As a result of the atmosphere surrounding the Earth trapping some of the incoming solar radiation, the average temperature of the Earth is approximately 15°C. Estimate the amount of radiation that is trapped by the atmosphere, including CO₂ and methane, which provides the shield to maintain the temperature at a level that sustains living organisms. Comment on the current concern about global warming as a result of an increasing percentage of CO₂ and methane in the atmosphere surrounding the Earth.