The UN framework convention on climate change will start tomorrow in Warsaw, Poland. By chance, but fitting to the occasion, I heard a talk on friday given by David Chapman from the University of Utah.
He opened his talk with a remarkable chart, shown below:
This chart shows the thermal gradient measured in multiple boreholes (labelled ETK, FCK, TUL, etc.) that were drilled in northern Alaska. At depth, ranging from about 125m to 175m bgs., temperature increases linearly with increasing depth. However, for shallower depths between about 70m to 100m bgs, there is a deviation from the linear slope recognizable, indicated by the grey shaded areas. The authors found that the deviation from the expected temperature gradient is a few degrees warmer (between 2.2C and 7.4C) in the last 100 years or so.
What a great “reservoir” the earth is! The chart above is from this paper:
Lachenbruch, Arthur H, and B Vaughn Marshall. 1986. “Changing Climate: Geothermal Evidence From Permafrost in the Alaskan Arctic.” Science 234 (4777) (November 7): 689–696. doi:10.1126/science.234.4777.689.
Note that this was published about one year before Hansen’s and Lebedeff’s land-mark paper. Based on Lachenbruch’s and Marshall’s work work, Chapman continued to do related work, particularly with meteorological measurements, in the west of Utah.