Are you sitting down? You should probably be sitting down for this.
Ha! Just kidding. If your'e a person with an Actual Brain, you're just going to add this to the evergrowing list of ways that the Global Climate Change Alarmism Club has tried to manipulate climate data in order to convince everyone that global warming is going to KILL EVERYONE UNLESS WE PAY GIANT CARBON TAXES AND DRIVE PRIUSES OMG.
According to the sourcelink, it turns out that published temperature graphs for several weather stations in South America have been "adjusted" to show that the Earth warmed more than it actually did. Who's making the adjustments? The US government's Global Historical Climate Network. Following that, the Goddard Institute for Space Studies and the National Climate Data Center "amplified" those results.
Since this discovery, it turns out that at weather stations in the Arctic, Canada, and Siberia, similar adjustments were also made.
Why? Great question. The Global Historical Climate Network isn't talking. The author of the sourcelink suggests, "This really does begin to look like one of the greatest scientific scandals of all time."