The severity of two record-setting hurricanes hitting the nation’s coasts in less than two weeks is shining a spotlight on the importance of climate assessment, the process by which knowledge on climate change, such as its influence on extreme events, is evaluated and communicated. A 2014 report by the National Climate Assessment (NCA) warned that intense hurricanes and heavy rain are expected to increase as the climate warms. The NCA, one of a number of organized efforts among scientists and decision-makers to elucidate the causes and impacts of major environmental problems, has been a hot topic of discussion in recent weeks following a decision by the Trump Administration to disband a connected federal advisory committee and fears from scientists that its latest report's findings may be suppressed.

"Assessment is a powerful process for understanding how the climate is changing, what risks it poses for people and the planet, and how societies might respond,” said Katharine Mach, a senior research scientist at Stanford’s School of Earth, Energy & Environmental Sciences. “But we haven’t done the best job of explaining to the public what assessment is and why it’s important."



In a new paper published in the journal Annual Review of Environment and Resources, Mach and coauthor Chris Field, director of the Stanford Woods Institute for the Environment, take a deep dive into the methods and approaches to assessment of major environmental issues. Assessment provides definitive summaries of knowledge on topics such as ozone depletion, biodiversity loss, and climate change, supporting decisions on responses from governments, businesses and other sectors. However without dedicated attention, it can be influenced by bias, politics, and miscommunication between scientists and decision makers. Learning from the successes and failures of the past, the researchers recommend ways to improve the process.

EPA Administrator Scott Pruitt is adding fuel to the fire on assessment with plans for a public debate to reevaluate and challenge the scientific understanding of climate change. The EPA’s approach would involve a “red team” of researchers with dissenting views on mainstream climate science critiquing the work of a “blue team” of climate scientists, who represent the consensus view that human activities are the dominant cause of global warming.

Proponents of the plan argue it would allow the public to see a transparent exchange of ideas on climate science and expose biases. Mach and Field explain that, indeed, transparent scientific assessment is of paramount importance and “red teaming” is also key – its essence central to the processes of peer review and assessment of climate change science. However, they argue it’s critical that “red teaming” not become an excuse for creating political theater and sowing doubt on well-established facts. They explain "red teaming” would be more appropriate, if, for example, it built from the nearly 30 years of comprehensive global assessment of climate change risks and challenged thinking that limits how society might respond.

“The science on climate change is clear and the evidence is overwhelming,” said Field. “Recent challenges to climate science underscore that we as scientists can’t only focus on improving science if we want better climate policies. To make knowledge actionable on the hardest issues, we also need to be driving meaningful innovation in how science is made relevant to decisions.”

Mach and Field, who both worked on the Intergovernmental Panel on Climate Change (IPCC) assessment that provided the overall understanding of climate change risks and response options underpinning the Paris Agreement, focus on what they consider the hardest challenges. For example, providing specific projections for how much sea levels might rise this century is difficult because of uncertainties about how fast the West Antarctic Ice Sheet could collapse. It's also impossible to figure out an ideal pathway for reducing emissions of greenhouse gases because future technology costs are uncertain. Additionally, different stakeholders in the process have different goals that go far beyond climate.

The study points out that within assessment frameworks there are things that can be done to account for bias in how information is weighted on particular issues, such as using opinion surveys to clarify the different worldviews and values of both scientists and decision-makers. Documenting individual judgments of experts on the evidence can provide context for what makes it into policy summaries. The authors also discuss how training and improved communication between scientists and decision-makers can lead to better results.

Assessments, the researchers explain, are not just vehicles to list numerical facts about rising temperatures, melting ice and increasing carbon emissions. Instead, the authors describe a social process between scientists and decision-makers that engages each in unfamiliar roles.

“There’s this perception among scientists that all we need to build public support and convince leaders to act on climate is to do more and better science,” said Field. “But action on climate can depend as much on perceptions of a fair and inclusive assessment process as on scientific results.”

The paper is part of a larger effort at Stanford to innovate, test, and deliver new assessment approaches. The Stanford Environment Assessment Facility(SEAF), directed by Mach, tackles issues such as conflict in a changing climate, pathways for deep decarbonization, and the resilience of our investments in climate change response.

“Assessment can be an empowering way to support interactions and engagement among scientists and the many people managing environmental risks,” said Mach. “We’ve got a lot of lessons to work from, and a lot of opportunities to tap.”

See related research brief for more details.

Katharine Mach is also an adjunct assistant professor at Carnegie Mellon University, visiting investigator at the Carnegie Institution for Science, and director of the Stanford Environment Assessment Facility at the Stanford Woods Institute for the Environment. Chris Field is also the Melvin and Joan Lane Professor for Interdisciplinary Environmental Studies, the Perry L. McCarty Director of the Stanford Woods Institute for the Environment, professor in Stanford’s School of Earth, Energy & Environmental Sciences and the Department of Biology, and senior fellow at the Precourt Institute for Energy.