Surface Temperature Reconstructions for the Last 2,000 Years (2006) / Chapter Skim
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1 Introduction to Technical Chapters
1 Introduction to Technical Chapters
Pages 25-28
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From page 25... ...
This chapter describes how large-scale surface temperature reconstructions contribute to our understanding of the sensitivity of global mean temperature to natural and human-induced perturbations of the Earth's energy balance. It also offers a perspective on the importance of surface temperature reconstructions, as compared with other kinds of evidence, in assessing the extent to which the warming of the late 20th century is attributable to human activities.
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From page 26... ...
. The external forcings considered to be of greatest importance for climate over the last 2,000 years are changes in atmospheric concentrations of carbon dioxide and other greenhouse gases, aerosol concentrations, volcanic activity, and solar radiation.
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From page 27... ...
In recent decades the increases have been documented on the basis of direct measurements at a network of stations. Increases in concentrations of carbon dioxide, methane, and nitrous oxide starting in the 19th century, following many millennia of nearly constant concentrations, are clearly discernible in air bubbles trapped in ice cores recovered from the Greenland and Antarctic ice sheets (Petit et al.
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From page 28... ...
Most of what we know about how the temperature of the Earth has varied on the timescale of the last 2,000 years is based on proxy records, including documentary records, archeological evidence, and a variety of natural sources including tree rings, corals, ice cores, ocean and lake sediments, borehole temperatures, and glacier length records. The sources and characteristics of the various proxy datasets are discussed in Chapters 3 8.
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