Connecting Changing Ocean Circulation with Changing Climate

• Published in: Journal of climate Vol. 26; no. 7; pp. 2268 - 2278
• Main Authors: Winton, Michael, Griffies, Stephen M., Samuels, Bonita L., Sarmiento, Jorge L., Frölicher, Thomas L.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.04.2013
• Subjects: Anomalies; Atmospheric circulation; Carbon; Carbon capture and storage; Carbon dioxide; Carbon sequestration; Carbon uptake; Circulation; Circulation anomalies; Climate; Climate change; Climate models; Climatology; Climatology. Bioclimatology. Climate change; Connecting; Cooling power; Earth, ocean, space; Equator; Exact sciences and technology; Experiments; External geophysics; Fluid dynamics; Global warming; Heat; Heat storage; Heat transport; Influence; Latitude; Marine; Meteorology; Northern Hemisphere; Ocean circulation; Ocean currents; Ocean models; Oceanic climates; Oceans; Physics of the oceans; Radiative forcing; Sea transportation; Sea-air exchange processes; Surface temperature; Surface water; Uptake; Uptakes; Water circulation; Southern Ocean; South America; ocean currents; Coupled model; global change; Carbon dioxide; climate warming; Climate models; digital simulation; ocean-atmosphere interaction; ocean circulation; climate change; greenhouse gas
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/JCLI-D-12-00296.1

The influence of changing ocean currents on climate change is evaluated by comparing an earth system model’s response to increased CO₂ with and without an ocean circulation response. Inhibiting the ocean circulation response, by specifying a seasonally varying preindustrial climatology of currents, has a much larger influence on the heat storage pattern than on the carbon storage pattern. The heat storage pattern without circulation changes resembles carbon storage (either with or without circulation changes) more than it resembles the heat storage when currents are allowed to respond. This is shown to be due to the larger magnitude of the redistribution transport—the change in transport due to circulation anomalies acting on control climate gradients—for heat than for carbon. The net ocean heat and carbon uptake are slightly reduced when currents are allowed to respond. Hence, ocean circulation changes potentially act to warm the surface climate. However, the impact of the reduced carbon uptake on radiative forcing is estimated to be small while the redistribution heat transport shifts ocean heat uptake from low to high latitudes, increasing its cooling power. Consequently, global surface warming is significantly reduced by circulation changes. Circulation changes also shift the pattern of warming from broad Northern Hemisphere amplification to a more structured pattern with reduced warming at subpolar latitudes in both hemispheres and enhanced warming near the equator.