A simulation model for modern and glacial climates

In 1920, the meteorologist Milutin Milankovic proposed that small changes in Earth's orbit, precession, and inclination affect the heat balance and modify climate (the alterations called "solar forcing"). The Milankovic hypothesis was not taken seriously until 1976, when teams studying sediment cores from the ocean floor constructed a history of ocean temperature that matched the predictions of the Milankovic hypothesis, with two different ocean cores providing similar results. Until now, simulation models of Earth's climate history have been either ocean models or atmosphere models, with no model accounting for the interact- ions between the ocean and the atmosphere aside from adjustable heat flux parameters that result in only a weak theory. In general, complete solutions of these individual models have involved prohibitive computation times. The term "glacial maximum" refers to the time or position of the greatest extent of glaciation, and the term "hydrologic cycle" refers to the complete cycle through which water passes: from the ocean, through the atmosphere, to the land, and back to the ocean. .... ... Ganopolski et al (4 authors at Potsdam Institute for Climate Impact Research, DE) now report a moderately simplified global coupled ocean-atmosphere model to simulate the equilibrium climate of both the present and of the last glacial maximum, and that the model successfully predicts the atmospheric and oceanic circulations, temperature distribution, hydrologic cycle, and sea-ice cover of both periods without using flux adjustments. The authors suggest that changes in oceanic circulation, particularly in the Atlantic Ocean, play an important role in glacial cooling, and that ultimately the challenge is to produce a simulation of glacial cycles driven only by the Milankovic cycles in solar forcing.

QY: Stefan Rahmstorf rahmstorf@pik-potsdam.de
Nature 22 Jan 98

Índice das novidades científicas