Energy balance at the Earth's surface: Heat flux history in eastern Canada

The heat exchange at the air/ground interface is determined by many complex processes making the energy balance at the earth's surface extremely diffi cult to quantify and model. A new methodology allows heat flux at the Earth 's surface to be estimated using ground surface temperature history reconst ructed from geothermal data. We found that over a large region in eastern a nd central Canada, the average heat flux into the ground during the last 10 00 years was on the order of 2.8 mWm(-2). Our results suggest that signific ant change in the ground heat flux occurred in the last two centuries. The 200 years averaged heat flux since 1765 is 17.0 mWm(-2), while the average heat flux over the latest 100 years is 74.0 mWm(-2). The sensitivity of the subsurface to very small energy imbalances makes these type of data and an alysis useful complements to the paleoclimatic record; they also provide co nstrains for general circulation model land-surface parameterization over a wide range of spatial-temporal scales.