Their latest study, released early on Monday (GMT), concludes that the average temperature of the Earth's land has risen by 1.5C (2.7F) over the past 250 years.
The team argues that the good correspondence between the new temperature record and historical data on CO2 emissions suggests human activity is "the most straightforward explanation" for the warming.
The paper reiterates the finding that the land surface temperature has risen 0.9C just in the last 50 years.