Deep, old water explains why Antarctic Ocean hasn't warmed
The waters surrounding Antarctica may be one of the last places to experience human-driven climate change. New research from the University of Washington and the Massachusetts Institute of Technology finds that ocean currents explain why the seawater has stayed at roughly the same temperature while most of the rest of the planet has warmed.
The study resolves a scientific conundrum, and an inconsistent pattern of warming often seized on by climate deniers. Observations and climate models show that the unique currents around Antarctica continually pull deep, centuries-old water up to the surface -- seawater that last touched Earth's atmosphere before the machine age, and has never experienced fossil fuel-related climate change. The paper is published May 30 in Nature Geoscience.
"With rising carbon dioxide you would expect more warming at both poles, but we only see it at one of the poles, so something else must be going on," said lead author Kyle Armour, a UW assistant professor of oceanography and of atmospheric sciences. "We show that it's for really simple reasons, and ocean currents are the hero here."
Emily R. Newsom et al. Southern Ocean warming delayed by circumpolar upwelling and equatorward transport. Nature Geoscience, May 2016 DOI: 10.1038/ngeo2731
Observed warming over the past 50 years (in degrees Celsius per decade) shows rapid warming in the Arctic, while the Southern Ocean around Antarctica has warmed little, if at all. Credit: K. Armour / UW
