Evidence of climate warming from underground temperatures in NW Italy

The ground surface temperature (GST) history in NW Italy was reconstructed for the last three centuries by means of temperature–depth data recorded in a borehole in 1982. The results indicate relatively warmer periods in the 18th century and at the end the 1970s. A more recent set of underground temperature data was recorded in 1996. The comparison with the earlier thermal logging shows an evident temperature increase in the uppermost 80 m. Two different inversion techniques yield a subsurface temperature increase of 0.8–1.0 K since the 1980s. The inferred climatic model is consistent with the air temperature variations recorded at the Genoa University meteorological station.