Scientists Rank Global Cooling Hacks

Not all climate hacks are created equal.

The dozens of ways that scientists, as well as crackpots, have proposed to geoengineer the world's climate won't all be equally effective. In fact, some of them, particularly the ones that rely on sucking up carbon dioxide instead of blocking out solar radiation, will hardly have any impact at all, a new study in the journal Atmospheric Chemistry and Physics found.

"By 2050, only stratospheric aerosol injections or sunshades in space have the potential to cool the climate back toward its pre-industrial state," earth scientists Tim Lenton and Naomi Vaughan of East Anglia University in England write.

Many global cooling approaches have been floated. The broad range of the proposals — from injecting the upper atmosphere with sun-blocking particles to creating plankton blooms by feeding them extra iron to burying carbon-filled "biochar" in soil — has made comparing them very difficult. The new study provides the first useful comparisons of a wide variety of geoengineering ideas.

The study did not calculate the costs or environmental impacts of any of the techniques, but for most of the climate hacks, they could be large. For those reasons, the authors of the paper recommend reducing the amount of our emissions, not just banking on geoengineering to bail us out.

"Climate geoengineering is best considered as a potential complement to the mitigation of CO2 emissions, rather than as an alternative to it," they write.

The study of climate change tries to compute the change in the energy balance between energy coming from the sun — shortwave radiation — versus the longwave radiation emitted by the Earth. When there's more carbon dioxide, less longwave radiation escapes and the world heats up. Scientists calculate that humans' carbon dioxide emissions from 1800 to 2005 are causing 1.6 watts of extra energy per square meter of surface area to stay in Earth's atmosphere. If CO2 levels double again, that number goes to 3.71 watts.

So, logically enough, the scientists decided to evaluate geoengineering schemes with the same watts-per-square-meter metric. How much cooling or climate balancing could each scheme provide? Though "not intended to be definitive" the researchers claim their numbers are at least as good as previous analyses of individual techniques.

The clear winners, cost aside, are strategies that would block out some solar radiation. Perhaps the most currently workable version of this technique is injecting millions of tons of sulfur dioxide into the atmosphere. Of course, the injections would have to continue until the greenhouse gases in the atmosphere were brought back down and the environmental costs could be high. Another high-impact technique would increase the albedo — or reflectivity — of the tops of clouds.

The results are presented in the table below. Short descriptions of each technique follow. For more detailed information on each technique, check out the full text of the paper (.pdf), which is available online.

1. Stratospheric aerosols Inject enough sulfur dioxide into the stratosphere to reflect the small percentage of sunlight necessary to offset increased warming caused by carbon dioxide. This scheme is akin to the cooling induced by large volcanic explosions.
2. Albedo increase: cloud, mechanical Manufacture sea salt spray to change the way clouds form over the ocean to increase their reflectivity.
3. Albedo increase: desert Cover the earth's non-sandy deserts with a material composed of a white polyethylene top and an aluminum bottom. That would increase the albedo of those surfaces, cooling the earth.
4. Air capture and storage Use chemical processes to pull carbon dioxide out of the air and sequester it in geological reservoirs.
5. Ocean phosphorous addition Add phosphorous intentionally to the oceans, fertilizing the water, and creating more carbon-munching life there. Eventually, those creatures or the creatures that eat them die and drift into the deep ocean, taking that carbon with them.
6. Albedo increase: grassland Breed or genetically engineer shinier plants to increase the reflectivity of the world's savannahs and shrublands.
7. Bio-char production Create charcoal from biomass, effectively sequestering the carbon in the plant matter, and bury it.
8. Carbonate addition to oceans Add carbonate to the oceans, increasing their carbon intake and fighting ocean acidification.
9. Albedo increase: cropland Breed or genetically engineer shinier crops to increase the reflectivity of the world's farmed land.
10. Ocean nitrogen fertilization Add nitrogen intentionally to the oceans, fertilizing the water, and creating more carbon-munching life there. Eventually, those creatures or the creatures that eat them die and drift into the deep ocean, taking that carbon with them.
11. Iron fertilization Add iron intentionally to the oceans, fertilizing the water, and creating more carbon-munching life there. Eventually, those creatures or the creatures that eat them die and drift into the deep ocean, taking that carbon with them.
12. Afforestation/reforestation Plant massive amounts of trees across the Earth and count on them to sequester more carbon dioxide naturally.
13. Albedo increase: human settlement Make the areas where humans live considerably more reflective by, say, painting roofs white.
14. Enhance upwelling Bring nutrient-rich water up from the deeps to foster carbon-using life at the surface of the ocean.
15. Albedo increase: cloud, biological Add dimethyl sulfide to a patch of ocean to create more microorganisms that act as formation sites for water droplets and eventually lead to clouds.
16. Enhance downwelling Cool down huge amounts of water with large pumps to form and thicken sea ice that would in turn cool the sea water. That water would descend to the depths, taking a bit of extra carbon with it.
17. Albedo increase: urban areas Make cities considerably more reflective by, say, painting roofs white.

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Ocean fertilisation no good for storing carbon

Fertilisation test: Image shows a drifting sediment trap called PELAGRA used by the CROZEX mission to collect samples of sinking algal material at 150 m depth.

PARIS: Proposals to combat global warming by sowing the sea with iron to promote carbon-gobbling plankton may be badly overblown, according to a new study.

Ocean fertilisation has ignited fierce scientific controversy, with supporters saying these schemes could stave off damaging climate change and critics warning that swathes of ocean may turn stagnant or acidic.

Fertilisation has now touched off a political storm as well. A recent experiment by scientists aboard a German research ship in waters off Antarctica has pitted Germany's environment ministry, which opposes the scheme, against the country's research ministry, which supports it.

Political storm

The idea behind fertilisation, one of many ideas for 'geoengineering' the planet to combat climate change, is to scatter iron powder in swathes of the ocean, providing nutrients for phytoplankton algae in the warm upper layers of the sea.

These tiny marine plants suck in carbon dioxide by photosynthesis. The idea is that when they die, some of them would sink to the depths and their carbon remains would be stored, or sequestered, there.

In other words, greenhouse gas would be transferred from the atmosphere to the depths of the ocean, and so would not be around to trap solar radiation.

But new research, published today in the British journal Nature, casts doubt on some claims of the effectiveness of the process.

Researchers led by Raymond Pollard of the National Oceanography Centre in Southampton, England, looked at seas around the Crozet Islands, a small archipelago on the northern rim of the Southern Ocean.

Storage solution?

The flow of ocean currents means that the seas just north of the islands are rich in natural iron – carried off Crozets' volcanic rocks – and causes blooms of plankton in the southern summer that last for months.

South of the islands, though, is nutrient-poor, and plankton blooms there are far smaller and short-lived.
Comparing the two zones, the so-called CROZEX mission found that iron-rich seas doubled or even tripled plankton growth and the absorption of CO₂.

But the amount of carbon that was actually stored was just five or six per cent, explained senior researcher Richard Sanders.

"If we think of a hundred units of carbon being fixed by phytoplankton in the upper ocean, around 90 per cent of that will be recycled in the upper ocean and around 10 per cent will sink out of this sunlit upper layer," he said. "Of those 10 units sinking, one will get to the sediment at the bottom," where it will be effectively stored forever.

The rest, though, will be recycled in the midwater region or, in the lower depths, eventually get pushed to the surface by deep ocean currents, which would prompt them to surrender their carbon, he explained.

This overturning takes place on a time scale of decades to a couple of hundred years, meaning the carbon would be stored out of harm's way for a long while but not permanently.

Massive underestimate

The study said carbon sequestration around the Crozet islands fell massively short – by 15 to 50 times – of some geo-engineering estimates, although it was also 20 times more than that calculated for a fertilisation experiment called SERIES.

These findings have "significant implications" for claims for ocean fertilisation, it said.

Around a dozen experiments in ocean fertilisation have been carried out, but the data they have yielded is often sketchy and contradictory. The experiments are complex and difficult to carry out and often do not look at the long-term effectiveness.

Some oceanographers, looking at published data, contend the sequestration yield is so poor that iron would have to be dumped over vast areas to make any inroad into the greenhouse-gas problem.

This would make the technique commercially unviable in addition to posing unknown risks for marine ecology, they say.

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Wind jobs outstrip the coal industry

photo: Todd Woody

Here’s a talking point in the green jobs debate: The wind industry now employs more people than coal mining in the United States.

Wind industry jobs jumped to 85,000 in 2008, a 70% increase from the previous year, according to a report released Tuesday from the American Wind Energy Association. In contrast, the coal industry mining employs about 81,000 workers. (Those figures are from a 2007 U.S. Department of Energy report but coal employment has remained steady in recent years though it’s down by nearly 50% since 1986.) Wind industry employment includes 13,000 manufacturing jobs concentrated in regions of the country hard hit by the deindustrialization of the past two decades.

The big spike in wind jobs was a result of a record-setting 50% increase in installed wind capacity, with 8,358 megawatts coming online in 2008 (enough to power some 2 million homes). That’s a third of the nation’s total 25,170 megawatts of wind power generation. Wind farms generating more than 4,000 megawatts of electricity were completed in the last three months of 2008 alone.

Another sign that wind power is no longer a niche green energy play: Wind accounted for 42% of all new electricity generation installed last year in the U.S. Power, literally, is shifting from the east to west, to the wind belt of the Midwest, west Texas and the West Coast. Texas continues to lead the country, with 7,116 megawatts of wind capacity but Iowa in 2008 overtook California for the No. 2 spot, with 2,790 megawatts of wind generation. Other new wind powers include Oregon, Minnesota, Colorado and Washington state.

But last year’s record is unlikely to be repeated in 2009 as the global credit crisis delays or scuttles new projects because developers are unable to secure financing for wind farms. Layoffs have already hit turbine makers like Clipper Windpower and Gamesa as well as companies that produce turbine towers, blades and other components.

The Obama administration’s $825 billion stimulus package includes a three-year extension of a key production tax credit that has spurred the wind industry’s expansion. But given the dearth of investors with tax liabilities willing to invest in wind projects in exchange for the credits, the stimulus is unlikely to be stimulating to the industry unless the tax credit is made refundable to developers.

The U.S. wind industry is dominated by European wind developers and turbine makers - General Electric (GE) and Clipper are the only two domestic turbine manufacturers - and those companies’ fortunes rise and fall with the global economy. As the U.S. market has boomed, European companies have been moving production close to their customers - the percentage of domestically manufactured wind turbine components rose from 30% to 50% between 2005 and 2008, according to the American Wind Energy Association.

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