Now, the controversy surrounding geoengineering is provoking a vigorous debate and certainly generating a lot of hot air. There are strong scientific, ethical, and political arguments over whether humans should deliberately seek to further manipulate the Earth’s climate, possibly with unforeseen effects and consequences. Geoengineering therefore has many supporters and detractors, so we’ve decided to conclude today’s programme by putting it on trial. Making the case for the prosecution is Mark Maslin, professor of Earth System Science at University College London and author of Climate Change: A Very Short Introduction. Defending geoengineering is David Keith, a professor in the Department of Geophysical Sciences at the University of Chicago and author of A Case for Climate Engineering. The court is now in session. Chris Smith invites Mark Maslin to make the case for the prosecution...
Mark - So for me, we are already undertaking one of the biggest geoengineering experiments ever in humanity. We are dumping huge amounts of greenhouse gases into the atmosphere, they are warming up the atmosphere and we are seeing the effects all around the world, whether it's extreme weather events, whether it's rising sea levels, whether it's melting glaciers and ice sheets. So we are already doing a massive geoengineering effort and what I think is that we have solutions to that. We can decarbonise the global economy. We know renewable energy is cheaper, more reliable and cleaner than fossil fuels. We need to deal with the pollution we are already creating. The problem with solar geoengineering as opposed to other geoengineerings is that it is about putting more pollution in the atmosphere to reflect some sunlight, to cool the planet, to hide the effects of those greenhouse gases. Now that is a temporary respite but it is not a solution to climate change. The only solution to climate change is removing those greenhouse gases or not putting the greenhouse gases in the atmosphere in the first place. The second problem is that if we do this solar radiation modification, we will have to do it every single year, and underneath the climate will be warming up but it will be cooled down by this reflection and, unfortunately, if we stop any one year that thermal shock of all that climate change that has been building up will suddenly hit us in an incredibly short period of time with no chance of adaptation. So for the prosecution I would say we should clean up our mess now. We should actually stop polluting the atmosphere, and not pollute the atmosphere with aerosols to clean up the other pollution that we're already doing.
Chris - David, the accusation is that this is the climate equivalent of sweeping dirt under the carpet and then laying an even bigger rug to cover it up. What do you think?
David - I think the number one priority of climate policy should be decarbonisation, should be stopping the pollution we're putting into the atmosphere and I think there's extraordinarily good news in that regard. There's a good chance that global emissions will peak in the next couple years which is a stunning achievement. We'll see a decoupling of economic growth from the growth of emissions. I think the hard reality is that even if we brought emissions to zero, which we absolutely can do, we still have warming that will go on for millions of years. The only way to reduce that damage is to remove the CO2 from the atmosphere or temporarily preserve some of the reflectivity of the Earth with these sunlight reflection methods and we have to think hard about the trade-offs we face over the next century. So in my view, priority one is cutting emissions but there's no way to do that in a decade and even if we did do it in a decade, we'd still have very high temperatures with people dying and ecosystems being hurt and, as I read it, the scientific evidence that a moderate, small amount of added sunlight reflection which would simply be to maintain the reflectivity of the Earth as it is for example and that would achieve a level of environmental protection that I think there's a clear sign of a consensus cannot be achieved simply by cutting emissions.
Chris - When you say small, I mean we need to be clear here, it's small in relative terms relative to the carbon in the atmosphere, but the amount of material we would have to put into the atmosphere to achieve a meaningful reduction in temperature. If we take as one of our earlier contributors did, Mount Pinatubo when it erupted in the early '90s, that was something like 20 million tonnes of sulphates ejected from that one volcano which translated into possibly a half a degree of cooling. So it's a big undertaking, David.
David - So there's nothing we have to do and I'm absolutely not saying that we have to do sunlight reflection. What I am saying is there's quite strong evidence that it would reduce risks particularly for vulnerable people and ecosystems and as to how much, that's a political choice but the number you said is very large. The kind of thing I would support, I think most people would support, would be a gradual ramp up to cooling by about half a degree Celsius which could be achieved by something like one million tonnes a year of sulphur put in the stratosphere, and for comparison the world was putting 70 million tonnes a year of sulphur into the lower atmosphere in 1980. It's now been cut to about 30 million tonnes which is accelerating warming but saving a huge number of lives from air pollution, and so we're talking about something that's of order a few percent of the sulphur that we're now putting into the lower atmosphere and I think there's a very good scientific basis to be able to predict what the results of that would be. Not that there would be no side effects, any big environmental intervention will have side effects and surprises but there's good basis to predict what that will do.
Chris - Does that make you any more comfortable, Mark? The fact that we're not talking about a huge intervention we're talking about a smaller intervention with a slower ramp up and therefore not ignoring the elephant in the room which is the big problem which is the warming that's already baked in from the CO2 that's up there and addressing that issue.
Mark - So I think the first thing is that where David and I will agree is I think there needs to be a lot more research done on solar radiation modification and just because scientists undertake the research doesn't necessarily mean that they are endorsing actually policymakers to use it but again considering that we have all the technology to decarbonise the global economy now by 2030 we will be putting in one terawatt of renewable energy, we only have 10 terawatts at the moment in the world, we're already on that transition. What we have to do is actually get the policymakers to shift quicker to do things quicker and I think actually having this option on the table which is: "oh perhaps we don't have to do it's quick the fossil fuel lobbyists can turn around and go no no let's keep making profit out of polluting the planet' is problematic" for many people because it's like almost having like a get out clause: "oh I don't have to do it it's not going to be that bad we have this solution which is we can cool the planet and buy some time." So unfortunately I still think that we should just focus on mitigation, removing carbon from the atmosphere, and protecting people, and adapting to climate change, and protecting people who are the most vulnerable around the world.
Chris - We do have a habit don't we David as as humans of waltzing into a crisis, solving the crisis, breathing a sigh of relief, and then creating a new one. I'm thinking 100 plus years ago we had lots of people starving on Earth because we'd reached the carrying capacity of the land. The Haber-Bosch process gets invented, we get ammonia, we get really good fertilisers, now the population's eight and a half going on for nine billion.
David - I strongly agree with the concern that there's a what's often called a 'moral hazard concern', indeed I believe I was the first person to raise that concern about climate engineering more than a quarter century ago, and I absolutely agree that big fossil fuel countries or fossil fuel motivated industries will exaggerate and lie about the utility of sunlight reflection as a way to try and reduce the pressure to decarbonise. I think that is a political reality but that doesn't answer the ethical question because as much as we do have the technology to carbonise it's just a fact that is undisputed that even if we decarbonise tomorrow there would still be people dying of heat and ecosystems harmed and glaciers melting for thousands of years and sunlight reflection can by every estimate no serious paper disputes this significantly reduce those risks saving of order a million lives from heat late this century and those are real humans who face real risks and I think the argument is that there is no one solution to a big complicated problem like climate change. We need to do many different things. We need to cut emissions which there's real progress in doing. We will eventually need to remove CO2 from the atmosphere. We need to do adaptation and in my view we need to very seriously consider sunlight reflection. It's not a single silver bullet.
Chris - What would it take, Mark, for you to feel reassured that in fact this was a sound initiative, geoengineering to reflect more sunlight and and that it could be safely deployed and there wasn't going to be a risk let's assume there isn't to be a risk that this would enable people to ignore the present crisis because it buys us time?
Mark - Oh that's a huge question. So I think the first thing is that I'm not sure anything is going to convince me that certain countries are not going to ignore the problem. We have a COP meeting in Turkey and it's clear that certain countries are quite happy to ignore the problem with emissions and the impacts of climate change. But again I will gently push back to David which is if we decarbonise, if we stop using fossil fuels, then there are something like eight million people that die prematurely every year from air pollution from fossil fuels. So the health benefits of dealing with climate change now are so much greater than trying to develop over the next 10 years technology that can try to cool the planet. So I'm much more based in the practical now which is how do we reduce the emissions? How do we clean up air pollution? How do we save lives now? Because the thing is that a lot of those vulnerable people are vulnerable because of the situation they are in, because of extreme poverty. Now, we generate over a hundred trillion dollars of new money every single year. Now, if that was distributed in a different way that people were then supported, they were able to buy food, shelter, air conditioning, and things like that then of the vulnerability would be greatly reduced. So I think there are much better solutions dealing with climate change, dealing with inequality, dealing with the insecurity that we have at the moment, are much better solutions than deciding to have this technology to throw more pollution into the atmosphere to try to actually delay decisions on how we're going to deal with climate change.
Chris - And David, to Mark's earlier point about the fact that if we do do this that there is a risk that this ends up resting on one organisation's shoulders, and that if they are suddenly disinclined to continue or unable to continue, there is the opportunity for a climate shock in the immediate aftermath. How can we mitigate that?
