Climate from borehole data: Energy fluxes and temperatures since 1500

Abstract

Variations in the Earth's surface energy balance are recorded in the ground as perturbations of the subsurface thermal regime. Here I apply singular value decomposition (SVD) inversion methods to 826 temperature-depth profiles distributed world wide, in order to reconstruct ground surface temperature histories (GSTH) and surface heat flux histories (SHFH) from the temperature and heat flux anomalies detected in the shallow subsurface. Inversions yielded a mean ground surface temperature and surface heat flux histories for the Earth's continents for the last 500 years. Results indicate that the global average ground temperature and ground heat flux have increased an average of 0.45°K and 18.0 mWm2 respectively over the last 200 years, and 0.9°K in the last five centuries.