According to foreign media reports, scientists have studied plant fossils left in ancient forests 23 million years ago, and the results show that some plants may grow rapidly with the increase of carbon dioxide index. Scientists have found well preserved fossils of leaves from an ancient lake in southern New Zealand, and for the first time have linked the high-temperature climate of 23 million years ago in which the leaves are located to the high concentration of carbon dioxide in the atmosphere. < / P > < p > the team listed some ancient plants that could use carbon dioxide more effectively for photosynthesis — the biological process of using sunlight to produce food for plants. This discovery may provide important clues for revealing the dynamic changes of plants. The current atmospheric carbon dioxide index has increased year by year, and is now close to the ancient index. < / P > < p > at present, the amount of carbon dioxide absorbed by plants is far more than expected. Can planting millions of trees effectively prevent climate change? What can we learn from ancient leaf fossils? < / P > < p > at present, the team has drilled 100 meters deep at the bottom of a dried up lake in New Zealand, which is located in a dead volcano pit with a diameter of about 1.6 km. The biomaterials discovered 100 meters from the drilling site have been fossilized, including plants, algae, beetles, flies, fungi and other biological remains. The history of these organisms can be traced back to a warm climate period in the early Miocene, when the global average temperature was 3-7 degrees higher than today, and most of the polar ice sheets had disappeared. < / P > < p > scientists are still controversial about the carbon dioxide index during this period, which is one of the reasons why the research has attracted much attention. Surprisingly, these leaves are basically mummified, so the original chemical composition of the leaves can be obtained, and all the subtle features of the leaves can be seen under a microscope. The ancient leaves are so well preserved that they can see tiny grains and pores that allow them to breathe in air and release water during photosynthesis, a process that can be observed under a microscope. < / P > < p > shown here is part of a highly enlarged mummified leaf. In these features, a single epidermal cell and a mouth shaped stomata can be seen. The leaf absorbs carbon dioxide and releases water through the opening. < / P > < p > the scientists analyzed the different carbon chemical forms, or carbon isotopes, of leaf fossils found in the leaves of six tree species in different sedimentary layers. This will help to predict the ancient atmospheric carbon content, which the researchers concluded was about 0.045% at that time. Previous conclusions showed that the ancient atmospheric carbon dioxide content was about 0.03%, lower than the latest conclusion. The atmospheric carbon dioxide content of 0.045% is similar to the corresponding value of pre industrial age, which is insufficient to explain the higher temperature in the early Miocene. Affected by human activities and vehicle exhaust emissions and other factors, the current atmospheric carbon dioxide content is about 0.0415%. It is estimated that the atmospheric carbon dioxide content will reach about 0.045% in the coming decades, which is similar to that in the forest atmosphere of New Zealand 23 million years ago. < / P > < p > at the same time, the researchers also analyzed the geometry and other structural features of leaf pores, and compared them with modern leaves. They found that ancient leaves were extraordinarily efficient in absorbing carbon through stomata and did not evaporate too much water, which is a key challenge for all plants. < / P > < p > this allows trees to grow in dry areas on the edge of forests, which the researchers say may be prevalent in temperate forests in the northern hemisphere, where more land is located on earth. < / P > < p > when carbon dioxide concentration increases, many plants increase the rate of photosynthesis because they can remove carbon from the air more effectively and save water in the process. In recent decades, NASA’s data show that the rising global carbon dioxide emission is mainly due to the US satellite activities. According to statistics, since 1980, the number of trees and plant leaves has increased in one quarter to one-half of the world’s plant growing areas. The phenomenon will continue to exist as the global carbon dioxide index continues to rise, but the latest study suggests that the phenomenon should not be regarded as good news. The increase of carbon dioxide absorption by trees will not offset the carbon dioxide released into the atmosphere by human activities. At the same time, due to the evolution of most modern plants in the environment with mild climate and low carbon dioxide content, some natural and agricultural ecosystems may be seriously damaged by the increase of carbon dioxide content, the rise of temperature and the change of precipitation. < / P > < p > not all plants benefit, and among those that can take advantage of this advantage, the results may vary depending on temperature, water or availability of nutrients. At present, there is evidence that when photosynthesis of some major crops accelerates, they absorb less carbon, zinc and other important minerals for human nutrition. The leaf fossil deposit area is located in a farm near the city of Dunedin in southern New Zealand. At the bottom of this ancient lake, the surrounding environment has formed a continuous sedimentary layer for tens of millions of years. This ancient lake is very deep with low oxygen content, which means that although it has a history of 23 million years, the ancient leaves deposited there are relatively intact. They include numerous leaves from the subtropical evergreen forest. The sedimentary area is layered with black organic matter, alternating with the silicon rich white strips formed by the algae that bloom every spring. < / P > < p > the feature of this sedimentary area is only discovered in the past 15 years. Scientists have named it “foulden Maar”, which is the only sedimentary area of this type in the southern hemisphere, but it is better preserved than a few similar sedimentary areas known in the northern hemisphere. Global Tech