Question

At present, the concentration of atmospheric ${CO}_{2}$ is _ _ _ _ _.
(a) 100 ppm
(b) 240ppm
(c) 380ppm
(d) 520ppm

Answer 1

Carbon dioxide is a crucial trace gas in Earth's atmosphere. It is an integral part of the carbon cycle, a biogeochemical cycle during which carbon is exchanged between the Earth's oceans, soil, rocks, and the biosphere. Plants and other photoautotrophs use solar power to supply carbohydrates from atmospheric carbon dioxide and water by photosynthesis.

Complete answer:
Carbon dioxide concentrations are rising mostly due to the fossil fuels that individuals are burning for energy. Fossil fuels like coal and oil contain carbon that plants pull out of the atmosphere through photosynthesis over the span of the many millions of years. ${CO}_{2}$ is a major pollutant of air and a greenhouse gas that contributes to global warming. The concentration of ${CO}_{2}$ within the atmosphere is expressed in terms of parts per million or ppm. According to recent research by forecasting systems, ${CO}_{2}$ concentration has begun to be about 380 ppm which in recent years has increased up to 400 ppm.
Carbon dioxide is a greenhouse gas that absorbs and radiates heat. Warmed by sunlight, Earth’s land and ocean surfaces constantly radiate thermal infrared energy (heat) . Unlike oxygen or nitrogen (which structures most of our atmosphere) , greenhouse gases absorb that heat and release it gradually over time, like bricks during a fireplace after the fire goes out. Without this natural greenhouse effect, Earth’s average annual temperature would be below freezing rather than near to 60 degrees Fahrenheit.
So, the correct answer is '380 ppm'.

Note: The global atmospheric concentrations of carbon dioxide, methane, nitrous oxide, and particularly greenhouse gases have all increased crucially over the last few hundred years. Increases in greenhouse gases have overbalanced the Earth's energy budget out of balance, trapping extra heat and raising Earth's average temperature.