NCDC shows US May temperatures increasing since 1895, and that this past May was well above normal temperature.
The actual thermometer readings which they use show the exact opposite, before they tamper with it.
The graph below shows how much tampering they are currently doing. By massively cooling the past, they have created the appearance of a warming trend – which never actually occurred.
The animation below shows their handiwork, which would make Enron accountants feel envious. They have turned a cooling trend into a strong warming trend, which just by coincidence happens to suit their political agenda.
Disclaimer : NCDC reported temperatures are strictly for political purposes, and should not be referred to in any scientific context. They need to keep up with the IRS, DOJ and EPA. Read Orwell et al (1949) for more context.