could clouds mitigate global warming?

[lemur]

If ocean temperatures were rising along with air temperature, wouldn't this cause more evaporation and more cloud cover? If so, wouldn't the additional clouds reflect a great deal of sunlight back into outer space? Could this be a natural check on global warming? On the other hand, if cloud cover increased significantly and sunlight decreased accordingly, what effect would this have on plant-growth and the ability to process CO2 into O2?

 

BTW, I started to post this on the thread about sea level and sea floor but it seemed too divergent.

[John Cuthber]

" has this been considered?"

yes.

[Mr Skeptic]

Unfortunately, water vapor is also a greenhouse gas. In cloud form it increases earth's albedo and cools the earth (at least during the day, at night it is like a blanket).

 

Perhaps it might also be instructive to consider that some people think that climatologists don't know about clouds.

[SMF]

This is a complicated subject. For example in addition to the above comments, as temperature and water vapor go up so does precipitation, which constrains the amount of clouds. Also different kinds of clouds can produce opposite effects. A recent evaluation of the effects of clouds on climate is- http://www.sciencema...6010/1523.short with a full text PDF here- http://geotest.tamu..../dessler10b.pdf. This paper finds that clouds are probably a small positive (warming) feedback. See - http://www.skeptical...ntermediate.htm for a general discussion of this issue. SM

Edited March 5, 2011 by SMF

[JohnB]

The effects of clouds is probably the biggest unknown in the climate system. We simply don't know.

 

Clouds may be a positive feedback or a negative one. If Dr. Spencer is right, then they can act as both a forcing and a feedback.

 

I doubt that anybody in the field would claim to have a definitive answer.

[ecoli]

There's also the matter that clouds seem to have local effects, while the general warming trend is global.

[JohnB]

There's also the matter that clouds seem to have local effects, while the general warming trend is global.

 

Thus illustrating the complexity. A "local" cooling effect in the low tropics means less heat to be transported to the temperate zones by the Hadley cells.

[lemur]

There's also the matter that clouds seem to have local effects, while the general warming trend is global.

What if you measure cloud cover in terms of its addition to global luminosity as observed from orbiting satellites? Couldn't you then subtract this amount of light from the total amount of light calculated to reach sea-level?

[ewmon]

Insolation is a key word here. Notice the "sol" in the word; this term refers to the solar energy that reaches the surface of the earth (ie, crops, oceans, homes, etc). Some of the same gases that cause the "greenhouse effect" also reduce insolation.

[Brainteaserfan]

I think that clouds will at least slow down Global Warming. For sure there will be more clouds as the world heats up. However, there will need to be a lot of clouds to make a sizable difference, and we need the sun to grow food. I am glad that the US has not yet gone too far down the road of solar, because we would get less and less energy as the temperture rises (if global warmimg is really happening).

Edited May 19, 2011 by Brainteaserfan