Iceberg Melt Weakens Ocean System that Regulates the Global Climate
NSF NCAR postdoctoral fellowship enables study led by UC Davis researcher
Jul 14, 2026 - by Staff
Melting and breaking icebergs in the far-off, northeastern region of the Pacific Ocean can weaken a massive current system in the Atlantic Ocean, according to a study by researchers at University of California, Davis (UC Davis) and the U.S National Science Foundation National Center for Atmospheric Research (NSF NCAR).
The Atlantic Meridional Overturning Circulation, or AMOC, regulates the global climate by acting as a massive conveyor belt, moving warm, salty water from the tropics to the North Atlantic. Responsible for 70% of oceanic heat transport across the equator, AMOC influences global climate by redistributing heat and energy.
Melting icebergs in the North Atlantic Ocean were previously considered the primary drivers of AMOC weakening during Earth’s last ice age, leading to global climate shifts, including cooling in the Northern Hemisphere and warming in Antarctica. Scientists refer to these events and their time periods as Heinrich stadials.
“More recently, however, scientists have found that these North Atlantic iceberg melting events happened after the AMOC was weakened and Greenland was cooled,” said lead author Chijun Sun, an assistant professor in the UC Davis Department of Earth and Planetary Sciences. “So the iceberg discharge events in the North Atlantic could not have driven AMOC weakening.”
For the study, Sun and his NSF NCAR colleagues recreated these events using paleoclimate data and supercomputer simulations run on the Derecho supercomputer at the NSF NCAR-Wyoming Supercomputer Center. They found that the more likely culprit influencing Henrich stadials are iceberg discharge events — in which large amounts of ice break from a glacier or ice sheet — and meltwater from the northeast Pacific Ocean.
The study is funded by the National Science Foundation and NSF NCAR. It was published in Nature Communications. Sun pursued the research through the NSF NCAR Advanced Study Program which allows graduate and postdoctoral students to focus on emerging areas of science.
To learn more about the research, see the UC Davis news release.