The language of climate change and environmental sustainability: the OED October 2021 update

The language of climate change and environmental sustainability: the OED October 2021 update

Over the course of the last 30 years or so, the OED’s editors have researched and recorded many of the best-known terms related to climate change, such as global warming, microplastic, and emissions, as well as carbon and its associated compounds.

However, language is ever evolving, and earlier this year, the OED embarked on a project to broaden and review its coverage of vocabulary related to climate change and sustainability. With the increase in climate strikes and extreme weather in recent years, it is clear that this is a rapidly changing area of vocabulary, and one that our lexicographers have been carefully monitoring.

Below we explore some of the new and revised entries added in this update (shown in bold below), as ­well as looking at language related to climate change previously recorded in the OED, and terms that we are still monitoring. We reveal some of the spikes and dips in usage we are seeing, as well as changes in the way certain words related to climate change are now being used.

From the ‘greenhouse effect’ to ‘climate crisis’

Something that leaps immediately to attention is the dramatic increase in more emotive language being applied to climate change. The term greenhouse effect, a mild term in comparison to related terms such as global warming, has become much less frequent since the 1990s. There was a slight spike in frequency in 2019 (when there was a general rise in frequency in many environment-related words), but overall usage is decreasing.

While the terms climate change and global warming are not exactly synonymous (you can find out more about this here), climate change certainly seems to be used more frequently, as we can see from this chart from Google Ngrams:

And just as climate change has overtaken global warming, climate crisis (recorded in the OED for the first time in this update) is increasingly being used in preference to climate change.  Many organizations and governmental bodies have also declared a climate emergency, while others, such as the Guardian, have made it a matter of editorial policy to use more strongly worded vocabulary to communicate a sense of urgency about the problem.

Of this group of terms, climate change is still the most frequent in general usage and mainstream media, but climate emergency and climate crisis have significantly increased in frequency in the last two years. In the Oxford Monitor Corpus of English (a corpus of web-based news material from late 2017 to the present day, currently containing c. 14.5 billion words), climate emergency was 76 times more frequent in the first half of 2021 than it was in the first half of 2018, and climate crisis had increased nearly 20-fold over the same period. Climate emergency saw a spike in 2019, and since the second half of 2019 climate crisis has overtaken it in frequency.

Another new entry in the OED in this update is global heating. Global warming is still much more frequent than global heating in general use and mainstream media, but global heating has increased in frequency in the past few years. The Oxford Monitor Corpus shows that it was approximately fifteen times more frequent in the first half of 2021 than it was in the first half of 2018.


The wider social and psychological impact of climate change (and lack of concerted international action in the face of it’) is reflected in the addition of terms such as climate refugee, which has seen a steady increase in usage in the past two decades:

Our research shows that at the end of the 19th century ‘climate refugee’ was a term applied (especially in a somewhat disparaging tone by Californian newspapers) to a person who moves to a place where the climate is healthier or more congenial:

However, we now associate this term with people forced to move home in response to the aforementioned extreme weather events, or rising sea levels resulting from global warming. 

Climate refugee is joined in the OED new words list by eco-anxiety, food insecurity, and water insecurity, and these now sit alongside existing entries such as ecocide (a term discussed in detail here). We have also provided definitions for certain terms that were previously covered in the OED, but which, as they have come to be much used in discourse on sustainability, have warranted revision—for example, overconsumption and unsustainable, where the negative connotations of the prefixes convey a moral standpoint on the limits to growth. This kind of prefix also makes an appearance in degrowth and decoupling, which demonstrate that traditional orthodoxies regarding perpetual economic growth are being challenged, and in single-use, another new entry which acknowledges further rising concerns regarding waste and consumption.

Single-use is also the second most statistically significant collocate occurring within 5 words either side of plastic in the Oxford Monitor Corpus of English:

Salient collocates of plastic in the Oxford Monitor Corpus of English


Solutions and stewardship

The OED does not in general include chemical formulae, but CO2 is now so ingrained in our language that it has warranted its own OED entry—one of only three chemical formulae to ever be included as an OED entry (the others, for interest, are NOX, n.2 and H2O, n.).

This might seem concerning, especially when we also look at the use of the term fossil fuel. As we investigated the usage of fossil fuel in recent years, its frequency had not reduced as we might have anticipated. The graph below shows the frequency of the terms fossil fuel(s) and renewable energy:

But further investigations led us to find that people are talking about fossil fuels in different ways. Comparing the collocates of fossil fuel in the Oxford English Corpus (2000–2014) and the Oxford Monitor Corpus of English (2018-present day), we found that there are some interesting differences: in the more recent data there are many more collocates relating to moving away from and finding alternatives to fossil fuels, such as divestment, transition, and phasing out.

It’s not the only term which has seen a shift to more solutions-focused language. Words such as flood, wildfire, and superstorm have become all too familiar in recent years, and the need for increasing mitigation of extreme weather events is shown by the inclusion of the term rain garden, a soakaway area to which rainfall can be diverted to prevent overloading urban drainage systems and rapid temperature changes in associated rivers.

A recognition of the ecological impact of conventional agribusiness is reflected in terms such as urban agriculture and vertical farming, novel methods of farming using less land, entailing less biodiversity loss, and requiring fewer food miles to deliver produce to consumers.

Some solutions-focused terms remain too specialized within their sectors to merit current inclusion in the OED, but of those that have established themselves within mainstream language, we have included carbon capture, a range of technologies which controversially might allow the continued emission of greenhouse gases from the combustion of fossil fuels and biomass.

Conversations about the likely need for a transition to electricity as our primary source of power, generated increasingly via renewable means, have meant that wind park and solar park have been added to the OED in this update. That this transition is sometimes taking place on a local as opposed to a national scale is marked by the inclusion of terms such as air-source and ground-source (applied to heat pumps), windmill in the sense ‘wind turbine’, and microgrid.  Our entry for retrofit has also been updated to reflect the increasingly common use of this word in relation to upgrading poorly insulated housing stock.

The move towards smart charging electric vehicles might come hand in hand with range anxiety, the worry that their batteries may not take drivers as far as they wish. And while the amount of embodied energy involved in the production of electric vehicles and the electricity used to charge their batteries means that their eco-credentials can be open to question, active travel (which received a boost for reasons of public health during the pandemic) recognizes that walking, cycling, and other human-powered means of getting from A to B are sustainable transport options that can help to reduce your carbon footprint.

Terms such as natural capital and ecosystem services, added in this update, provide evidence of an increasing awareness of the vital roles that ecosystems have to play, and of the risks of human overexploitation of the Earth’s resources. In 2018, New Zealand Prime Minister Jacinda Ardern proposed the Māori concept of kaitiakitanga, the human duty of environmental stewardship, as the key to combating climate change, and this loanword enters the OED with our update this year (for more details on this, see this blog post by our World English Editor, Danica Salazar). As most climate terms used throughout the world are English words which were imported into the local language as loan words, or literally translated, kaitiakitanga stands out.

Many commentators have argued that humanity now sits at a tipping point. The language recorded in this update encompasses the very bleakest scenario (mass extinction), but also reflects the steadily growing awareness of climate change over decades and the increasing impetus towards actions, innovations, and technology that could tip the balance towards a more favourable outcome.

Further reading:

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