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Global greenhouse gas emissions continue to rise, at a time when they need to be rapidly falling.

To effectively reduce emissions we need to know where they are coming from – which sectors contribute the most? How can we use this understanding to develop effective solutions and mitigation strategies?

Below we look at the breakdown of emissions – total greenhouse gases, plus carbon dioxide, methane and nitrous oxide individually – by sector.

Annual greenhouse gas emissions by sector

Where do our greenhouse gas emissions come from?

This chart shows the breakdown of total greenhouse gases (the sum of all greenhouse gases, measured in tonnes of carbon dioxide equivalents) by sector.

Here we see that electricity and heat production are the largest contributor to global emissions. This is followed by transport, manufacturing and construction (largely cement and similar materials), and agriculture.

But this is not the same everywhere. If we look at the United States, for example, transport is a much larger contributor than the global average. In Brazil, the majority of emissions come from agriculture and land use change.

How you can interact with this chart

On these charts you see the button Change Country in the bottom left corner – with this option you can switch the chart to any other country in the world.

Per capita greenhouse gas emissions: where do our emissions come from?

Looking at the breakdown of greenhouse gases by sector on aggregate is essential for countries to understand where emissions reductions could have the largest impact. But it can often be unintuitive for individuals to see where there emissions are coming from.

In this chart we show how the average person’s emissions would be distributed across the different sectors – in effect, this shows the average ‘footprint’, measured in tonnes of carbon dioxide equivalents per year.

How you can interact with this chart

  • On these charts you see the button Change Country in the bottom left corner – with this option you can switch the chart to any other country in the world.
  • If you drag the blue time-slider you will see the bar chart transform into a line chart, and show the change over time.

Annual CO2 emissions by sector

The above charts looked total greenhouse gas emissions – this included other gases such as methane, nitrous oxide, and smaller trace gases.

How does this breakdown look if we focus only on carbon dioxide (CO2) emissions? Where does our CO2 come from?

This chart shows the distribution of CO2 emissions across sectors.

The global breakdown for CO2 is similar to that of total greenhouse gases – electricity and heat production dominates, followed by transport, and manufacturing and construction. One key difference is that direct agricultural emissions (if we exclude land use change and forestry) are not shown; most direct emissions from agriculture result from methane (production from livestock) and nitrous oxide (released from the application of fertilizers).

Like total greenhouse gas emissions, this breakdown varies between countries.

Per capita CO2: where do our emissions come from?

In this chart we show the per capita breakdown of CO2 emissions by sector. This is measured in tonnes per person per year.

This allows us to better understand our domestic carbon footprint. However, it does not correct for the goods and services we buy from other countries.

Annual CH4 emissions by sector

The breakdown of CO2 emissions mirrors total greenhouse gas emissions closely.

The distribution of methane emissions across sectors is notably different. This chart shows methane emissions by sector, measured in tonnes of carbon dioxide equivalents.

We see that, globally, agriculture is the largest contributor to methane emissions. Most of this methane comes from livestock (they produce methane through their digestive processes, in a process known as ‘enteric fermentation’). Rice production is also a large contributor to methane emissions.

Aside from agriculture, fugitive emissions produce a significant amount of methane. ‘Fugitive emissions’ represent the unintentional leaks of gas from processes such as fracking, and more traditional oil and gas extraction and transportation. This can happen when gas is transported through poorly maintained pipes, for example.

Waste is third largest contributor. Methane is produced in landfills when organic materials decompose.

Per capita CH4: where do our emissions come from?

In this chart we show the per capita breakdown of methane (CH4) emissions by sector. This is measured in tonnes per person per year.

How you can interact with this chart

  • On these charts you see the button Change Country in the bottom left corner – with this option you can switch the chart to any other country in the world.
  • If you drag the blue time-slider you will see the bar chart transform into a line chart, and show the change over time.

Nitrous oxide (N2O) emissions by sector

In this section

Annual N2O emissions by sector

Nearly all of our nitrous oxide (N2O) emissions come from agriculture, as this chart shows.

Nitrous oxide is produced by microbes in nearly all soils. But the application of nitrogen fertilizers makes much more nitrogen readily available for microbes to convert to N2O – this is because not all of the applied nutrients are taken up by crops.

As the application of nitrogen fertilizers has rapidly increased over the past 50 years in particular, N2O emissions have also increased. But nitrous oxide is not only produced when synthetic nitrogen fertilizer is applied; the same processes occur when we use organic fertilizers such as animal manure.

Per capita N2O: where do our emissions come from?

In this chart we show the per capita breakdown of nitrous oxide (N2O) emissions by sector. This is measured in tonnes per person per year.

As expected, nearly all of our nitrous oxide emissions come from agriculture.

Food production is responsible for one-quarter of the world’s greenhouse gas emissions

When it comes to tackling climate change, the focus tends to be on ‘clean energy’ solutions – the deployment of renewable or nuclear energy; improvements in energy efficiency; or transition to low-carbon transport. Indeed, energy, whether in the form of electricity, heat, transport or industrial processes, account for the majority – 76% – of greenhouse gas (GHG) emissions.1

But the global food system, which encompasses production, and post-farm process such as processing, and distribution is also a key contributor to emissions. And it’s a problem for which we don’t yet have viable technological solutions.

The visualization shown here – based on data from the meta-analysis by Joseph Poore and Thomas Nemecek (2018), published in Science – summarizes food’s share of total emissions and breaks it down by source.2

Food is responsible for approximately 26% of global GHG emissions.

There are four key elements to consider when trying to quantify food GHG emissions. These are shown by category in the visualization:

Livestock & fisheries account for 31% of food emissions
Livestock – animals raised for meat, dairy, eggs and seafood production – contribute to emissions in several ways. Ruminant livestock – mainly cattle – for example, produce methane through their digestive processes (in a process known as ‘enteric fermentation’). Manure management, pasture management, and fuel consumption from fishing vessels also fall into this category. This 31% of emissions relates to on-farm ‘production’ emissions only: it does not include land use change or supply chain emissions from the production of crops for animal feed: these figures are included separately in the other categories.

Crop production accounts for 27% of food emissions. 
21% of food’s emissions comes from crop production for direct human consumption, and 6% comes from the production of animal feed. They are the direct emissions which result from agricultural production – this includes elements such as the release of nitrous oxide from the application of fertilizers and manure; methane emissions from rice production; and carbon dioxide from agricultural machinery.

Land use accounts for 24% of food emissions.
Twice as many emissions result from land use for livestock (16%) as for crops for human consumption (8%).3Agricultural expansion results in the conversion of forests, grasslands and other carbon ‘sinks’ into cropland or pasture resulting in carbon dioxide emissions. ‘Land use’ here is the sum of land use change, savannah burning and organic soil cultivation (plowing and overturning of soils). 

Supply chains account for 18% of food emissions.
Food processing (converting produce from the farm into final products), transport, packaging and retail all require energy and resource inputs. Many assume that eating local is key to a low-carbon diet, however, transport emissions are often a very small percentage of food’s total emissions – only 6% globally. Whilst supply chain emissions may seem high, at 18%, it’s essential for reducing emissions by preventing food waste. Food waste emissions are large: one-quarter of emissions (3.3 billion tonnes of CO2eq) from food production ends up as wastage either from supply chain losses or consumers. Durable packaging, refrigeration and food processing can all help to prevent food waste. For example, wastage of processed fruit and vegetables is ~14% lower than fresh, and 8% lower for seafood.4

Reducing emissions from food production will be one of our greatest challenges in the coming decades. Unlike many aspects of energy production where viable opportunities for upscaling low-carbon energy –  renewable or nuclear energy –  are available, the ways in which we can decarbonize agriculture are less clear. We need inputs such as fertilizers to meet growing food demands, and we can’t stop cattle from producing methane. We will need a menu of solutions: changes to diets; food waste reduction; improvements in agricultural efficiency; and technologies that make low-carbon food alternatives scalable and affordable. 

How much of ghgs come from food

Food waste is responsible for 6% of global greenhouse gas emissions

Food production accounts for around one-quarter – 26% – of global greenhouse gas emissions.5 This is a lot, but it’s slightly easier to digest when we remind ourselves that food is a basic human need. 

What’s harder to make sense of is the amount of greenhouse gas emissions which are caused in the production of food that is never eaten.

Around one-quarter of the calories the world produces are thrown away; they’re spoiled or spilled in supply chains; or are wasted by retailers, restaurants and consumers.6 To produce this food we need land, water, energy, and fertilizer inputs. It all comes at an environmental cost.

Joseph Poore and Thomas Nemecek (2018), in their large meta-analysis of global food systems, published in Science, estimated how much of our greenhouse gas emissions come from wasted food.7

In the visualization here I show the emissions from wasted food in the context of global greenhouse gas emissions.

The study by Poore and Nemecek (2018) found that almost one-quarter – 24% – of food’s emissions come from food that is lost in supply chains or wasted by consumers. Almost two-thirds of this (15% of food emissions) comes from losses in the supply chain which result from poor storage and handling techniques; lack of refrigeration; and spoilage in transport and processing. The other 9% comes from food thrown away by retailers and consumers.

This means that food wastage is responsible for around 6% of total global greenhouse gas emissions.8 In fact, it’s likely to be slightly higher since the analysis from Poore and Nemecek (2018) does not include food losses on the farm during production and harvesting.

To put this in context: it’s around three times the global emissions from aviation.9 Or, if we were to put it in the context of national emissions, it would be the world’s third largest emitter.10 Only China (21%) and the United States (13%) emitted more.11

Ghg emissions from food waste poore nemecek