Should we Geoengineer the Climate?
Last week, the Royal Society held a public lecture entitled ‘Geoengineering the climate: A brave new world?’, following their September 2009 publication ‘Geoengineering the climate: Science, governance and uncertainty’. The lecture panelists, like the authors of last year’s publication, were from a wide range of disciplines, reflecting the diversity of issues which arise from geoengineering proposals.
Geoengineering solutions for combating global warming fall into two broad categories. The first, Carbon Dioxide Removal (CDR), addresses the principal cause of climate change by removing CO2 from the atmosphere, and so reducing the greenhouse effect. The second, Solar Radiation Management (SRM), involves countering the warming effects of high atmospheric CO2 by reflecting some of the radiation from the sun.
Examples of suggested CDR techniques include biochar; aforestation; ocean fertilisation; and enhancement of weathering. SRM methods include increasing the albedo of the earth, such as by painting building roofs white; increasing the reflection of radiation from the stratosphere by releasing aerosols; and space-based methods which reduce the amount of radiation reaching the earth, such as by launching reflectors into space.
The immediate benefit of CDR over SRM is that it removes CO2 and so would counter ocean acidification (and other CO2-related problems), whereas SRM only prevents warming. However, some methods for SRM could be deployed very rapidly, most CDR methods would take years or decades to become effective.
The only panelist who opposed any further research into geoengineering was Greenpeace senior scientist Dr. David Santillo. The opinion of Greenpeace, and of many other opponents, is that focussing on geoengineering solutions to the climate problem diverts attention (and funds) from what is sometimes termed ‘Plan A’: the reduction of CO2 emissions. The possibility of a ‘Plan B’ may be regarded by governments, industry and the public as an excuse to continue burning all remaining fossil fuel reserves. An uncertain cure in the place of a more reliable prevention.
However, it can not be assumed that all serious advocates of climate geoengineering see it as an alternative to emissions reduction, but rather as a necessary additional measure. This is the logical conclusion from the increasingly popular view that present levels of atmospheric CO2 are already so high that certain tipping points in the earth climate system have been reached (most recently). This position asserts that even if emissions fall to zero tomorrow, ‘catastrophic climate change’ is still probable.
The problems with geoengineering are wide-ranging and hard to predict, but stem from three main areas:
Firstly, designing successful methods to reduce either atmospheric CO2 levels, or solar radiation absorption require an excellent understanding of the earth system. At the Royal Society, Professor Corinne Le Quéré, from the University of East Anglia, reminded us that current models are still not accurately reproducing observation in a number of fields, Arctic ice melt, for example.
Secondly, implementation of the technology itself could prove prohibitively expensive. This is certainly the case with space-based SRM methods. As well as monetary costs, implementation of some technologies may be expensive in terms of space and resources. Aforestation, for instance, risks competing for fertile land with agriculture.
Thirdly, and perhaps most critically, major geoengineering projects would require international cooperation. Although some CDR techniques, such as biochar and land use changes, could be applied in specific areas, without need for consent from others, they would actually need to be implemented across large areas of the world to be effective. Certain SRM techniques, however, could be carried out by one country (perhaps by releasing aerosols into the stratosphere), and would be effective over the entire globe. This category of technique could be damaging to the climates of certain parts of the world, for example by reducing precipitation. Added to this is the fact that once a particular SRM is started, it will have to continue indefinitely. If suddenly terminated, rapid warming would commence, with disastrous consequences. After the recent failure of world leaders to agree upon emission reductions at Copenhagen, how can we rely upon them to reach an agreement over the much more complex issue of geoengineering?
Plan A may have already failed, plan B is not a silver bullet solution, which leads me to consider plan C: Adaptation. Millions, perhaps billions of people are at risk of being displaced by sea level rise, drought, famine and other effects of climate change. Humankind has adapted to changes in climate before, by migrating, by changes in behaviour, and by inventing new technologies. With a population of nearly seven billion, the task is certainly tougher this time. But perhaps it’s the most feasible option left to us.
Thanks for this Kate, sounds like an interesting meeting.
I think the concept of tipping points is useful when thinking about geoengineering. If the climate system has tipping points, points at which the climate can be forced past, from which it won’t relax back to its previous state when the forcing is removed, geoengineering can be thought of as a reversing force. If we are at or past a tipping point then a passive response to reduce the forcing (mitigation) cannot be expected to ‘fix’ the system. The only option is to apply an opposing force – geoengineering.
To suggest we are at or near tipping points, is to say mitigation is not enough and some form of geoengineering is required.
My general take on geoengineering is that we can have a go at things that are easily-reversible. We’re not advanced enough to know the outcomes of a lot of these things (take our current situation as an example), so should restrict ourselves to doing things that we can back out of without doing permanent damage. For instance, (extreme example) mirrors in space can be thrown away if they have negative side effects, whereas other proposals are harder to get away from once started.
There is a problem with SRM geoengineering is that the year the mirrors or the aerosols go up there will be floods, hurricanes, droughts, etc. just as normal. Determining whether a change in the climate has occured would take decades but psychologically it will be instant. If for example the monsoon in India fails the year the geoengineering intervention is implemented and the year after it is not much better, how long will the Indian public wait to have it proved whether SRM geoengineering caused the change?
There would be a great psychological difference between SRM geoengineering and climate change that should not be underestimated. If it was to be applied by a single country, and our India example were to pan out, there would be a great build up of international tension and potentially military action against the perpetrator.
If we were very sure of how the climate would respond to SRM geoengineering and it responded as we expected there would still be winners and losers. The losers might not respond to happily to the global consensus that it was a good idea and if the international response to global warming is anything to go by there would be little more than token compensation.
I think there would need to be an unprecedented level of international cooperation to stick out the first X years of uncertainty after the initiation of a SRM geoengineering intervention and to keep the climate losers happy. These political challenges may be even more challenging than the daunting technical challenges of predicting, testing and operating a geoengineering intervention on the climate.
Picking up on the points made by Peter Irvine. To be able to trial any Geo-solution, and make a clear analysis of the viability for full scale deployment, you need to be able to accurately baseline the before state. Otherwise any meaningful conclusion and final decision will be flawed.
With the whole climate system being such a volitile soup of cause and affect, constantly changing, no accurate baseline could be taken.
Many times man has tried to tame or manipulate nature and nature has decided to take its own path.
We can’t even accurately predict the weather, so why do we still think we can control the whole climate system!
We may not be able to predict the fine detail of the weather very well, but we can predict macroscopic effects fairly well. We can predict with confidence that summer will be warmer than winter as we know the northern hemisphere will be receiving more sunlight during summer months than winter months.
Similarly, we could predict with some confidence that a geoengineering solution blocking out some sunlight would have a macroscopic cooling trend. What we can’t know is the detail – the effect on the monsoon as Pete mentioned. It is this detail and the associated winners and losers that are problematic, and of course attribution could never be known with certainty.
My take on geoengineering is that it must be the weapon of last resort. If we offer geoengineering too early then that just gives the fossil fuel lobby more excuses to keep burning coal and non-conventional oil. However, if the worst happens and the methylhydrates become unstable and start going into the atmosphere in large volumes then we would have to throw everything at the problem – including geoengineering.
Heard a bit more about geoengineering today at the Geological Society Geochemistry Group Meeting. Two things interested me…
1. Joe Cartwright (Cardiff University), who described himself as a mud-expert, talked about subsurface sequestration of CO2. This is a commonly discussed method of carbon storage, where CO2 is pressurized before being pumped into underground aquifers. Mud-experts are useful here, because mudstones (and I’m talking about geological mud here, millions of years old mud, rather than the stuff your shoes get coated in when it rains!) are considered to be good seals. Put some CO2 under some mudstone, and it won’t leak back up to the surface. According to Professor Cartwright, this is junk-thinking. CO2 will always leak. Wherever you put it, it will pretty much ALWAYS start leaking out again (and I’m talking about soon, not a thousand years later). This shouldn’t dissuade discussions on CO2 storage, just that inevitable leakage should be a recognised as a cost which is less than that of leaving the CO2 on the atmosphere…
2. A technique which I have heard little about before involves putting calcium-rich waste materials (cements, for example) into soils. The CO2 in the atmosphere reacts with the calcium to form calcium carbonate (think limestone). The CO2 is effectively locked up in this way cheaply, effectively, safely. It seems this idea is in the early stages of development, scale was the only cited potential issue. I’d like to know more about this.
The Geological Society are hosting a talk on geoengineering this month, I think on the 10th. I can’t check because their website is down, possibly due to the street-wide power cut this afternoon which rendered much of our meeting electricity-free.
Here’s the link to The Geological Society talk:
http://www.geolsoc.org.uk/gsl/site/GSL/lang/en/page6434.html
About CO2 always escaping. As CO2 is a larger molecule than CH4 (natural gas) and gas is proved itself containable then in theory CO2 should also be containable. Anything that can hold CH4 for millions of years should be able to hold CO2 just as well. No?
Yeah true, but I think the point was that some HAS leaked out though… The methane that we are sucking up now has not just sat in the place in which it was formed for millions of years… it migrates through the rock, and some is lost. So there is less methane in these stores than there once was, I guess?
The guy wasn’t saying that everything would just pop right out again as soon as it was put there. Just that naturally, gas (or CO2) is constantly migrating through rock, and does sometimes reach the surface. The perspective of the talk was partly from a monitering point of view… If a government agrees to underground storage, then it will want to moniter the area, both above ground and using seismic to look underground, to check that the CO2 was staying put. This guy was saying that this monitering will show that the CO2 does migrate, and that we shouldn’t be overly worried about it.
I think that was it anyway!
I wonder how good these sites that we are mining gas from are as storage sites? Shouldn’t we be able to work that out? If we knew how much gas was formed in a gas field originally, and how old it is, and how much is in there now… we should be able to work it out? Hmmm…
Oh, also, we will be pumping CO2 into old gas fields faster than the natural gas accumulated there. This apparently means that we can expect CO2 to leak more than the original gas did. Not sure I quite understand why that is.