Stone tools found in a cave in Mexico have archaeologists rewriting the human history of the Americas.
The last time global carbon dioxide levels were around 400ppm was four million years ago. On average, the world was 3℃ warmer, but in high northern latitudes, it was up to 14℃ warmer than today.
During the transitional period between the Pleistocene and Holocene epoch, the Earth's temperature underwent massive change, forcing prehistoric humans in Indonesia to change their diet.
The Yarrabubba asteroid landed 2.2 billion years ago. Around the same time, the icy Earth went through a big thaw.
New research shows that warming by more than 2°C could be a tipping point for Antarctica's ice sheets, resulting in widespread meltdown and changes to the world's shorelines for centuries to come.