This article is part of the 4sea project.
Most of us who care about the oceans know well the threats posed by climate change – of rising seas, disappearing coral reefs and changing circulation. Less well known, however, are the threats posed by our attempts to solve the climate crisis. In our efforts to curb the problems associated with the greenhouse effect, it is very possible that we could accidentally make them worse.
The prime suspect? A proposed ‘solution’ to the climate crisis known as geoengineering – the idea to meddle with environmental processes in an attempt to slow down climate change. This term covers a range of ideas, from making ecosystems take up more carbon from the air, to artificial cooling, to collecting and storing carbon dioxide to keep it out of the atmosphere. Unsurprisingly due to the ocean’s vital role in the climate system, most of these schemes either centre on altering aspects of the marine environment, or would be likely to cause large side effects.
Back from the Dead?
Ideas such as dumping large amounts of iron to stimulate algal blooms, seeding the Pacific to control storms, and eliminating permafrost to allow ship passage across the arctic have been around as far back as the 1950s, though often for military rather than environmental purposes. The 2000s saw multiple small-scale experiments, not to mention a famous offer of $25 billion from Richard Branson to anyone who could invent a feasible technology to remove atmospheric CO2. By 2010, geoengineering was gaining steam to the extent that the UN felt it necessary to put in place a moratorium on all large scale experiments.
For a few years, it seemed that geoengineering was dead, with focus back on mitigating climate change by reducing fossil fuel emissions. However, geopolitics has shifted in recent years, with the most visible change being the rise to power of climate sceptics such as Donald Trump. Even with ‘alternative facts’ at their disposal, the ever growing scientific consensus is making it harder for sceptics to deny the overwhelming scientific consensus on climate change. For those who want to keep burning fossil fuels, geoengineering could be the perfect plan B – a quick fix that means they can keep polluting, as long as they balance it out with a few tweaks to the climate.
This is not just speculation – it looks increasingly likely that geoengineering will become the Trump administration’s preferred approach to climate change. Once again, experiments are being launched – not in labs, but in the field. Maybe most significantly, the UN and the IPCC are incorporating dubious technologies into the conversation. All of their best case emissions scenarios assume the major use of carbon dioxide removal technologies, despite the fact that they do not yet exist.
The Great Ocean Iron Dump
One of the most popular geoengineering proposals is ‘iron fertilisation’. Vast swathes of the oceans, known as ‘high nutrient low chlorophyll’ zones, have low biological productivity despite essential nutrients such as phosphate and nitrate being abundant. It is believed that this is due to low iron content, evidenced by a pattern of increased productivity in areas fertilised by iron-rich dust blown into the sea from the Saharan desert. The idea of fertilisation is to dump large quantities of iron in the ocean to remove this limit on productivity. Phytoplankton grow by assimilating carbon, so, in theory, if more iron could increase rates of photosynthesis it would result in more carbon in the plankton and less in the atmosphere.
While this seems straightforward, when we look a little deeper, we find that it is not necessarily so simple. The oceans are vast and interconnected – altering the food web in one region is like to have unintended effects elsewhere. While fertilising one region could increase algal growth in that area, it could subtract from growth in other places. It is likely that there would be other unintended effects too, such as altering phytoplankton species composition.
On top of these possible side effects, there is the fact that what sounds great on paper does not always play out as you would expect in the field. Previous experiments have provided little evidence that iron dumping would actually have any long term positive effects on oceanic carbon sequestration. While algal blooms were generally sparked, the organic matter didn’t necessarily sink. This could indicate that iron dumping would not result in carbon sinking and therefore being stored on long time scales, but instead being respired and released back into the atmosphere by grazers at the surface.
Blocking the Sun
Another well known proposal is the idea to promote artificial cooling of the earth by blocking the sun. This could be done using methods ranging from giant solar umbrellas, to injecting tiny, reflective aerosols into the stratosphere. These ideas are collectively referred to under the term ‘solar radiation management’.
In this case, the link to the oceans is not immediately obvious. While there could be direct effects such as aerosols ending up in the ocean, it is the potential socio-political effects that are the most worrying. It boils down to the fact that solar radiation management focusses on balancing out the earth’s temperature, ignoring the fact that carbon dioxide has other effects besides warming.
One of these effects is ocean acidification. This is not a side effect of warming, but a direct result of carbon dioxide concentrations in the atmosphere. Carbon dioxide dissolves in the surface ocean and reacts with water to form carbonic acid. This is the first in a series of reactions involving carbonate, the material used by many marine organisms to build their skeletons and shells. The result of this increased level of carbon dioxide is to lower pH – in other words to make waters more acidic.
Some fear that solar radiation management would risk making us believe that we could emit as much carbon as we want. After all, what would be the purpose of deploying this expensive technology if we still intended to reduce carbon emissions to a safe level anyway? Combined with the fact that ocean acidification is a much less high profile issue than climate change, there is a real danger that solar radiation management could lead to a neglect of emissions reductions, and therefore a worse level of acidification in the oceans.
Carbon Capture and Storage
Finally, there is carbon capture and storage: the silver bullet relied upon by the IPCC in order to keep warming below 1.5 degrees. CCS, again covers a huge range of scenarios, but all involve storing carbon dioxide over long time periods.
In the 00s, there was a lot of talk about deep ocean storage of captured carbon dioxide, with the idea that we could inject it directly into deep waters of the ocean. This was soon put to bed with concerns of how it would affect benthic marine life.
Nowadays, proposals are mainly to store CO2 in geological formations on shelf seas rather than the deep ocean. It was recently reported that the North Sea was ready for large scale carbon storage, with existing pipelines making it easy to pump liquified carbon into underground rock formations.
The possibility of carbon leaking from these reservoirs makes this a scary prospect – leakage could lead to high levels of local acidification, harming corals and other calcifiers, as well as carbon escaping back into the atmosphere in large quantities.
If we reduce emissions now, taking these risks is not necessary.
Despite deep sociological, ethical and technical concerns, it seems that proponents will continue to put forward ideas for geoengineering schemes, each claiming to be the ‘miracle cure’ to climate change.
If we don’t want to have to rely on geoengineering in the future, and all the risk and uncertainty that comes with it, the best thing we can do now is mitigate carbon emissions – and fast.
By focussing on stemming the cause of climate change rather than developing miracle technologies, we can reduce our dependence on finite fossil fuels, get ocean acidification under control, and have no need to cause huge disruption to ecosystems.
About the author: Fran Mills is an oceanography graduate interning in Helsinki, and an organiser for UK Youth Climate Coalition. She has been volunteering to write articles for the 4sea project since getting involved with the YOUNGO oceans working group. She is passionate about climate justice and the protection of nature.
It´s World Ocean´s Day this Friday and this article has been written in the context of 4sea. 4sea, a project about the importance of the world oceans, addresses the interdependence between the oceans and climate change, entraining everyone to become ocean lovers. 4sea is a joint project between the youth organisations CliMates, Youth for Ocean and Vitamin Sea. Love it? Stay tuned for more !