Thursday, August 30, 2012
Public release date: 30-Aug-2012
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Contact: Michael Bishop
Institute of Physics
[ Print | E-mail | Share ] [ Close Window ]
Contact: Michael Bishop
Institute of Physics
Delivering solar geoengineering materials may be feasible and affordable
A cost analysis of the technologies needed to transport materials into the stratosphere to reduce the amount of sunlight hitting Earth and therefore reduce the effects of global climate change has shown that they are both feasible and affordable.
Published today, 31 August 2012, in IOP Publishing's journal Environmental Research Letters, the study has shown that the basic technology currently exists and could be assembled and implemented in a number of different forms for less than USD $5 billion a year.
Put into context, the cost of reducing carbon dioxide emissions is currently estimated to be between 0.2 and 2.5 per cent of GDP in the year 2030, which is equivalent to roughly USD $200 to $2000 billion.
Solar radiation management (SRM) looks to induce the effects similar to those observed after volcanic eruptions; however, the authors state that it is not a preferred strategy and that such a claim could only be made after the thorough investigation of the implications, risks and costs associated with these issues.
The authors caution that reducing incident sunlight does nothing at all to reduce greenhouse gas concentrations in the atmosphere, nor the resulting increase in the acid content of the oceans.
They note that other research has shown that the effects of solar radiation management are not uniform, and would cause different temperature and precipitation changes in different countries.
Co-author of the study, Professor Jay Apt, said: "As economists are beginning to explore the role of several types of geoengineering, it is important that a cost analysis of SRM is carried out. The basic feasibility of SRM with current technology is still being disputed and some political scientists and policy makers are concerned about unilateral action."
In the study, the researchers, from Aurora Flight Sciences, Harvard University and Carnegie Mellon University, performed an engineering cost analysis on six systems capable of delivering 1 million metric tonnes of material to altitudes of 18 km: existing aircraft, a new airplane designed to perform at altitudes up to 30 km, a new hybrid airship, rockets, guns and suspended pipes carrying gas or slurry to inject the particles into the atmosphere.
Based on existing research into solar radiation management, the researchers performed their cost analyses for systems that could deliver around one million tonnes of aerosols each year at an altitude between 18 and 25 km and between a latitude range of 30°N and 30°S.
The study concluded that using aircraft is easily within the current capabilities of aerospace engineering, manufacturing and operations. The development of new, specialized aircraft appeared to be the cheapest option, with costs of around $1 to $2 billion a year; existing aircraft would be more expensive as they are not optimised for high altitudes and would need considerable and expensive modifications to do so.
Guns and rockets appeared to be capable of delivering materials at high altitudes but the costs associated with these are much higher than those of airplanes and airships due to their lack of reusability.
Although completely theoretical at this point in time, a large gas pipe, rising to 20 km in the sky and suspended by helium-filled floating platforms, would offer the lowest recurring cost-per-kilogram of particles delivered but the costs of research into the materials required, the development of the pipe and the testing to ensure safety, would be high; the whole system carries a large uncertainty.
Professor Apt continued: "We hope our study will help other scientists looking at more novel methods for dispersing particles and help them to explore methods with increased efficiency and reduced environmental risk."
The researchers make it clear that they have not sought to address the science of aerosols in the stratosphere, nor issues of risk, effectiveness or governance that will add to the costs of solar radiation management geoengineering.
Notes to Editors
1. For further information, a full draft of the journal paper or contact with one of the researchers, contact IOP Press Officer, Michael Bishop: Tel: 0117 930 1032 E-mail: Michael.email@example.com
Cost analysis of stratospheric albedo modification delivery systems
2. The published version of the paper 'Cost analysis of stratospheric albedo modification delivery systems' (Justin McClellan, David W Keith and Jay Apt 2012 Environ. Res. Lett. 7 034019
Environmental Research Letters
Posted by stang289 at 8:18 PM
Sunday, August 19, 2012
Tuesday, August 14, 2012
Posted by stang289 at 7:25 PM
Thursday, August 9, 2012
Monday, August 6, 2012
Experiment in New Mexico will try to establish the possibility of cooling the planet by dispersing sulphate aerosols
Two Harvard engineers are planning to spray thousands of tonnes of sun-reflecting chemical particles into the atmosphere to artificially cool the planet, using a balloon flying 80,000 feet over Fort Sumner, New Mexico.
The field experiment in solar geoengineering aims to ultimately create a technology to replicate the observed effects of volcanoes that spew sulphates into the stratosphere, using sulphate aerosols to bounce sunlight back to space and decrease the temperature of the Earth.
David Keith, one of the investigators, has argued that solar geoengineering could be an inexpensive method to slow down global warming, but other scientists warn that it could have unpredictable, disastrous consequences for the Earth's weather systems and food supplies. Environmental groups fear that the push to make geoengineering a "plan B" for climate change will undermine efforts to reduce carbon emissions.
Keith, who manages a multimillion dollar geoengineering research fund provided by Microsoft founder Bill Gates, previously commissioned a study by a US aerospace company that made the case for the feasibility of large-scale deployment of solar geoengineering technologies.
His US experiment, conducted with American James Anderson, will take place within a year and involve the release of tens or hundreds of kilograms of particles to measure the impacts on ozone chemistry, and to test ways to make sulphate aerosols the appropriate size. Since it is impossible to simulate the complexity of the stratosphere in a laboratory, Keith says the experiment will provide an opportunity to improve models of how the ozone layer could be altered by much larger-scale sulphate spraying.
"The objective is not to alter the climate, but simply to probe the processes at a micro scale," said Keith. "The direct risk is very small."
While the experiment may not harm the climate, environmental groups say that the global environmental risks of solar geoengineering have been amply identified through modelling and the study of the impacts of sulphuric dust emitted by volcanoes.
"Impacts include the potential for further damage to the ozone layer, and disruption of rainfall, particularly in tropical and subtropical regions - potentially threatening the food supplies of billions of people," said Pat Mooney, executive director of the Canadian-based technology watchdog ETC Group. "It will do nothing to decrease levels of greenhouse gases in the atmosphere or halt ocean acidification. And solar geoengineering is likely to increase the risk of climate-related international conflict - given that the modelling to date shows it poses greater risks to the global south."
A scientific study published last month concluded that solar radiation management could decrease rainfall by 15 per cent in areas of North America and northern Eurasia and by more than 20 per cent in central South America.
Last autumn, a British field test of a balloon-and-hosepipe device that would have pumped water into the sky generated controversy. The government-funded project - Stratospheric Particle Injection for Climate Engineering (Spice) - was cancelled after a row over patents and a public outcry by global NGOs, some of whom argued the project was a "Trojan horse" that would open the door to full-scale deployment of the technology.
Keith said he opposed Spice from the outset because it would not have improved knowledge of the risks or effectiveness of solar geoengineering, unlike his own experiment.
"I salute the British government for getting out and trying something," he said. "But I wish they'd had a better process, because those opposed to any such experiments will see it as a victory and try to stop other experiments as well."
The Guardian understands that Keith is planning to use the Gates-backed fund to organise a meeting to study the lessons of Spice.
Posted by stang289 at 7:44 PM
Saturday, August 4, 2012
Climate fixes 'pose drought risk'
Attempts to control the climate might change precipitation, say researchers
The use of geo-engineering to slow global warming may increase the risk of drought, according to a paper in Science journal.
Methods put forward include reflecting solar radiation back into space using giant mirrors or aerosol particles.
But the authors warn that such attempts to control the climate could also cause major changes in precipitation.
They want the effect on rainfall to be assessed before any action is taken.
Gabriele Hegerl of the Grant Institute at University of Edinburgh and Susan Solomon of National Oceanic and Atmospheric Administration (NOAA) at Boulder, Colorado, write that "if geo-engineering studies focus too heavily on warming, critical risks associated with such possible "cures" will not be evaluated appropriately".
They argue that climate change is about much more than changes in temperature. So using temperature alone to monitor the effects of geo-engineering could be dangerous.
They cite the powerful effects on rainfall of volcanic eruptions which also prevent solar radiation reaching the Earth's surface, albeit by throwing up dust rather than reflecting the radiation back into space.
For example in 1991, the eruption of Mount Pinatubo not only reduced global temperatures but also led to increases in drought.
The pair correlated 20th Century weather records with data for the increase in greenhouse gases and dates for major volcanic eruptions.
This revealed that greenhouse emissions tend to slightly increase rainfall in the short term but also showed that reduction in rainfall in the months following a major volcanic eruption is far more dramatic.
The authors note that current climate models tend to underestimate the effects on precipitation of both greenhouse gases and of volcanic eruptions.
The article warns that geo-engineering of this type, combined with the effects of global warming could produce reductions in regional rainfall that could rival those of past major droughts, leading to winners and losers among the human population and possible conflicts over water.
They conclude: "optimism about a geo-engineered 'easy way out' should be tempered by examination of currently observed climate changes."
Posted by stang289 at 6:51 PM