Geoengineering the Climate

Catherine Brahic reports in NewScientist (2007.06.05) on research suggesting a solar shield could serve as an effective stopgap measure to brake global warming.

A solar shield that reflects some of the Sun's radiation back into space would cool the climate within a decade and could be a quick-fix solution to climate change, researchers say. Because of their rapid effect, however, they should be deployed only as a last resort when "dangerous" climate change is imminent, they warn.

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Solar shields are not a new idea - such "geoengineering" schemes to artificially cool the Earth's climate are receiving growing interest, and include proposals to inject reflective aerosols into the stratosphere, deploying space-based solar reflectors and large-scale cloud seeding.

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Ken Caldeira at the Carnegie Institution of Washington, in California, US, and Damon Matthews at Concordia University, Canada, used computer models to simulate the effects that a solar shield would have on the Earth's climate if greenhouse gas emissions continued to rise along a "business as usual" scenario.

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"We have been trying to pinpoint the one really bad thing that argues against geoengineering the climate," says Caldeira. "But it is really hard to find."

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His computer models simulated a gradually deployed shield that would compensate for the greenhouse effect of rising carbon dioxide concentrations. By the time CO2 levels are double those of pre-industrial times - predicted to be at the end of the 21st century - the shield would need to block 8% of the Sun's radiation.

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The researchers found that a sulphur shield could act very quickly, lowering temperatures to around early 20th-century levels within a decade of being deployed.

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"The trouble is, the decadal timescale works both ways," says Caldeira. A sulphate shield would need to be continuously replenished, and the models show that failing to do so would mean the Earth's climate would suddenly be hit with the full warming effect of the CO2 that has accumulated in the meantime.

Added by Edit: original Carnegie press releaseI'd be interested in seeing a Science forum discussion of solar shields and other geoengineering options to deal with climate change.The topic is creative possibilities for dealing with climate change--geoengineering--and the planet-sized variables these capabilities involve.______Edited by Archer Opterix, : added link.

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ArcherAll species are transitional.

Hi Archer,You state that you want a science forum discussion. Does this mean that you do not want it in Coffee House? If not where do you see it going.

Thread moved here from the Proposed New Topics forum.As this is not a creationism/evolution topic, the "Coffee House" is the only place for it. Topic promoted, in part per RAZD's repeated requests.AdminnemooseusEdited by Adminnemooseus, : Added comments.

I dunno... that sounds like a lot of unnecessary work. Might I suggest we organize a world wide prayer for global warming to go away? This will kill two birds with one stone. On the one hand, we'd be solving the climate problem. On the other, we'd be proving the existence of god by this miracle.

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We are BOG. Resistance is voltage over current.

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

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He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

Just read the New Scientist release - the Carnegie article link returns a "not found" notice.Using their 8% of the earth's disk area gives 4 million square miles of area for this shield. Whether released in the atmosphere or placed in orbit, it will spend half its time in the dark night side and not provide any shielding, so we'll need two of these. That's 8 million sq. miles of shield. If this is some kind of membrane shield launched into orbit, it can't actually be too thin because of the severe radiation environment it must survive for a reasonable amount of time.Let's optimistically assume it can be made as thin as one mil (1/1000th inch.) thickness. That's 20 billion cubic feet or over half a billion tons if light weight organic material can be used!!! This doesn't include the structure to keep it stretched out and the mechanism to keep it perpendicular to the earth-sun line. Given that there's typically a 200:1 ratio of launch weight to payload weight (with 90% of the launch weight in propellants) to get a payload into low earth orbit, I'm guessing that it would take a major fraction of the known petroleum reserves to get this shield into orbit.Nothing in the New Scientist article seems to address any such issues of practicality. I subscribe to NewScientist and find it a fun read but about 1/3 science, 1/3 pseudo-science, and 1/3 silly pictures that add nothing to the articles they are associated with. I hope nobody takes this concept too seriously without a very detailed analysis of its actual implementation.

Solar shield article:

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A solar shield that reflects some of the Sun's radiation back into space would cool the climate within a decade and could be a quick-fix solution to climate change, researchers say.

​

Ken Caldeira at the Carnegie Institution of Washington, in California, US, and Damon Matthews at Concordia University, Canada, used computer models to simulate the effects that a solar shield would have on the Earth's climate if greenhouse gas emissions continued to rise along a "business as usual" scenario.

​

"We have been trying to pinpoint the one really bad thing that argues against geoengineering the climate," says Caldeira. "But it is really hard to find."

​

His computer models simulated a gradually deployed shield that would compensate for the greenhouse effect of rising carbon dioxide concentrations. By the time CO2 levels are double those of pre-industrial times - predicted to be at the end of the 21st century - the shield would need to block 8% of the Sun's radiation.

​

The researchers found that a sulphur shield could act very quickly, lowering temperatures to around early 20th-century levels within a decade of being deployed.

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Caldeira and Matthews also found that a solar shield would not correct abnormalities in rainfall. Most notably, the tropics would receive less rain than in the absence of the greenhouse effect, as predicted by climate change models.

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Climate considerations and First Steps:Increased heat retention will be focussed in larger stronger storms, thus increasing the number of potentially fatal hurricanes, tornadoes and thunderstorms.GOES-18 Test Site - Imagery Viewer - NOAA / NESDIS / STAR
http://hurricane.accuweather.com/hurricane/index.asp?part...Hurricanes and other storms are driven by the difference in heat energy between two components. It would be possible to create an artificial cloud in advance of hurricanes, with remote controlled drones that are powered by solar energy, that could shade and cool water in front of hurricanes: this would provide a first step test of the technology.Start with small shields for weather control and build up to the size needed for global warming.Some Current Technology:http://www.tfot.info/content/view/117/

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Helios is the most ambitious of NASA's solar UAV projects to date. With a 247-foot wingspan (greater than a 747 Jumbo Jet), 62,120 bi-facial solar cells and a projected maximum flying altitude of 100,000 feet, the Helios is the peak of two and a half decades of solar aviation research. Like its predecessors the Helios was built by AeroVironment and has been used on the Environmental Research Aircraft and Sensor Technology (ERAST) program. The Helios applies hybrid technology - solar energy using photovoltaic cells by day and fuel cells by night.

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Increase area for solar collectors and add reflective areas ...pull sheets of reflective material behindahausa.com - ahausa Resources and Information.

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This drone was designed to carry lightweight video equipment for patrol and surveillance purposes. The current model is quite inexpensive, and it incorporates conventional radio control equipment.

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The design may be expanded to carry more substantial loads; also, radio control equipment providing greater security and range may be incoroporated into an enlarged version, enabling a greater radius of action.

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AHA offers the Wasp also as a semi-automated drone. This aircraft will follow a pre-programmed flight path at a steady altitude; utilisations may include pipeline and boundary inspections, coastal patrol and so on.

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Add solar collectors and reflective areas ... the drones could use hydrogen for lift as there would be no living passengers.These are but two possible routes for making fleets of remote controlled drones that could make artificial clouds over specific patches of the earth. The could form such a reflective and absorptive cloud (taking energy from the sun to power their flight to hold location and related electronics) over hurricanes, tornado storms, thunderstorms and even forest fires, thus cooling all those systems down to lower energy levels during the day (hard to work at night eh?).They could also produce a side benefit if they carry things like cell-phone antennaes and equipment to replace towers and to blanket the earth with good reception for all forms of communication (including wireless high band internet) and thus do double duty. Some could also run as GPS satillites, increasing coverage in remote areas and cloudy wehather. Running these off solar power would also reduce fuel use on the ground.This is possible with current technology.Future Considerations:Again from the article:

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"The trouble is, the decadal timescale works both ways," says Caldeira. A sulphate shield would need to be continuously replenished, and the models show that failing to do so would mean the Earth's climate would suddenly be hit with the full warming effect of the CO2 that has accumulated in the meantime.

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What it would do is give you time to remove the high CO2 (and other GHG's) from the atmosphere so that as the shield aged and dissipated it would be met with reduced levels. It gives us time to take back the climate.Enjoy.Edited by RAZD, : .

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So are they saying we should release millions, even billions, of mylar balloons into the upper atmosphere? Because back in school we used to joke about how some engineer would think it was a great idea to do just that to reflect the sunlight back out into space.Edited by clpMINI, : No reason given.

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I mean, this is America. Everybody loves seeing lesbians go at it, as long as they are both hot and not in a monogamous, legally sanctioned relationship.

Unfortunately, the exact opposite is currently happening. Global warming is shrinking polar ice-caps and glaciers, rapidly and greatly increasing the earth's solar absorptivity. We are 'de-shielding' the earth! What if everyone in the world painted their rooftops white (which is essentially titanium oxide, a plentiful mineral)? What if we got all the Chinese to wear white hats? How long before white supremacists blame global warming on the dark skinned races?

A two-fer: this would also reduce roof heating and thus the load on air conditioners, saving production of heat (thermodynamics) and energy by products.Interstate Products Inc - Not FoundWe should also do the same to asphalt parking lots and roads...Edited by RAZD, : url

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Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
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we are limited in our ability to understand
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... to learn ... to think ... to live ... to laugh ...
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