Global Climate Model – Biogeochemical Dynamics Laboratory

The surface expression of the Westerly Winds has moved poleward and increased over the last 30 years in both hemispheres, possibly as the first and most ferocious of the impacts of global warming. In our recent published work, the impact of this shift in the Northern Annular Mode on the northern hemisphere terrestrial vegetation and its subsequent impact on atmospheric carbon dioxide was documented. We have also produced a series of papers on the impact of the shift of the wind over the Southern Ocean in creating and destroying the water masses critical to the global carbon cycle, ocean circulation, and heat budget.

All of the latest climate models prepared for the IPCC 4th Assessment respond in a similar way to an increased atmospheric greenhouse gas burden: the surface westerly winds in both hemispheres increase in magnitude and shift poleward. This increased wind forcing over the Southern Ocean may counteract the increased stratification in the Antarctic (due to warming and freshening), allowing somewhat more of the rapidly-increasing anthropogenic carbon and heat to be sequestered in the deep ocean. The question is: Will the world warm so quickly that this “door” to the deep ocean will close or will the winds to keep pace?

Relevant Papers:

Russell, J.L., R.J. Souffer, & K.W. Dixon (2006), Intercomparison of the Southern Ocean Circulations in the IPCC Coupled Model Control Simulations. J. Climate, 19(18), 4560-4575. (pdf)
Delworth, T.L., A.J. Broccoli, A. Rosati, R.J. Stouffer, V. Balaji, J.A. Beesley, W.F. Cooke, K.W. Dixon, J. Dunne, K.A. Dunne, J.W. Durachta, K.L. Findell, P. Ginoux, A. Gnanadesikan, C.T. Gordon, S.M. Griffies, R. Gudgel, M.J. Harrison, I.M. Held, R.S. Hemler, L.W. Horowitz, S.A. Klein, T.R. Knutson, P.J. Kushner, A.R. Langenhorst, H-C. Lee, S-J. Lin, J. Lu, S.L. Malyshev, P.C.D. Milly, V. Ramaswamy, J.L. Russell, E. Shevliakova, M.D. Schwarzkopf, J.J. Sirutis, M.J. Spelman, W.F. Stern, M. Winton, A.T. Wittenberg, B. Wyman, F. Zeng, and R. Zhang (2006), GFDL’s CM2 Global Coupled Climate Models. Part I: Formulation and simulation characteristics. J. Climate, 19(5), 643-674. (pdf)
Gnanadesikan, A., K.W. Dixon, S.M. Griffies, V. Balaji, M. Barreiro, J.A. Beesley, W.F. Cooke, T.L. Delworth, R. Gerdes, M.J. Harrison, I.M. Held, W.J. Hurlin, H-C. Lee, Z. Liang, G. Nong, R.C. Pacanowski, A. Rosati, J.L. Russell, B.L. Samuels, Q. Song, M.J. Spelman, R.J. Stouffer, C.O. Sweeney, G. Vecchi, M. Winton, A.T. Wittenberg, F. Zeng, R. Zhang, and J.P. Dunne (2006), GFDL’s CM2 Global Coupled Climate Models. Part 2: The baseline ocean simulation. J. Climate, 19(5), 675-697. (pdf)
Goodman, P.J. (2001), Thermohaline adjustment and advection in an OGCM, J. Physical Oceanography, 31, 1477-1497. (pdf)

“Civilization exists by geological consent, subject to change without notice.”
—Will Durant