Where are We Going? The Ice Core — Paleoclimate Inverse Problem

Significant progress has been made recently (e.g. Bales and Choi, this volume; Neftel this volume) toward understanding the transfer functions that describe how stable isotopes, chemical species, and other impurities get from the polar atmosphere into deep polar ice. This research is motivated by the reverse process, i.e., a need to derive quantitative paleo-climate information from ice core data. Even when the transfer functions from atmosphere to ice are known, the Inverse Problem,i.e. inference of concentrations in the paleo-atmosphere from concentrations in ice cores, may be neither straightforward nor simple. The need to solve Inverse Problems in many different fields has lead to the creation of Inverse Theory. Inverse Methods (a) provide a conceptual framework in which to understand the limitations common to all efforts that use data to infer properties of physical systems, (b) determine how much information can be obtained from the data, and (c) assess the reliability of that information. The ability of Inverse Methods to assess the Resolving Power of the data (i.e. to determine how well the Inverse Problem can be solved) is a key feature of great value to the ice core Inverse Problem, Inverse Theory takes many forms; this paper outlines a few concepts to show how Inverse Methods can provide a useful focus for ice core - atmosphere paleoclimate studies.