With the visible effects of climate change growing, is it time for engineers to step in and make fundamental changes to the eco-system?
Anyone who has delved into the morass of conflicting reports and opinions that surround the thorny issue of climate change will readily admit that plain ‘truth’ is not easy to come by. There are many fields in science where controversies still remain. This is healthy for science. It keeps us on our toes and forces us to question our assumptions and models. So it is revealing that, when it comes to climate change, the overwhelming majority of scientists acknowledge that it is taking place, that it is potentially catastrophic and is, in all likelihood, caused by humans.
Having given this acceptance, the next question on scientists’ lips is whether anything can be done. The drive is on, albeit grudgingly and at an agonisingly torpid pace, to limit the volume of greenhouse gases that are pumped into the atmosphere, but that alone is unlikely to be sufficient. What is really required is a solution that will reverse the climate-change effects, and this has been dubbed ‘geoengineering’.
Geoengineering has become popular among scientists looking to combat climate change, but it is an idiom that is prone to misconception. At its simplest, it could be defined as the intentional management of the planetary system, but it is generally applied to the management of the planet’s energy budget.
Many supporters of geoengineering believe that we need a broader definition of the term because in any meaningful sense we are all geoengineers - humanity combined pours something like 10 billion tonnes of carbon into the atmosphere every single year, which has an effect on global warming, ocean acidification and the depletion of species.
According to Mark Lynas, award-winning author of a number of books on climate change and visiting research associate at Oxford University’s School of Geography and the Environment, that is only one of a host of different system-level processes which we affect very dramatically. “We have increased the amount of carbon dioxide in the atmosphere by a third since pre-industrial times, but we have actually doubled the production of terrestrial nitrogen for example,” he says. “We have doubled the nitrogen cycle on land by producing artificial fertilisers, which is running off into water courses. There’s good and bad in all of these areas. We’ve even changed the colour of the sky with the aerosol loading down in the atmosphere.”
Cutting solar radiation
Geoengineering, as it is conventionally defined, is generally restricted to solar radiation management, which is the idea that you can alter, or at least have some impact on, the amount of solar radiation reaching the surface. It is a way to mitigate not the carbon contribution of the atmosphere, but the actual heating up product of global warming.
The thinking is to effectively replicate the effect that volcanoes have, such as when Mount Pinatubo erupted in 1991. “That incident released so much aerosol, mainly sulphates, into the stratosphere that it reduced the planet’s temperature by half a degree for the following two years,” Lynas adds. “That is geoengineering done by nature.”
Two years ago the Royal Society published a report on geoengineering chaired by Professor John Shepherd. It concluded that manmade climate change is happening which has led to growing interest in geoengineering. “However, despite this interest, there has been a lack of accessible, high-quality information on the proposed geoengineering techniques which remain unproven and potentially dangerous,” Prof Shepherd says.
“Carbon Dioxide Removal (CDR) techniques, which remove CO2 from the atmosphere, address the root cause of climate change - rising CO2 concentrations, and have relatively low uncertainties and risks. However, these techniques work slowly to reduce global temperatures.
“Solar Radiation Management (SRM) techniques reflect a small percentage of the sun’s light and heat back into space. These methods act quickly, and so may represent the only way to lower global temperatures quickly in the event of a climate crisis.
“However, they only reduce some, not all, effects of climate change, while possibly creating other problems. They also do not affect CO2 levels and therefore fail to address the wider effects of rising CO2, including ocean acidification.”
A strong supporter of geoengineering is Professor Jim Al-Khalili, physicist and chair in the public engagement in science at University of Surrey. “I think it is fair to say that people are broadly sceptical of both the need for and the effectiveness of attempts to control the whole planet’s climate and ecosystem, and that it is dangerous and may be intrinsically unethical,” Professor Al-Khalili says.
“It is unclear whether geoengineering is socially economically or even ecologically viable,” he adds. “At best, even if all of the problems are ironed out, the danger is that geoengineering is seen as a ‘get out of jail free’ card.”
This is known as the ‘moral hazard’ argument and it can stop us from acting on actually reducing carbon emissions in the first place, as it lulls us into a false sense of security without tackling the root cause of the damage to our planet. Many have argued that such large-scale meddling might make matters worse.
Battling climate change
So given those concerns, why should geoengineering be attempted? The simple answer from supporters is yes, because climate change is happening. “Its impact and cost will be large, serious and unevenly spread across the globe,” Professor Al-Khalili says. “The impacts may be reduced by adaptation, moderated by mitigation especially by reducing the emissions of greenhouse gases. However, global efforts to reduce emissions haven’t yet been sufficiently successful to provide confidence that the reductions needed to avoid dangerous climate change will be achieved in time.”
It is likely that global warming will exceed 2°C this century unless greenhouse gases are cut by at least 15 per cent of the 1990 levels by half way through the 21st century, and by more thereafter. There is no credible emissions scenario under which global mean temperature would peak and then start to decline by 2100 unless future efforts to decrease greenhouse gas emissions are more successful than they have been so far.
“Additional action will be required should it become necessary to cool the Earth this century, especially given our consequent thirst for energy and the society around the world’s reluctance to give up on fossil-fuel burning,” Al-Khalili argues. “So then additional action might then involve geoengineering.”
There are generally considered to be two approaches to geoengineering. There is carbon dioxide removal and the control of solar radiation. There are a number of ways under consideration for the first option, including enhancing carbon sink restoration, increasing the CO2 uptake of the oceans and, probably most promisingly, the direct removal of CO2 from the atmosphere.
Then there is the second method of geoengineering, which is to control solar radiation. This involves trying to increase reflectivity of the Sun’s rays back into space. Again, there are different options and scenarios including reflecting it from the land - anything from painting buildings to growing high reflectivity crops to covering deserts with reflective material, and other more ambitious options such as injecting sulphur aerosols into the atmosphere and placing large reflective shields out in space.
Managing the problem
“CO2 removal may have fewer uncertainties and return the planet to a more natural state, but none of the methods have yet been demonstrated to be affordable or effective,” Al-Khalili adds. “It does though complement CO2 emissions.
“Radiation management is faster acting, it’s more ambitious and I think it is seen as more of a way of trying to reduce the Earth’s temperature in an emergency, when we have to act quickly. Neither approach offers immediate solutions, nor removes the need to reduce CO2 emissions. And that is my main point: it may be necessary.”
The question is who decides when the point of last resort has been reached and that geoengineering should be taken seriously? Already the Earth has warmed by about 1°C and there will be a further degree rise of temperature even if there were no further increase of CO2 emissions, because of the time lag in the warming effect of the planet.
In the short term we need to improve client models to test accurately the impact of large-scale projects. “Clearly no large-scale research or certainly any deployments should take place until appropriate international governments mechanisms are replaced,” Al-Khalili says.
“So for me there are four points. First, better climate change models are required to assess the need for geoengineering. Then a code of practice for validation and monitoring is needed, and many argue this has to be in place within a decade. Then the technology needs public acceptability - there is a lot of scepticism and worry among the general public. Finally, there needs to be transparency, both in the research and the international decision making process.
“The greatest challenges are social, ethical, legal and political rather than scientific. As a scientist my interest is assessing the wider environmental impact of such projects and to weigh these against the potential impact if we do nothing.”
Geoengineering in action
One person who has been heavily involved in one of the few meaningful geoengineering experiments is Professor Peter Liss, fellow of the School of Environmental Sciences at the University of East Anglia and chair of the Royal Society’s Global Environment Research Committee.
His area of research was in coaxing the world’s oceans into storing more CO2, to act as reservoirs. The oceans are a natural reservoir for CO2 and if they didn’t exist the atmospheric level of CO2 due to man-made emissions would be something like 30 or 40 per cent higher, with all the climatic consequences that that would create. “The oceans provide a great service for humanity for soaking up carbon dioxide,” Professor Liss says.
“The big question is, can we enhance that if we choose to do it. Just like on land, plants and oceans need nutrients to grow, but in 25 per cent of the ocean the nutrients are not used up, therefore the plants do not grow to their full potential.”
Scientists have been questioning why that is for years. The answer turned out to be that it’s the element iron. About 20 years ago scientists began conducting experiments, although at the time the possibility of geoengineering had not been considered. In an attempt to increase plant growth, a programme of added iron to areas of the ocean was undertaken; if it could be accomplished, this extra plant growth would increase the ocean’s absorption of CO2.
“These experiments were not done with that in mind,” Professor Liss continues. “We just wanted to find out how the oceans work in terms of biological productivity and was the lack of iron the thing that limited the growth of plants?”
All the experiments that were carried out showed substantial increase in plant production by the addition of the ferrous sulphate.
“Now this is where it now impinges on geoengineering, because at the same time as this production you get a draw down - a taking out of CO2 by the plants. Inside the fertilised patch the carbon dioxide was drawn down. That’s what you might have expected, but this has led other people to speculate whether this is the geoengineering approach that we could use. We can now extrapolate what would happen if we really did a geoengineering activity.”
These results were fed into a climate model that fertilised all the relevant areas in the oceans for ten years, and then for 100 years. If the oceans were fertilised for 100 years, you would get only 33 parts per million draw down - less than 10 per cent of what the atmospheric level is now. “That means that this doesn’t look quantitatively like an approach that you can propose to society through politicians,” Professor Liss adds.
“However, as well as drawing down the carbon dioxide you will also produce more of another greenhouse gas in the oceans called nitrous oxide, which would back off some of the CO2 benefits,” Professor Liss continues. “So you don’t get that 33 parts per million, you get somewhat less, because of, in climate terms, the extra production of nitrous oxide.” *