Deep Earth heat surprise
The key to understanding Earth's evolution is to look at how heat is conducted in the deep lower mantle—a region some 400 to 1,800 miles (660 to 2,900 kilometers) below the surface. Researchers at the Carnegie Institution, with colleagues at the University of Illinois, have for the first time been able to experimentally simulate the pressure conditions in this region to measure thermal conductivity using a new measurement technique developed by the collaborators and implemented by the Carnegie team on the mantle material magnesium oxide (MgO). They found that heat transfer is lower than other predictions, with total heat flow across the Earth of about 10.4 terawatts, which is about 60 % of the power used today by civilization. They also found that conductivity has less dependence on pressure conditions than predicted. The research is published in the August 9, online Scientific Reports.