文档介绍：© AAPG 2007 - Geological Perspectives of Global Climate Change, 2001, pp. 1 -15
Gerhard, L. C, W. E. Harrison, and B. M. Hanson,
Introduction and overview, 2001, in L. C Gerhard,
W. E. Harrison, and B. M. Hanson, eds., Geological
perspectives of global climate change, p. 1-15.
Introduction and Overview
Lee C. Gerhard
William E. Harrison
Kansas Geological Survey
Lawrence, Kansas, .
Bernold M. "Bruno" Hanson
Independent Petroleum Producer (Deceased)
Global climate has varied since the most primitive atmosphere developed on earth billions of years
ago. This variation in climate has occurred on all timescales and has been continuous. The sedi•
mentary rock record reflects numerous sea-level changes, positional changes, and
temperature changes, all of which attest to climatic variation. Such evidence, as well as direct his•
torical observations, clearly shows that temperature swings occur in both directions. Past climates
have varied from those that create continental glaciers to those that yield global greenhouse condi•
tions. Many people do prehend that this means their living climate also varies—it gets
warmer or cooler—but typically does not remain the same for extended periods of time. Human
history shows us that in general, warmer conditions have been beneficial, and colder conditions
have been less kind to society (Lamb, 1995). We currently are living in a not-pleted inter-
glacial stage, and it is very likely that warmer conditions lie ahead for humanity, with or without
any human interference. Interglacial stages appear to last for about 11,000 years, but with large in•
dividual variability. We have been in this interglacial for about 10,000 years.
Geologic processes are not in equilibrium. Geologic processes are one set of drivers for climate
and therefore climate cannot be in equilibrium. This makes assessing any cumulative human im•
pact on climate difficult. What is the range of natural global