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Brighter, whiter clouds could fight global warming

By

February 22, 2010

Dr Philip Rasch is Pacific Northwest National Laboratory's first Chief Scientist for Clima...

Dr Philip Rasch is Pacific Northwest National Laboratory's first Chief Scientist for Climate Science Credit: PNNL

Scientists in the US have been cloud-spotting over shipping lanes and have noticed something more interesting than teddy-bear shapes and faces. They have detected that rising steam from passing ships has caused brightening in the clouds which they theorize alters the reflectivity of the cloud and prevents the energy from reaching the Earth. They propose that if this could be achieved artificially via geoengineering it could be an effective defense against global warming.

Previous research into clouds in shipping lanes showed that natural or man-made particles of dirt, water and gas known as aerosols change cloud characteristics by increasing the number of droplets while decreasing their size. Findings suggested that these droplets reflect more sunlight and make the cloud seem brighter. However, it also revealed the cloud seemed darker in places, and was unclear in conclusion whether the net effect led to brighter, more reflective clouds or whether in fact the two effects canceled out one another.

To address this question, the Pacific Northwest National Laboratory (PNNL) modeled the reflectivity of clouds in a detailed simulation that aimed to determine the net effect of increased aerosols on cloud reflectivity. Chief climate scientist Phil Rasch and his team at the US Department of Energy Office of Science's PNNL in Richland, Washington, simulated three ships chugging along in a 93-mile by 37-mile area of the Pacific Ocean, several hundred miles southwest of Los Angeles. Their findings suggest that introducing aerosols near the surface would, in fact, result in cloud brightening and reflectivity and therefore form an effective tool against global warming, except in clouds already drizzling which would be largely unaffected.

While the aerosols currently affecting clouds in shipping lanes are expelled from ships as polluting steam, the artificially-brightening aerosol could be seawater sprayed from ocean vessels. But there are still unanswered questions as to how safe, efficient or predictable such methods might be. Rasch and his team are also using the simulation to explore when might be the best time of day to spray, given further information as to how the aerosols are affected by climate and prevailing weather; what effect brighter clouds have on rain, whether aerosols are burned off by the rising sun and how long they maintain a brighter cloud.

This is one of a few circulating ideas to fight global warming with geoengineering and is not the first of these to suggest modification of Earth's atmospheric particles. Tim Flannery's slightly disturbing idea compounds global dimming with the proposed addition of sulfur to aircraft fuel that will change the color of the sky when dispersed but leave protective reflective particles in the atmosphere. Another suggestion that less brings to mind an apocalyptic sky is from Colorado's National Center for Atmospheric Research (NCAR) supporting white roofs in densely-populated warmer climate cities. It is clear that drastic times call for drastic measures and the sky is the limit.

Rasch's paper Climate effects of geoengineering using cloud seeding and stratospheric aerosols was presented in a symposium "Can geoengineering save us from global warming?" at the American Association for the Advancement of Science 2010 annual meeting at the San Diego Convention Center on Saturday. He also discussed the results from a Community Climate System Model study which found that increasing aerosols in the ocean air can either increase the amount of sea ice to previous levels, restore precipitation, or reduce temperatures, but not all at the same time. These were published in environmental research letters in December 2009.

8 Comments

Oh Wow.. Did he not get the memo?

The senior scientist working with the IPCC, Professor Phil Jones. Just declared last week that he was wrong, and that new evidence (really old evidence that was never look at because as he said "it was lost in his cluttered office") admitted that in the last 15 years there had been no ‘statistically significant’ warming,

He is now backing down on all this "Man Made - the sky is falling" crap.

So I'm so sorry ... this guy will be out of a job soon so I guess he is just trying to get that government money before it all dries up.

Facebook User
22nd February, 2010 @ 10:20 pm PST

It is my understanding that we have to be concerned beyond the occurance of climate warming as at a certain point a natural and sudden drop in global temperatures will occur causing perhaps an ice age. wouldn't tampering with the reflectivity of cloud cover to reflect light/heat away from the earths' surface then accellerate the potential for the onset of an ice age?

pieter prall
23rd February, 2010 @ 03:20 am PST

This story appeared on a cable access show a few months ago along side of some other attempts to stave off or reverse global warming. I think is was on the History Channel, Discovery or NatGeo. The method used to create these white clouds was to burn smoke flares, generating the smoke. The problems with this method are as follows:

!st The effected area is far to minimal to make a difference alone. A blanket would need to be laid by many ships. This leads to the next issue.

2nd. The heat energy output caused by the flares is far greater than the radiant heat reflected by the white smoke thus causing a warming affect not a cool one. This leads to the compound affect.

3rd"""If""" a new method were created in favor of the cooling effect, it would make little difference because they propose to travel the oceans for the purpose of spreading that smoke. The problem is the fuel their ships burn. They would have to make an international law mandating all ships to be equipted with the smoke generators, in order to have a positive effect.

Joe Cuschieri
23rd February, 2010 @ 09:30 am PST

Pieter,

The seawater droplets precipitate out of the atmosphere within a few days, so if any ill effects start, theoretically, you can stop spraying more water up and the clouds will return to normal within days.

Joe,

You're thinking of Discovery Project Earth. Rather lame program, if you ask me. Most of the ideas were half-baked. The smoke flares were just to test the cloud dispersion, not as a method that they could have used for full-scale cloudmaking. That episode was one of the most disappointing of Project Earth. They didn't even try to make anything resembling the final product. They just tested whether droplets of the appropriate size formed and separately tested whether the Magnus rotor worked.

Gadgeteer
23rd February, 2010 @ 05:38 pm PST

Instead of "Can geoengineering save us from global warming?" can someone save us from this global warming lie?

Francesco Baldacchini
24th February, 2010 @ 04:39 am PST

I'm thinking of an articlk\e that I read in 1972 or 73. This article appeared in Natural History Magazine and I don't think they would publish anything that falls into the catagory of lame.

Pieter Prall

pieter prall
6th May, 2010 @ 11:58 am PDT

I'm so sick of the climate-change arrogance. We are too insignificant and powerless to change the direction of our climate in any measurable way. The entire global-warming debate is a waste of time - it makes not a licking bit of difference whether or not it's changing, which way, or what the cause is. NOBODY CAN DO ANYTHING ABOUT IT!!!!!!!!!!!!!

christopher
1st July, 2014 @ 07:29 pm PDT

This article makes it seem like spraying the world with aluminum that causes disease is a good thing!

njaohnt
5th July, 2014 @ 08:28 am PDT
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