Navigating the maze of climate-altering terminology 

By Mark Turner and Paul Rouse 

One of the fundamental challenges in any new field of knowledge is navigating the many terms people create to describe it.   

How C2G and others describe emerging approaches to deliberately alter the climate is no small matter. Terminology can frame the debateit associates ideas with other ideas, and can have a significant impact on the readiness of audiences to engage, how they engage, and on the outcomes of their discussions.  

Varying terms and definitions can overlap or conflict with each other, including (and excluding) different sets of ideas. This can create confusion, making governance conversations more difficult. Choosing terms can in itself be a form of governance. 

Those who have followed us over time will note C2G’s terminology has evolved. In 2019, we removed the word ‘geoengineering’ from our name¹, and decided not to use it in our briefings 

This followed a decision by the IPCC to step back from the term in its 2018 special report on global warming of 1.5°CC2G also followed the IPCC by switching to the term solar radiation modification’², rather than ‘solar geoengineering’ or ‘solar radiation management’.  

Why did we do thisIn short, because we find that aligning with IPCC terminology is helpful for our mission to catalyse broad-based governance of CDR and SRM. The IPCC glossary offers an inter-governmentally recognised lexicon that helps us to communicate with those involved in intergovernmental processes. 

But should this be interpreted as C2G or others determining which are the correct terms? No. In fact, there is research to suggest there are advantages to having a plurality of terms for new ideas. And as new communities come to these conversations, they will bring further terminologies to the table, which may help advance various goals. 

At the same time, there will be situations – in particular for international cooperation – where some level of agreement on terminology will be important, as often happens with international agreements. 

All this is normal, but can make it a challenging field to enter. How does the world discuss the governance of new ideas if they use different terms to describe them? 

To that end, we wanted to share some of our recent insights about terminology, but without being prescriptive. As a first stepC2G has updated its glossary – in multiple languages – and we invite you to take a lookThis blog is another part of that effort. We welcome any more suggestions for furthering this conversation. 


C2G has mostly stopped using the word geoengineering, but others haven’t – and the way they use that term can vary considerably 

The IPCC in its Fifth Assessment Report (AR5) defined geoengineering as “a broad set of methods and technologies that aim to deliberately alter the climate system in order to alleviate the impacts of climate change”. That included both CDR and SRM techniques. 

Some continue to use the term in this broad sense, whilst others use it to refer to a smaller subset of interventions. Some consider ‘geoengineering’ to refer to ‘technological’ approaches alone, separate from ‘nature-based’ approaches. Others reserve its use specifically for solar radiation modification, or specific technologies such as stratospheric aerosol injection. 

For its part, C2G tends to describe CDR and SRM collectively as climate-altering³ approaches. This is not to coin a new term, but it can help to introduce the topic to new audiences. 

At the same time, we usually accompany that by further explanationWhatever term you choose, it is helpful to clarify its meaning at the start of a conversation, to avoid misunderstandings.  

Nature and technology 

There is a lot written about ‘nature’, ‘technology’, and their relationship with each other. That is beyond the scope of this blog, but we would note that these concepts can have a significant impact on how people understand and feel about CDR, SRM, and their governance. 

People sometimes make the assumption, for example, that ‘CDR’ is inherently about ‘technologywhile nature-based approaches are something separate, and judge accordinglyBut according to the IPCC (and we agree) CDR includes both nature- and technology-based approachesand the two do not have to be mutually exclusive. 

C2G uses technology in the sense of applying specific scientific or engineering knowledge to get something doneTechnologies can be used as part of various techniques, which in turn form part of climate-altering approachessuch as CDR and SRM. 

We might describe afforestation, for example, as one technique to achieve carbon dioxide removal. It is nature-based, and may take advantage of some technologies to get it done. But is it a technology in itself? Opinions may differ; in our view, probably not. 

This can all feel quite confusing, and of course the lines are blurred. But the simple takeaway is that climate-altering approaches can involve a wide range of techniques, some of which may rely on biology, and some of which may take advantage of human technology. 

Given the strong feelings these ideas can evoke, we find it worthwhile to openly explore them with interlocutors, and to clarify where they stand. 

Solutions and approaches 

The term ‘solutions’ is widely used in climate circles, as well as by those who report on climate. It has a proactive and positive feel to it, which may help people stay engaged and maintain hope.  

For our partwe tend to avoid it. Solutions’ assumes that something can be ‘solved’while in practice it’s usually more complicated than that. Describing something as a solution may downplay risks and trade-offs, and may give a sense that it alone could do the job – while experience tells us that a portfolio of techniques is needed. 

One specific term is worth highlighting: ‘nature-based solutions’ (NBS). This is defined by the International Union for Conservation of Nature (IUCN), and may include some CDR techniques, but also includes techniques that would restore ecosystems but not remove CO2 at scale. C2G tends to refer to nature-based approaches to CDR, to differentiate these ideas. 


A growing number of people are talking about restoring the climate. In some cases, they propose various CDR and SRM techniques to help achieve that. 

C2G tends to steer away from this term, because we think the idea masks some of the complexity involved. What would we be restoring the planet to, who decides on the restore point? Does restoration refer to recreating a previous relationship, or a specific state?  Is restoration even possible? It’s not clear. 

At the same time, we recognise the term has gained traction of late. We would simply note the complexities involved, and the governance challenges the concept of restoration might give rise to. 

Carbon capture and carbon dioxide removal 

There is often confusion between carbon capture and storage (CCS) and carbon dioxide removal (CDR)but they are not the same thing. 

CCS entails capturing CO2 emissions at source (such as a fossil fuel power plant) and then storing that CO2 securely away, for the very long-term. Attached to a fossil fuel power plantthis could be considered part of cutting emissions by avoiding new emissions being released into the atmosphere 

CCS stops the volume of CO2 in the atmosphere growing.  

CDR is the idea of removing CO2 already in the atmosphere, and then storing it away securely and for the very long-term 

CDR reduces the total stock of atmospheric CO2reducing CO2 concentrations. The difference could be seen as akin to cleaning up pollution (CDR), as opposed to not making more of a mess in the first place (CCS). 

However, there is an added complication that some of the most discussed CDR approaches do include an element of CCS as defined above. For example, in Bioenergy with Carbon Capture and Storage (BECCS) biomass is grown (removing carbon from the atmosphere) and burnt in generators, producing energy or heat. Gases released from combustion are then captured at source and sequestered permanently (e.g., in geological formations). 


Offsets and carbon dioxide removal 

There is also sometimes conflation between ‘carbon dioxide removal’ and offsets. While there may be a relationship, they are not the same thing. 

Offsets and credits have generally been used as a policy and accounting mechanism to provide flexibility in emission reductioncommitments – whereby a nation, company or individual can achieve its emission reductions by paying for another entity to reduce (or remove) emissions on its behalf. 

Carbon dioxide removal might better be thought of as a physical activitywhich could be used as part of counterbalancing difficult-to-eliminate sources of emissions to reach net-zero (including on a global level)and eventually to achieve net negative emissions globally to remove excess CO2. 

Continuing the discussion 

There are no simple solutions to how we use language in this evolving debate. However, we need to be aware that differences exist, and that they may be significant for the governance of climate-altering approaches 

For example, the conflation of CCS and CDR could underplay the perceived necessity for both emissions reductions and carbon dioxide removal, and slow down the transformative action required to achieve the Paris Agreement goals. 

We hope to have a new Policy Brief and a C2GDiscuss soon on these questions. In the meantime, please do explore our updated Glossary and share your thoughts with us in the comments section below, or by email. 

¹ In a blog explaining C2G’s decision, we noted that the term geoengineering “brought with it many negative connotations and misunderstandings, which hampered our ability to engage with society, and to catalyse the learning processes necessary to take informed decisions”.

²  What’s in a name? Why we became C2G  – C2G (

³ We think of ‘climate-altering’ as an approach that deliberately and actively affects the climate system. We would not generally describe emissions reduction approaches as climate-altering.



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