CCT2 - Rationale and Goals


General methodology for using proxies in reconstructing past climate and environment (modified from Committee on Surface Temperature Reconstructions for the Last 2000 Years, National Research Council, 2006).

Widespread, reliable instrumental records are only available for the past 150 years. Climate and environment variations in the more distant past can be estimated by analyzing proxy datafrom sources such as tree rings, corals, ocean and lake sediments, cave deposits, ice cores, boreholes, glaciers, and historical documents.

Considerable advances in the quality of proxy-based reconstructions have been made over recent decades. However, the demand for accuracy, precision, resolution and quantitative interpretation is increasing as the questions asked in global change research become more detailed. In addition, quantitative reconstructions of climate parameters other than temperature are being called for. It is important to meet these demands in order to maximize the usefulness of paleoscience in complementing observational and projection studies.

Proxy-data are the products of a series of steps (see figure below), each with their inherent pitfalls and limitations, which add up to the proxy data uncertainties, which limit the interpretation of proxy records and reconstructions.

This CCT promoted efforts to identify and reduce the shortcomings and pitfalls in proxy record generation and interpretation.


The overarching goal of this CCT was to support advances in the precision and accuracy of paleo-proxies in order to generate high-quality records of past global change that can complement instrumental data and modeling efforts. To this end, specific aims included improvement in proxy interpretation and development, refinement of analysis and calibration, and encouragement/facilitation of inter-laboratory comparisons.

To improve the quality of proxy records and the resulting reconstructions, the following key objectives were identified in the steps from site selection to reconstruction:

- Discovering new proxies

- Opitimizing site selection

- Improving sample analysis

- Providing calibration datasets

- Validating proxy interpretation

- Quantifying and expressing proxy-data uncertainties

See the figure above for more information.