How are weather observations used to predict climate? What else goes into observing climate? Are there errors in the observational data?
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The global observing system was designed to monitor daily weather, not long-term climate, so it has well-known deficiencies that climate researchers carefully account for. For example, weather stations in large cities are excluded from global climate analyses in order to separate the urban heat-island effect from worldwide warming. Surface air temperatures over the ocean are inferred from sea-surface temperature data collected by ship; these readings track closely with the overtopping air temperatures over periods of a few weeks or more. Although some biases in the ship-based readings have recently been found and corrected, these biases were having virtually no effect on the long-term global trend.
Several groups of scientists (at NOAA, NASA, and the University of East Anglia in Britain) have independently developed methods that take data from around the world and average it to calculate trends in global temperature. There are small differences from year to year between these analyses, which means that, for instance, a given year might rank #5 for warmth in one group’s analysis and #6 in another. However, the long-term warming trend is clear and consistent across all three analyses.
Above the surface, temperatures in the tropopause are measured by radiosondes as well as satellite-based sounders. Major discrepancies between these data sets have now been largely resolved, and both sets show overall warming since the 1980s, as noted by a National Research Council study, several recent scientific papers, the Intergovernmental Panel on Climate Change, and the U.S. Climate Change Science Program.
More information: Earth Observations from Space: The First 50 Years of Scientific Achievements. Committee on Scientific Accomplishments of Earth Observations from Space, National Research Council. National Academies Press
Reconciling Observations of Global Temperature Change. Panel on Reconciling Temperature Observations, Climate Research Committee, Commission on Geosciences, Environment, and Resources, National Research Council. National Academies Press
Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences. Thomas R. Karl, Susan J. Hassol, Christopher D. Miller, and William L. Murray, editors, 2006. A Report by the Climate Change Science Program and the Subcommittee on Global Change Research, Washington, DC
GISS Surface Temperature Analysis: NASA Goddard Institute for Space Studies
National Climatic Data Center Climate Modeling: State of the Climate Reports
Temperature Data. Climate Research Unit, University of East Anglia -