Read here and here. Climate "scientists" across the world have been blatantly fabricating temperatures in hopes of convincing the public and politicians that modern global warming is unprecedented and accelerating.
The scientists doing the fabrication are usually employed by the government agencies or universities, which thrive and exist on taxpayer research dollars dedicated to global warming research. A classic example of this is the New Zealand climate agency, which is now admitting their scientists produced bogus "warming" temperatures for New Zealand.
"NIWA makes the huge admission that New Zealand has experienced hardly any warming during the last half-century. For all their talk about warming, for all their rushed invention of the “Eleven-Station Series” to prove warming, this new series shows that no warming has occurred here since about 1960. Almost all the warming took place from 1940-60, when the IPCC says that the effect of CO2 concentrations was trivial. Indeed, global temperatures were falling during that period.....Almost all of the 34 adjustments made by Dr Jim Salinger to the 7SS have been abandoned, along with his version of the comparative station methodology."
A collection of temperature-fabrication charts.