Question

If there was no water on Earth, what would the Earth atmosphere energy balance be like, and what effect would it have on animal life on Earth?

Without liquid water, there would be no life -- at least no life as we know it. So an Earth without water would be a planet without life. In addition, of course, the water (in the form of atmospheric water vapor) is an important component of our atmosphere. Water vapor contributes to the greenhouse effect and helps raises the average surface temperature of the planet, although it is not the dominant greenhouse gas. Both atmospheric clouds and surface snow and ice are highly reflective; without them the Earth would absorb much more of the sunlight that strikes our planet, and this would raise the temperature even without a greenhouse effect. Water also plays a key role in the energetics of the atmosphere, since it can store or release energy as it undergoes phase changes from vapor to liquid (clouds) and back. We would not have major storms such as hurricanes or typhoons were it not for the ability of atmospheric water to concentrate energy in these storms.

David Morrison
NAI Senior Scientist
October 6, 2003