When we talk about climate change we seem to portray CO2 as the cause of all evil, but we look past the other gases that are also driving up our global temperatures. Carbon dioxide is one of the many gases that add to global warming, but methane, nitrous oxide and water vapour are also greenhouse gases that keep the planet warm by trapping solar energy that would usually radiate out to space, in our atmosphere. This is when the term CO2e comes in, it stands for “carbon dioxide equivalents” and includes CO2 but also all the other GHGs previously mentioned.
To help this make sense we need to go back to the basics and look at what greenhouse gases actually are.
What are Greenhouse Gases?
Greenhouse gases are gases which naturally occur in our atmosphere and are also released by humans. And put simply; they trap heat.
The main greenhouse gases include;
- Carbon dioxide
- Nitrous oxide
- Fluorinated gases
- Water vapour
These are all naturally occurring, except for fluorinated gases which are synthetic and are emitted from a variety of industrial processes.
In the US in 2020:-
- 79% of the total greenhouse gas emissions were carbon dioxide
- 11% methane
- 7% nitrous oxide
- 3% fluorinated gases.
However, water vapour is the most abundant greenhouse gas in the atmosphere but human activity has very little effect on atmospheric concentrations of water vapour so is not included in GHG emissions data.
Each gas remains in the atmosphere for a different period of time making them more or less deadly for global warming. CO2 remains in the climate system for thousands of years making it the most dangerous greenhouse gas, whereas methane lasts around a decade and nitrous oxides last around 100 years on average.
What do Greenhouse Gases do?
During the day, the sun's rays shine through our atmosphere warming the surface of the earth and the greenhouse gases help to trap this heat, then at night some of the heat is released back into the atmosphere and the earth cools slightly. This process is necessary for survival, without GHGs the temperatures would drop to as low as -18 degrees which is far too low to sustain life on earth.
Why are we worried about GHG Levels?
But human activity is upsetting the normal and natural GHG levels. Since the industrial revolution humans have been releasing significantly larger quantities of greenhouse gases into the atmosphere, mainly from the burning of fossil fuels. Since 1750 the UK alone has emitted more than 78 billion tonnes of CO2 and since 1970 alone CO2 emissions have increased by 90%. This increase in GHG emissions disrupts the normal greenhouse gas effect and instead of trapping the heat and then emitting it back into space at night, there are too many GHGs and the heat cannot escape our atmosphere which has warmed the earth. Global temperatures have been accelerating for the last 30 years and are now the highest temperatures on record.
What is Co2e and what does is stand for?
Well CO2e stands for “carbon dioxide equivalent” and is a term for describing all the other greenhouse gases in a common unit. For any quantity of a greenhouse gas CO2e signifies the amount of CO2 which would result in the same amount of warming. For example, if 1kg of methane is emitted into the atmosphere this can then be expressed as 25kg of CO2e, CO2e gathers all greenhouse gases into one place.
What’s the Difference Between Co2 and Co2e and why is it so important?
CO2 however, only accounts for carbon dioxide emissions but is often used as a shorthand to describe all greenhouse gases. But if we calculate emissions only based on CO2 we are gathering an inaccurate picture if we don’t take into account other warming gases. Seeing a full picture of the gases that are causing climate change allows for genuine change to be made rather than ignoring the other gases that are also driving up global temperatures.
For example, in 2018 Germany released over 760 million metric tonnes of CO2, but if you add in all the other emissions the total actually reaches 854.4 million tonnes of CO2e. The extra 94.4 million tonnes of emission cannot be ignored as that is a huge number that would play a huge role in climate change, meaning that it has to be addressed with the same urgency as the CO2 emissions are.
The main difference between CO2 and CO2e is that one addresses only carbon dioxide and the other takes into account all greenhouse gases. It is important that we pay attention to the CO2e numbers so that we can slow down the rapidly accelerating global temperature that comes as a result of this over production of greenhouse gases.