Editorial: 鈥�Give geo- and genetic engineering a fair trial鈥�
Update 14 September 2011: The field test will be conducted at an abandoned airfield in Sculthorpe, UK. Matthew Watson of the University of Bristol, UK, presented details of the project at the in Bradford, UK.
Original article, posted 9 September 2011
Advertisement
FIELD trials for experiments to engineer the climate have begun. Next month a team of UK researchers will hoist one end of a 1-kilometre-long hose aloft using a balloon, then attempt to pump water up it and spray it into the atmosphere (see diagram).
The water will not affect the climate. Rather, the experiment is a proof of principle to show that we can pump large quantities of material to great heights. If it succeeds, a larger-scale version could one day pump sulphate aerosols into the stratosphere, creating a sunshade that will offset the greenhouse effect.
The trial, led by Matthew Watson of the University of Bristol, UK, is part of a 拢2 million project called . Funded by two UK research councils, it also aims to find out the ideal particles to use in an atmospheric sunshade and will attempt to model their effects in greater detail than ever before. The test is not alone: a string of other technologies that could be used to 鈥済eoengineer鈥� our environment are being field-tested (see 鈥淐oping with emissions鈥�).
In his blog, , Watson argues that we need to investigate the effects of sulphate aerosols as a last-resort remedy should the climate start to change rapidly. Researchers contacted by 快猫短视频 agreed with Watson that such research should continue, if only to find out whether the techniques are feasible. 鈥淚鈥檇 say there鈥檚 a 50-50 chance we鈥檒l end up doing it, because it鈥檒l get too warm and people will demand the planet be cooled off,鈥� says of Columbia University in New York. But there was less enthusiasm for SPICE鈥檚 approach to the problem.
聯We need to investigate the effects of sulphate aerosols on climate as we might have to use them聰
There are 鈥渓arge gaps鈥� in our understanding of geoengineering, says of the University of Bern in Switzerland. Stocker helped to organise an in June for the Intergovernmental Panel on Climate Change. It identified key unanswered questions that should be a focus for research. However, it is not clear that field trials like Watson鈥檚 will provide the answers.
One area of doubt over injecting aerosols into the stratosphere is whether it will change the behaviour of high-altitude clouds. That could in turn affect the climate in ways beyond what was intended 鈥� and for now, we don鈥檛 know how, or how much. Aerosols could also deplete the ozone layer, contribute to air pollution and may alter visibility in the same way as large volcanic eruptions can.
The SPICE test won鈥檛 answer any of these questions, says of Harvard University. 鈥淚 think it鈥檚 a little reckless.鈥� The most interesting result will be how the public reacts, he says.
What鈥檚 more, Keith adds, in the long run delivering sulphates to the stratosphere with a hose would be a bad idea. Spraying aerosols locally allows the particles to clump together, making them less effective at reflecting sunlight and more likely to be swept down by rain ().
Keith鈥檚 own studies suggest that if we were ever forced to try to screen out some of the sun鈥檚 rays globally, it would be more effective to spray sulphuric acid from aircraft ().
It would also be cheaper, costing a few billion dollars a year according to a , an aeronautical firm in Cambridge, Massachusetts. Such figures are tiny compared to the trillions that the consequences of climate change could cost the global economy if emissions continue to rise at current rates.
The point, says of the Carnegie Institution for Science in Stanford, California, is that experiments like Watson鈥檚, which test relatively simple delivery systems, address the issue of cost. But, since the Aurora study has shown that cost is not a critical factor 鈥� a sunshade will be relatively inexpensive 鈥� the critical questions relate to potential risks.
More importantly, since a stratospheric sunshade is intended to have a global impact, all countries must agree to such a project and to its precise extent, which is unlikely to happen.
One possibility that may help countries agree is that the sunshade need not be applied evenly across the globe. Caldeira has created, in a climate model, a sunshade with much larger quantities of aerosols above the poles than above the tropics. This produced a temperature distribution much closer to the pre-industrial climate than could be achieved with a uniform sunshade ().
Caldeira and others are now toying with the idea of regional geoengineering, or 鈥済eoadaptation鈥�. Some techniques, such as making clouds over the seas more reflective, should have localised effects, so countries could in theory tinker only with their own climate.
聯Making clouds over the sea more reflective could allow countries to tinker with their own climate聰
But here too uncertainties need to be resolved. of the NASA Goddard Institute for Space Studies in New York points out that changes in one area will have a knock-on effect on the other side of the planet. 鈥淲hat happens in Vegas does not stay in Vegas,鈥� he says. We could perhaps predict these long-range effects, but we cannot eliminate them.
Schmidt says that what we need is not field tests, but better modelling studies. Most simulations of geoengineering are 鈥渘aive鈥�, he says, and cannot model all the possible side effects. 鈥淧eople are not doing the right kinds of experiments to assess these effects,鈥� he says.
Additional reporting by Catherine Brahic
Coping with emissions
THE pipe-to-the-sky experiment is not the only geoengineering method that is being tested.
In 2009, a team of Russian scientists sprayed a small amount of sulphate aerosols into the atmosphere and found that they blocked between 1 and 10 per cent of incoming solar radiation ().
Iceland is testing a less contentious technique to deal with our carbon emissions: turning them into rock. The project aims to capture carbon dioxide from a local geothermal power plant, dissolve it in water and inject it into basalt rock, where it will react with magnesium, calcium and iron to form carbonates. If it works, the CO2 should stay put even in an earthquake. It is the safest way of storing CO2, according to project leader of the University of Iceland in Reykjavik. The team plans to start the gas injections later this month.
Adding iron to the ocean can trigger plankton blooms that suck up CO2, but a 2009 field test gave mixed results. That鈥檚 because the test site was unsuitable, says of the National Oceanography Centre in Southampton, UK. He and colleagues hope to repeat the trial.
Elsewhere, of the Carnegie Institution for Science in Stanford, California, has permission to add sodium hydroxide 鈥� an alkali 鈥� to a small patch of ocean to see if it can reverse the effects of ocean acidification.
Finally, California-based engineer Armand Neukermans is building a nozzle that will spray seawater into clouds, making them whiter and better able to reflect sunlight into space.
