Greenhouse Gas Bulletin by World Meteorological Organization (WMO)

The Greenhouse Gas Bulletin is an annual publication by the World Meteorological Organization (WMO), first released in 2004. It reports on atmospheric concentrations of long-lived greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Read here to learn more.

For 2023, the Bulletin compiles data from the Global Atmosphere Watch (GAW) Programme, a network monitoring greenhouse gas worldwide.

It highlights ongoing trends in greenhouse gas accumulation, attributing significant emissions to human activities and emphasizing the need for urgent climate action to stabilize atmospheric levels and mitigate warming.

Read: Greenhouse effect and Global warming

Greenhouse Gas Bulletin

The Bulletin reveals that CO₂, the most significant greenhouse gas due to its large concentration and long lifespan, continues to increase due to fossil fuel combustion and land-use changes.

Methane and nitrous oxide, while present in smaller amounts, have potent warming effects.

The Bulletin underscores that rising greenhouse gas concentrations directly impact global temperatures, contributing to extreme weather events, sea level rise, and changes in ecosystems.

In addition to informing policymakers and climate negotiators, the Greenhouse Gas Bulletin serves as a scientific foundation for understanding and addressing climate change through international agreements like the Paris Agreement.

Greenhouse Gas Bulletin 2024

• GHG concentration: The globally averaged surface concentration of CO₂, CH4 & N2O (in 2023), are 151%, 265% and 125% of pre-industrial (before 1750) levels.
• Radiative forcing (1990 to 2023): By long-lived LLGHGs increased by 51.5%, with CO₂ accounting for about 81%.
• Atmospheric methane (CH4): It saw its largest 3-year increase on record, driven by higher emissions from natural wetlands due to climate change.
• Climate change: It could make ecosystems release more greenhouse gases, wildfires emit more CO2, and oceans absorb less, amplifying global warming and ocean acidification.

Other Key highlights of the report:

• CO2 concentrations have increased by 11.4 % in just 20 years
• A long lifetime of CO2 in the atmosphere locks in future temperature increase
• El Niño and vegetation fires fuel surge in the later part of 2023
• The effectiveness of carbon sinks like forests cannot be taken for granted
• An improved understanding of carbon-climate feedback is needed

Radiative Forcing

Radiative forcing is a concept used to quantify the influence of factors like greenhouse gases, aerosols, and other components on Earth’s energy balance.

It is defined as the difference between the sunlight energy absorbed by Earth and the energy radiated back to space.

Measured in watts per square meter (W/m²), radiative forcing helps scientists evaluate the potential for climate change by determining how these changes in energy balance impact global temperatures.

Positive vs. Negative Radiative Forcing:

• Positive Radiative Forcing: Positive forcing occurs when there’s an increase in energy retained by Earth, which leads to warming. Greenhouse gases like carbon dioxide, methane, and nitrous oxide cause positive forcing by trapping heat within the atmosphere.
• Negative Radiative Forcing: Negative forcing leads to a cooling effect by reducing the amount of energy retained by Earth. This can result from increased cloud cover, aerosols like sulfates, or other particles that reflect sunlight away from Earth’s surface.

Key Contributors to Radiative Forcing:

• Greenhouse Gases: Carbon dioxide, methane, and other gases that trap heat in the atmosphere are the largest contributors to positive radiative forcing and global warming.
• Aerosols and Clouds: Certain aerosols reflect sunlight, contributing to negative forcing, while others, like black carbon, absorb heat, creating a warming effect.
• Land Use Changes: Deforestation and urbanization impact Earth’s albedo (reflectivity) by decreasing vegetative cover, which can alter radiative forcing locally and globally.

Greenhouse gases

Greenhouse gases (GHGs) are atmospheric gases that trap heat from the Sun, preventing it from escaping back into space, and thereby warming the Earth.

This process, known as the greenhouse effect, is critical for maintaining temperatures conducive to life but can lead to excessive warming if GHG concentrations rise significantly.

Major Greenhouse Gases and Their Sources:

• Carbon Dioxide (CO₂): The most prevalent GHG, CO₂ is primarily emitted through burning fossil fuels (coal, oil, and gas) for electricity, heat, and transportation, as well as from deforestation and certain industrial processes like cement production.
• Methane (CH₄): Methane is more effective than CO₂ at trapping heat but exists in smaller concentrations. It is released during the production and transport of coal, oil, and natural gas, as well as from livestock digestion, rice farming, and the decay of organic waste in landfills.
• Nitrous Oxide (N₂O): Emitted from agricultural and industrial activities, as well as from burning fossil fuels and biomass. Nitrogen-based fertilizers are a major source of N₂O, making agriculture a primary contributor.
• Fluorinated Gases (F-gases): These are synthetic gases, including hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF₆), and nitrogen trifluoride (NF₃), used in industrial applications like refrigeration, air conditioning, and electronics manufacturing. They have high global warming potentials (GWP) despite their lower concentrations.
• Water Vapor (H₂O): Though naturally occurring, water vapour is the most abundant greenhouse gas. Human activities indirectly increase its concentration by warming the atmosphere, which holds more water vapour.

Impact on Climate

Increasing GHG concentrations intensify the greenhouse effect, leading to higher global temperatures. This warming contributes to:

• Melting ice caps and glaciers
• Rising sea levels
• Increased frequency of extreme weather events
• Shifts in ecosystems and biodiversity loss

Conclusion

To limit GHG emissions, efforts focus on renewable energy adoption, energy efficiency, deforestation reduction, sustainable agriculture, and technological innovations like carbon capture and storage (CCS).

International frameworks like the Paris Agreement aim to limit global warming by reducing GHG emissions globally through national commitments and cooperative initiatives.

Reducing greenhouse gases is essential to mitigating climate change, protecting ecosystems, and promoting long-term sustainability for future generations.

Frequently Asked Questions (FAQs)

Q. Why is it called a greenhouse gas?

Ans: That’s because the glass walls of the greenhouse trap the Sun’s heat. The greenhouse effect works much the same way on Earth. Gases in the atmosphere, such as carbon dioxide, trap heat similar to the glass roof of a greenhouse. These heat-trapping gases are called greenhouse gases.

Q. What are the main greenhouse gases?

Ans: Several major greenhouse gases that result from human activity are included in international estimates of greenhouse gas emissions:

• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous oxide (N₂O)
• Industrial gases: Hydrofluorocarbons (HFCs) Perfluorocarbons (PFCs) Sulfur hexafluoride (SF₆) Nitrogen trifluoride (NF₃)

Related articles:

• Global warming: Impact on global climate
• Kyoto Protocol, 1997
• Methane emissions

-Article by Swathi Satish