New understanding of changes in North Pacific Ocean circulation over the past 1.2 million years could lead to better global climate models.
(From AGU Blogsphere / by Tim Stephens) — An unprecedented analysis of North Pacific ocean circulation over the past 1.2 million years has found that sea ice formation in coastal regions is a key driver of deep ocean circulation, influencing climate on regional and global scales. Coastal sea ice formation takes place on relatively small scales, however, and is not captured well in global climate models, according to scientists at the University of California, Santa Cruz, who conducted the study.
A paper on the new findings has been accepted for publication in Paleoceanography, a journal of the American Geophysical Union. “We have identified an important process that current global climate models don’t adequately capture,” said Karla Knudson, a graduate student in Earth and planetary sciences at UC Santa Cruz and first author of the paper. “Coastal sea ice formation may be important to future climate change because the arctic and subarctic regions are warming at twice the rate of other parts of the world.”
When sea ice forms, it expels salt into the surrounding water, increasing the density of the water and causing it to sink, carrying oxygenated surface water into the depths. One result is a flow of cold deep water toward the equator and warm surface water toward the poles, and this “overturning circulation” plays a crucial role in moving heat around the globe.