, and you don't you know what was in their minds when they searched for the terms."