Compare the current atmospheres of Earth, Venus, and Mars in terms of composition, thickness (and pressure at the surface), and the greenhouse effect.

The atmosphere of Earth is about 1/5 part oxygen and 4/5 part of nitrogen,

The atmosphere of Venus is mostly of carbon dioxide and have pressure of about 90 times higher than Earth,

The atmosphere of Mars is also mostly of carbon dioxide and have pressure one hundredth that of the Earth.

Due to high concentration of carbon dioxide, Venus, shows greenhouse effect, and thereby leading to high surface temperature.

Mars has a runaway refrigerator effect, and thereby having thinner atmosphere and colder temperature.

Earth is also overcoming with the problem of green house effect, due to increased carbon dioxide in the atmosphere.