Climate experts surveyed for views on future warming

A new survey of climate experts reveals that a majority believes the Earth to be headed for a rise in global temperatures far higher than 2 degrees Celsius above pre-industrial levels.

The study, published Sept. 12 in Communications Earth & Environment, is based on a survey of more than 200 authors of reports from the Intergovernmental Panel on Climate Change (IPCC). More than two-thirds of respondents said they believe the world may achieve net-zero emissions of carbon dioxide during the second half of this century. This indicates some optimism that mitigation efforts may be starting to bend the emissions curve toward what would be needed to achieve the Paris Agreement's temperature goal.

“These experts’ answers are consistent with the success and further strengthening of current climate policies, which may be encouraging to those concerned about the negative impacts of climate change that we’re already seeing,” said study co-author Steve Davis, a professor of Earth system science at the Stanford Doerr School of Sustainability.

A majority of survey respondents also acknowledged the potential for removing carbon dioxide from Earth’s atmosphere, with a median response indicating belief that the technology could remove up to five gigatons of carbon dioxide annually by 2050. That is at the lower end of the range believed to be necessary to meet the 2015 Paris Agreement’s goal of keeping global warming well below 2 degrees Celsius above pre-industrial levels, and preferably below 1.5 degrees Celsius.

“We wanted to survey some of the top climate experts in the world to get some insight into their perceptions of different future climate outcomes,” said lead study author Seth Wynes, an assistant professor of geography and environmental management at the University of Waterloo. “These scientists also engage in important climate change communication, so their optimism or pessimism can affect how decision-makers are receiving messages about climate change.” 

Gauging beliefs

The 211 survey respondents were generally pessimistic about the likelihood of reaching the Paris targets given current policies, with 86% estimating warming above 2 degrees Celsius by 2100. The median estimate was 2.7 degrees Celsius, which is expected to have catastrophic consequences for people and the planet.

Co-author Damon Matthews, a professor in Concordia University’s Department of Geography, Planning and Environment, noted that this does not mean such extreme warming is inevitable.  “These responses are not a prediction of future warming, but rather a gauge of what the scientific community believes. The answers are surprisingly consistent with previous estimates of what would happen if our current climate policies continued without any increase in ambition, which range from about 2.5 to 3 C,” he said.

Along with questions about the likelihood of future climate outcomes, the respondents were also asked to estimate their peers’ responses to the same questions. 

“There was a strong correlation between what people believe and what they sense their peers believe,” Wynes said. “They had a bias to see their beliefs as representative of the larger group. This can indicate an overconfidence in their own beliefs, so we think this is a good opportunity for them to reevaluate what their peers actually believe.”

Working with data, not policy

An IPCC author himself, Matthews admits that scientists’ views on possible climate scenarios are valuable, but other perspectives on the issues around climate change are necessary if we hope to slow it.

“Climate scientists certainly have expertise in climate systems and energy transitions, but it will be policy implementation and societal change that actually determine how quickly emissions drop,” he said. “Ultimately, the decision as to what we do and how we respond to the climate challenge is up to policymakers and the public that they represent, and I think the full range of outcomes is still very much on the table.”

Read the study in Communications Earth & Environment: Perceptions of carbon dioxide emission reductions and future warming among climate experts

Additional authors not mentioned above are affiliated with George Mason University, Imperial College London, the International Institute for Applied Systems Analysis, and Simon Fraser University.

This research was supported by the Natural Sciences and Engineering Research Council of Canada and the Social Sciences and Humanities Research Council of Canada.

This story was adapted from an article originally published by Concordia University.