You need to know this in order to correctly predict the coming climate changes.
On November 29, an expedition of St. Petersburg scientists left for Antarctica. It includes specialists from the Mining University and the Arctic and Antarctic Research Institute (AARI). One of the goals of the expedition is to try for the first time to obtain reliable information about what the climate was like on the planet a million years or more ago.
Carbon dioxide concentration is skyrocketing
… The climate is obviously changing. And in the direction of warming. Winter is coming, and in St. Petersburg the temperature is above zero. And in recent years, this picture has been observed regularly. Deviations from the usual climatic norms are now occurring in different parts of the globe
Scientists have not yet come to a consensus on what is the main reason for this phenomenon - cyclical climate changes or anthropogenic factors, that is, the impact on the environment of civilization. After all, with the beginning of the industrial era, people began to burn fossil fuels in increasing quantities - coal, oil and gas. Forests are being cut down on a huge scale, swamps are drained, and previously dry lands are flooded. And this does not go unnoticed.
“Over the past two hundred years, the concentration of carbon dioxide in the atmosphere has increased from 280 to the current record 400 ppm, or 0.04 percent,” Vladimir Lipenkov, head of the laboratory of climate and environmental changes at the AARI, told the Komsomolskaya Pravda correspondent. - Meanwhile, it has already been established that the air temperature is associated with the level of carbon dioxide concentration. By the way, this was first proved as a result of experiments carried out at the Russian polar station Vostok.
However, it should not be forgotten that there are natural sources of increased carbon dioxide concentration. Among them is the decay of organic material, such as dead trees and grass.
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But the climate is influenced by other factors that are cyclical. In particular, the change in the orbital parameters of the Earth. By the way, it was a million years ago that the current duration of the periods of alternation of glacial and interglacial epochs arose - one hundred thousand years. Before there were forty thousand years. Why this happened is still unknown to science.
Antarctica ice is a valuable source of information
The weather has been observed over the past two hundred, maybe three hundred years. Meanwhile, it is very important to know what happened on our planet much earlier.
- There is a task to study the so-called paleoclimate, that is, the Earth's climate in past epochs, before the start of instrumental meteorological observations, - says Aleksey Yekaykin, Associate Professor of the Department of Physical Geography and Landscape Planning, Institute of Earth Sciences, St. Petersburg State University. - Without understanding climate change in the past, it is impossible to predict future changes, and without this no country can plan its development.
How do scientists determine what the climate was like hundreds of thousands of ice ago. The most valuable source of information here is the ice that composes the glaciers of Antarctica and Greenland.
Photo: Alexey Ekaikin. Snowy tunnel in Antarctica.
Ice is known to be deposited in layers of falling snow. Layer by layer. At the same time, air bubbles in the ice layers do not undergo changes for tens of thousands of years. Techniques are available to determine the rate of ice formation. Exploring layer by layer, you can find out what was the gas composition of the atmosphere in different eras.
To determine the temperature, isotopic analysis of the ice itself is carried out. Let's not bore readers with an explanation of the physical nature of this analysis. Let's just say that the relative concentration of different types of water molecules testifies to the magnitude of air temperature in the past.
This is how the connection between the average temperature on the planet and the concentration of carbon dioxide in the atmosphere was proved.
The ice required for research is extracted by drilling wells. Drilling depth can exceed three kilometers. The so-called ice core rises to the surface. He is sent for research.
When will the Holocene end?
In 1999, as a result of the study of the core mined in Antarctica at Vostok station, in the work of which St. Petersburg scientists participate, it was possible to build a temperature series lasting 420 thousand years. The international team of scientists working on the EPICA (European Project for Ice Coring in Antarctica) project at the Concordia station in Antarctica has achieved even greater success. They received a time sweep for almost eight hundred thousand years.
“The already achieved results allow us to draw a number of important conclusions,” says Vladimir Lipenkov. - We are now living in another interglacial period. This last, so to speak, interglacial, which scientists call the Holocene, has been going on for about eleven thousand years. Whereas the duration of the previous three did not exceed six thousand years. It is quite possible that it was thanks to such a long period of relatively stable and warm climate on our planet that modern civilization arose. A correct understanding of current climate trends is impossible without answering the questions: why is the current interglacial period so long and when might it end?
By the way, scientists have found that the planet experienced a period similar to the current one just over 400 thousand years ago. It is known to science under the name "Marine isotope stage 11" or MIS 11. It lasted 28 thousand years, but then there was no anthropogenic impact on the natural environment.
The participants of the St. Petersburg expedition hope that according to the results of their work, a temperature series will be built, lasting a million years or more.
We have already said that at about this time on Earth there was a transition of a 40-thousand-year periodicity in the change of glacial and interglacial epochs to a 100-thousand-year one. And the reasons that led to the restructuring of the planet's climate system are unknown. And this is important to know. To better understand the role of the carbon cycle in global climate change. Note that the atmosphere contains carbon not only in the form of carbon dioxide, but also in the form of carbon monoxide and methane.
Photo: Alexey Ekaikin. Drilling complex, with the help of which ice core is extracted.
According to Vladimir Lipenkov, the expedition to Antarctica has several tasks. Among them, to determine the time of ice formation, which lies near Vostok station in the depth interval of 3310-3539 meters; to obtain the necessary data on climate change and the gas composition of the atmosphere over the past 1-1.5 million years from the core raised from these depths; to investigate the role of individual climate-forming factors, in particular, changes in the concentration of greenhouse gases in the Earth's atmosphere, in the global restructuring of the climate system.
After the completion of the expedition "Komsomolskaya Pravda" plans to tell about its results.
reference
In December 1997, Japan signed the Kyoto Protocol, which obliged developed countries and countries with economies in transition to reduce or stabilize greenhouse gas emissions. The European Union - by eight percent, the United States - by seven, Japan and Canada - by six, the countries of Eastern Europe and the Baltic states - by an average of eight, Russia and Ukraine - to keep the average annual emissions in 2008-2012 at the 1990 level. In April 2016, the Paris Agreement was signed, regulating measures to reduce carbon dioxide in the atmosphere from 2020. On June 1, 2017, US President Donald Trump officially announced the US withdrawal from this agreement.
By the way
Since the beginning of the 20th century, the average annual air temperature on the planet has increased by 0.74 ° C and is now 15.1 degrees.
DAVID GENKIN