Global and regional temperature change over the past 4.5 million years. (https://pubmed.ncbi.nlm.nih.gov/38386742/)

These scientists wanted to learn more about the Earth's climate over a really long time, like millions of years. They looked at tiny sea creatures called foraminifera that lived in the ocean a long time ago. By studying the oxygen in the foraminifera, they could figure out how warm the Earth was back then.

They found out that the Earth went through two big cooling periods over millions of years. During the second cooling phase, which happened about 1.5 to 0.9 million years ago, the Earth cooled down even faster. This period was special because the Earth's temperature changed from warming and cooling every 41,000 years to every 100,000 years.

The scientists think that these changes in temperature were linked to how carbon moved around in the Earth's oceans. At first, the changes were caused by natural processes in the Earth, but later on, the Southern Ocean played a big role in these changes too. By studying all of this, the scientists can understand better how the Earth's temperature has changed over a really long time.

Clark PU., Shakun JD., Rosenthal Y., Kohler P., Bartlein PJ. Global and regional temperature change over the past 4.5 million years. Science. 2024 Feb 23;383(6685):884-890. doi: 10.1126/science.adi1908. Epub 2024 Feb 22.