Why is there so much more carbon dioxide in the atmosphere of Venus than in that of Earth? Why so much more carbon dioxide than on Mars?

The high levels of carbon dioxide in the atmosphere of Venus can be attributed to several factors:

1. Volcanic Activity: Venus is known to have a lot of volcanic activity. Volcanoes release carbon dioxide into the atmosphere.

2. Lack of Water: On Earth, carbon dioxide is absorbed by the oceans and is then used by marine life. This process helps to regulate the amount of carbon dioxide in our atmosphere. However, Venus lacks water bodies, so this process does not occur there.

3. Lack of Plate Tectonics: On Earth, carbon dioxide is also regulated by the process of plate tectonics. Carbon dioxide is absorbed into the ground and then released back into the atmosphere over millions of years. Venus does not have plate tectonics, so this process does not occur there either.

4. Runaway Greenhouse Effect: Venus has experienced a runaway greenhouse effect. This is a process where the greenhouse effect, the warming of a planet due to the presence of certain gases, spirals out of control. On Venus, the high levels of carbon dioxide have caused the planet's temperature to rise, which in turn releases more carbon dioxide, creating a vicious cycle.

As for Mars, it has less carbon dioxide than Venus because it's a smaller planet with less volcanic activity. Mars also has a thinner atmosphere than Venus, which means it can hold less carbon dioxide. Additionally, some of the carbon dioxide on Mars is locked up in its polar ice caps.