Geoengineering with Artificial Clouds

                                              "Hey.....You......Get off my cloud"  --- Mick Jagger

Most proposals for Geoengineering the Earth to mitigate global climate change involve scaling up natural processes that already occur on the earth.  For instance, cloudy days tend to be cooler then sunny days because clouds block the sun.  One proposal to counteract global warming involves creating artificial clouds.  A NASA review of climate change states:

"Even small changes in the abundance or location of clouds could change the climate more than the anticipated changes caused by greenhouse gases..." 

Artificial clouds aren't very hard to make.  Thousands of huge artificial clouds, called contrails, are created by jet aircraft everyday.   As thousands of passenger jet flights pass occur over the United States, contrails made of steam appear behind each jet engine as a by-product of combustion of jet fuel in the jet engines.  Currently about 60 billion gallons of jet fuel are consumed each year by jet aircraft in the USA.  The stream exhaust is superheated when it leaves the jet engine and quickly expands to about 100 times its original volume in the low air pressure found in stratosphere where jet travel occurs and then freezes into ice crystals to form visible clouds.  Based on the volume of jet fuel consumed, about 10 trillion cubic feet of clouds are produced.  Surely these clouds are cooling the climate?  Perhaps the ideal Geoengineering program would involve subsidies to encourage frequent free jet travel to Rio and Paris and Vegas and other exotic places in order to make even more jet contrails and counteract Greenhouse Warming?

Unfortunately, no.

Yes, clouds block solar radiation and can produce some local cooling.  But water itself is a greenhouse gas, and clouds absorb long wave radiation emitted by the earth and keep the earth's surface warmer than it would be without clouds.  This effect is especially noticeable at night----the very coldest nights tend to be clear, while cloudy nights are warmer.

When the warming and cooling effects of cloud cover are compared, the warming effect is actually somewhat larger than the cooling effect.  Some scientists actually believe jet contrails and other artificial clouds are playing a significant role in INCREASING planetary global warming.  

So Mick Jagger had it right all along...

I was sick and tired, fed up with this
And decided to take a drive downtown
It was so very quiet and peaceful
There was nobody, not a soul around
I laid myself out, I was so tired and I started to dream
In the morning the parking tickets were just like
A flag stuck on my window screen
I said, Hey! You! Get off of my cloud
Hey! You! Get off of my cloud
Hey! You! Get off of my cloud
Don't hang around 'cause two's a crowd
On my cloud

—NASA