Sunshades in the stratosphere to reflect sunlight away from our planet. Dumping iron into the oceans to encourage algae blooms that would take up carbon dioxide. Painting every rooftop white. These are just a few of the geoengineering schemes that have been suggested to artificially alter the planet’s climate and counteract global warming.
Now researchers have helpfully ranked 17 proposals on their possible efficacy, saying that it’s past time to take a hard look at the ambitious ideas. “There is a worrying feeling that we’re not going to get our act together fast enough,” says [coauthor Tim] Lenton, referring to international efforts to limit greenhouse gas emissions. Scientists have reached a “social tipping point” and are starting to wonder which techniques might complement emissions cuts, he says [New Scientist]. The study, published in Atmospheric Chemistry and Physics, didn’t include an analysis of costs and environmental impacts.
Lenton says there has been too much hype and not enough analysis regarding geoengineering schemes, so he decided to start by asking a straightforward question. At the most basic level, earth’s surface temperature is governed by a balance between incoming Solar radiation and outgoing terrestrial radiation [Physics World]. The researchers examined how each of the geoengineering schemes would sway that balance, either by reflecting away solar radiation or reducing carbon dioxide that traps heat in the atmosphere. They found that a few proposed technologies could have a planet-wide cooling impact, but say those would be extremely hard to pull off.
Some geoengineering techniques rely on increasing the earth’s reflectivity or “albedo.” The most dramatic of these ideas–placing sunshades in space or continuously sprinkling sun-blocking particles in the upper atmosphere to mimic the effect of a volcano eruption–could actually cool the planet significantly even if carbon dioxide emissions continue to increase. But these are also the riskiest options, Lenton says, because they require constant (and probably massively expensive) upkeep. “You are effectively masking the effect of a warming climate system,” Lenton [said], “if we failed to keep the process going – perhaps due to political unrest – we would leave the planet open to the Sun’s full force” [Physics World].
Increasing the planet’s albedo through other means, like genetically engineering crops to be more reflective, scattering mirrors across the world’s deserts, or painting rooftops white would have only a small impact, the researchers say. And techniques that involve removing carbon dioxide from the atmosphere, like planting trees, capturing and burying emissions from power plants, and fertilizing oceans with iron to spur algae blooms, don’t have a fast enough impact to make them worthwhile, Lenton says.“There’s been far too much focus on iron fertilisation” given its lack of potential, says Lenton. His calculations suggest that the boost which agricultural fertilisers inadvertently give ocean plankton in runoff is probably already more effective that iron seeding is ever likely to be [New Scientist]. These findings may be of interest to the researchers who are currently dumping iron into Southern Ocean in an ocean fertilization experiment.
One other technique that got a positive review from the researchers was combusted biomass waste, or biochar, which Lenton says could have “win-win benefits” for the climate as well as for soil fertility. Bio-char, a high-carbon substance that can store CO2 and enhance soil nutrients, is created by heating farm waste or wood in airtight conditions [Reuters]. While its cooling effects can’t rival those of a sunshade in space, the technique is cheap and low-tech, researchers note.
Related Content:
80beats: Dumping Iron Into the Ocean Might Not Save the Climate, After All
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80beats: Experiment Trying to Create Algae Bloom Goes Ahead Despite Enviro Fears
DISCOVER: 5 Most Radical Ways to Squelch a Climate Crisis (photo gallery)
Discoblog: The Softer Side of Climate Control?, which includes biochar
DISCOVER: Black Gold of the Amazon, a look at how pre-Columbian South Americans used biochar agriculture
Image: Lenton, T. M. and Vaughan, N. E
January 29th, 2009 at 8:53 pm
Cheap and low-tech.
For a problem that is literally planet-wide, a scale that’s pretty hard to comprehend on our mere human levels, a solution better be cheap and low-tech because that’s how 99.9% of the world lives.
Even better if you can rig a simple solar/wind/hydro power system to power the bio-char process. Bonus points if you use it for carbon water filtration before burying it – you get the added bonus of clean water and then the junk that was in the water becomes even MORE fertilizer. That’s like a win-win-win situation, a win^3 if you will.
January 30th, 2009 at 1:22 am
Biochar Soil Technology
Biotic Carbon, the carbon transformed by life, should never be combusted, oxidized and destroyed. It deserves more respect, reverence even, and understanding to use it back to the soil where 2/3 of excess atmospheric carbon originally came from.
We all know we are carbon-centered life, we seldom think about the complex web of recycled bio-carbon which is the true center of life. A cradle to cradle, mutually co-evolved biosphere reaching into every crack and crevice on Earth.
It’s hard for most to revere microbes and fungus, but from our toes to our gums (onward), their balanced ecology is our health. The greater earth and soils are just as dependent, at much longer time scales. Our farming for over 10,000 years has been responsible for 2/3rds of our excess greenhouse gases. This soil carbon, converted to carbon dioxide, Methane & Nitrous oxide began a slow stable warming that now accelerates with burning of fossil fuel.
Wise Land management; Organic farming and afforestation can build back our soil carbon,
Biochar allows the soil food web to build much more recalcitrant organic carbon, ( living biomass & Glomalins) in addition to the carbon in the biochar.
Biochar, the modern version of an ancient Amazonian agricultural practice called Terra Preta (black earth), is gaining widespread credibility as a way to address world hunger, climate change, rural poverty, deforestation, and energy shortages… SIMULTANEOUSLY!
Senator / Secretary of Interior Ken Salazar has done the most to nurse this biofuels system in his Biochar provisions in the 07 & 08 farm bill,
http://www.biochar-international.org/newinformationevents/newlegislation.html
Charles Mann (”1491″) in the Sept. National Geographic has a wonderful soils article which places Terra Preta / Biochar soils center stage.
http://ngm.nationalgeographic.com/2008/09/soil/mann-text
It’s what Mann hasn’t covered that I thought should interest any writer as a follow up article;
Biochar data base;
http://terrapreta.bioenergylists.org/?q=node
NASA’s Dr. James Hansen Global warming solutions paper and letter to the G-8 conference, placing Biochar / Land management the central technology for carbon negative energy systems.
http://arxiv.org/ftp/arxiv/papers/0804/0804.1126.pdf
The many new university programs & field studies, in temperate soils; Cornell, ISU, U of H, U of GA, Virginia Tech, JMU, New Zealand and Australia.
Glomalin’s role in soil tilth, fertility & basis for the soil food web in Terra Preta soils.
Given the current “Crisis” atmosphere concerning energy, soil sustainability, food vs. Biofuels, and Climate Change what other subject addresses them all?
This is a Nano technology for the soil that represents the most comprehensive, low cost, and productive approach to long term stewardship and sustainability.
Carbon to the Soil, the only ubiquitous and economic place to put it.
Erich J. Knight
540 289 9750
January 30th, 2009 at 12:18 pm
The ultimate solution is to maximize geothermal energy, and stop using all carbon fuel. Through the use of sterling engines and closed loop steam plants, all the power needed for U.S. consumption is available from hot spots in the Cascade Mountains, and the deserts of Nevada. This is proven technology. It’s time to move foreward.
February 2nd, 2009 at 12:08 am
http://www.cuttingthroughthematrix.com/
September 4th, 2009 at 10:07 am
Don’t use wind power etc to power microwaves; just put the biomass to be charred into an airtight tower in the middle of a solar farm. The present solar farms generate heat of about 5 k degrees, so you wouldn’t need that much sunlight to heat your biocharring procedure. That eliminates the need for generating the heat since the sunlight is already there.
One thing that hasn’t been mentioned about biocharring is that there are also potentially valuable organic chemicals that can be distilled out like methanol and various foodstuffs.