Projects in Wadhurst U3A
- Earth’s atmosphere evolved from its beginning with 95% carbon dioxide and no oxygen to the current day composition of 21% oxygen and 0.04% carbon dioxide 4.5 billion years later, but those of Venus and Mars stayed very much the same, at least in composition. My talk attempts to provide an explanation for this observation in three parts: 1) The evolution of the Earth’s atmosphere during the past 4.5 billion years and the important interplay between the atmosphere and the evolution of life. 2) The carbon cycle and greenhouse effect that control the small variations in the present day atmosphere (nevertheless a potentially serious threat for humans). 3) The contrast between the destinies of Venus, Earth and Mars.