...Recent revelations from the Climategate emails, originating from the Climatic Research Unit at the University of East Anglia, showed how all the data centers most notably NOAA and NASA conspired in the manipulation of global temperature records to suggest that temperatures in the 20th century rose faster than they actually did...
...the global surface station data is seriously compromised.
There was a major station dropout and an increase in missing data from remaining stations which occurred suddenly around 1990. Just about the time the global warming issue was being elevated to importance in political and environmental circles.
A clear bias was found towards removing higher elevation, higher latitude, and rural stations the cooler stations during this culling process, though that data was not also removed from the base periods from which averages, and then anomalies, were computed.
The data also suffers contamination by urbanization and other local factors, such as land-use/land-cover changes and improper siting.
There are also uncertainties in ocean temperatures. This is no small issue, as oceans cover 71% of Earths surface....
