Have you ever traveled in the Arctic? How does it feel like it’s cold outside in Celsius? But maybe if you lived 56 million years ago, you probably would have felt differently.

That’s because tens of millions of years ago, the Earth was in a period of global warming and also known by the scientific name of Paleo-Eocene Thermal Maximum. During this period, the Earth’s temperatures were so hot that both poles reached almost tropical temperatures. In other words, both the Arctic and Antarctic today also have temperatures at hot thresholds and tropical-like landscapes.

The Earth has experienced extremely hot periods many times. Especially the poles also froze and thawed countless times. Now the Earth is warming but very different from the old days. It’s just as hot as it used to be but now there’s the impact of climate change, leading to a record high heat record every month.

The Earth’s climate has fluctuated naturally over tens of thousands of years, the planet’s rotation around the Sun has gradually changed, resulting in a change from season to light. Part of the result of these fluctuations is the fact that the Earth has experienced ice ages and warmer periods.

But to create a Paleo-Eocene-like period will require more than a change in the tilt of the Earth’s axis or its path around the Sun. But besides that, another invisible culprit can also create the typical climate of the Paleo-Eocene period, which is CO2.

Greenhouse gases, including CO2, were responsible for causing high temperatures across the planet’s surfaces during the Paleo-Eocene period. But how to increase the concentration of CO2 without the presence of humans? Scientists do not seem entirely certain.

Sébastien Castelltort, a geologist at the University of Geneva, said the cause could be due to volcanic activity is strong, releasing CO2 into the atmosphere. CO2 then covers the Earth and makes sunlight unable to escape, thereby causing global warming, releasing glaciers at the poles. As the ice at both poles gradually melted, methane, a greenhouse gas many times more toxic than CO2, unintentionally escapes.

Take the Permian-Triassic extinction event, for example, that occurred several million years before the rise of the dinosaurs and took control of the planet. It is really a major climate disaster for the Earth. This warming event happened 252 million years ago and is extremely serious. This event is caused by volcanic activity causing climate chaos and destruction of many species.

Paleontologist Stuart Sutherland at the University of British Columbia told Live Science that at the time of the severe drought, the plants were dead and the Saharah desert spread across the continent. The temperature was almost beyond the endurance of the creatures.

It’s not clear what greenhouse gas concentrations were in the Permian-Triassic period, but they are much more likely than they are today. Some climate models predict that greenhouse gas concentrations would then have reached 3,500 parts per million ppm. While there are still only just over 400ppm.

But to lead to the Permian-Triassic extinction event, the Earth must take thousands of years to reach such a terrible temperature milestone. Specifically, according to some studies, the time can last up to 150 thousand years. In the Paleo-Eocene period, temperatures can increase extremely quickly when it takes only 10-20 thousand years to achieve such a terrible temperature.

And today’s warming on Earth seems to take only 150 years.

That is the big difference between climate change and global warming today compared to the warming of the past. The extreme and extremely fast developments make the consequences of climate change now extremely unpredictable.

Castelltort said his concern at the moment was not only that the planet was getting warmer, but that we did not know everything was moving so fast that humans could not adapt.

He said that no climate experts dare to assert that the current pace of global warming has no serious consequences. It’s just that we don’t know what the future climate scenario will be like.