Blog6th October 2026

Solar radiation modification: Why ethics matters

Professor Catriona McKinnon

Working Group Chair Professor Catriona McKinnon shares thoughts on the key ethical questions surrounding solar radiation modification (SRM).

The environment & healthGeoengineeringClimate

Solar radiation modification (SRM) technologies are emerging interventions that could potentially suppress global temperatures that are rising due to climate change, by reflecting sunlight back into space. Last week, the UK Government published its view that it does not support the deployment of SRM and has no plans to use it. However, it says it is committed to ‘responsible research that advances scientific understanding of the risks and impacts associated with SRM’.

The UK is currently the world’s biggest public funder of SRM research. Some small-scale outdoor experiments in the UK are imminent, and activity is scaling up in many other countries. How to conduct SRM research responsibly is therefore a pressing question, which may only become more urgent in the future.

When people first hear about SRM they tend to move quite quickly to the question, ‘Well, should we do it?’. Given our perilous times, this is understandable. But, in my view, it is not the right question to start with. Hidden within this seemingly simple question are a myriad of ethical considerations that need to be unpicked.

The ‘it’ we might ‘do’ can mean many different things. There are diverse SRM proposals on the table. And there are multiple stages of SRM research and development that could count as ‘doing it’. These range across desk-based modelling work, indoor experiments, outdoor experiments at different scales, and intentional deployment.

The question ‘should we do it?’ is inherently ethical, and whilst the answer will differ according to exactly what we mean by ‘it’, any answer must consider factors that go beyond the cooling potential of any particular SRM intervention.

In general, when we ask whether we ought to do something, we consider the broader impacts it might have. For example, we take into account the possible unintended consequences of our actions on other people. Or, at the level of policy choices, we assess potential impacts on political processes and structures of power at home and abroad.

Most ethical approaches ask us to focus on how our choices will affect the most vulnerable among us. Many ethical approaches include future generations and non-human nature in this category. With SRM, asking the ethical question ‘should we do it?’ must have this focus.

What does this mean, then? One set of considerations is that the global majority are not responsible for accelerating climate change and many of them are already being harmed by its impacts. Could SRM help to protect these people? Or could it worsen and entrench these unjust vulnerabilities?

Another set of considerations relates to future people, to whom we are presently bequeathing a dangerously unstable climate. Could SRM buy us time to get our acts together on climate mitigation? Or would SRM ‘lock-in’ future people to a continuously geoengineered world?

And yet further considerations relate to nonhuman nature. As we enter the sixth mass extinction of life on Earth, how might SRM advance or hinder efforts to address the global collapse of biodiversity?

None of these questions can be answered just by thinking about the technology itself, or the intentions of researchers and funders. Addressing these questions brings a focus on geopolitical realities, economic drivers, institutional structures, and social contexts. The hardest questions about SRM are ethical, and must relate to the way the world is along these dimensions.

The ethical issues we must grapple with when we ask ‘should we do it?’ raise profound questions of what we owe to one another in an already deeply unjust world. The advent of SRM is an opportunity for us to surface these questions and identify what we need to do better to reduce injustice.

This is the challenge that our Working Group is taking on. Through our independent review of SRM, we are bringing together diverse perspectives, examining the ethical and health implications across research and development, and considering the interests of people today, future generations and nonhuman nature. Our aim is not to offer a simple answer to ‘should we do it?’, but to help ensure that ethics is embedded in the decisions that come before any answer, through practical recommendations for researchers, funders, regulators and policymakers.