Solar Geo-Engineering and International Law: An Odd Couple?

Başak Çalı

Başak Çalı

In the aftermath of the U.N. climate conference (COP21) held in Paris in November, our planet is looking for concrete results in hesitant hopes. The gap between the pledges states are making to cut carbon emissions and those that scientists say are needed to maintain the increase in the average global temperature below 1.5–2 degrees Celsius is significant. At this stage, it seems simple. Either states pledge to do what is needed or our planet, our only home, will experience the worst effects of climate change to come.

Why is it that, despite all the scientific knowledge about climate change, states are unable to come to an agreement about the steps necessary to protect our children and our children’s children? Looked at through the lens of international law, this is not a new problem. It’s an old one. However, it’s an old one that is being served in dangerous, volatile new bottles.

International law is unlike domestic law. It is largely based on the consent and co-ordination of sovereign states. There is no world legislative. This is no world court. This is no world police. For international law to emerge and, crucially, to remain effective, we rely on common agreement and state enforcement. This is where climate change has hit a big brick wall. It is very difficult for states with wildly diverse political regimes, economic growth and cultures of law to reach common agreement. This has proved to be the case despite cries from the scientific community and increasing environmental activism.

What is worse, in times of disagreement, states often seek to agree on rules that protect their own interests rather than the global public interest. Why should we, developing nations such as Turkey, India or Brazil, shoulder the burdens of the prosperous economies of North America, Europe or Japan? Why should we ask the poorest countries in the world, spend more money to save the planet than richer countries?


This is a significant standoff. It is a stand-off with immense negative consequences for all involved.  Climate change does not and will not only hit one sovereign nation. There are no borders to be respected. The consequences will be severely felt across the globe - from Istanbul to California and from the Maldives to Tuvalu. This is where, we can hope, geo-engineering promises a way out.

Geo-engineering is deliberate intervention in the world’s climate system in order to counter the effects of climate change. For the layperson, myself included, the idea of geo-engineering can be conceived as a painkiller for a terrible headache. The painkiller does not treat the root causes of our headache, but it helps the discomfort go away so long as we take it. Similarly, geo-engineering does not seek to reduce the current pace of emissions, but it proposes ways to block the effects of emissions. It will attempt, for example, to block solar radiation in the upper atmosphere or to increase the uptake of carbon dioxide through ocean fertilization. As states are unable to reduce greenhouse gas emissions effectively, a focus on the treatment of the symptoms of emissions is becoming an increasingly popular idea. If you cannot treat the cause of your headache, you may as well throw some analgesics down your throat.


Solar geo-engineering or solar radiation management (SRM) as otherwise known, is one proposed geo-engineering intervention to offset the effects of greenhouse gas emissions. Solar geo-engineering is the idea of reflecting a small proportion of the sun’s energy from the Earth back into space. This, the scientists argue, would counteract planetary temperature rises due to the increased levels of greenhouse gases in the atmosphere. As greenhouse gases absorb energy and raise temperatures, the less energy we have in our atmosphere, the better. 

Solar geo-engineers propose a number of techniques to reflect sunlight back to space. Albedo enhancement proposes to increase the reflectiveness of clouds or land surface. Space reflectors aim to block the small proportion of sunlight before it reaches the earth. Stratospheric aerosols aim to introduce small, reflective particles into our upper atmosphere to reflect sunlight before it reaches the Earth’s surface.

These methods are currently in research and experimentation stage and are enveloped in a good deal of scientific, ethical and legal controversy. For example, scientists debate whether small scale experiments are adequate to model large scale experiments, or whether large scale experiments will themselves be necessary to test how research ideas operate in practice. In addition, there is also the controversy concerning the potential harm the experiments could cause. Whilst some argue that smallscale experiments are, to a large extent, harmless, others advocate caution with regard to all types of experiments.


If reaching common solutions regarding the curbing of greenhouse gas emissions through international law have thus far proved unsuccessful, what hopes could we have for international law to offer effective solutions for governing solar engineering experiments, and potentially, well into the future, to govern solar engineering initiatives themselves? Here, it may be helpful first to visit extant international law with relevance to solar engineering. As early as the 1970s, states agreed that the manipulation of weather conditions as a tool of war was to be explicitly prohibited. This reflects a common concern amongst states that technologically advanced states could create unfair military advantages by using solar geoengineering.

Once we move to the regulation of solar engineering in peacetime, however, international law is thinner. There is no general comprehensive regulation of solar engineering and different international law regimes to encourage or caution against it.

The UNFCCC’s Kyoto Protocol arguably encourages solar engineering when it calls for the minimization of the “adverse effects of climate change” in a rapid and inexpensive manner “so as to ensure global benefits at the lowest possible cost”. This, however, comes nowhere near to a comprehensive regulation.

The Convention on Biological Diversity (CBD) — the most significant multilateral environmental treaty — advances caution. It obligates state parties to comply with several procedural obligations, such as monitoring, concerning activities that are likely to have “significant adverse impacts” on biodiversity.

Solar engineering interventions could clearly do this. The 2010 Conference of the state parties to the CBD further issued the first multilateral statement reinforcing this caution asking “appropriate consideration of the associated risks” and hinted the need for a transparent global regulatory framework. This statement, however, is merely a political document and has no binding legal status in international law.

As with any state practice with the potential to cause environmental harm, solar engineering would be subject to general principles of international environmental law. General principles of international environmental law are first and foremost based on the premise of the permissibility of individual state conduct. These principles, however, demand that when an individual state carries out individual acts that may have effects on the environment the state must; a) have taken due regard of the protection of the environment, b) have taken all precautionary measures prior to taking action, c) compensate all harm caused by actions taken, d) carry out an environmental impact assessment prior to the action and, e) ensure transparency of action to the public.

Readers may already have remarked that general principles of international environmental law are silent on who governs solar engineering. Instead, it is statecentric. For example, if the United States decides to carry out largescale solar engineering experiments, it does not have to seek prior consent from the global community. The US is obligated to ensure that its solar engineering experiments do not create adverse effects, and to compensate for any subsequent failure in this regard.


International law questions raised by any discussion of solar geoengineering are not far removed from current problems posed by the need for the reduction of greenhouse gas emissions. In the latter, each state, depending on its own economic and political priorities, has burnt fossil fuels and has contributed in some way to the growing threat of climate change. With no legal framework governing solar geo-engineering, we are at a similar juncture. The ideal international law solution to geo-engineering governance would be to set up an international authority that oversees both the experimentation and licensing of solar engineering interventions. Such an authority would need to oversee both the potentials and risks of solar engineering for the global public as a whole in the light of technological advances and rising climate change challenges. Such an authority would have to be composed of both lawyers and scientists. There are precedents for this. The UN Convention on the Law of the Sea, for example, has created the ‘International Seabed Authority’ requiring states to demand permission from it when carrying out activities in international deep seabed.

If states choose to govern solar geo-engineering individually, these interventions may then have adverse consequences on the environment not only locally, but also internationally - just like the issue of climate change. We are, as yet, unable to foresee what these consequences would be. It is important to recall what each layperson knows all too well: the painkillers, too, have side effects.


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