Global Greenhouse Gas Emissions: An Overview in 2024

Advancements in renewable energy and commitments to reduce greenhouse gas emissions are positive steps in the right direction. But is the current rate of change fast enough to avoid severe impacts of climate change? Let’s take a closer look.

What are greenhouse gases?

Greenhouse gases capture heat from the sun, trap it, and warm the Earth’s surface. This natural process maintains the planet’s temperature and makes it habitable. However, our activities have increased the concentrations of these gases in the atmosphere, creating a greenhouse effect that leads to global warming.

The key greenhouse gases are:

These gases’ global warming potential (GWP) is calculated considering the amount of heat each trap in the atmosphere over a specified time compared to carbon dioxide (CO₂), which has a GWP of 1.

GWP indicators consider the following elements:

1. Radiative efficiency: The amount of heat each molecule of the gas can absorb and emit
2. Atmospheric lifetime: The average time a gas molecule remains in the atmosphere before natural processes remove it
3. Integration over time: The gas’s radiative forcing usually over 100 years

Think of greenhouse gas levels as a bank account growing with compound interest. The rate at which we add emissions means the concentration grows faster than it did historically. This accelerated growth is concerning because it leads to faster and more severe climate impacts.

How are greenhouse gas emissions measured?

Measuring global GHG emissions requires a mix of direct methods, estimation, and modeling techniques.

• Ground-based monitoring stations, satellites, and aircraft measure the concentration of gases in the atmosphere. For example, the Global Atmosphere Watch network monitors gas concentrations in specific locations, while NASA’s OCO-2 satellite provides global coverage and can track changes in gas concentrations over time.
• Estimation methods provide data when direct measurement isn’t feasible. For example, producers estimate total greenhouse gas emissions in the energy sector by multiplying the fuel consumed by a specific emission factor (the average fuel emissions produced per unit). Similarly, in agriculture, emissions from livestock can be estimated based on the number of animals and the average emissions per animal.
• Modeling techniques integrate various data sources to simulate GHG behavior in the atmosphere and predict future emissions under multiple scenarios.

These methods undergo rigorous vetting processes to guarantee reliability. International bodies like the Intergovernmental Panel on Climate Change (IPCC) review the latest scientific knowledge and provide standardized methodologies for estimating and reporting greenhouse gas emissions.

An essential metric to consider is per capita greenhouse gas emissions, which measures the average emissions per person in different countries. This metric provides a different perspective by accounting for population size.

Key authorized sources for data and information on global emissions:

• Intergovernmental Panel on Climate Change (IPCC)
• National Aeronautics and Space Administration (NASA Climate)
• National Oceanic and Atmospheric Administration (NOAA Climate)
• European Space Agency (ESA Climate Office)
• United Nations Framework Convention on Climate Change (UNFCCC)
• Environmental Protection Agency (EPA Greenhouse Gas Emissions)
• World Meteorological Organization (WMO)
• Global Atmosphere Watch (GAW)
• International Energy Agency (IEA)

How long do greenhouse gases remain in the atmosphere?

The atmospheric lifetimes of gas emissions vary widely, depending on each gas’s chemical properties and how it’s removed from the atmosphere:

• Methane emissions: around 12 years
• Nitrous oxide emissions: approximately 114 years
• Fluorinated gas emissions:
  • Hydrofluorocarbons: from 1 to 270 years
  • Perfluorocarbons (PFCs): thousands of years
  • Sulfur hexafluoride (SF₆): about 3,200 years
• Water vapor: 9 days
• Carbon dioxide emissions: no single defined lifetime because it’s continuously exchanged between the atmosphere, oceans, and land biosphere

While the atmospheric lifetime is an important metric, it doesn’t tell the whole story. We should also consider a gas’s ability to trap heat, greenhouse gas concentrations in the atmosphere, and the sources of emissions. For instance, methane has a much shorter lifetime than carbon dioxide, but its GWP over 100 years is 28-36 times greater. This means that methane is far more effective at trapping heat in the short term.

On the other hand, carbon dioxide is present in much higher concentrations than other greenhouse gases, making it the primary driver of human-caused climate change despite its relatively lower GWP.

Global greenhouse gas emissions by economic sector

Energy production generally accounts for 73.2% of overall emissions, and fossil fuel combustion for electricity and heat is the largest source of global emissions. Let’s break down the numbers:

• Heat and electricity generation: 24.2%
• Industrial production, manufacturing, and construction: 24.2%
• Transportation: 16.2%
• Other energy (fuel extraction, refining, processing, and distribution): 8.6%

Agriculture and land use also play significant roles, with substantial emissions coming from livestock (methane), rice production (methane), agricultural soil management (nitrous oxide), and biomass burning.

• Agriculture: 11.1%
• Deforestation and land use change: 7.3%

Non-energy-related emissions from chemical, cement, metal, and other industrial activities account for 5.2% of global greenhouse gas emissions, while waste management contributes 3.2%.

Note: These percentages are estimates and can vary depending on the methodologies used for calculation.

Trends in global greenhouse gas emissions

In 2023, the concentration of carbon dioxide in the atmosphere increased by 2.8 parts per million (ppm). This might sound like a small number, but consider this: the current level of CO₂ in the atmosphere is around 419.3 ppm, up from pre-industrial levels of about 280 ppm. This means CO₂ has increased by over 50% since the Industrial Revolution.

Sector-specific trends

The power sector remains the most significant contributor to global emissions, although there has been notable progress in adopting clean energy technologies. The good news is that renewables like wind and solar have helped limit the rise in emissions. Furthermore, advanced economies saw a record decrease in emissions, bringing them back to levels seen 50 years ago. However, transportation and industrial emissions continue growing, particularly in developing regions with accelerating industrialization and urbanization.

Regional shifts and peaking emissions

Some countries have already peaked their greenhouse gas emissions, while others are projected to do so soon. For example, several major emitters, including China and the United States, have set targets or shown trends indicating a peak in emissions. If clean technology growth trends continue, global emissions might decline from 2024.

Policies and international agreements

The Paris Agreement has led to progress, but it’s not enough to limit global temperature rise to 1.5°C. According to the Emissions Gap Report 2023, fully implementing current Nationally Determined Contributions (NDCs) would limit the temperature rise to approximately 2.5-2.9°C by the end of the century. More comprehensive policy measures are needed to bridge this gap and achieve the targets.

Global emissions FAQs

Which countries emit the most greenhouse gases?

China is the world’s largest emitter of gas emissions (approximately 27%) due to its rapid industrialization and reliance on coal for energy. Despite significant investments in renewable power sources, its energy consumption keeps its emissions high.

The United States follows with 11% of the global emissions. The country is a major consumer of fossil fuels. Efforts to reduce emissions include regulations on vehicle efficiency, shifts towards natural gas and renewables, and state-level initiatives. India is currently the third-highest producer of global emissions, with approximately 7%.

However, when considering per capita greenhouse gas emissions, Qatar, Bahrain, and Kuwait rank as the highest emitters.

Qatar has the highest per capita emissions globally, driven by its substantial oil and gas industry, with around 37.05 metric tons of CO₂ equivalent per person per year. Bahrain relies heavily on fossil fuels for energy production, too. Additionally, the country has a relatively small population, meaning that the emissions from industrial and energy sectors result in a higher per capita rate than larger countries. Kuwait follows with approximately 23.9 metric tons per person due to its significant oil production and high energy consumption.

For more context, the United States records 14.2 metric tons of CO₂ per person. Also, China emits 8.2 metric tons per person and is the most significant overall emitter due to its vast population. And, with 1.9 metric tons per person, India has low per capita emissions despite being the third-largest overall emitter, reflecting its lower energy consumption per capita.

Which gases are the largest contributors to greenhouse gas emissions?

CO₂ remains the dominant greenhouse gas due to its volume and longevity, while methane and nitrous oxide have higher warming potentials despite their lower concentrations — N₂O has a GWP of about 298 times that of CO₂ over 100 years. Although present in much smaller quantities, fluorinated gases are also extraordinarily powerful and long-lived.

What efforts are being undertaken to reduce greenhouse gas emissions?

• We’re gradually transitioning from fossil fuels to renewable energy sources. Many governments support this transition through subsidies, tax incentives, and investments in renewable energy infrastructure.
• New building codes, fuel efficiency standards, and incentives for adopting energy-efficient technologies improve energy efficiency in buildings, transportation, and industry.
• Carbon pricing mechanisms, such as carbon taxes and cap-and-trade systems, create economic incentives for reducing direct greenhouse gas emissions.
• Improved public transportation and electric vehicles (EVs) reduce transportation emissions.
• Precision farming, agroforestry, and sustainable land management lower emissions from agriculture and deforestation. Reforestation and afforestation efforts also act as carbon sinks for more effective long-term carbon storage.
• Local waste-to-energy programs have been highly effective, with a significant portion of waste being converted to energy rather than going to landfills.

How HomeBiogas helps reduce global greenhouse gas emissions

HomeBiogas systems help reduce global greenhouse gas emissions on a small scale but with exponential impact over time. HomeBiogas small-scale biodigesters convert organic waste into biogas for cooking and produce liquid fertilizer. This prevents methane emissions from decomposing waste and reduces the need for fossil fuels or biomass. 

The effects of these efforts are particularly visible in developing countries where traditional cooking methods often involve burning wood or coal.

To date, HomeBiogas has mitigated over 336,000 tons of CO₂ emissions. To put this in perspective, this amount of carbon dioxide savings is comparable to taking approximately 72,000 cars off the road for an entire year. Another way to visualize it is by considering that the average tree absorbs about 48 pounds of CO₂ annually. The CO₂ savings from HomeBiogas systems are equivalent to the annual carbon absorption of roughly 14 million trees.

While one biodigester might seem too small to combat emissions growth, the cumulative effect of thousands of units helping families worldwide is transformative. And, as more households rely on HomeBiogas systems to manage organic waste and produce cooking gas, the collective impact continues to reduce emissions and promote self-sufficiency.

Final thoughts

The measures meant to mitigate the effects of global greenhouse gas emissions are making promising strides, with significant advancements in renewable energy, energy efficiency, and international commitments.

And the pace must accelerate to meet the urgent climate targets necessary to prevent the severe impacts of climate change. Nationwide efforts, alongside individual actions such as reducing energy consumption and supporting sustainable practices, are crucial. We can create a sustainable future by amplifying these efforts, embracing innovative technologies, and encouraging global cooperation.