Climate Change Acronyms - what does it all mean?

My role as both CEO and head of climate positivity at Presca means that I’m directly responsible for our climate impact in our quest to make the most sustainable sportswear possible. The first step is understanding the emissions of our clothing and all our operations, then reducing them where possible, and offsetting the rest. Then we look at different schemes we can help fund to actively draw CO2 out of the atmosphere or stop it getting there in the first place. We’re currently investing in mangrove restoration projects to make each garment climate positive.

My background in sustainability means I’ve been talking in climate-related acronyms for years now. But I know that outside a small bubble of climate nerds there’s much less understanding of all the acronyms and phrases, so we thought it was about time I take some time to explain them all. So hold on to your hats – thinks could get a bit spicy as we dive into the lexicon of climatology:

Global warming: It’s the long-term increase in earth’s average surface temperatures, brought about by increased levels of greenhouse gases. Once the preserve of climate scientists and environmental activists, the term has made it well and truly into the mainstream dialogue over the last decade. 

Greenhouse gas (GHG): any gas that when present in the atmosphere actively traps warmth, increasing the average temperatures.  This is known as the greenhouse effect. The GHG that everyone knows is Carbon Dioxide (CO2) but there are many others, including methane, nitrous oxides, water vapour, and CFCs. Some are far more potent as GHGs than CO2, but the sheer volume of CO2 makes it the biggest contributor to global warming.

Global greenhouse gas emissions by gas

Greenhouse gas emissions are converted to carbon dioxide-equivalents (CO22eq) by multiplying each gas by its 100-year 'global warming potential' value; the amount of warming one tonne of the gas would create relative to one tone of CO2 over a 100-year timescale. This breakdown is shown for 2016. - Research and data to make progress against the world's largest problems. Source: Climate watch, the World Resources Institue (2020). Licensed under CC-BY by the author Hannah Ritchie.

Greenhouse effect: It’s the reason our planet is habitable and for millenia has created a stable climate for humans to evolved and thrive.  But as the balance of gases in the atmosphere is changing due to the burning of fossil fuels so the greenhouse effect is increasing global temperatures. The mechanism is pretty simple – the sun emits radiation over a wide spectrum, which is then either reflected or absorbed by the atmosphere or the earth (and everything on it).  About 50% of the suns energy that reaches the planet is absorbed by the earth.   Absorbed radiation is then emitted again as infrared (IR) radiation. Think of the feeling of hot tarmac on a warm summer’s day – that’s IR radiation. Greenhouse gases are particularly good at trapping IR radiation so as those gases accumulate in the atmosphere heat builds up.

CO2: we all know what this means by now. It’s the biggest culprit in global warming.  Carbon Dioxide, one Carbon Atom and two Oxygens.  

Carbon Dioxide, one Carbon Atom and two Oxygens.

It has many natural sources, but we humans are also pumping a LOT of it into the atmosphere. 87% of the CO2 we release is the result of burning fossil fuels, and the biggest contributor is Coal (over 1/3rd of the total emissions). The majority of our fossil fuel use (about 40%) is for heat and electricity use, followed but transportation (roughly 25%). There are also many sinks for CO2 (things that absorb it). The main one that we all know about is plant growth, where chlorophyll locks CO2 up into sugars and other plant material. Other sinks include the oceans, where CO2 is locked up through photosynthesis by plant-like organisms (phytoplankton) or reacting with the water creating carbonic acid. This “ocean acidification” in itself causes other problems but that’s for another blog.

Tonnes CO2: we all know what a tonne is. What you might not know is that because it’s so light a tonne of CO2 occupies a big space - approximately 540m3:

Visualisation of 1m3 of CO2,

Visualisation of 1m3 of CO2,

Kilotonne (Kt): a thousand tonnes
Megatonne (Mt): a million tonnes
Gigatonne (Gt): a billion tonnes

CH4: Methane is another villain in the greenhouse effect. It’s a naturally occurring gas that comes from anaerobic (lacking the presence of oxygen) breakdown of organic material.  Whether that’s in a cow or a sheep’s stomach, emitted as burps and farts, or in landfills where food and other organic matter slow breaks down and releases the gas.  

Methane is the second most important GHG. Unit for unit it’s often quoted as being 28 times more potent than CO2 as a GHG, but actually that relates to the total heating impact of the methane v CO2 in the atmosphere over a 100 year period. Methane only lasts a decade where CO2 lasts many hundreds of years in the atmosphere, so the short-term impact of methane is actually far higher, approximately 100 times greater GWP over that ten year period. 

So methane is a big problem in the short term and one that received a lot of attention at the recent COP26 conference. There are many potential sources of methane, and we need to cut down as many as possible. One part of the solution is the widely discussed need to reduce meat and dairy consumption.  

Global Warming Potential (GWP): the amount of heat absorbed by a GHG in the atmosphere, as a multiple of the heat absorbed by the same mass of CO2, commonly measured over a 100 year period.

CO2e:  This stands for Carbon Dioxide equivalent. It’s a measure of how much of a certain GHG would create the same warming as one tonne of CO2. CO2e of a GHG is equivalent to 1/[GWP of the GHG]

Carbon: The basic building block of all organic matter, the 4th most abundant element in the universe (after hydrogen, helium & oxygen). It’s often interchanged with CO2 when discussing climate change (see following examples). However, carbon itself isn’t the issue, it’s the increasing levels of CO2 that are causing the problems.

Carbon intensity: The amount of CO2 produced per unit of something. This could be per unit of electricity (you can see the carbon intensity of electricity in many countries here), or per unit of economic output.  E.g the amount of CO2e per £ of Gross Domestic Product. If we’re going to carry on growing (more electricity, ever greater GDP) then it’s vital that carbon intensity falls and eventually gets to zero.  There’s a greater philosophical question about whether we should even aim for infinite growth, which is clearly not achievable on a finite planet. But that’s for another blog.

Carbon positive: we’re not really sure what this is meant to mean, but it is a marketing term we see wheeled out fairly often. We’ve even made the mistake ourselves in the past. I get the reason for wanting to use “positive” language instead of “negative”, but surely carbon positive just means creating CO2?

Carbon negative: the idea that the creation of a product produces less CO2 than is locked up in that product (or an associated offsetting scheme).

Climate neutral: equivalent emissions are locked up in the creation of a product or delivery of a service, compared to the amount created. In reality most products or services demand resource or energy input that is responsible for some amount of GHG emissions. With that in mind the most common way to become climate neutral is to offset the associated emissions.

Net zero: a steady state where the carbon cycle is in equilibrium – when total GHG emissions are equal to the amount absorbed. This may at a planetary level, where natural plus human-made emissions equal emissions absorbed, right down to a company level which at the moment means that the same amount of GHG emissions have been offset as have been created.

Climate positive: See Carbon negative, but with the benefit of more positive language! This is the term we favour, because it shows positive action in the fight against climate change.

Carbon offsetting: Investing in schemes that will actively sequester CO2, or will reduce amount of CO2 being emitted. This may be nature-based (e.g. tree planting or peatland restoration) or a technical solution (e.g. funding renewable energy to replace energy from fossil fuels)

Carbon insetting: similar to carbon offsetting but a project which occurs within a company’s supply chain or supply chain communities 

Sequestration: The process of capturing and storing CO2 from the atmosphere.  It’s what plants are doing all day every day, and it’s what humans are looking to create through Carbon Capture and Storage (CCS), through locking CO2 up into rocks deep under the earth’s surface.

If anything in this blog has sparked your interest do feel free to contact us on 

Rob Webbon
CEO & Scientist

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