Perspective
What’s in a Name? How We Describe SRM at SRM360
There are many different ways to describe ideas to reflect sunlight in order to lower global temperatures. Pete Irvine and Mark Turner explore some of the options, SRM360’s choice of terminology, and invite experts to weigh in.
The words people choose to describe technologies matter. A 2018 research paper found that “the name that is given to a technology can determine the evaluation of that technology, even in the presence of information about the technology”. In other words, the words used to describe a technology can matter as much as, if not more than, the facts about it.
At SRM360, we have chosen to use the term “sunlight reflection methods”, both for its intuitive descriptive power and because its acronym – SRM – is familiar to many. But we recognise this is a relatively new term, so we also add the explainer: “also known as solar radiation modification or SRM”, referring to the terminology used by the Intergovernmental Panel on Climate Change (IPCC).
However, many different terms for these ideas are used, all of which bring with them a broad set of ideas and associations. In this piece, we go through some of the more common terms in more detail, explain what led to our particular choice, and feature views on our choice from several different experts.
Geoengineering
Perhaps the most commonly used term to describe these ideas is “geoengineering”.
In 2009, the UK’s Royal Society published a landmark report: “Geoengineering the climate: science, governance and uncertainty”, which defined geoengineering as: “the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change”.
The challenge is that this is an umbrella term used to describe both sunlight reflection methods and carbon dioxide removal – a set of ideas to capture carbon dioxide from the air and store it.
At the time of the Royal Society’s report, both approaches shared the characteristic that they were outside of mainstream climate discussions, relatively unknown, and raised difficult governance challenges and questions about humanity’s relationship with nature.
But they are fundamentally different in character. While their conflation may be useful for some political or governance purposes, it can also be quite misleading.
For example, a BBC News article from 2024 that focused on SRM began with the following: “In what is already a multi-billion-dollar industry, scientists around the world, including in the UK, are researching geo-engineering – ways of manipulating the climate to tackle global warming.”
While it is true that carbon dioxide removal is a multi-billion-dollar industry, there is not a multi-billion-dollar industry for SRM.1 This misleading impression would have been avoided if the article had used more specific terms.
A proposal for an assessment of “geoengineering” at the United Nations Environment Assembly failed in 2019. This may have been due to the bundling of carbon dioxide removal, which has been identified as critical to meeting current climate goals by the IPCC, with SRM – a much more controversial set of ideas.
A similar challenge of conflation applies to the terms “climate engineering” and “climate intervention”. These can help audiences conceptualise the idea of human large-scale interference in the earth system but can also obscure critical differences.
To address this challenge, some experts differentiate these umbrella terms by adding the word “solar” or “carbon”. For example, “solar geoengineering” is often used to refer to SRM. Similarly, “solar climate engineering” is sometimes used in Europe, while “solar climate intervention” is commonly used in the United States.
Solar radiation management (SRM)
“Solar radiation management” was originally coined as a joke title for a workshop, to avoid the scrutiny of NASA managers.
“The term was introduced humorously with the intent of sounding as bureaucratic as possible, and thus allowing the meeting to pass by NASA bureaucrats who were sensitized to possible controversy surrounding the term ‘geoengineering’”, the scientist Ken Caldeira wrote in a 2016 retrospective on SRM research.
The term came to be widely adopted.
However, some feel the concept of “management” may imply more control than is possible. More recently, the IPCC – which assembles regular mammoth scientific reports to inform international climate policy – adopted the term “solar radiation modification” and the acronym “SRM”.
This official endorsement makes solar radiation modification (SRM) a reasonable choice for any organisation working in this field. However, what solar radiation modification means is not immediately obvious to the public, and it contains the word “radiation” which could easily be misunderstood.
“Sunlight reflection methods” (also SRM), on the other hand, is not widely used by researchers, but it is much clearer what it means.
At SRM360, we have chosen to use both terms together, for both clarity and consistency with international discussions.2
Climate repair
Climate repair, or restoration, refers to the idea that these technologies can help to bring the earth system back to a state that existed before human interference.
More often used to refer to carbon removal techniques, but sometimes also used to refer to SRM, this has an intrinsic appeal. The concept of repair or restoration can be attractive at a time of rapid and often harmful change.
But this positivity also raises difficulties. It inherently implies a beneficial outcome and may mask some of the difficult trade-offs any such intervention could entail. It may also imply that restoration to a “state of nature” is possible at all, when in fact it may not be.
Sunlight reflection methods
The debate over the best terminology to use in this field has been running for years and is unlikely to be resolved any time soon. At SRM360, we have settled on “sunlight reflection methods” clarifying that this is also known as solar radiation modification or SRM.
Diverse groups will choose different terminologies based on their own understanding and goals. That is entirely normal and even desirable in a new and evolving field, where much is still not known.
However, we think we have found a reasonable compromise that should be both clear to the public and align with international definitions.
What others think about our choices
These are the choices we have made, but what do others working in the field think of these choices?
Douglas MacMartin (Cornell University):
“I switched a few years back to using ‘Sunlight Reflection Methods’ because I think it is important to clearly communicate what we’re talking about in plain English rather than technical jargon, with the added bonus of keeping a widely-used acronym. There is absolutely no reason to have an umbrella term that captures both SRM and carbon dioxide removal; as such a term like “geoengineering” leads to confusion.”
Josh Horton (Harvard Kennedy School):
“I’m afraid that creating yet another term to add to the mix will result in more confusion rather than greater clarity. This isn’t helped by the fact that the acronym SRM is already shared by two other terms. But I hope I’m wrong!”
Oliver Morton (The Economist):
“Nothing says ‘shifty’ like using an alias. The term ‘SRM’ was invented as a way of avoiding the controversial and/or off-putting word ‘geoengineering’; it was a deliberate attempt to hide what was being discussed. But the controversy is avoided only for as long as it takes to explain what SRM means. Those explanations always either include the phrase ‘also known as geoengineering’ or are met with the response ‘isn’t that geoengineering?’. Avoiding the G-word this way has become a self perpetuating habit, but it is a bad one: at best a waste of time, at worst manipulative, even misleading.”
Cynthia Scharf (International Center for Future Generations):
“With SRM, different terminologies emphasize different issues, including legitimacy, agency, scientific rigor, governance, inclusion, and public understanding. Terms should be memorable and comprehensible by the layperson and, if possible, evoke an image. They should also make clear these are intentional actions to cool the planet. In my view, ‘sunlight reflection methods’ succeeds on many of these points, but not, in and of itself, the latter.”
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Endnotes
- There are two commercial efforts that we are aware of that amount to a couple of tens of millions of dollars of investment: Make Sunsets and Stardust Initiative.
- There is a minor issue with this choice: the two definitions are not precisely aligned. “Sunlight reflection methods” is plural, while “solar radiation modification” is not. We have chosen to use SRM as if it were singular in our articles: “SRM is …”, rather than “SRM are …” to align with the scientific literature.
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