The group says since the '80s, global average surface temperature data produced by NOAA and NASA was unfairly adjusted to show a steady increase in temperature.
Right-wing outlets said the study "dropped a bomb" and "could totally dismantle" the idea of humans causing global warming. Breitbart said the findings show "nearly all recent global warming is fabricated."
But scientists think the findings were misconstrued. While agencies do alter their data, it's done to account for errors in how temperatures were recorded over the past 150 years.
And the revisions aren't the politicized, one-way street the Heartland paper claims. Roughly half of the adjustments have made the warming trend seem less dramatic, not more so.
Researchers who independently reviewed the study also said some of its content was "grossly misleading," and that its authors had "very limited understanding" of how temperature records are measured.
But scientists admit that data collection methods aren't perfect. One study showed that since 1998, global warming occurred 140 percent faster than satellites initially showed due to their decaying orbits.