by Nicola Davis (The observer, Thursday 6 November 2014 07.00 GMT)
Last August, Berlin hosted an international conference on the controversial issue of geoengineering. We ask expert Dr Naomi Vaughan from the Tyndall Centre for Climate Change Research at the University of East Anglia to explain why it’s such a hot potato for climate scientists.
What do we mean by geoengineering?
Geoengineering means large-scale interventions in the Earth’s climate system to try to tackle climate change. There are, broadly, two types. The first would try to take some of the greenhouse gases that are causing climate change out of the atmosphere. The second would try to balance out that we have too many greenhouse gases in our atmosphere by reflecting more sunlight back into space.
How would we capture CO2?
Oceans and land take a lot of carbon out of the atmosphere each year. There are ideas to try to make those processes happen more quickly [for example, by planting more trees]. The other type would be to use chemical engineering to scrub the atmosphere of CO2 – but once you have caught it you need to store it somewhere for a long time.
And reflecting the sunlight?
The idea that would seem to be able to do a big enough job for us, given the challenge of climate change, is to reflect more sunlight back into space by putting tiny little particles high up into our atmosphere, into the stratosphere.
Have there been any experiments carried out?
There has been some laboratory-based work on the particle, what size the particle might be, what it might be made of and how it goes about reflecting the sunlight, but most of the work on reflecting sunlight back into space has been done on computer models or desk-based research. There are a couple of startup companies looking at what chemical processes might be the best ones for capturing CO2. [For] storage there are already demonstration projects globally.
What are the concerns with geoengineering?
The idea of reflecting more sunlight back into space raises a lot of ethical, moral and legal questions. If you do [use particles] you have to keep doing it. If you stop it, or it fails, the climate will bounce back but very quickly – quicker than the climate change that would have occurred. That causes a lot of concerns. You’d be affecting the global climate with an intentional intervention – so who is responsible for that? What if there are side effects? Taking CO2 out of the atmosphere raises [fewer] big ethical questions, but there [is] still a set of questions about what we do with all this CO2 we are going to store … what kind of burden are we placing on future generations?
How does it fit in with reducing emissions?
Reflecting sunlight back into space is not a replacement for reducing our emissions – it might be something we could do on top of reducing our emissions and adapting to changes. When we are talking about taking CO2 out of the atmosphere it is a lot cheaper not to put it there in the first place.