It has long been recognized that temperature changes at the earth's surface are propagated into the subsurface but with an amplitude attenuation and time delay that increase with depth. Thus corrections to heat flow are sometimes calculated for the effect of the Pleistocene ice ages, and the effects of the Little Climatic Optimum of the 10th and 11th centuries and the Little Ice Age of the 17th and 18th centuries may be detected in some geothermal records. Many borehole temperature profiles show changes in the temperature gradient in the uppermost 100m that may be driven by a secular change of surface temperature over the past century. The purpose of this project is to enable four geothermal laboratories (University of Michigan, University of North Dakota, University of Utah, Southern Methodist University) to interrogate and analyze their respective borehole temperature archives for data relevant to questions of global climate change. These archives contain extensive data from the USA and Africa south of the equator.
