Geoengineering: Can it reverse climate change?

The study of geoengineering as a way to not just slow, but reverse the impacts of climate change, has had a surge of popularity in recent years. However, the science is still in its infancy, and we must ask, are the risks worth the reward? Could this fledgeling idea become mainstream?

Phytoplankton bloom, visible from space, in the Barents Sea between Russia and Scandinavia. Photo Credit: NASA Goddard Space Flight Center.

In 2015, the Paris Agreement was ratified by 55 countries, who account for at least 55% of current global greenhouse gas emissions. The parties made a new commitment on climate change – to limit the increase in global temperature to 2°C above industrial levels. But even before the US pulled out of the Paris Agreement, many were skeptical; skeptical that the commitments would be followed through with concrete action (Raftery et al., 2017) and skeptical that even the promised action would be sufficient to limit emissions so that warming stays below 2°C (Rojelj, et al., 2017).

Given the possible consequences of warming beyond 2°C; including food shortages from less productive crops, decreased available freshwater, biodiversity loss, and rising seas causing mass displacement and refugee crises; this is concerning. It is especially concerning when you consider that some of these consequences are likely even if we succeed at limiting warming to 2°C.

Preventing climate change in the first place is a clear priority. However, for problems of this scale, proper risk planning is critical. And when dealing with risk, it is important to do two things. It is crucial to mitigate the chance of a negative event, but it is equally crucial to take measures to mitigate the impact of such an event, in case it does occur. The philosophy is to ‘aim for the best, prepare for the worst’ and by doing so, make the whole system resilient.

Neglecting either element of this philosophy prevents the creation of a truly robust system. Emission reduction is crucial to preventing climate change from occurring, but there has been less preparation used to address the possible impacts of climate change.

What is Climate Engineering?

Climate engineering, also known as geoengineering, is the name for a variety of technologies used to intentionally manipulate ecosystems on a large scale. It covers a variety of possible techniques, some of which aim to alter the Earth’s climate as a whole. Techniques such as ocean fertilisation have been suggested to help revitalise pelagic fish populations (Jones & Harrison, 2013). Cloud seeding is being trialled in California as a way to break droughts and assist in food production. More ambitious methods aim to undo the greenhouse effect by actively removing excess carbon from the atmosphere. One example of this is ocean seeding, which involves adding masses of iron or nitrogen to the ocean, stimulating colossal algal blooms, which feed on iron and nitrogen. Algal blooms are also powerful photosynthesizers, recycling atmospheric carbon dioxide into oxygen. Like a forest, these blooms can absorb masses of carbon dioxide from the atmosphere, and (theoretically) sink that carbon into the deep ocean for hundreds, if not thousands of years, where it can no longer contribute to the greenhouse effect (Lawrence, 2014).

In essence, if the goal of renewable energy is to avoid making the greenhouse effect worse, the goal of climate engineering is to actively make the carbon balance better – to restore it to pre-industrial levels.

An algal bloom off the Southern coast of England. It has been theorised that manmade algal blooms could act as immense carbon sinks to mitigate climate change.

Is this viable? What’s the risk?

At present, the science of geoengineering is still very much in its infancy, and there are a number of unknowns. As very few large-scale experiments have been run, progress is hindered by a lack of reliable data. This leaves significant uncertainty, and thus scepticism, about the possible impact of certain geoengineering technologies. Aside form this, there also remains disagreement about whether certain methods would be economically viable (Harrison, 2013). This, of course, could merely be a problem of economies of scale – solar panels, now a booming industry, were once critiqued as economically unfeasible.

There is also the matter of risk. If mismanaged, certain types of geoengineering could cause serious ecological damage, for example, by robbing lake ecosystems of much-needed oxygen. And the question of who would regulate these sorts of experiments, and to what standard of rigour and safety, also remains unanswered.

At present, the consensus is clear. We are not yet ready to roll out full scale geoengineering en masse. There are just too many unknowns. However, almost no one advocates that geoengineering be rolled out blindly today. Before we are ready for that task, we need to lay the groundwork, and uncover the data. While unbridled geoengineering would be foolish, advocating for regulated, sensible experimentation is a different story. Carefully run, mid-scale experiments, with the aim of getting better data and moving the science of geoengineering forward seems like an opportunity we cannot afford to avoid. The alternative – unpreparedness in the face of climate change – seems devastatingly grim.

If the Paris agreement is insufficient, as many experts seem to think, we will need proven, carefully tested techniques to deal with the impact of climate change. Otherwise, countries will be forced to adopt increasingly drastic, unproven methods in response. And this is the crucial lesson. If we are going to be forced to play god, we might as well get good at it first.


Harrison, D. (2013). A method for estimating the cost to sequester carbon dioxide by delivering iron to the ocean. International Journal of Global Warming, 5(3), p.231.
Jones, I.S.F., and Harrison, D.P., (2013). ‘The Enhancement of Marine Productivity For Climate Stabilisation and Food Security’. In the Handbook of Microalgal Culture (2nd Edition). John Wiley & Sons, Ltd.
Lawrence, M.W. (2014). Efficiency of carbon sequestration by added reactive nitrogen in ocean fertilisation. International Journal of Global Warming, 6(1), p.15.
Newcomb, A. (2016, February 7). Cloud Seeding: How Humans Helped Make It Rain During El Niño Storm in LA. [online] ABC News (Accessed 2 March, 2018).
Raftery, A. E., Zimmer, A., Frierson, D.M.W., Startz, R., and Liu, P. (2017). Less than 2C warming by 2100 Unlikely. Nature Climate Change, 7, p.637-641.
Rogelj, J., Fricko, O., Meinshausen, M., Krey, V., Zilliacus, J. and Riahi, K. (2017). Understanding the origin of Paris Agreement emission uncertainties. Nature Communications, 8, p.15748.

Jack Rafferty is a University of Sydney Graduate, having completed degrees in Environmental Science and Philosophy. He works in the private sector, and is primarily interested in climate change, commons dilemmas, and arms races. He lives in Sydney.