From Scripps Institution of Oceanography
Research Highlight: Arctic Sea Ice Loss Likely To Be Reversible
Scenarios of a sea ice tipping point leading to a permanently ice-free Arctic Ocean were based on oversimplified arguments
New research by Till Wagner and Ian Eisenman, scientists at Scripps Institution of Oceanography, UC San Diego, resolves a long-running debate over irreversible Arctic sea ice loss.
Ever since the striking record minimum Arctic sea ice extent in 2007, the ominous scenario of a sea ice tipping point has been a fixture in the public debate surrounding man-made climate change and a contingency for which Arctic-bordering countries have prepared.
For decades, scientists have been concerned about such a point of no return, beyond which sea ice loss is irreversible. This concern was supported by mathematical models of the key physical processes (known as process models) that were believed to drive sea ice changes. The process models forecasted that increased global warming would push the Arctic into an unstoppable cascade of melting that ceases only when the ocean becomes ice-free.
Implications of a permanently ice-free Arctic for the environment and for national and economic security are significant, driving deep interest in predictive capabilities in the region.
Wagner and Eisenman’s research was co-funded by the Office of Naval Research (ONR) and by the National Science Foundation. It supports the goals of the Navy’s U.S. Arctic Roadmap, which calls for an assessment of changes in the Arctic Ocean to clarify the national security challenges for future naval operations as this strategic region becomes increasingly accessible.
“The Navy has broad interest in the evolution of the Arctic,” said the ONR’s Frank Herr. “Sea ice dynamics are a critical component of the changing environmental picture. Our physical models lack important details on the processes controlling ice formation and melting, thus ONR is conducting a series of experimental efforts on sea ice, open water processes, acoustics, and circulation.”
During the past several years, scientists using global climate models (GCMs) that are more complex than process models found sea ice loss in response to rising greenhouse gases in their computer simulations is actually reversible when greenhouse levels are reduced.
“It wasn’t clear whether the simpler process models were missing an essential element, or whether GCMs were getting something wrong,” said Wagner, the lead author of the study. “And as a result, it wasn’t clear whether or not a tipping point was a real threat.”