UW Professor’s Research Selected as ‘Editor’s Choice Paper’ for Journal’s 50th Anniversary

In celebration of the 50th anniversary of the American Geophysical Union’s journal Geophysical Research Letters, a paper co-written by University of Wyoming Assistant Professor Daniel McCoy was selected by the editor-in-chief as the “Editor’s Choice Paper.”

Geophysical Research Letters is a gold open access journal that publishes high-impact, innovative and timely communications-length articles on major advances spanning all of the major geoscience disciplines.

The paper, “Causes of Higher Climate Sensitivity in CMIP6 Models,” was co-written with Mark Zelinka, a research scientist for Lawrence Livermore National Laboratory at the University of Washington. The paper discusses the ability to predict how much the earth warms in response to changes in greenhouse gas using Earth system models (ESMs).

“I was really pleased to see this paper selected by the Geophysical Research Letters editorial board,” says McCoy, who works in UW’s Department of Atmospheric Science. “At the time when Mark Zelinka reached out to me to collaborate, it was clear that he had identified a big shift in how our models were representing future climate and that it was important to disseminate it to the community.”

Other contributors to the paper were Timothy Myers, who works in the Physical Sciences Laboratory at the National Oceanic and Atmospheric Administration; Paulo Ceppi, a senior lecturer of climate science at Imperial College London; and Stephen Po-Chedley, a research scientist; Peter Caldwell, Climate Modeling Group leader and staff scientist; Stephen Klein, an atmospheric research scientist; and Karl Taylor, director of the Program for Climate Model Diagnosis and Intercomparison, all of Lawrence Livermore National Laboratory.

“When I saw the initial results that cloud feedback had gotten more amplifying in the latest models, I immediately reached out to Daniel for his help in interpreting them since his previous work had greatly influenced my thinking,” Zelinka says. “He provided useful calculations to strengthen our case that changes in the cloud liquid content were a key part of the story in leading to a new class of highly sensitive models.”

The group found that the temperature response to an abrupt quadrupling of atmospheric CO₂ has increased substantially in the latest generation of global climate models relative to previous generations. This is primarily because cloud water content and coverage decrease more strongly with global warming, causing enhanced planetary absorption of sunlight -- amplifying feedback that ultimately results in more warming. Differences in the physical representation of clouds in ESMs drive this enhanced sensitivity relative to the previous generation of models.

“It was really exciting to be part of this study. What Mark and my co-authors showed in this paper is that an important source of ESM uncertainty on a time scale that matters to the near future are these difficult-to-treat, small-scale processes, such as clouds, convection, aerosol and precipitation,” McCoy says. “It allows us to identify and target specific processes that have a lot of leverage on our predictions of future climate for observations and for continued model development and evaluation.”

Since its publication in 2020, the paper has exceeded 1,000 citations, placing it in the top 1 percent of geoscience articles.

UW will host a US Climate Variability and Predictability workshop, titled “Micro2Macro: Origins of Climate Change Uncertainty,” Oct. 28-30. The workshop will address issues related to McCoy’s representation of microscale processes in global ESMs.

McCoy is director of the Perturbed Physics Ensemble Regression Optimization Center for ESM Evaluation and Development (PROCEED), a collaboration among the UW Department of Atmospheric Science; the UW School of Computing; the University of Hawaii-Manoa; Pacific Northwest National Laboratory; and Lawrence Livermore National Laboratory. PROCEED seeks to leverage UW’s unique access to the National Center for Atmospheric Research-Wyoming Supercomputing Center to reduce uncertainty related to subgrid phenomena in ESMs.

For more information about McCoy, go to www.uwyo.edu/atsc/directory/faculty/mccoy.