Climate Engineering

Could we stop climate change by pumping particles into the ozone? And more importantly, should we? Dr Kirsty Kuo- Research is an associate at Cambridge University Department of Engineering and works on a project called SPICE. SPICE is trying to mitigate climate change by using a giant balloon to pump sulphur dioxide into the atmosphere. She told Ginny Smith what climate engineering is and how we could use it to help stop climate change.

Kirsty -  The field that I'm working on is called climate engineering.  It's an idea that has been around for some time, but it hasn't really been talked about because it's quite controversial.  The idea is that we could modify the Earth's climate so we could make it hotter or we could make it colder.  And now because global warming is such a challenge for us in this generation, we're starting to think about ways that we could make the climate colder so that we could counteract the effect of global warming.

Ginny -  I thought global warming, we're causing that by burning lots of fossil fuels, putting on this carbon dioxide up there.  We just need to stop that, find new methods of making energy and then we'll be okay.  You're doing something a bit different though.

Kirsty -  Yes, so our message is that absolutely, we have to reduce our carbon dioxide emissions.  There's no way we can get around that.  It's something that we have to do.  But it's a bit like your house being on fire really.  If your house is on fire, you want a fire engine to come and put it out.  And that's a bit like, if climate change happens, we want something that can have quite an instant effect and quite a big effect.  And so, we're thinking about this idea of climate engineering.  Unlike a fire engine which the effect is to put the fire out and that's all it does, climate engineering would have lots and lots of different effects.  It wouldn't just lower the Earth's temperature.  It would also cause changes in rainfall and changes in local climates, and also, changes in chemistry in the atmosphere.  And these changes are really serious and it's not something that we want to take on without thinking about it and doing research, knowing exactly what's going to happen.

Ginny -  So, how are you going to go about making the Earth cooler then?

Kirsty -  So, our idea comes from volcanic eruptions particularly in 1991, Mt. Pinatubo erupted and it put lots of ash and other chemicals up into the atmosphere.  One of the things they put up was sulphur dioxide.  These sulphur dioxide particles are really quite small, but they're just a perfect size to reflect some of the sun's light that's coming towards Earth.  And so, these particles produced a cooling effect of about half a degree C for 12 to 18 months after the volcanic eruption.  Our idea is that if we could imitate a volcanic eruption then maybe we could see a similar cooling effect.

Ginny -  I don't really like the idea of imitating a volcano.  A volcano is quite scary and quite dangerous.  I'm guessing you're going to do it in a slightly more controlled way.

Kirsty -  That's right.  We're not going to go and just blow up volcanoes around the Earth.  So the idea is to get some kind of reflective particle whether it's sulphur dioxide or something else, and to pump it up into the stratosphere and at a height of 20 km because that's where it will stay for about 12 to 18 months before these particles start to fall down to the Earth.

Ginny -  How on earth do you get it up that high?

Kirsty -  Well, there's lots of different ideas of how you could do it.  So, you could say, Well, we've got airplanes that fly at about 10 km.  There are some very special military ones that can fly at 20 km, so why don't we use those?  The problem is, is that it takes a lot of energy to get the aircraft up to 20 km and get it back down again with a package of these particles.  So, much more energy efficient way of doing it is to build a giant structure where we could pump these chemicals up.  Now building a giant tower isn't possible because the strength of the material isn't large enough.  But the way we propose to do it is to build a giant hose and this hose would be held up by a balloon and the balloon would have to be the size of the Wembley stadium to hold up this 20 km of hose and through the hose, we can pump these particles and spray them out at 20 km.

Ginny -  What's the balloon filled with?  Is it helium, like an almost sort of party balloon that floats?

Kirsty -  It would probably have to be hydrogen because helium is in quite short supply and it's very expensive.

Ginny -  So, we've got a giant hydrogen balloon in the sky with a hose and then how do you get the material to go up the hose?

Kirsty -  Well, you have to pump it up like when you turn on your hose pipe at home, there's water pressure which is driving the water through the hose.  In the same way we'd have to supply pressure at the ground level to move these materials up through the hose.  The problem is that the pressure is going to be extremely high.  Even in industrial applications where they use very high pressures, it's even higher than that.  So, that's one of the big engineering challenges of thinking about this kind of technology.

Ginny -  And how much of the stuff would you have to put up there to make a difference?

Kirsty -  Well, they've estimated that to cause a 2-degree change in the global mean temperature.  We'd need 10 million tons of sulphur dioxide.  That sounds like an awful lot, but once it gets spread around the Earth, it actually turns out to be about 1 teaspoon of material for 1 square km of the Earth's area.

Ginny -  Fascinating!  So, who's got any questions on that?  We've got lots of hands up already.  One down the front to start with...

Freddy -  I'm Freddy from Little Downham.  I was thinking because I watched a YouTube video about ways the universal or the world could end.  And it included super volcanoes which could block out the sky and create another ice age.

Ginny -  Freddy, are you asking Kirsty whether she's planning to end the world?

Freddy -  No, I was thinking, is that the same sort of thing or is that slightly different?

Kirsty -  Yes, that's exactly the same thing.  And so, yeah, it is quite scary, isn't it?  But Mt. Tambora erupted about 200 years ago and this eruption was so big that it caused something that was called 'The year without a summer'.  Basically, in Europe, there was no summer that year because of this volcanic eruption and it led to huge food shortages and famines.  The interesting thing about that year without a summer was that, that was a year that Mary Shelley wrote Frankenstein.  And so yes, it is possible that a big volcanic eruption would cause huge problems around the world.

Ginny -  So, if in a few years' time, you see Kirsty and she's stroking a white cat and asking for a million pounds or she'll blow up the world, she could do it.

Erusha -  My name is (Erusha) and I'm from Cambridge.  My question is, would you need to get some kind of international agreement to do this presumably because it's global temperatures that you're affecting?

Kirsty -  Yes, that's one of the huge challenges.  So, what we've done to date is we've been doing a feasibility study to try and understand the effect of climate engineering.  We haven't done any actual experiments and that's because of the international agreement that you would need.  There's a lot of discussions that are going on as to how you would get this international agreement.  It's not really clear how that would happen and whether it would ever happen.  And so, there is a fear that someone could decide to do this on their own and it would affect the whole Earth.  But hopefully, we'll never get to that stage.

Ginny - David...

David -  I'm a bit concerned about acid rain.  So, you put sulphur dioxide in the atmosphere, when it rains, you wash all these sulphur dioxide down and that's sulphuric acid.

Kirsty -  Yes.  So, acid rain is one of the problems with sulphur dioxide.  One of the other major problems is that it destroys ozone and so, you would essentially destroy our ozone layer.  And that's why, part of this research project is to look at different types of particles and to see if there's a better particle that we could use that wouldn't have the same effects on stratospheric chemistry.

Sam -  My name is Sam.  I'm 12 and I'm from St. Yves.  You said there'll be a big balloon in the size Wembley.  What if there was a thunderstorm?

Kirsty -  That's a great question.  Now, most of our weather happens much closer to the Earth in 20 km and so, it's unlikely that the balloon would get hit by lightning.  But it's very likely that the hose could get hit by lightning because basically, we've just stuck a giant lightning rod up into the atmosphere saying, "Come and hit this thing with lightning."  And so, that is something that we have to think about and whether we make it out of a non-conducting material to try and reduce that effect, or whether we have to take other measures to try and reduce the possibility of it being hit by lightning or somehow manage that.

Peter -  My name is Peter from Cambridge.  I was wondering, could you try it first by pumping ozone into the ozone layer before trying it out with sulphur dioxide?

Kirsty -  That's an interesting idea.  Well, I think however it gets tried out, it's going to have to be very carefully managed because once you disturbed the atmosphere, it's not just a single point that you're disturbing.  Because of the winds that travel around the Earth, you're going to be disturbing the whole climate.  And it's also very difficult to know what effect pumping anything into the atmosphere has because I can pump it in here but then how do I know if the rainfall in India has changed because of what I've done or because of some other process.  And so, that's one of the real challenges with, how could you test this type of engineering technology.

Helen -  I'm Helen from Cambridge.  So, the idea is to lower the temperature, but obviously, some places, temperatures has been lowering and that's not a good thing, well that would make it worse in some places and better in others.

Kirsty -  Yes, that's absolutely right.  So, climate engineering will not be a win-win situation for everyone.  It would cause a global mean temperature drop, but some places will get hotter, other places will get cooler.  Also, the rainfall patterns will change.  So, some places will get less rain, some will get more rain, and it doesn't solve all the problems of climate change even because there's ocean acidification because we have more carbon dioxide in the air.  It's becoming dissolved in our ocean.  It's destroying coral reefs and things like that, and climate engineering wouldn't fix ocean acidification.  So, there are many cons to this type of technology and it's something we'd have to think very long and hard about before we decided to do something like this.

Ginny -  Kate, you've got one final question.

Kate -  Yeah, for me.  So Kirsty, everyone has been saying, "There's a problem with this and it will raise the temperature, it might destroy the ozone."  There are so many problems with this.  Why are you still doing it?

Kirsty -  It does keep me awake at night, thinking of all the problems with this kind of technology.  Basically, we're worried that one day, we might get to a point where doing nothing is no longer an option and doing something to lower the global mean temperature despite what the side effects are, whether they're known side effects or unknown ones, it might be something that we accept because the situation is so dire.