Statement of Task
The committee will describe and assess the state of scientific efforts to reconstruct surface temperature records for the Earth over approximately the past 2,000 years. The committee will summarize current scientific information on the temperature record for the past two millennia, describe the main areas of uncertainty and how significant they are, describe the principal methodologies used and any problems with these approaches, and explain how central the debate over the paleoclimate temperature record is to the state of scientific knowledge on global climate change. As part of this effort, the committee will address tasks such as:
Describe the proxy records that have been used to estimate surface temperatures for the pre-instrumental period (e.g., tree rings, sediment cores, isotopes in water and ice, biological indicators, indicators from coral formations, geological boreholes, historical accounts) and evaluate their limitations.
Discuss how proxy data can be used to reconstruct surface temperature over different geographic regions and time periods.
Assess the various methods employed to combine multiple proxy data to develop large-scale surface temperature reconstructions, the major assumptions associated with each approach, and the uncertainties associated with these methodologies.
Comment on the overall accuracy and precision of such reconstructions, relevant data quality and access issues, and future research challenges.