The environmental changes on the earth are extremely slow, often tens of millions of years span, the slowly changing climate is the largest "behind-the-scenes driver" of the rich and changeable species on the earth, no species will always dominate the earth, in the slow climate change, often the "old god" fell "new god" to the throne.
Of course, such a relatively mild "attitude" of the earth will not always be maintained, from the Paleozoic Devonian to rule the ocean for 100 million years of Dunshi fish collapse, and then to the end of the Mesozoic Cretaceous and Cenozoic Paleogene dinosaur era, the drastic climate has become the dominant factor in the mass extinction event of the earth's species, the reason behind the ups and downs of climate change has always been a hot research topic in the scientific community, and in these climate upheavals, the Paleocene-Eocene extreme heat event that lasted only 200,000 years can definitely be called the most bizarre climate upheaval.
<h1 class="pgc-h-arrow-right" data-track="3" > earth had a "high fever"</h1>
The cause of this Paleocene-Eocene extreme heat event is also from 65 million years ago, after the asteroid that led to the end of the dinosaur era hit the earth, the balance that the earth has been hard to establish for tens of millions of years has been broken again, I don't know whether it is because the huge energy brought by the impact has changed the movement of the earth's crust, resulting in frequent volcanic occurrences, or the sharp reduction of the number of plants after the mass extinction of organisms, the ability to reduce carbon sequestration has deteriorated, anyway, the result is that the carbon cycle has been blocked. Huge amounts of carbon dioxide from volcanic eruptions or fires are increasingly flooding the atmosphere, and the average global temperature begins to rise dramatically, rising by 3°C over a 10 million years, leading to extremely hot events.
55 million years ago, the Earth's temperature suddenly rose by 5-8 ° C, and many literature records believe that this "sudden" lasted less than 20,000 years, 20,000 years in the geological age of the earth is shorter than the blink of an eye, what caused such a sudden high temperature?
The most convincing view is still inclined to incline to the earth's 10 million years of continuous warming, the final quantitative change triggers qualitative change, climate warming has a very large impact on ocean currents, a large number of warm currents flow to the perennial cold deep sea, and the deep sea "greenhouse bomb" combustible ice is released in large quantities, the main component of combustible ice is methane, methane's thermal insulation capacity can be more than 20 times stronger than carbon dioxide, the release of methane has promoted the further rise of temperature, so the earth's temperature directly "took off", and methane is not stable in the atmosphere. It is oxidized by ultraviolet rays and will also escape into the universe, which explains why the Earth's temperature dropped rapidly after the end of an extreme heat event.
South Pole combustible ice sampling
So how much carbon was released during that time? By analyzing the cores of marine sediments from this period, Marcus Goodyear's team calculated that it was about 3 trillion tons, and the entire emission process lasted about 50,000 years, so much more carbon than the carbon from global fossil fuel reserves, and now the annual carbon emissions from fossil fuels are about 1 billion tons, and the global carbon dioxide emissions in 2020 are 31.98 billion tons.
Such a huge number directly caused the earth to launch a "high fever", and after the end of the extreme heat event, the earth's temperature is still rising steadily, and in 5 million years it has slowly returned to the high temperature level of the extreme heat event, which is a great opportunity for animals and plants.
<h1 class="pgc-h-arrow-right" data-track="14" > forced whale ancestors into the sea</h1>
This warm period that lasted for millions of years is known as the Early Eocene Warm Period, and the most significant change in the high temperature belt is the abundant precipitation in the local area, in today's Pakistan, the precipitation at that time made the riverbed in this area all over the riverbed, the river channel, so that many animals that originally ran on the ground had no place, including the ancestor of the whale, the Bucky whale.
Discovered in Pakistan in the 1980s, bucky whales are considered to be the oldest and most primitive cetaceans known to date, living 53 million years ago, during the Warm Period of the Early Eocene.
Bucky whale and today's whale looks completely different, it is about 1 meter long, four legs walk not to say that there is a long tail, although there is a "whale" in the name, but Bucky whale has a very strong limbs, their teeth are also a typical type of canine molars in land carnivorous mammals, such an image is like a big dog today, but Bucky whale and canines are only "similar", in the classification more inclined to the ancestors of hippos, so Bucky whale is exactly an omnivorous animal, At the same time, obvious traces of grass plant wear were also found on the excavated fossil teeth of Bucky whales.
The first step to the sea was not difficult for Bucky whales, and in fact it may have to turn to underwater foraging, when the Pakistani region faced shallow seas, coupled with the thick swamp, the thick limbs seemed to have no use for running, but instead "dog planing" in the water was more suitable. At the same time, bucky whales have evolved to be as smooth as crocodiles, with their nostrils facing upwards, and the orientation of their eyes and ears suggest that Bucky whales are focused primarily on the underwater, which indicates that Bucky whales have begun to adapt to life underwater and on land.
A friend on the Internet asked whether Bucky whale is an amphibian mammal, in fact, in the biological classification of amphibians and mammals are two completely different concepts of animals, there is no overlap in the tree of life, amphibian mammals themselves are unreasonable.
<h1 class="pgc-h-arrow-right" data-track="22" > will there be a new warming period for global warming today</h1>?
In the Paleocene-Eosocene extreme heat event, the global average temperature peaked at about 23 °C, while the global average temperature reached 14.9 °C in 2020, according to the predictions of meteorologists, at the current rate of carbon emissions, the total amount of carbon in the Paleocene-Eocene extreme heat event may be reached in 2159, and as of 2016, humans have emitted a total of about 150 million tons of carbon.
At the same time, according to a new study published by the University of Copenhagen in Natural Climate Change, the temperature in most of the Arctic Ocean region has risen steadily in the past 40 years at a rate of about 1 °C per 10 years, which is very similar to the rate of heating in the last ice age, and it can be said that it is urgent to control global carbon emissions and drag down global warming.
But will there be a great warm period like the One in the Paleocene-Eocene Extreme Heat Event? This is difficult to say, because the crustal movement and ecological environment at that time were very different from today's situation, the extreme heat event itself stayed for a short time, and there were few traces left in the geology, which is difficult to compare with today's earth environment.
Field profile of Paleocene-Eosocene extreme heat events in the Dingri region of southern Tibet
However, it is definitely not a good thing that the world is warming at this rate, and what the outcome of the quantitative change to the qualitative change may only be known on the day of arrival, but isn't it a little too late at that time?