Greenhouse gases (for example methane) role in the atmosphere is often compared to the roof of a glasshouse. Sunlight enters through the glass roof, and when the radiation is absorbed, the soil and plants heat up. These, in turn, emit thermal radiation, but the glass roof does not allow any of the heat to pass outside.
Naturally, such a definition of the greenhouse effect is just a simplification. To be more specific, the earth absorbs the short-wave radiation from the sun it receives. Then the radiation is converted into heat energy, warming its surface. The planet, in turn, emits long-wave radiation, which escapes into space through the atmosphere. The system is in equilibrium when the flux of incident energy equals the flux of leaving energy. We can thus calculate that the average temperature for our hemisphere would be about -18 degrees Celsius in the absence of an atmosphere. Meanwhile, the average temperature globally is about 14.5 degrees Celsius. In other words, the difference between the effective temperature without the atmosphere and the actual temperature is approximately 33°C. This is precisely how the natural greenhouse effect is measured.
Human activity has changed the atmosphere’s composition. Greenhouse gas increases do not change the amount of solar radiation reaching the earth’s surface, but it prevents the infrared radiation emitted by our planet’s surface from escaping into space.
Greenhouse gases: methane is more harmful, but…
Methane (CH4) is the second most important greenhouse gas in terms of its impact on the climate simply because it can absorb thermal radiation up to 25 times more than carbon dioxide (CO2). However, they have very different life cycles. Methane remains in the atmosphere for around 12 years and CO2 for over a hundred.
Methane is dangerous for the climate, but we can get rid of it quickly by taking decisive action. This is important in the context of global efforts to mitigate global warming.
However, the current trend is that this gas is becoming more and more abundant. As the National Oceanic and Atmospheric Administration reported in early April, the amount of atmospheric methane reached a record high in 2021. According to the release, the rise in atmospheric methane last year was 17 parts per billion, the highest amount of this greenhouse gas recorded since systematic measurements began in 1983.
So, where does it come from, and how can we reduce its emissions?
Methane: where do emissions come from?
Methane is produced naturally by the anaerobic decomposition of organic matter in wetlands and lakes. CH4 is a major component of natural gas and biomethane, the gas from agricultural waste. It is also produced in other biological processes: in soils, in the stomachs of ruminants, in nests built and inhabited by termites. Large amounts of methane are also released during oil, coal extraction, and waste streams, primarily open-air landfills.
Identifying the precise sources responsible for changes in the annual methane increase is complex. The good news is that industrial sources of methane are quite easy to locate and control with current technology. European Commission data indicate that anthropogenic methane emissions account for about 60 per cent of all gas in the atmosphere. In the EU, 53% of such emissions are reported to come from agriculture, 26% from waste and 19% from energy.
Agreement to reduce emissions
More than 111 countries have already pledged to reduce anthropogenic methane emissions. During the COP26 conference, dozens of them joined the Global Methane Pledge initiated by the US and the EU. The aim is to reduce the release of this gas by at least 30% by 2030 through technological innovation and incentives, and partnerships with farmers.
The agreement was reached, among others, by Portugal, Malaysia, Kuwait, Denmark, Canada and Estonia. Poland was not among the signatories.
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