About 4.6 billion years ago, the earth would acquire its first atmosphere, but this is completely different from the atmosphere we know today. The oxygen-rich atmosphere that we are familiar with today did not form until the Proterozoic. Between 2,500 and 541 million years ago, oxygen-producing bacteria killed most of the previously prosperous life in the Archean.
This, and the study of large insects, such as 75 cm wingspan Permian grass Dragonflies from the Permian period and reconstructed temperature, oxygen and carbon dioxide levels Paleoclimatology It shows that we humans cannot recognize the period of the earth’s atmosphere and accompanying climate.
Human history covers only a small part of the earth’s history, which can be said to be one of the coldest and least eventual periods of the latter, but man-made (man-made) climate change is now likely to change this quickly. But wait, how do we know what the climate is like on such a large time scale? Let’s take a look at how we managed to reconstruct the ancient climate of the earth and what these discoveries mean for our prospects as a species today.
Welcome to the Holocene
The current geological age is called New generation (Also known as the Mammal Age), including 66 million years, divided into three periods:
- Paleogene: 66 – 23.03 million years ago (Mya)
- Neogene: 23.03 – 2.58 Mya
- Quaternary Period: 2.58 Mya-Today
The Quaternary roughly formed a period of recognizable human existence, including two periods:
- Pleistocene (2.58 Mya – 11,700 ya)
- Holocene (11,700 – today)
Some people have proposed that we recognize a new geological era, called the Anthropocene (“the human era”), which is defined as the era when human activities first began to leave important traces in the geological record.Although still The subject of intense debate, The search is to find a so-called “golden spike” in the geological record, which may be composed of radionucleotides, heavy metals, fly ash, and similar discoveries, which will indicate the rise of human activities in the early 20’sday century.
If the Anthropocene becomes the current new era, its beginning may appear around the 1950s. However, in terms of the Earth’s current climate and global temperature, the Holocene and to some extent the Pleistocene may be our best indicator of what is currently “normal” and the result of the so-called “forcing”. These influences force the global temperature to be higher or lower than the original temperature, from volcanic eruptions, meteor impacts and solar activity to human activities.
As explained by the National Environmental Information Center (formerly NCDC) of the National Oceanic and Atmospheric Administration (NOAA), Forcing in the past 1000 years very clear.When comparing the effects of solar activity (through radioactivity 14and 10Are isotopes in ice cores and tree rings) and isotopes in volcanic eruptions (through sulfate (SO)42-) Layer) there is a strong correlation in the simulation until 20day century.
This becomes clearer when we look at the comparison below Global temperature Based on nearly ten published studies:
Although the preceding graphs fairly clearly show that the global temperature rise observed in the 20th century and the current 21st century was not forced by increased solar activity or similar positive effects, the use of earth’s Geological temperature record In the past 500 million years:
As in the past thousand years, these temperatures are passed Climate agent: Geological and other markers that can be inferred from meteorological measurements (such as temperature) are recorded in some way. Each of these agents has a limit, and how far they can take us back in time due to the gradual (radioactive) decay of the markers or due to how many agents exist (such as the thickness and age of the ice sheet).
Among these agents, Ice core Probably the most well-known. These can take us back to about 800,000 years ago and provide us with air samples from a specific period of time when the bubbles were trapped. In addition, impurities such as sand and ash can provide clues to atmospheric events-our own Jenny List wrote an article on how lead was found in mountain glaciers during human smelting activities in the 13th century.This allows us to construct the graph using Dongfang Station Ice core:
The graph covers the past 420,000 years, CO2 The level is well below 300 ppm (parts per million).Atmospheric carbon dioxide2 Today (as of June 2021) the measured value is Far more than 410 ppmIn the absence of other forcing events, this may explain the rapid rise in global temperature. carbon dioxide2 Level And similar gases such as methane (CH4) Is an obvious reason Radiative forcing. This effect is often referred to as the “greenhouse effect”.
Although the Earth’s atmosphere is kept warm in this way to sustain the biosphere and the fragile life in it, by changing the magnitude of the radiative forcing, this can lead to a sharp rise or fall in global temperature.This for example see Cambrian (541 Mya – 485.4 Mya) and atmospheric CO2 At a level of about 4,500 ppm, the global temperature is 7 °C higher than the pre-industrial temperature in the 19th century.
Another such maximum is the Paleocene-Eocene thermal maximum (PETM), around 55.5 Mya, the global temperature has risen significantly by 5–8 °C. This is related to major changes in volcanic activity and the earth’s carbon cycle. Due to these changes, many species became extinct on a large scale.
Obviously, the Earth’s climate is already much warmer and has more atmospheric carbon dioxide2 Compared with today, what is going on with today’s changes and the goal of keeping global temperature rise below 3°C? The answer here can be succinctly summarized by pointing to the knowledge that these mass extinctions found in the geological record and that humans have only evolved for a thousand years in the past 300,000 years.
One of the signs of evolution is that species evolve to adapt to specific environments. As the Earth’s climate changes between extremes, certain species will find that they cannot cope with these changes.This may involve a drop or rise in temperature, changing oxygen levels (which may cause Giant nerve Extinction of dragonflies) and habitat destruction, such as desertification.
Although people may scorn the rising temperature and consider the amazing technologies we have, such as air conditioning, remember, body temperature 40°C (104°F) is considered a medical emergency. When exposed to high temperatures, the body’s temperature regulation may have failed. Wet bulb temperature 35°C (95°F) for more than 6 hours, resulting in fatal hyperthermia.
Steven C. Sherwood et al.Found that due to thermal stress, many parts of the earth’s surface May become uninhabitable Due to this heat stress, it is even fatal to humans. Like humans, other animals and all plants will be exposed to these temperatures. Although we can put ourselves in air-conditioned rooms and vehicles, we cannot do the same with livestock, crops, and the entire ecosystem. Eventually, just a few hundred years later, this could lead to the worst extinction event since PETM.
The end of the Anthropocene
One might wonder what a golden spike is, which indicates the end of the Anthropocene (the fiercely debated “human age” mentioned earlier) and the beginning of a new era. The pessimistic view is that humans may not witness this change with their own eyes, so it may not matter. Regarding the optimistic view, there is a view that humans may find a way to avoid forcing that will eventually destroy the habitat and climate on which they depend.
Here to reduce pollution, especially the release of carbon dioxide and other gases2 And CH4 As described by Steven C. Sherwood et al., entering the atmosphere is generally considered to be the most effective way to prevent the worst. However, this method has also proven to be extremely difficult. As evidenced by the continued use of fossil fuels by humans, fossil fuels are considered to be the main source of these carbon-based gases:
Obviously, most of the energy that powers human society today comes from fossil fuel sources, which replace traditional biomass (ie burning wood and the like). Each of these sources has its own “carbon budget.” When we look at the life cycle carbon emissions of these sources when they are used for electricity production, we can see:
If we want to quickly reduce the amount of CO2 And CH4 In the atmosphere, we should use more sources on the right instead of any sources on the left. Although we as a species are reluctant to admit this, at this point in time, at the very edge of the geoclimatic record, human beings are the main driving factor of the earth’s climate.
Although changing the climate is a very unique feature, it has not appeared since Proterozoic bacteria wiped out most of the life on the earth by producing toxic oxygen, but it also brought certain responsibilities. Here, we have an excellent opportunity to prove that human beings are actually the pinnacle of intelligent life.