Greenhouse effect on other planets

Figure 1. Photograph of Mars, showing its thin atmosphere.[1]

The greenhouse effect is not the same on all planets, and differs dramatically based on the thickness and composition of the atmosphere. Three planets that show how dramatically the conditions of a planet can change with the different levels of the greenhouse effect are Venus, Earth, and Mars.

Although Earth, Mars, and Venus are different distances from the Sun, they are not so drastically different that one would expect dramatic temperature differences to occur solely because of this. Since they are a fairly similar distance from the Sun, they formed out of the same material and had approximately the same initial temperatures several billion years ago.[2] Despite these similar initial conditions, Venus is now too hot for life and Mars is too cold. This difference in temperatures is caused partially by the different values for energy incident on these planets. The main difference is still caused by the composition and thickness of a planets atmosphere.

Temperature Difference and the Greenhouse Effect

Looking at Earth's atmosphere, it is mainly nitrogen and oxygen with trace amounts of greenhouse gases. The small percentage of greenhouse gases is still enough to raise the Earth's average temperature by 33°C! With no greenhouse gasses, the average temperature of the Earth would be -18°C. Life on Earth needs the greenhouse effect to make the average temperature of the Earth 15°C. The thickness of the Earth's atmosphere, combined with the moderate amount of greenhouse gases works to trap enough radiant heat within the atmosphere to create a temperate, habitable planet.[3]

Mars' climate is quite different from Earth's; Mars has a very thin atmosphere—with its atmospheric density being 1% of Earth's atmospheric density. [3] Additionally, the composition creates major differences. Mars' atmosphere is composed mainly of carbon dioxide, but there is so little carbon dioxide overall that the greenhouse effect is essentially negligible. This, coupled with the distance from the sun means that the temperature of Mars is significantly lower than the Earth's temperature.

Venus is the opposite of Mars in all the ways that were listed above. Venus has an atmosphere that is 100x denser than Earth's atmosphere, and 96% of the atmosphere is carbon dioxide. This creates an enormous greenhouse effect that increases the temperature of Venus approximately 462°C—hot enough to melt lead![3] Although the presence of a runaway greenhouse effect on Venus is a significant part of the reason it is so hot, the proximity to the Sun contributes. The greenhouse effect on Venus doubles the absolute temperature from what it would be if Venus had no atmosphere at all[2]

Overall, Earth, Mars, and Venus have similar atmospheres, interiors, surfaces, and similar greenhouse gases in the atmosphere. However, the different levels of greenhouse gases in the atmosphere change the temperatures of the planets quite significantly. Carbon dioxide dominates the greenhouse gases in the atmospheres of these planets, but the warming on the planets varies significantly.[4]

For Further Reading

References

  1. "Mars atmosphere". Transferred from de.wikipedia to Commons. Original source: taken from Viking Orbiter Raw Image Archive on CD-ROM (PDS) (info;order). Licensed under Public Domain via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Mars_atmosphere.jpg#/media/File:Mars_atmosphere.jpg
  2. 2.0 2.1 Nick Strobel. (May 7, 2015). Planetary Science [Online]. Available: http://www.astronomynotes.com/solarsys/s9.htm
  3. 3.0 3.1 3.2 R. Wolfson. (May 7, 2015). Environment and Climate, 2nd ed. New York, U.S.A. Norton, 2012, pp. 335-337
  4. Eddie Schwieterman. (May 7, 2015). Comparing the Greenhouse Effect on Earth, Mars, Venus, and Titan: Present Day and through Time [Online]. Available: http://www.astro.washington.edu/users/eschwiet/essays/greenhouse_ASTR555.pdf

Authors and Editors

Bethel Afework, Jordan Hanania, Kailyn Stenhouse, Jason Donev
Last updated: June 25, 2018
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