For some, twenty-five years of data doesn?t sound like much for use in establishing long-term trends in global temperature. But, the temperature data collected by NASA satellites corresponds with the time when the potential human impact on climate should have been greatest. It has been collected consistently from samples of the atmosphere over the entire globe. This makes it of great importance. Because the data nearly ?cover the earth,? these measurements are unique among existing climate datasets. This also makes them an invaluable tool in assessing the impact of human activity on the global atmosphere. The satellite data now spans a quarter century. Happy anniversary!
The satellite data record indicates the atmosphere has warmed up over the last twenty-five years (1) less than the amount calculated using observations taken at the earth?s surface, and (2) much less than the amount calculated by most global climate models, which incorporate observed changes to the atmospheric system (i.e., volcanic eruptions, solar variations, greenhouse gas increases, aerosol changes, etc.). The discrepancy in these measurements casts doubt on what scientists really know about what is going on with regard to ?global warming.? It raises three immediate questions: are the climate models functioning correctly, is the satellite data accurate, and/or is there a flaw in the surface observations?