CH4 effect on people and climate

　　A team of 80 scientists on an expedition to Siberia made a startling discovery that the waters of the eastern Siberian sea were boiling as if they were boiling. The discovery shocked everyone, as no one had ever seen such a phenomenon before.

　　The purpose of the trip of the team of scientists originally wanted to study the impact of the melting of the permafrost in the eastern Arctic, but did not expect to find this strange phenomenon by accident. In fact, the phenomenon is caused by methane bubbles rising from the sea floor. The researchers said that the methane concentration in the eastern Siberian sea is six to seven times higher than the global average, and the elevated methane concentration is caused by the thawing of the permafrost.

　　In 2017, Russian scientists had surveyed the giant craters that had appeared in the Siberian Arctic, which were formed by large underground bubbles of methane, which can form huge pits when they catch fire or explode. Researchers believe that excess methane levels have an impact on climate change, with methane emissions increasing by 20 percent for every 1 degree Celsius rise in global temperature.

　　Anthropogenic methane emissions are the second largest source of greenhouse gas emissions, after carbon dioxide. It absorbs 23% more heat than carbon dioxide. Therefore, the more methane there is in the atmosphere, the faster climate change will occur. Methane has the molecular formula CH4 (the structural short form is the same as the molecular formula). The simplest organic compound. Methane is a colorless, odorless gas with a boiling point of -161.4°C, lighter than air, and it is a flammable gas that is extremely insoluble in water. A mixture of methane and air in the proper proportion will explode when exposed to a spark.

　　CH4  is basically non-toxic to human beings, but when the concentration is too high, it makes the oxygen content in the air decrease significantly and suffocates human beings. When the methane in the air reaches 25%-30%, it can cause headache, dizziness, fatigue, inattentiveness, accelerated breathing and heartbeat, and ataxia. If not detached in time, it can lead to death by asphyxiation. Skin contact with liquefied product can cause frostbite. 

II. Toxicological Information and Environmental Behavior 

Toxicity: It belongs to the slightly toxic category. Allow the gas to diffuse safely into the atmosphere or be used as a fuel. There is a simple asphyxiating effect, in high concentrations due to the lack of oxygen asphyxia caused by poisoning. Dizziness, accelerated respiration and dyskinesia occur at 25-30% in air. 

Acute toxicity: mice inhalation 42% concentration × 60 minutes, anesthesia effect; rabbits inhalation 42% concentration × 60 minutes, anesthesia effect. 

Hazardous Characteristics: Flammable, can form explosive mixtures when mixed with air, there is a danger of combustion and explosion when exposed to heat and open flame. Reacts violently with bromine pentoxide, chlorine, hypochlorous acid, nitrogen trifluoride, liquid oxygen, oxygen difluoride and other strong oxidizing agents. 

Combustion (decomposition) products: carbon monoxide, carbon dioxide.

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