Global greenhouse gas (GHG) emissions grew by 51% from 1990 to 2021. These emissions are causing the planet to warm at an alarming rate and contributing to the increasingly devastating storms, floods, fires and heatwaves the world is now grappling with.

But where exactly do emissions come from?

WRI's Climate Watch platform publishes comprehensive emissions data for all countries, sectors and gases, offering insight into the root causes of the climate crisis and where the world must take action to solve it. We analyzed the data to explain what's causing the most greenhouse gas emissions globally:

Greenhouse Gas Emissions Come from 5 Sectors

To understand where emissions come from, it's helpful to break them down by both sectors (such as energy or agriculture) and "end uses," or the specific activities that emit greenhouse gases.

Today, greenhouse gas emissions can be traced back to five economic sectors:

• Energy
• Agriculture
• Industrial processes
• Waste
• Land use, land-use change and forestry

The energy sector produces the most greenhouse gas emissions by far, accounting for a whopping 75.7% worldwide.

The energy sector includes emissions from electricity and heat (29.7% of all emissions), transportation (13.7%), manufacturing and construction (12.7%) and buildings (6.6%).

It also includes fugitive emissions (greenhouse gases released during fossil fuel production or transmission) and emissions from other fuel combustion.

We can also look at which specific activities (or end-uses) drive the most emissions within each sector.

For example, residential buildings account for the largest share of energy sector emissions and 12.5% of all emissions globally. This includes emissions from generating the electricity used in homes as well as from direct fossil fuel use, such as cooking with gas.

Another major GHG source in the energy sector is road transportation, which accounts for 12.2% of global emissions.

Non-energy sectors contribute just one-quarter of global emissions.

Agriculture is the second highest emitting sector after energy, accounting for 11.7% of global emissions. Major emitters in this sector include livestock farming and agricultural soils, such as methane from manure. Agriculture can also drive emissions through land-use change and energy use.

Industrial processes make up 6.5% of global emissions. This includes emissions from chemical and cement production, among other things (but excludes energy use).

Waste emissions, such as methane and nitrous oxide from landfills, make up 3.4% of the global total.

Land use, land-use change and forestry make up another 2.7%. This net total includes both emissions released by lands and forests — such as when trees are cut down or when organic matter breaks down in soil — as well as carbon removed from the atmosphere as forests grow. Gross emissions from the sector (not including removals) are therefore higher than what's shown here.

Here’s a bigger-picture view of all sectors, sub-sectors and end-uses driving global emissions. Note that end-uses may repeat as they can fall under several sub-sectors. For example, residential buildings show up under both Electricity (because they use electricity generated at power plants) and Buildings (because they create emissions directly).

Industry Is the Fastest Growing Source of Greenhouse Gas Emissions

Since 1990, the four emissions sources that have grown the fastest are: industrial processes, which grew by a massive 225%; electricity and heating (a subsector of energy), which grew by 88%; transportation (also a subsector of energy), which grew by 66%; and manufacturing and construction, which grew by 60%.

Related

Carbon Dioxide Makes Up Most, but Not All, Greenhouse Gas Emissions

Carbon dioxide (CO2) comprises 74% of greenhouse gas emissions. The vast majority (92%) of this comes from fossil fuel use.

While other greenhouse gases such as methane (CH4) and nitrous oxide (N2O) make up a much smaller share of the total, they play a big role in global warming. Known as "super pollutants," these gases are much more potent than CO2 in the near term.

Most methane and nitrous oxide emissions come from agriculture, waste treatment and gas flaring. Fluorinated gases — including HFCs, perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3) — from industrial processes also make up a small share of global emissions. Tackling these super-pollutant sources provides powerful but often overlooked opportunities for mitigation.

Understanding Emissions Flows Is Essential to Developing Climate Solutions

Stemming GHG emissions at their source is the primary way to cap temperature rise and avoid increasingly devastating climate impacts. Indeed, targeting the highest-emitting sectors is a top priority for climate action. But governments, companies and others cannot develop effective plans to do so unless they know exactly where emissions come from.

This requires a broader view of how different sectors, end uses and gases connect, helping to avoid tunnel vision as decision-makers craft their action plans.

Higher Ambition Starts with Clear Information

The world is already facing deadly consequences from climate change. To avoid much more dangerous and costly impacts, we need to limit global temperature rise to 1.5 degrees C (2.7 degrees F). But countries aren't aiming nearly high enough: This target requires slashing emissions 42% by 2030 and 57% by 2035, relative to 2019. Current policies will achieve less than a 1% reduction by 2030 and 2035.

All countries — particularly major, high-emitting economies — need to massively step up their climate ambition. That means submitting stronger national climate plans (known as NDCs), developing long-term climate strategies and committing to reach net-zero emissions as soon as possible.

The largest emissions sources should take first priority. But rapid transformations are needed across all sectors and systems. Countries must work to phase out coal in electricity generation, halt deforestation, increase the share of low-carbon fuels in transportation, and scale up public and private climate finance, among other actions.

Across the board, having the right data to craft targeted, effective strategies is an essential first step.

Explore Emissions Data by Sector and Gas

1 Various greenhouse gases can have different warming effects due to differences in their ability to absorb energy and in the length of time they persist in the atmosphere. "Global warming potential" (GWP) was developed to measure how much energy the emissions of one ton of gas will absorb over a given time period (typically 100 years) relative to the emissions of one ton of carbon dioxide (CO2). Carbon dioxide equivalent (CO2e) is a measure used to aggregate emissions from various GHGs on the basis of their global warming potentials by equating non-CO2 GHGs to the equivalent amount of CO2. Thus, CO2e provides a standardized unit for measuring the warming effects of various GHGs.

Editor's note: This article was originally published in 2020. It was updated in December 2024 to reflect the latest data on global sectoral emissions from Climate Watch.