Spatial Pattern and Mechanisms of Heat-Content Change in the North Atlantic

• Published in: Science (American Association for the Advancement of Science) Vol. 319; no. 5864; pp. 800 - 803
• Main Authors: Lozier, M. Susan, Leadbetter, Susan, Williams, Richard G, Roussenov, Vassil, Reed, Mark S.C, Moore, Nathan J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 08-02-2008; The American Association for the Advancement of Science
• Subjects: Atmospheric models; Atmospherics; Buoyancy; Climate change; Climate models; Earth, ocean, space; Enthalpy; Exact sciences and technology; External geophysics; Geophysics; Gyres; Heating; Ocean currents; Oceanography; Oceans; Physics of the oceans; Thermodynamics; Thermohaline structure and circulation. Turbulence and diffusion; Tropical climates; Atlantic Ocean; North Atlantic; North Atlantic region; AN, North Atlantic; AN, North Atlantic, North Atlantic Oscillation; time series analysis; trend-surface analysis; Latitudinal variation; 1950-2000; Thermal energy storage; climate variability; ocean-atmosphere interaction; ocean basins; Spatial distribution; cooling; warming; heat storage; heat transfer; climate change
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1146436

The total heat gained by the North Atlantic Ocean over the past 50 years is equivalent to a basinwide increase in the flux of heat across the ocean surface of 0.4 ± 0.05 watts per square meter. We show, however, that this basin has not warmed uniformly: Although the tropics and subtropics have warmed, the subpolar ocean has cooled. These regional differences require local surface heat flux changes (±4 watts per square meter) much larger than the basinwide average. Model investigations show that these regional differences can be explained by large-scale, decadal variability in wind and buoyancy forcing as measured by the North Atlantic Oscillation index. Whether the overall heat gain is due to anthropogenic warming is difficult to confirm because strong natural variability in this ocean basin is potentially masking such input at the present time.