Although it is the best known and second most common greenhouse gas, carbon dioxide is only one of the gases we have to deal with. When sunlight reaches Earth, the surface of the planet absorbs some of the energy of that light and reflects it back as infrared waves, which we feel as heat, writes euronews.com.
If left unchecked, these waves make their way up into the atmosphere and into space. Atmospheric gases such as oxygen and nitrogen do not interfere with their journey. But others absorb energy at the right wavelength to absorb that infrared energy and re-radiate it.
About half of this energy escapes into space, but the other half returns to Earth as heat. This is known as the greenhouse gas effect, because greenhouse gases such as carbon dioxide reduce the Earth's ability to cool by radiating energy back into space. This is the cause of global warming.
Although it is the best known and second most abundant greenhouse gas, carbon dioxide is only part of the equation. Many other gases are also regulated by the UN Framework Convention on Climate Change and the EU with emissions monitoring and reporting requirements.
The most famous greenhouse gas is carbon dioxide (CO2)
Carbon dioxide is part of the natural cycle that keeps the Earth habitable. It helps act as a blanket, trapping heat to keep temperatures in a range that allows life to thrive. Too much of it, however, disturbs the delicately balanced ratio of gases. Turbocharged by our burning of fossil fuels, carbon dioxide is now the single largest contributor to the climate crisis.
The amount of CO2 in the Earth's atmosphere has increased by 50 percent in less than 200 years. The insulating blanket has grown too thick, overheating the Earth. And it's still growing at an alarming rate. Although other gases have a much more powerful heat-trapping ability per molecule, they are simply not as abundant in the atmosphere. CO2 is also quite persistent. Once it enters the atmosphere, 40 percent will remain for 100 years, 20 percent will remain for 1000 years, while the last 10 percent will take 10 years to reverse.
The global warming potential (GWP) of each greenhouse gas is measured by comparing it to carbon dioxide, which is given the number one. The greater the GWP, the more that gas warms the Earth compared to CO2 over that time period.
Methane emissions are a growing concern
This powerful greenhouse gas is 30 times more powerful than carbon dioxide. Scientists say it is responsible for about a third of the global warming we feel today. And world leaders are more than aware of the threat it poses. At COP26 in Glasgow in 2021, more than 100 countries pledged to reduce methane emissions by 30 percent by 2030.
Approximately 60 percent of all methane emissions are the result of human activity. The biggest sources are agriculture, fossil fuels and the degradation of waste in landfills. There are other cycles in motion that increase emissions from natural sources. Global warming, for example, is causing wetlands to release more of their stored carbon in the form of methane.
As the second largest source of human emissions, the energy sector is an important target for methane reduction pledges. If all the commitments currently made by countries and companies were implemented and achieved in full and on time, it would reduce methane emissions from fossil fuels by 50 percent by 2030. But if you look at those with detailed policies or regulations planned or already in place, they will reduce methane from oil and gas alone by 20 percent before the end of the decade.
In May this year, the EU adopted its first rules for measuring, reporting and verifying emissions of this greenhouse gas. From 2025, energy operators will face requirements to provide mitigation measures, such as detection and remediation of methane leaks, as well as measurement of emissions at source.
Efforts to address nitrous oxide emissions are controversial
Nitrous oxide molecules can remain in the atmosphere for an average of 121 years before being removed by some kind of sinking or destroyed by chemical reactions. The warming potential of this gas is about 265 times that of carbon dioxide. Although it is present in the atmosphere as part of the Earth's natural nitrogen cycle, approximately 40 percent of all N2O emissions come from human activities.
Three-quarters of this comes from agricultural soil management, including the application of synthetic and organic fertilizers. The rest comes from a mix of activities such as land management (burning forests and grasslands), transport and wastewater treatment.
Efforts to limit this greenhouse gas in the EU have proved controversial among farmers. In July, the EU approved a €105 million subsidy scheme to encourage Dutch livestock farmers to move away from conservation areas in a bid to tackle nitrogen emissions. This came after widespread farm protests where the Farmer-Citizen Movement (BBB) became part of a new right-wing coalition in the Netherlands.
Fluorinated gases come almost entirely from human activity
Fluorinated gases or F-gases are artificial substances that contain fluorine. They have no significant natural sources and come almost entirely from human-related activities. Their GWPs range from thousands to tens of thousands, trapping significantly more heat than CO2. These powerful greenhouse gases have a range of everyday applications from refrigeration and heat pumps to fire protection, insulation and aerosol propellants.
They were originally developed as a replacement for ozone-depleting substances, which are being phased out under an international agreement called the Montreal Protocol.
F-gases can also have much longer lifetimes in the atmosphere, with some persisting for thousands of years. Many are removed only when they are destroyed by sunlight in the upper atmosphere. There are four main categories of F-gases: hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride.
Hydrofluorocarbons (HFCs)
It is the largest subgroup of F-gases, making up over 90 percent of all emissions. They are commonly used in air conditioning, refrigeration and building insulation. These gases are of great concern because, although they currently account for only about 2 percent of total greenhouse gases, their GWP is tens of thousands of times greater than carbon dioxide. The most common HFC warms the planet 3790 times more than CO2 over a 20 year period. HFC use is growing at an average rate of 10 percent each year. These gases are mostly contained in the equipment and escape as a result of poor maintenance, wear and tear or at the end of the product's life cycle.
Perfluorocarbons (PFCs)
Although the total emissions of PFCs are relatively small, they are extremely potent with a GWP almost 10 times that of carbon dioxide. They are produced as a by-product of aluminum production and are used in the electronics industry to make semiconductors, a material that can conduct electricity under certain conditions. These gases were also previously used to soundproof windows. PFCs can also persist in the atmosphere for thousands of years because there are no significant sinks for them.
Sulfur hexafluoride (SF6)
The GWP of SF6 is 23, making it the most potent greenhouse gas assessed by the Intergovernmental Panel on Climate Change. This colorless, odorless gas is primarily used to insulate power lines. This means that our rapidly electrifying world has led to a rapid increase in atmospheric concentrations of SF500 this century.
New F-gas regulations in the EU have tightened the timelines for phasing out gases such as SF6. But they don't go as far as the original proposals, which sought to phase out this gas in all new switchgear - electrical transmission equipment. Scientists say the biggest source of SF6 right now is China, which has offset reductions elsewhere in the world over the past 10 years.
Nitrogen trifluoride (NF3)
NF3 has a GWP 17 times that of carbon dioxide over a 200-year period. It is mainly released during the manufacturing process of electrical equipment such as LCD panels, solar panels and chemical lasers. The average lifetime of this gas in the atmosphere is about 100 years. And the rapid development of the consumer electronics market has led to a huge growth in its use. But of the NF550 used in electronics manufacturing, only 3 percent is thought to leak into the atmosphere, with the rest destroyed in the process.
Annual reporting of production, consumption and emissions of NF3 wastes by major producers is required in many industrialized countries in response to observed atmospheric growth and the international Kyoto Protocol.
Water vapor is the most abundant greenhouse gas on Earth
Water vapor is present wherever there is measurable humidity and makes up about 80 percent of the total greenhouse gas mass in the atmosphere. It is responsible for about half of the total greenhouse gas effect. But it doesn't actually cause global warming and is part of the vital process that traps heat in Earth's atmosphere to keep the planet habitable. Water vapor also has a short cycle, lingering for an average of 10 days before becoming part of a weather event and falling back to the surface. This means that it cannot accumulate in the same way as a gas like carbon dioxide. But as global warming worsens, water vapor plays a role in the cycle that warms the planet above normal.
Emissions such as CO2 cause global air temperatures to rise. Warm air holds more moisture and also increases evaporation. For every degree Celsius the temperature rises, the laws of thermodynamics say that the water vapor in the atmosphere can increase by 7 percent.
Increasing concentrations of water vapor in the atmosphere lead to further global warming. And so this cycle, known as the stratospheric water vapor feedback, continues. It does not cause this change, but instead is a consequence of the changes caused by human-made greenhouse gases, which then amplify their effects.
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