I use climate models and statistical methods to investigate the causes of climate change across time scales ranging from years to millions of years. The models range in complexity from simple low-order dynamical systems to complex three-dimensional models of the atmosphere. I have worked on developing a theory for long-time scale climate change (ice ages and millennial scales) primarily using low-order models. More recently my interests have shifted to inter-annual to decadal scale climate variability in the Holocene and the relationship between climate change and human activities. This research involves the development of proxy data from ice core chemistry as well as other climate sensitive geologic deposits and archaeological remains. The physical meaning of climate proxy records must be established by calibrating these records to present day instrumentally measured climate records. I am also actively involved in modeling present-day and future regional scale climate change using a nested high resolution model of the atmosphere (WRF). One of the projects using the regional climate model involves modeling future climate change for New England with a focus on winds over the Gulf of Maine.