Kabir Rao1
[1] Industrial activities, such as fossil fuel burning and other human activities such as tropical deforestation have increased greenhouse gas concentrations in the atmosphere. Increasing global temperatures are likely to have extreme effects on global climate and may result in species extinction, changes in agricultural production and deleterious effects on health. Studies have been conducted in recent years on the effects of increase of greenhouse gases on the thermohaline circulation. There are several hypotheses that state that the prolonged effect of global warming could eventually “shut down” the thermohaline circulation and lead to cooling in certain regions in the North Atlantic Ocean. Several ocean-atmosphere models have been used to predict the effect of increase of carbon dioxide (a greenhouse gas) concentration on ocean circulation. Two such models are discussed and their results are analyzed.
1. Introduction
[2] Global temperatures have seen a dramatic increase since the Industrial Revolution. Several climate models have projected an increase of between 1.1° C to 6.4° C in the global average temperature due to the continued effect of global warming (IPCC (2007)). Apart from the resulting adverse effect on global climate, increasing global temperatures may result in species extinction, changes in agricultural production, deleterious effects on health, rise in the sea level, reductions in the ozone layer and disruption in the ice shelf. Another possible outcome of global warming is what is now termed as the “shutdown of the thermohaline circulation”. Wallace S. Broeker, the man responsible for the term “Global Conveyor Belt”, called the thermohaline circulation the “Achilles heel of our climate system” (Broeker, 1997). There is much research that focuses on the effect of greenhouse gases on ocean circulation. Two such models are discussed in future sections. Some
References: Broecker S.W (1997), ‘Thermohaline Circulation, the Achilles Heel of Our Climate System: Will Man-Made CO2 Upset the Current Balance?’, Science, Vol. 278, 1582-1588. Kamenkovich I.V, Sokolov A.P. & Stone P.H. (2003), ‘Feedbacks affecting the response of the thermohaline circulation to increasing CO2: a study with a model of intermediate complexity’, Climate Dynamics (2003) Vol. 21, 119-130. Stouffer R.J, Manabe S (2002), ‘Equilibrium response of thermohaline circulation to large changes in atmospheric CO2 concentration’, Climate Dynamics (2003) Vol. 20, 759-773. Joos F, Plattner G, Stocker F S, Marchal O, Schmittner A (1999), ‘Global Warming and Marine Carbon Cycle Feedbacks on Future Atmospheric CO2’, Science, Vol. 284, 464-467. Schmittner A, Stocker F S (1999), ‘The Stability of the Thermohaline Circulation in Global Warming Experiments’, American Meteorological Society, Vol. 12, 1117-1133. Rhines P.B, Häkkinen S, (2003), ‘Is the Oceanic Heat Transport in the North Atlantic Irrelevant to the Climate in Europe?’, ASOF Newsletter, Vol. 1, 13-17. Seager R, D.S. Battisti, Yin J, Gordon N, Naik N, A.C. Clement, M.A. Cane (2002), ‘Is the Gulf Stream responsible for Europe’s mild winters?’, Q. J. R. Meteorol. Soc., Vol. 128, 2563-2586 IPCC, 2007: Summary for Policymakers Hansen J (2005), ‘A slippery slope: How much global warming constitutes “dangerous anthropogenic interference”?’, Climatic Change, Vol. 68, 269-279. Wood A.R, Vellinga M, Thorpe R (2003), ‘Global warming and thermohaline circulation stability’, Phil. Trans. R. Soc. Lond., Vol. 361, 1961-1975. Bryden H, H.R. Longworth, S.A. Cunningham (2005), ‘Slowing of the Atlantic meridional overturning circulation at 25° N’, Nature, Vol. 438, 655-657. Quadfasel D (2005), ‘Oceanography: The Atlantic heat conveyor slows’, Nature, Vol. 438, 565-566. Schiermeier Q (2006), ‘Climate Change: A Sea Change’, Nature, Vol. 439, 256-260. Pickard G, Emery J, ‘Descriptive Physical Oceanography’, New York: Pergamon Press, 1982. National Aeronautics and Space Administration, 15 Apr. 2004, NASA, 5 November 2007 <http://www.nasa.gov/centers/goddard/news/topstory/2004/0415gyre.html> ESRL Global Monitoring Division, Dr