Some people say that climate change will increase cloud cover which will protect us from global warming by reflecting more light.. To address this question we can look at our neighbor Venus. Venus in some ways is rather similar to earth. Venus is twice as far from the sun as Mercury is. Yet despite the heavy cloud "protection" and longer distance from the sun, it is 300 °C hotter than mercury. This discrepancy is due to the CO2 rich atmosphere that covers Venus.
| MERCURY | VENUS |
 |
 |
| dist
from sun: 57,910,000 km1 mean temp: 179°C |
dist
from sun: 108,200,000 km1 mean temp: 482°C |
While this is an oversimplification of the situation, it certainly goes a long way to prove that clouds will not nullify the effects of CO2 driven (anthropogenic) climate change. As an added note, the excess CO2 is also increasing the oceans acidity by turning into carbonic acid. The acidification of the ocean could end all known forms of coral by 2065. 10, 11, 12 Clouds will not be able to prevent this from occurring. In fact, water vapor is the primary cause of this action.
| Venus and Mercury in Relation to the Sun |
 |
| Despite being twice as far away from the sun Venus is over 200 degrees C hotter. |
The European Space Agency recently launched a satellite called the Venus Express for the purpose of understanding why a planet that is so similar to ours is the most inhospitable in the solar system, how effective clouds actually are in reflecting or even trapping radiation, and more. On April 20, 2006 Venus Express completed it's first orbit around Venus. For more info on the kind of information Venus Express has been sending back go here.
The Guardian has a well written article called "Venus: the hot spot" which describes how our planet was once like Venus:
| "'On Earth, carbon dioxide is absorbed by the oceans,
where it forms carbonate
minerals and over the millennia is deposited as rock. That
process was arrested early on Venus when it lost its oceans.'
In other words, it was Earth - not Venus - that changed. Billions of years ago both had thick atmospheres of carbon dioxide but, thanks to our oceans, which continue to absorb the gas, we lost ours. Venus - with no oceans - kept its carbon dioxide. 'We should not be too complacent,' added Taylor. 'As temperatures rise, seas become less and less able to hold on to carbon dioxide. Soon they will absorb less of the gas and may eventually start to give it off. That will have a very serious impact on our planet.'" |
For more technical info on greenhouse gases and cloud feedbacks please see:
Introduction to Atmospheric Chemistry, by Daniel J. Jacob (chapters 6 and 7)
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