Borehole temperatures record changing climate



Recent changes in the Earth's surface temperature can now be probed by measuring the temperature of rocks beneath the surface. Rock temperatures at shallow depths are an archive of temperature changes that have occurred at the surface of the Earth in the recent past. Thus, subsurface temperatures comprise a valuable complement to surface meteorological data in understanding the Earth's surface temperature history, particularly for times before the establishment of a worldwide network of meteorological stations. The subsurface observations are relevant to an assessment of the role of atmospheric greenhouse gases in the global warming of the 20th century.