Question

Earth has a very active carbon cycle which keeps its atmosphere free of excess carbon, while Venus does not. Why doesn't Venus have a carbon cycle?

(a) Venus does not have continuous plate tectonics to help return carbon to its interior.
(b) Venus' atmosphere is acidic and carbon won't dissolve in acid.
(c) Venus has no oceans to trap carbon.
(d) Venus doesn't have enough carbon to have a carbon cycle.
(e) Both (a) and (c)

Answer 1

Venus lacks a carbon cycle due to no plate tectonics and the absence of oceans, which on Earth help recycle carbon and trap it, respectively. The correct option is e.

Step-by-step explanation:

Venus does not have a carbon cycle similar to Earth's for a few key reasons. Unlike Earth, Venus lacks continuous plate tectonics, which on Earth help to recycle carbon back into the interior. Earth's tectonic activity is driven by mantle convection, resulting in the recycling of surface materials, including carbon. Venus lacks this mechanism.

Additionally, Venus does not have oceans that could trap carbon. On Earth, CO₂ is chemically bound in rocks or dissolved in ocean water. Venus's oceans, if they ever existed, have evaporated due to extreme temperatures, eliminating this potential carbon sink.

The high temperature on Venus led to the evaporation of any potential water bodies, releasing more CO₂ from the rocks. This process, along with the loss of water to space, has left Venus with an atmosphere that is predominantly composed of carbon dioxide (96%).

The correct answer to why Venus doesn't have a carbon cycle is therefore both (a) Venus does not have continuous plate tectonics to help return carbon to its interior and (c) Venus has no oceans to trap carbon, making (e) the correct choice. The correct option is e.