1. What is the greenhouse effect?
In a greenhouse, sunlight enters and heat is retained. The greenhouse effect describes a similar phenomenon on a planetary scale but instead of the glass of a greenhouse, certain gases are increasingly increasing the global temperature.
The Earth’s surface absorbs just under half of the sun’s energy, while the atmosphere absorbs 23%, and the rest is reflected back into space. Natural processes ensure that equal amounts of energy come and go, keeping the planet’s temperature stable.
However, human activity leads to increased emissions of so-called greenhouse gases (GHGs), which, unlike other atmospheric gases such as oxygen and nitrogen, are trapped in the atmosphere, unable to escape. off the planet. This energy returns to the surface, where it is reabsorbed.
As more energy goes in than out of the planet, the surface temperature rises until a new equilibrium is reached.
© Apratim Pal
In arid land, severely affected by drought, the two women search for their daily water supply.
2. Why is warming important?
This increase in temperature has long-term, adverse effects on the climate, and affects a multitude of natural systems. Impacts include an increase in frequency and intensity of extreme weather events – including floods, droughts, wildfires and hurricanes – affecting millions of people and causing trillions in economic losses. copper.
“Human-induced greenhouse gas emissions pose a danger to human health and the environment,” said Mark Radka, Head of the United Nations Environment Program.UNEP) Energy and Climate Branch. “And the effects will be more widespread and severe without drastic climate action.”
Greenhouse gas emissions are crucial to understanding and addressing the climate crisis: despite the initial decline due to COVID-19, the latest UNEP Emission Distance Report shows a recovery and forecasts that global temperatures will rise catastrophically by at least 2.7 degrees this century, unless countries do more to reduce emissions.
The report shows that greenhouse gas emissions need to be halved by 2030, if we are to limit global warming to 1.5°C above pre-industrial levels by the end of the century.
Unsplash / Johannes Plenio
Carbon dioxide levels continue to be at record levels, despite the economic downturn caused by the COVID-19 pandemic.
3. What are the main greenhouse gases?
Water vapor is the largest overall cause of the greenhouse effect. However, almost all water vapor in the atmosphere comes from natural processes.
Carbon dioxide (CO2), methane and nitrous oxide are the main greenhouse gases of concern. CO2 stays in the atmosphere for up to 1,000 years, methane for about a decade, and nitrous oxide for about 120 years.
Measured over a 20-year period, methane is 80 times more potent in causing global warming than CO2, while nitrous oxide is 280 times more potent.
4. How does human activity produce these greenhouse gases?
Coal, oil and natural gas continue to power many parts of the world. Carbon is the main element in these fuels, and when they are burned to generate electricity, transport energy or provide heat, they produce CO2.
Oil and gas extraction, coal mining and waste landfills account for 55% of man-made methane. About 32% of human methane emissions come from cows, sheep and other ruminants fermenting food in their stomachs. Composting is another source of agricultural gases, as is rice farming.
Human-caused nitrous oxide emissions are largely derived from agricultural activities. Bacteria in soil and water naturally convert nitrogen to nitrous oxide, but fertilizer use and discharge further accelerate this process by introducing more nitrogen into the environment.
Fluorine gases – such as hydrofluorocarbon, perfluorocarbon and sulfur hexafluoride – are greenhouse gases that do not occur naturally. Hydrofluorocarbon is a refrigerant used as an alternative to chlorofluorocarbon (CFC), which depletes the ozone layer, which has been phased out thanks to the Montreal Protocol. Others have industrial and commercial uses.
While fluorinated gases are much less common than other greenhouse gases and do not deplete the ozone layer like CFCs, they are still very powerful. Over a 20-year period, the global warming potential of some fluorine gases is up to 16,300 times greater than that of CO2.
Unplash / TJK
Wind farms generate electricity and reduce dependence on coal-powered energy.
5. What can we do to reduce GHG emissions?
Transitioning to renewable energy, setting a price on carbon and phasing out coal are all important factors in reducing GHG emissions. Ultimately, stronger emissions reduction targets are needed to maintain the long-term health of people and the environment.
“We need to implement strong policies to support these ambitions,” said Mr. Radka. “We cannot continue to follow the same old path and expect better results. It is necessary to act now”.
During COP26, the European Union and the United States launched the Global Methane Pledge, which will see more than 100 countries set a target of a 30% reduction in methane emissions in the fuel industries, agriculture and waste by 2030.
Despite the challenges, there is a reason to be positive. Between 2010 and 2021, policies were put in place to reduce annual emissions by 11 gigatts by 2030 compared to what has already happened. Individuals can also join the UN’s #ActNow campaign to get ideas for positive climate action.
By making choices that have less harmful impact on the environment, everyone can be part of the solution and influence change. Speaking up is one way to replicate the impact and create change on a much larger scale.
