The levels of carbon dioxide in the atmosphere are estimated to be higher than at any time in the past 420,000 years. That is option B
Carbon dioxide is a very harmful compound which is easily released into the atmosphere through burning of fossil fuels and other carbon compounds in plenty of air.
The released carbon dioxide rises to the upper atmosphere and blocks the radiation of solar energy back into the space. This precipitates a global temperature increase called the greenhouse effect.
According to Intergovernmental Panel on Climate Change (IPCC) in a current research discovered that CO2 concentration in the earth’s atmosphere is higher than at any point during the last 650,000 years. They where able to study this through the study of higher levels of CO2 concentration which coincide with higher temperatures.
Therefore the correct option is B which states that the levels of carbon dioxde in the atmosphere are estimated to be higher than at any time in the past 420,000 years.
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