UW researchers in ESS, ATM and Oceanography are actively working on climate reconstructions on all time scales--from the last several centuries when human impacts on climate have become apparent, to the last 10,000 years when modern human civilizations first began to flourish, to the ice age cycles of the last million years, the warm Eocene period 50 million years ago, the 'Snowball Earth' episodes 800-500 million years ago, and beyond. We use a very wide array of tools and techniques to reconstruct the climate of the past, including geochemical--both organic and inorganic, geophysical, molecular, macrobiological, and purely theoretical. Our "archives" range from polar ice cores, to marine sediment cores, to lake and peat cores, archeological deposit, and land forms. The understanding we gain from reconstructing the climate of the past allows us to better determine the natural variability of the climate system under a variety of boundary conditions. In so doing we are working to improve our ability to predict changes in the climate that may occur in the future from anthropogenic and natural perturbations.