Almost half of the National Oceanic and Atmospheric Administration's (NOAA) corrected data are cooler than the original records. NOAA's corrections of temperatures over the ocean — done to compensate for changes in methods of observing the temperature of water at the surface of the ocean — reduced the warming trend in global temperature.

For more details, visit https://climate.nasa.gov/blog/3071/the-raw-truth-on-global-temperature-records/.