Does data processing make temperature data warmer?

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/.