What is CO2e?

We hear about CO2 a lot — but it's not the only gas causing global warming. That's why we're changing up how we talk about greenhouse gases moving forward. 

When we talk about climate change, we tend to portray CO2 as the cause of all evil. But we all know carbon dioxide isn’t the only driver of rising temperatures. Carbon dioxide is just one of several greenhouse gases, such as methane, nitrous oxide, ozone, and water vapor, that add to global warming. And that’s why you’ll come across the term CO2e — aka carbon dioxide equivalent — in our blog and the Klima app in the future.

CO2 is often used as a proxy for all of those other gases, whereas CO2e is more accurate, as it includes all the molecules that capture heat and warm our atmosphere. But before diving into what CO2e actually means, let’s brush up on greenhouse gases real quick, for the sake of clarity.

What are greenhouse gases?

Let’s put this straight: Greenhouse gases are naturally present in the atmosphere (excluding synthetic ones like Chlorofluorocarbons, often used as refrigerants) and are essential to all life forms. These gases help keep our temperatures at a liveable constant, trapping some of the energy from the sun inside our atmosphere. This is what we call the greenhouse effect. Without it, the Earth would basically look like a giant popsicle, with average temperatures of -18°C (or 0°F)

The problem is, since the Industrial Revolution, we’ve pumped about 375 billion tons of carbon dioxide into the atmosphere, upsetting the natural carbon cycle (aka the Earth’s thermostat). 

Just recently, carbon dioxide in the atmosphere reached levels 50% higher than the start of the Industrial Era. Today, carbon dioxide alone accounts for about 76% of global greenhouse gas emissions. But what about the other gases?

Global greenhouse gas emissions per type of gas. Source: EPA.

How do different gases add to climate change? 

Each greenhouse gas has a specific global warming potential (also known as GWP), which is measured according to two major factors: How effective the gas is at trapping heat while in the atmosphere, and how long it remains there before breaking down. 

There are also different sources of greenhouse gases within human activities. Carbon dioxide, for instance, is mostly released by burning fossil fuels, trees, or organic waste. Although it’s not extremely powerful at absorbing heat, it takes hundreds to thousands of years to dissolve once in the atmosphere. 

Methane, on the other hand, is mainly released through agriculture and the decomposition of landfill waste. It accounts for at least 25% of global warming so far, and although it only stays in the atmosphere for around a decade, it absorbs 28 times more heat than carbon dioxide on a 100-year timescale.

Next up, nitrous dioxide: Mostly found in fertilizers, it is 265 times more potent than CO2. And let’s not forget water vapour, the most abundant greenhouse gas in the atmosphere — although most of it cannot be attributed to human activities and it only stays in the atmosphere for a few days. As you can see, CO2 is not the only “enemy” of climate change.

What is CO2e?

CO2e is a measure that was created by the United Nations' Intergovernmental Panel on Climate Change (IPCC) in order to make the effects of different greenhouse gases comparable (because every gas has a different global warming potential, remember?). 

CO2e describes the global warming potential of all greenhouse gases. In other words, the impact of different greenhouse gases is expressed in terms of the amount of CO2 that would result in the same amount of warming.

Essentially, the global warming potential of CO2 is 1 because CO2 is considered the base value. All other greenhouse gases are usually converted into equivalent amounts of CO2. For example, over 100 years, methane scores 25 (meaning that one ton of methane will cause the same amount of warming as 25 tons of CO2).

So, put simply, CO2e gathers all greenhouse gases into one single number, so that we can

CO2e is a more accurate way to measure your emissions, as it refers to all greenhouse gases.

Striving for accuracy

Our day-to-day choices and activities all are responsible for emitting multiple types of greenhouse gases. Driving a car burns fuel which releases carbon dioxide, for example, and the milk we drink comes from a methane-burping cow.

This is why CO2e is a much more accurate method to describe and measure our carbon footprints — and why we decided to integrate CO2e into our vocabulary. Mind you, this doesn’t mean we’re banning CO2 from our vocabulary completely. Whenever we’re actually referring to CO2 as carbon dioxide — for instance, whenever we're referring to the CO2-sucking power of trees — you’ll still see it around!

Get to know your carbon footprint better

Although CO2 accounts for the majority of greenhouse gases, it’s always important to look at the bigger picture. 

Think of eating less meat: Beside cutting CO2 emissions by preventing forests from being cut down for meat production, you’ll also cut methane emissions produced by livestock. Or take composting: Turning food waste into compost keeps bio waste from entering landfills and releasing methane.

These simple actions, if taken en masse, can make a huge difference. That's why being detail-oriented always pays off —  especially when it comes to the small things we can all do to save the climate.

One small thing you can do that has a great impact is offsetting and reducing your carbon emissions with Klima. It takes just three minutes to get started. Join the Klima community today!

Take climate action with Klima

Nicoletta Maestrini
by Nicoletta Maestrini
Lead Communications Manager
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