The timing of emissions reductions, even more so than how much we cut emissions, will be key to avoiding catastrophic thresholds for ice-melt and sea-level rise, according to a new Cornell study.

The study, published Oct. 10 in Nature Climate Change, models the impacts of different emissions trajectories, finding that emissions and uncertainties around ice sheet dynamics will have the most impact on sea-level rise through 2200.

“Roughly speaking, we found that somewhere between 2065 and 2075, emissions really start to become the dominant factor, as well as uncertainties related to emissions like Antarctic Ice Sheet tipping points,” said Vivek Srikrishnan, assistant professor of biological and environmental engineering in the College of Agriculture and Life Sciences. “As we get to 2060, 2065, the mitigation we do today will start to really materially impact the range of sea-level rise outcomes.”

It‘s well understood that future carbon dioxide emissions will impact global temperatures, the melting of ice sheets and sea-level rise, but there’s a great deal of uncertainty around what that will look like: We don’t know how or when emissions and increased temperatures will precipitate a rapid melting of ice sheets and surge in sea levels, or the best approach to avoid those tipping points.

Previous studies and models focused on or made central emissions’ impact on warming temperatures, without considering how those changes might interact with ice sheet and ocean dynamics over time in a detailed way. Srikrishnan and his team, including first author Chloe Darnell, M.S. ‘23, wanted to understand how emissions might have a nonlinear relationship to sea-level rise – as temperatures surpass thresholds and initiate a more rapid melting of ice sheets.

For more granular detail, the researchers used their own model of emissions and integrated it with a number of existing climate models, including ones that model ice sheet dynamics, to determine the factors impacting sea-level rise through 2200. They found that delaying emissions reductions by even a decade substantially reduces the chances of avoiding thresholds for sea-level rise, with the year emissions peak greatly influencing the probability of surpassing ice sheet tipping points, demonstrating that when we cut emissions matters just as much as how much we cut emissions.

Read the full article about the timing of emissions reductions by Caitlin Hayes at Cornell Chronicle.