D. The Earth's surface would be much colder than it is.
<h3>Step-by-step explanation:</h3>
This is because warm temperatures and high levels of atmospheric carbon dioxide happen at about the same time. So if atmospheric carbon dioxide concentrations double warm up by between 2 and 4.5 degrees Celsius. On the other hand, water vapor promotes, as the greatest contributor, to the Earth’s greenhouse effect. In this way, if carbon dioxide, methane, and water vapor were not in the atmosphere, then it's obvious that the Earth's surface would be much colder than it is.
