Some Lessons in Environmental History

One of the primary goals of Earth systems research is to learn how sensitive global climate 

Insofar as paleoenvironmental records reveal histories of both forcings and environments, the accuracy of GCMs may be tested by efforts to replicate these histories. Successful replication would suggest the models capture the essential behavior of the Earth and therefore have predictive ability. Further, GCM simulations of past climates may allow partitioning of net climate changes into components due to various forcings. GCM simulations of the ice-age Earth are very much works in progress. 

Recent revisions to the boundary conditions (ice-sheet topography and sea surface temperatures) have added uncertainty to many of the GCM calculations of the past two decades. Moreover, all of these calculations use prescriptions for at least one central component of the climate system, generally oceanic heat transport and/or sea surface temperatures. This limits the predictive benefit of the models. Nonetheless, these models are the only appropriate way to integrate physical models of diverse aspects of the Earth systems into a unified climate prediction tool. 

Lorius et al. (1990) performed a simple multivariate analysis in which they correlate the temperature changes of the past 160 kyr (as recorded in the Vostok SD record) with changes in five forcings atmospheric CO2 plus CH4, ice volume, aerosol loading (dust and sepa- 

Agassiz, L. (1840). Etudes sur les glaciers. Privately published, Neuchatel. 

---