Scientists don’t doubt that climate change is happening, or that humans are mainly responsible for it. And over the years, scientific certainty about climate change has increased. But how well are the media reflecting this?

Perhaps not that well. New research shows US newspapers are increasingly suggesting that there is room for doubt about climate science through the language they choose.

The paper, published in the journal Environmental Communication, examined how newspaper articles about the Intergovernmental Panel on Climate Change (IPCC)’s 2001 and 2007 climate science reports conveyed uncertainty.

The team from the University of Colorado Boulder chose two newspapers each from the US and Spain – the left-leaning New York Times and El País, and the right-leaning Wall Street Journal and El Mundo. The idea was to test US newspaper coverage against that from a country with a much less polarised climate debate.

To tease out whether – and how – the articles conveyed uncertainty, the researchers looked for ‘hedging’ words that typically suggest uncertainty – words like ‘almost’, ‘speculative’, ‘controversial’, ‘blurry’ and ‘disagreement’. In all, they identified 1193 hedging terms in the coverage.

More hedging about science

The authors were surprised to find newspapers increased their use of hedging language in covering the 2007 report even though “the scientific consensus that climate change is happening and that humans are contributing to it has substantially strengthened over time,” says lead author Adriana Bailey.

Although the 2007 IPCC report conveyed greater certainty about the role of humans in climate change, the researchers found the amount of hedging language either stayed the same (the Wall Street Journal and El País) or increased with time (the New York Times and El Mundo).  The paper says:

“This finding does not suggest that newspapers failed to communicate improvements in scientific understanding. Rather, as they did so, they also dedicated more word space to remaining uncertainties about the science and about the panel responsible for synthesizing climate information.”

Overall, however, the two US newspapers used significantly more hedging and qualifying language in both 2001 and 2007, the researchers found.

The researchers also examined the tone of the hedging language used in newspaper reports. They found that negative language criticising the IPCC or the science – words like ‘discredit’ and ‘speculative’ – increased over the release of the two reports.

While the US newspapers chose negative language much more frequently, their use increased in the Spanish publications between 2001 and 2007 – especially words indicating debate, disagreement and skepticism.

So while US newspapers have given more room to hedging language – especially negative hedging language – it has been on the increase in Spanish news, too.

IPCC communication 

The researchers also wanted to test whether IPCC efforts to clarify the way it talks about uncertainty had any effect on newspaper reporting. After the body’s third assessment report, scientists Stephen Schneider and Richard Moss worked on a framework for talking about uncertainty in the 2007 climate assessment.

This included creating a scale of likelihood for making statements about climate science, ranging from ‘Exceptionally unlikely’ for less than one per cent probability to ‘Virtually certain’ for over 99 per cent probability. The framework also recommends using numerical ranges to communicate the possible outcomes of climate change.

Despite giving more space to uncertainties – and having a more negative tone overall – US newspapers seem to have increasingly taken the IPCC’s recommended language on board. The use of the adjective ‘likely’ more than tripled between 2001 and 2007, and the use of numerical ranges did too.

Trends in coverage 

The researchers identified two important trends in how the newspapers covered the reports.

Although the US newspapers increasingly adopted language choices used (more frequently with time) by IPCC scientists and reported greater partial improvements in climate science in 2007, compared with 2001, they also increasingly “constructed” uncertainty in two surprising ways.

First, newspapers increasingly highlighted differences between IPCC reports, in effect presenting results that seem disparate. Second, they increasingly highlighted where observations failed to match scientific predictions.

For example, comparing the 2007 IPCC report to the one before it, the Wall Street Journal writes:

“Yet the real news in the fourth assessment from the Intergovernmental Panel on Climate Change (IPCC) may be how far it is backpedaling on some key issues”.

What the newspaper portrays as ‘backpedaling’ a scientist might describe as progression in their field of research. As Bailey says:

“Making sense of surprising observations is part of the scientific process; it’s how we build knowledge. Yet news stories don’t often provide readers with the background information necessary to understand this. As a result, news articles may create a sense of uncertainty that doesn’t accurately represent the state of scientific understanding.”

What’s next 

The study raises important questions about how climate science is presented in the public sphere, Bailey says:

“One of the key questions this study raises is why has the amount of hedging and qualifying language either remained the same or increased with time? Is it because newspapers are increasingly reporting about the scientific details of climate change? Or because climate change has become a politicised topic?”

In a world where reducing uncertainty around scientific issues is seen as necessary for political process, this report suggests that journalists have power to change the way science discourse plays out in the public arena.

How Grammatical Choice Shapes Media Representations of Climate (Un)certainty, Adriana Bailey, Lorine Giangola, Maxwell T. Boykoff, Environmental Communication, Vol. 8, Iss. 2, 2014