Geoengineering: the only way to beat climate change, or is it too good to be true?

By Sakib Kazi, Class of 2016

When it comes to climate change, humanity’s response has been one failure after another. We were late in realising it was a thing, we were late in organising a legal framework to deal with it, and a large proportion of the public still aren’t all that worried about it. We tried to tell ourselves that a 2°C warming was preventable – all we need to do is install solar panels on our roofs and use the heater a little less. We sat in a circle, holding hands and singing Kumbaya, confident that we’d never see that dreaded two degree increase. Now, it’s looking like we’ll miss even that modest target. If only we could rewind our carbon emissions, back to when we hadn’t completely screwed the atmosphere over.

But what if there was a way to reverse our climatic impacts? What if we could reduce atmospheric carbon dioxide concentrations and temperatures? This is what geoengineering proposes. ‘Geoengineering’ is a blanket term for the many proposed methods to reverse the effects of climate change through deliberate changes of climatic systems. Basically, it involves trying to alter atmospheric or climatic processes in order to change the climate itself, but this time in the opposite direction to what we’ve been doing for the past couple of centuries.

If that was all it was, then there’d be almost unanimous support for it across climate scientists. Unfortunately, because real life isn’t as convenient as we’d like it to be, that isn’t the case. A lot of the methods proposed to tackle increasing temperatures or CO₂ concentrations are untested on large scales, and may have side effects that do more harm than good.

But what exactly are these methods? What are their specific aims? The IPCC classifies them into two broad categories, based on which climatic system or process they target – solar radiation management (SRM) and carbon dioxide removal (CDR). Within each category are a bunch of often radically different proposals, but they tend to share a single common feature – they must be implemented in very large scales.

SRM techniques, as their name suggests, involve the changing of the way that solar radiation interacts with our planet. The methods many have come up with vary in their scale and simplicity, ranging from suggestions like painting all roofs white to reflect solar radiation, all the way up to the installation of giant space mirrors to do the same thing, but at a huge scale. Somewhere in the middle are more realistic ideas, like the use of fleets of ships to spray sea water into the air, which would create clouds. This would hopefully increase cloud albedo, or reflectance, and may be enough to hold global temperatures constant. The catch is that we’d need to be doing it constantly, and the costs may be far too high for politicians to support it. Added to that, there may be negative effects on local ecological scales, such as decreased rainfall in important biodiversity hotspots like the Amazon.

One of the problems of SRM is that they don’t address the damage we’ve already done to the atmosphere, namely in the ridiculously high CO₂ concentration we’re looking at today. Rising temperatures are definitely a major part of the climate change threat, but CO_s is another beast altogether. The oceans are becoming more acidic, as dissolved CO₂ reacts with sea water to eventually turn into acidic ions. These can do great harm to many forms of life, especially animals with shells. As the concentration of these acidic ions increase, the calcium carbonate shells of many marine invertebrates may start to dissolve. Given that invertebrates form the foundations of many, if not all marine food webs, increased ocean acidification would be very bad news for a lot of oceanic animals.

This is where CDR comes in to the picture. These methods actively try to reduce CO₂ in the air or the sea by physically taking them out. They are very similar to the carbon capture techniques proposed as a means to reduce greenhouse gas emissions from coal power plants – basically, some fancy chemistry is used to separate carbon out from emissions, then that carbon is kept underground. The carbon can either be captured in the form of gaseous CO₂, or reacted with metals to form carbonates. The problem, in a geoengineering context, is how we’d effectively capture that carbon from the atmosphere, rather than from the relatively high concentration environment of a power plant.

One plan involves the use of iron particles to capture carbon in the oceans. The idea is that the iron would be taken up by microscopic phytoplankton, which then use it in photosynthesis. When they photosynthesise, they naturally use CO₂ to make oxygen, but they also use CO₂ to build their carbonate skeletons. When they die, their skeletons (and the carbon in them) sink to the bottom, effectively removing that carbon from the atmosphere. Conveniently, because that carbon is now bound to calcium in the skeleton, it doesn’t contribute to ocean acidification. That means that the ocean can then take in more CO₂ from the atmosphere, reducing its concentration in the air. This might, hopefully, reverse the temperature increases we’ve seen in the past few decades.

Of course, it’s a bit more complicated than that. For this to be effective, we’d need to cover ridiculously large swathes of ocean with iron filaments – perhaps even the size of the entire Southern Ocean. This wouldn’t be economically viable, but more importantly, we have no idea how the increased phytoplankton numbers might affect marine ecology. If we do implement it at a huge scale, we might end up doing as much harm as good. In fact, that’s a common theme when it comes to geoengineering – we simply don’t know enough about the side effects of what is proposed. The fact that all of them involve large scale activity makes the risk much more dangerous.

Geoengineering is seen as too untested and dangerous to garner widespread support amongst climate scientists. At the moment, it remains a pretty out-there idea, and one that isn’t going to be implemented soon, in any of the ways people have suggested. In the future, should our climate situation deteriorate, and we become more desperate, it may become a legitimised option to counter what we’ve done. That being said, it’s probably safest if we try to make sure we never have to make that choice, so turn down the AC, start walking more and maybe even consider going veg, unless you want to (potentially) kill Flipper.