Atmospheric differences among the inner planets are influenced jointly by their proximity to the Sun and individual aspects of their evolution. Earth is our solar system's "Goldilocks:" Venus is too hot; Mars is too cold; Earth is just right. One of the big questions: Why are the inner planets, so similar in origin and relative composition of elements, so different? What accounts for the strange nature of Earth's atmosphere?
Life makes the difference. Carbon-dioxide-consuming and producing beings of the biosphere, tightly coupled with geological processes, have influenced Earth’s faces and flows for thousands of millions of years.