Interesting new research indicates that
… global temperature over the lower atmosphere — using the series of GPS (Global Positioning System) satellites — can be obtained by accurately by measuring the propagation of radio waves through the atmosphere. The importance of this new method is that a near-complete coverage of the Earth is afforded and that global atmospheric temperature can be determined without requiring any complex satellite inter-calibration. Only the precise atomic clock is needed to measure the relative delay in propagation of radio waves through the atmosphere which, in turn, allows for a direct assessment of the atmospheric temperature over the lower portion of the atmosphere.
Unsurprisingly, the GPS-based method confirms what was measured by the thermal infrared/microwave radiometers aboard other satellites; that the nearly-two-decade-long temperature hiatus is real and the thermometer-based record is the oddball. More specifically, global atmospheric temperatures are not warming in the way predicted by the CO2-driven climate models, which serves to argue that CO2 does not act as the thermostat for global atmospheric temperatures.
Read more about it here.