Who Releases the Most Greenhouse Gases?

Imagine you’re seated at an international climate conference, surrounded by delegates from all corners of the globe. A fierce debate is raging about who should bear the most responsibility for climate change. The room agrees: the countries that emit the most greenhouse gases are the most responsible. But then one representative poses a pressing question: “So, who releases the most greenhouse gases?”  

How would you answer? Is it the countries that are currently spewing out the most greenhouse gases or those that have grown rich by burning fossil fuels for over a century? Depending on how you count emissions, you could arrive at different conclusions. 

That question isn’t just theoretical; it’s at the heart of global efforts to shape fair climate policies and agreements. Who bears the most responsibility and, by extension, who should take on more of the costs of fighting climate change has been debated for decades.  

Since the early 1990s, the consensus has been that countries with higher emissions should shoulder a larger portion of the costs for transitioning away from fossil fuels. The challenge, however, lies in how to track emissions to determine which countries emit the most. 

Without a clear and consistent method for counting emissions, crafting fair international agreements on how to reduce them—by how much, how quickly, and with what techniques—becomes difficult. Here, knowledge isn’t just power; it’s crucial for designing fair policies that preserve a climate and allow future generations to thrive.  

In this resource, you’ll learn about the intricate and sometimes contentious process of accounting for emissions and determining who is responsible for climate change. That exploration will reveal the underlying complexities and challenges in creating fair and effective climate agreements.  

How the world tracks emissions 

Before determining who emits the most emissions, experts need to first calculate how much each country emits.  

The good news is that tracking those amounts is a relatively straightforward process. Many countries use a method called the "bottom-up approach" to estimate their greenhouse gas emissions. Here’s how it works: 

• Collecting data: Countries gather information on activities that produce emissions, like how much fuel a factory burns, the number of cars on the roads, or the amount of electricity generated from coal or gas. 
• Applying emission factors: Each activity has an “emission factor,” a number that indicates how much greenhouse gas is produced per unit of activity. For example, burning one ton of coal releases a specific amount of carbon dioxide. By multiplying the amount of fuel used by its emission factor, countries estimate the emissions from that activity. 
• Totaling up emissions: The previous two steps are repeated for all activities across different sectors—such as transportation, agriculture, and energy production. Adding up those numbers provides the total greenhouse gas emissions for the country. 

Tracking emissions is not just about determining who emits the most. It also helps international organizations gather worldwide data about climate change and set targets for countries to reduce their emissions. 

The main international organization involved in these tasks is the Intergovernmental Panel on Climate Change (IPCC). The IPCC helps countries measure and report their greenhouse gas emissions consistently. It then collects and uses emissions data from participating countries to create reports that inform policymakers and the public about climate change. Those reports project probable future climate scenarios based on different factors like changes in emissions, temperatures, and human choices. They are important because they help people understand what could happen based on their efforts—or lack thereof—to address climate change. They also allow countries to set specific goals for reducing emissions.  

Who emits the most greenhouse gases?  

Calculating emissions is one thing, but deciding how to use that information to determine a country’s responsibility can be a contentious issue. Part of the problem is that there are different ways to present countries’ emissions, and each one can tell a different story. Let’s break them down. 

Annual emissions: Who is polluting the most right now? 

This method focuses on identifying which countries are currently producing the most greenhouse gases. Right now, some countries are emitting much more than others. For instance, China is the largest emitter of greenhouse gases today, even though that wasn’t always the case. Historically, countries like the United States and many in Europe had higher emissions, but they have reduced their greenhouse gases in recent years due to stricter environmental regulations. Meanwhile, China’s emissions have increased because of its rapid economic growth. Measuring today’s emissions illuminates which countries are worsening climate change the most right now. 
 

Cumulative emissions: Who’s been polluting the longest? 

The measurement of “cumulative emissions” looks at emissions over time, adding up all the emissions a country has ever released since records began around 1850. By that measure, countries like the United States and other wealthy, industrialized nations are the biggest historical polluters. They have been burning fossil fuels for a long time, way before countries like China and India were industrialized. Many developing countries highlight that the uneven history of industrialization makes calls for them to reduce their emissions unfair. Wealthy countries faced no pressure to reduce their emissions as they developed then, so why should developing countries limit themselves now? 
 

Emissions per capita: How much does each person pollute? 

A third way to measure emissions is to look at how much each person in a country is responsible for—a method called “emissions per capita.” Some developing countries like to use emissions per capita because it shows that, despite high overall emissions, their emissions per person are lower than those of richer countries. Many countries with small populations but energy-hungry industries have high emissions per capita. In contrast, large countries like China and India don’t show up as high per-capita emitters because their huge populations spread out the total emissions. 
 

How to decide who’s responsible 

Reducing global emissions will take a lot of work and money, with many countries coordinating their efforts. But given those different counting styles, how should policymakers decide which countries should take on the most responsibility for fighting climate change? Should it be countries with high emissions in total or high emissions per capita? And should it be countries emitting the most today or countries who have emitted the most historically? 

The debate is ongoing, but countries generally agree on certain core principles. Since the first major global agreement on climate change in 1992—the UN Framework Convention on Climate Change—governments have agreed on this important idea: countries bear “common but differentiated responsibilities” to fight climate change. That means that although all countries need to pitch in to fight climate change, some need to do more than others. 

The 1992 agreement emphasized that wealthier, more developed countries have a special responsibility because they have historically emitted more greenhouse gases. Over the years, those countries have faced pressure both from other governments and their own citizens to cut emissions quickly and help fund energy transitions in poorer countries. Although emissions have decreased in some of those developed countries since 1992, the reductions haven’t been enough to meet global targets, and many promises to assist poorer countries have not been fulfilled. 

At the time of the 1992 agreement, countries like China, India, and many other low- and middle-income countries were not expected to reduce their emissions immediately. However, significant changes have occurred. Critics in more developed countries say it's unfair to expect fewer reductions from the low- and middle-income countries because some are now the world's largest polluters, and their economies have grown rapidly. Still, their total emissions and emissions per capita are often lower than those of wealthier nations.  

In the 2015 Paris Agreement, countries acknowledged that climate change required action from everyone, not just developed countries. Almost every country agreed to a target of keeping global warming, compared to preindustrial levels, to a rise of well below a 2°C, aiming for a limit of 1.5°C. To achieve that goal, every country had to set emissions reductions targets. Still, developing countries were expected to make less ambitious pledges than developed countries. 

But even if almost every country has agreed to reduce emissions, debate remains about how to pay for the costs of adopting new emissions-reducing technologies and practices. Many developing countries still argue that the world’s wealthiest countries should do more to finance transitions in poorer countries, because they bear greater responsibility. 

Addressing the concerns about responsibility is a critical issue in international climate discussions. Ultimately, though, world leaders can work to overcome those challenges and collaborate in their efforts to fight climate change.