23 million-year-old leaves were discovered, and scientists worry after research: the future of mankind is not easy

There have been many extinction events in the history of the earth, and although these species have disappeared permanently from the earth, they still have the opportunity to leave some traces on the earth, such as fossils. It is through digging and in-depth study of fossils that humans have been able to understand part of the past history of the earth. For example, by discovering dinosaur fossils and conducting extensive research on them, archaeologists have discovered that these behemoths once dominated the earth's biosphere for more than 100 million years, and the time of domination was even longer than humans.

In addition to getting information from animal fossils, researchers can also explore past Earth's climate from plant fossils. Some studies have pointed out that the earliest organisms on the earth were microorganisms, then plants, and finally animals. Therefore, the study of plant fossils can help humans understand the conditions of the earth before animals appeared. However, plant fossils are not as common as animal fossils, because they are easily decomposed under natural conditions and can only be preserved under special conditions.

Last year, a foreign research team announced the discovery of some relatively well-preserved leaf fossils. It was identified that these leaf fossils may be leaves from 23 million years ago, which is very rare in the history of human archaeology. So where were these leaf fossils found? What information can scientists gain from studying them?

Where were the fossil leaves found?

According to the scientific team, they found the leaf fossils near a farm in a city called Dunedin, New Zealand. Since fossils of algae, flies, and beetles were unearthed along with the leaf fossils, scientists defined the area as a "fossil deposition area." Today, this fossil deposit area is already a real land, but the researchers speculate that this area may not have been land in the past, but a lake.

Why do you say that? If the area was also land in the past, there is a high probability that the leaves will be decomposed by microorganisms after falling to the ground, and it is unlikely that there will be a chance to form fossils. But if it is a lake, as long as the lake has enough depth, the oxygen content in the deep water area will be maintained at a very low level, so that most microorganisms cannot survive normally, and the dead animals and plants can remain in the deep water area for a long time. Periods are not broken down.

The research team found a large number of animal and plant fossils from the fossil deposition area, and after dating analysis, they may all come from 23 million years ago. So what caused these creatures to sink to the bottom of the lake and gradually become fossils? Some researchers pointed out that a transitional process is required for lakes to become land, and this process is mud. Mire is also an area with very low oxygen content, and the remains of animals and plants can be preserved for a long time. In addition, researchers have always believed that the environment at that time should have undergone drastic changes, which led to the disappearance of many creatures.

What have scientists discovered from these ancient fossils?

How did the researchers come to this conjecture? By analyzing the chemical composition of the leaf fossils, they found that the leaf fossils contained some information related to the past climate. These leaves have a high degree of preservation, and the lines on their surfaces and the traces of insect bites are still clearly visible, so researchers believe that their chemical composition is not doped with too many things that affect the analysis. to extrapolate carbon dioxide levels in Earth's atmosphere 23 million years ago.

This method works because plants absorb carbon dioxide from the air during photosynthesis, and they also release carbon dioxide through respiration. The photosynthesis of plants is carried out in the chloroplast in the cell. This organelle can synthesize water and organic matter from carbon dioxide and water under the irradiation of sunlight. The carbon in carbon dioxide is converted into organic matter, and the organic matter is precipitated and becomes part of the plant. Oxygen is expelled from the plant, so it is possible to roughly infer the carbon dioxide concentration in the atmosphere 23 million years ago by analyzing the amount of organic carbon in the leaves.

In addition, the researchers used the same method for other animal fossils. The purpose is to analyze the concentration of carbon dioxide in the atmosphere during that period, and then combine multiple data to compare and get the final result. The identification of various leaf fossils shows that the carbon dioxide content in the atmosphere reached 0.045% during that period, which is the highest level in the past 30 million years. The researchers predict that at these levels, Earth's average temperature will rise by at least about 3 degrees Celsius, and the ice caps at the poles may all melt.

Can Fossil Leaves Really Reveal Earth's Past Climate?

Many people may not believe that it is possible to study the past climate of the earth with a small leaf? Before the discovery of the New Zealand leaf fossils, relevant research reports appeared in the journal Science. The report pointed out that after scientists conducted an in-depth study of leaf fossils from 55 million years ago, they found that they seemed to tell the living conditions of plants on Earth during that period. 55 million years ago, the earth was in a period of rapid global warming, with the global average temperature rising by about 10 degrees Celsius.

In the context of such a large temperature rise, the ice sheets in the Arctic and Antarctic regions have almost melted, and even plants originally distributed in the tropics and subtropics have begun to migrate to higher latitudes. Scientists caught their attention when they discovered a plant in the US state of Wyoming that was originally found only in the Gulf Coast. Combined with climate change 55 million years ago, scientists believe that the plant should have migrated from lower latitudes of Mexico to relatively higher latitudes of the United States

So how does this research help in studying climate issues now? Scott Wenger, a paleontologist from the National Museum of Natural History in the United States, said that the extremely hot period 55 million years ago proved that plants would migrate under the influence of climate, so under the artificial global warming, plants will also be in the future. The same situation occurs. Therefore, it is possible to infer the extent of climate warming by observing the distribution of plants in some areas for a long time, which is very important for formulating response plans.

What does a leaf fossil found in New Zealand portend?

Going back to the leaf fossils found in New Zealand, did their presence at this time convey any message to humans? The team's climatologists believe that the meaning of the leaf fossils is already obvious. If the problem of climate warming cannot be solved, many creatures on the earth will eventually become underground fossils. At the same time, the data obtained by the researchers from the fossil leaves show that the carbon dioxide content in the earth's atmosphere has not yet reached a historical peak, so humans still have a chance.

As we all know, the direct cause of global warming is that greenhouse gas emissions exceed a stable level, and human activities make the greatest contribution in this regard. Anyone who lives on earth is involved in activities that cause greenhouse gas emissions, such as going out to take a bus or self-driving car, using disposable utensils for meals, using electricity at home or outside, and so on. Among these activities, some activities are unnecessary, such as the use of disposable tableware and self-driving cars. Therefore, we should develop awareness of energy conservation and environmental protection, and contribute to energy conservation and emission reduction.

Will Earth become a second Venus?

If the greenhouse effect continues to develop, what will the earth be like in the future? Some people think that just look at Venus next door to Earth. In the past, people referred to Venus as Earth's "sister planet" because Venus and Earth were similar in size and mass. And Venus has the same atmosphere as Earth, but the atmosphere of Venus is much thicker, and it has been detected that there is a very serious greenhouse effect in the atmosphere of Venus, and the content of carbon dioxide exceeds 50%.

The result of the greenhouse effect is that the average temperature on the surface of Venus remains above 450 degrees Celsius all year round. So what causes Venus to have such a serious greenhouse effect? First, Venus, the second-closest planet to the sun, gets more solar radiation than Earth, which is one of the reasons for the severe greenhouse effect on Venus. Secondly, there are many active volcanoes on the surface of Venus, and some volcanoes are still active, and volcanic eruptions will further aggravate the greenhouse effect.

Obviously, the greenhouse effect on Venus is caused by natural factors, while the greenhouse effect on Earth is mainly caused by humans, but it is indeed possible for the Earth to go the same way as Venus, because human factors are also the most uncontrollable factors. Before the formation of human civilization, the Earth's climate did alternate between glacial and warm periods, but the emergence of humans accelerated the rate of warm periods, and it only took about two hundred years to push the greenhouse effect to a historically high level s level.

If the above assumptions are realized, where should mankind go?

If the earth really becomes the second Venus in the future, where can human beings take refuge? At this time, many people will turn their attention to Mars, a planet that humans have long longed to land on. If the climatic environment of Earth develops to be worse than that of Mars, then humans have no other choice but to flee to Mars for refuge. Although the Moon is the closest to Earth, the conditions on the Moon are a bit worse than on Mars.

As for planets such as Europa and Titan, not to mention, there is an insurmountable distance between them and the earth. From this point of view, Mars is the only choice, and it is also a helpless choice. Not to mention how high the success rate of human immigration to Mars is in the future, imagine that one day in the future human beings will really immigrate to Mars, standing on Mars and looking at the earth, no one should think that the homeland they once relied on will eventually become Second Venus.