Who has contributed most to global warming?
The US has caused 0.3°C of warming, followed by China at 0.2°C, and the EU at 0.17°C.
When we try to compare how much countries, gases, and sectors contribute to climate change we often compare emissions. We look at per capita emissions, or a country or sector’s share of the global pie.
That’s a very good proxy, but doesn’t directly measure climate impact.
A new paper by Matthew Jones and the team at the Global Carbon Project has quantified how much countries have contributed to global mean surface temperature rise since 1851.
I’ve been digging through the data and have picked out some key insights. I’ve also made it available in our data explorer at Our World in Data if you want to explore for yourself.
Let’s take a look.
Just two-thirds of warming to date has come from CO2 emissions
Before we dig into country-by-country contributions, let’s look at how much warming different gases have caused.
Mention climate change, and most people think about carbon dioxide (CO2). They assume it has been responsible for most of global warming. But other greenhouse gases – methane and nitrous oxide – have played a big role too.
In the chart I’ve shown how much warming each has contributed from 1851 to 2021. CO2 has contributed the most – 1.1°C, which is just over two-thirds of warming. Methane has added 0.4°C, one-quarter of warming.And nitrous oxide accounts for 5%.
You might notice that this adds up to 1.6°C. That’s already past the 1.5°C global target! The reason is that this data does not include the cooling effects of sulphur dioxide and aerosols. When we include them, the net change in global mean surface temperature is around 1.1°C. That’s the number we’re used to hearing.
We can break this down further by looking at the contributions of fossil fuels, agriculture and land use for each gas. This is shown in the chart below.
The biggest chunk of warming has come from CO2 emissions from fossil fuels. But this is still just half of the global total.
CO2 emissions from fossil fuels are becoming more dominant
We’ve taken a static look at how much warming each gas and source has caused to date. But it’s interesting to see how these contributions have changed over time.
In the chart we see the share of warming for each gas and source by year. In 1851, most warming was caused by land use change. Countries were cutting down forests, expanding farmlands, and had methane-emitting livestock. Only a few countries were using fossil fuels at any noticeable scale.
But over the last century we’ve seen fossil fuels take hold. Their contribution to warming has continued to increase, through to today where they are the largest contributor.
If you want to see this breakdown by country, you can explore it in our interactive chart.
Fossil fuel emissions are growing more quickly than land use
We can simplify this further by combining CO2, methane and nitrous oxide to look at the relative contribution of fossil fuels and land use to global warming.
In 1851, more than 80% of warming was caused by agriculture and land use. By 2021, it was contributing one-third. Fossil fuels and industry have driven 1.1°C of warming. Agriculture and land use have contributed just over 0.5°C.
Note that this doesn’t mean agriculture and land use are not a problem for climate change anymore. They are still causing warming, it’s just that fossil fuels are growing much faster.
Differences in fossil vs. land contributions by country
Globally, fossil fuels have driven two-thirds of warming. But this distribution varies a lot from country to country. We see this in the chart below.
In Brazil, for example, agriculture and land use dominate. Large-scale deforestation and a dominant cattle industry means that most of its warming has come from these sources rather than fossil fuels.
The other extreme is a country like the UK. Most of its warming since 1851 has come from fossil fuels. There are a few reasons for this. It was the birthplace of industrial coal and burned a lot of it for centuries. Second, its land use emissions look small because it had cut down most of its forests well before the 1800s.
Around 1000 years ago, 20% of Scotland was covered in forest. By 1750 this has fallen to 4%. England experienced a similar fall. The UK would have emitted a significant amount of CO2 from deforestation over this period, but this isn’t captured in the data which extends from 1850 onwards. Countries that deforested later have it ‘on record’ and it shows in their emissions accounts.
Which countries have contributed the most to global warming?
Finally, we can look at how much warming each country has contributed to date. This is the sum of warming caused by emissions of all three gases, and from all sources.
You can see these contributions in the map – or use our interactive chart to explore the data in more detail. If you’re screaming that this should be in per capita terms, I hear you and address this at the end.
The rankings of countries probably won’t surprise you. Countries with large populations such as China and India are among the top contributors. The United States and the European Union, with long histories of fossil fuel burning and rich lifestyles, are also up there.
The US has caused 0.28°C of warming, followed by China at 0.2°C, and the EU at 0.17°C.
As a share of total warming, that puts the US at 17%, China at 12%, and the EU at 10%.
A final note: if you’re looking at the warming caused by your country and thinking “that’s so tiny, why do we even bother?” you might want to read my recent article on why ‘negligible emitters’ really do matter.
Why don’t you adjust this warming for population?
Comparing countries on the basis of their total contributions to warming is unfair. Countries with large populations look bad. We should expect them to have a larger impact.
On Our World in Data we try to give most metrics in per capita terms. In our CO2 Data Explorer, almost every metric – CO2, methane, nitrous oxide, and total greenhouse gas emissions are given per person. Where the data is available we also try to give consumption-based emissions which adjust for trade and possible offshoring. We calculate emissions per unit of GDP, and per unit of energy. We try to show the data in as many ways that inform debates as we can.
But warming contributions are the exception: I have not calculated them in per capita terms. That’s because warming to date is a cumulative measure. It’s not about emissions today, it’s about how much has been emitted over centuries. Many generations have come and gone over that time. What population figure do we use, then?
The cumulative population since 1851? Maybe, but that doesn’t seem very informative to me. The population today? That also doesn’t seem fair.
When you give a metric in per capita terms people interpret it as a reflection of how individuals in a country live today. Neither of these population adjustments gives a fair reflection of peoples’ impact today.
Not adjusting for population is not fair either – it makes populous countries look bad. But most people understand that’s why those countries stick out. It’s about the size of their population, not about the behaviour of individuals. As soon as you put these numbers in per capita terms, that piece of context is washed away. People do perceive it as a reflection of people in that country.
That’s why I think no per capita adjustment is better than a dodgy per capita adjustment here.
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Jones, M.W., Peters, G.P., Gasser, T. et al. National contributions to climate change due to historical emissions of carbon dioxide, methane, and nitrous oxide since 1850. Scientific Data 10, 155 (2023).
To estimate warming from each gas, the researchers calculate cumulative emissions into carbon dioxide equivalents using the GWP* method.
This is not the same as GWP100, which some people argue, is a faulty conversion factor for methane because it's a short-lived greenhouse gas.
By using GWP* the researchers do take the fact that methane is a short-lived greenhouse gas into account.
Hannah, this is a great example of how while we might not always agree, we greatly admire your work. We find your intellectual honesty and avoidance of fear mongering so refreshing.
We like per capita comparisons for use in some situations but not in others.
And, the world should be infinitely grateful for your outstanding work. OWID is of enormous value. We wish more people would be more curious and use it more frequently.
Great post as always Hannah. I'd be really interested if you could do a post focused on the sulphur dioxide cooling effects and how much of an issue that is likely to be. E.g. how rapid would the warming impact be if this cooling effect was limited via policy changes?