The applications of paleoclimate modeling include: identifying mechanisms of climate change, quantifying the climate response to specific forcing factors, recognizing climatic feedbacks and processes that amplify/damp climatic forcings, identifying limitations of climate proxies from the geological record, and demonstrating strengths/shortcomings in numerical climate models. Paleoclimate modeling studies have contributed to many of the outstanding problems in paleoclimatology.
A few of the most significant advances have been made in: evaluating the plausibility of global glaciation and deglaciation in the Neoproterozoic; demonstrating the effect of super-continentality on Paleozoic climate; delineating the conditions required for glaciation in the Ordovician and Late Paleozoic; understanding the role of greenhouse gases during the Cretaceous, Eocene, and Pliocene periods of global warmth; demonstrating the influences of Cenozoic mountain uplift and ocean gateways on regional and global climate; simulating the conditions of the Last Glacial Maximum and Holocene; quantifying the influence of Earth's orbital variations on climate variability and ice volume in the Pleistocene and Holocene; and simulating the ocean's thermohaline variability and its influence on global climate. These paleoclimate modeling studies have provided insights into the causes and dynamics of past climate change, revealed the major climate forcings through Earth history, and identified shortcomings in our understanding of climate.
With regard to modern and future climate change, paleoclimate modeling has made several notable contributions. By investigating extreme climates outside of the range of modern climate variability, paleocli-mate modeling has provided a critical test of climate models, and has shown that they adequately simulate many, but not all, aspects of past climate on a global scale. Importantly, outstanding issues remain including the simulation of abrupt climate change and past warm climates. Paleoclimate modeling has also established greenhouse gases as one of the most important factors in past climates, and demonstrated that other factors (solar variability and volcanic outgassing) could not account for the global warming since the pre-Industrial Revolution, as discussed by Crowley.
sEE ALsO: Climate Models; Computer Models; Modeling of Ice Ages; Modeling of Ocean Circulation.
bibliography. T.J. Crowley, Causes of Climate Change over the Past 1000 Years," Science (v.289, 2000); A. Ganop-olski and S. Rahmstorf, "Rapid Changes of Glacial Climate Simulated in a Coupled Climate Model," Nature (v.409, 2001); C.J. Poulsen, et al., "The Impact of Paleogeographic Evolution on the Surface Oceanic Circulation and the Marine Environment Within the Mid-Cretaceous Tethys," Paleoceanography (v.13, 1998).
Christopher J. Poulsen University of Michigan
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