This is exactly what they are doing, making the past colder to make the present warmer!
Flashes between GISS 1999, and GISS 2014
NASA GISS: Science Briefs: Whither U.S. Climate?
in the U.S. there has been little temperature change in the past 50 years, the time of rapidly increasing greenhouse gases — in fact, there was a slight cooling throughout much of the country
– James Hansen, 1999
If the present refuses to get warmer, the past must become cooler, and government scientists must ramp up the cheating.
Centinel2012 
