Ground warming patterns in the Northern Hemisphere during the last five centuries

Changes in the Earth's surface energy balance recorded underground were used to reconstruct the temperature of the ground surface for the last 500 years in the Northern Hemisphere. We reconstructed ground surface temperature histories (GSTHs) from temperature versus depth profiles measured at 558 sites distributed between 30degrees and 60degreesN in the Northern Hemisphere. We show that the ground has warmed about 0.5 K in the last 100 years. Spatial analysis reveals that spatial variability is important and that the weighted average Northern Hemisphere GSTH shows some consistency with multiproxy and meteorological records reconstructions for the last two centuries. (C) 2004 Elsevier B.V. All rights reserved.