Climate Q&A

Yes.  Atmospheric temperatures have been measured by a series of satellites dating back to 1979.  Because each satellite operated differently, scientists have disagreed about how to correct the data for instrument errors and how to merge all the satellite data into a long-term record.

Over the past decade, different “merging” techniques resulted in different long-term temperature trends, not all of which showed the warming that climate models predicted should have occurred. Some early analyses even suggested that parts of the troposphere (lower atmosphere), where warming was expected, had cooled. The lack of an unequivocal warming trend in the troposphere was sometimes used to challenge both the reality of human-induced global warming as well as the reliability of climate models.

To help resolve the discrepancies, the U.S. Climate Change Science Program undertook a comprehensive review of surface and atmospheric temperature observations and trends. The group identified and corrected errors in early versions of satellite and weather-balloon data, and concluded “For recent decades, all current atmospheric data sets now show global average warming that is similar to the surface warming.”

Temperature trends

Some uncertainties remain, however, particularly in the tropics. While all the long-term atmospheric data sets now show a warming trend, they do not all show the amplified warming (greater warming of the atmosphere than the surface) that models predict. According to the U.S. Climate Change Science Program report, this remaining uncertainty may be due to additional errors in the observational data sets (the explanation favored by the report authors) or to limitations in the models’ ability to simulate the impact of global warming on different atmospheric layers.

  1. References

  2. Karl, T. R., Hassol, S. J., Miller, C. D., and Murray, W. L., editors. (2006).
    Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences. A Report by the Climate Change Science Program and the Subcommittee on Global Change Research, Washington, DC. Accessed June 8, 2007.
  3. Remote Sensing Systems. (2007). Description of MSU and AMSU Data Products. Accessed June 27, 2007.
  4. Schmidt, G. (2005). Et Tu LT? Real Climate. Accessed June 6, 2007.
  5. The University of Alabama in Huntsville (2007). The National Space Science and Technology Center. Accessed June 15, 2007.