There have been five major extinctions in the history of the earth so far. The most recent extinction occurred about 66 million years ago, when dinosaurs disappeared from the earth.

In recent years, many creatures are disappearing from the earth for a long time due to global warming and climate change caused by human activities. Therefore, it is getting more and more convincing to claim that the 6th extinction is going on now.

The extreme environmental changes, such as climate change, caused by the intricate intertwining of animals and plants living on the Earth's surface can amplify species extinction as a domino phenomenon (Strona and Bradshaw, 2018). In particular, considering the domino effect of extinction in the case of climate change caused by global warming, the extinction of the organism can be carried out about 10 times faster than anticipated.
Researchers at the European Commission Joint Research Center have experimented with how animals and plants that are intertwined with each other in the food chain are brought to co-extinction by environmental changes. The team first created a virtual earth. The hypothetical earth was supposed to contain thousands of animals and plants complexly intertwined by the food chain. In particular, we hypothesized extreme environmental changes, such as the so-called "nuclear winter", in which persistent warming or constant temperature drops in hypothetical global ecosystems, and investigated what changes could be made in the ecosystem.

The researchers did two kinds of experiments. First, we investigated how each individual animal or plant in the virtual district was annihilated when the temperature was constantly rising or falling beyond the limits of survival (primary extinction). The second was an experiment (2nd extinction), beginning with the beginning of extinction due to a certain species temperature change, to see how the extinction of this species affects the extinction of other species entangled in the food chain. Consumers who have consumed certain foods as a result of the disappearance of certain foods have experimented with the disappearance of the domino phenomenon and the extinction of the ecosystem, which leads to extinction.

Experiments have shown that if climatic changes persist, living creatures that are intricately intertwined with the food chain can be boosted up to 10 times more than previously expected. The domino effect of extinction means that extinction of living organisms due to climate change can proceed much more rapidly and on a large scale than ever before. The ecosystem can disappear.

The researchers emphasize that, given the domino effect of extinction, almost all of the creatures on the virtual world reach extinction, even if the global mean temperature rises 5 to 6 degrees C before industrialization. Experiments in virtual districts mean that if the average global temperature rises by 5 to 6 degrees Celsius, the Earth's ecosystem is likely to "swoop".

COP21, the United Nations Framework Convention on Climate Change (COP21), held in Paris in December 2015, agreed that by 2100 the global average temperature rise would be within 1.5 to 2 ° C below the pre-industrial level. At the 48th General Assembly of the Intergovernmental Panel on Climate Change (IPCC) held in Songdo, Incheon last October, the so-called 'Global Warming 1.5 ℃ Special Report', which ties the global average temperature rise to 1.5 ℃, was approved unanimously by the member countries. In a special report, to limit the global average temperature rise to 1.5 ° C, carbon emissions should be reduced to 45% by 2030, and until 2050 by human as much as possible, ).
However, the COP24 of the United Nations Conference on Climate Change (COP24) recently held in Katowice, Poland made it clear that the United States, Russia, Saudi Arabia and Kuwait can not accept the 1.5 ° C global warming report. The humanitarian effort to protect the global ecosystem by reducing the risk of climate change by linking the rise in global temperature to within 1.5 ℃ is in danger of being ignored by the international community.

If humans do not reduce GHG emissions but continue to emit them now (RCP 8.5), the IPCC expects that the global mean temperature in 2100 will rise by 2.6 to 4.8 degrees Celsius from 1986 to 2005. This virtual earth experiment shows that if the average global temperature rises by 5 to 6 degrees Celsius, the global ecosystem may be wiped out,

It is unclear whether the ecosystem is becoming increasingly dominoin extinction, as the international community is controversial about its own interests now with greenhouse gas reduction plans and goals. The researchers are now emphasizing that the Earth's ecosystem is like a fish that lives in an aquarium that has a broken thermostat.

<References>
* Giovanni Strona, Corey JA Bradshaw. Co-extinctions annihilate planetary life during extreme environmental change. Scientific Reports, 2018; 8 (1) DOI: 10.1038 / s41598-018-35068-1

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