Global warming goes way beyond carbon

Other villains in the atmosphere equally dangerous


September 3, 2021

/ By / Paris

Global warming goes way beyond carbon

Methane’s global warming potential is far higher than that of carbon, with oil, gas, and coal mining and transport accounting for 20 pc of emissions.(Photo: Chris LeBoutillier/Unsplash)

Though it has been in the focus ever since global warming and climate change tracking began, carbon dioxide, which is the favourite whipping boy of climate activists, is not the only cause of global warming. There are other noxious gases which add up to the spike in temperatures across the world.

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With over 40 gigatonnes released in the atmosphere in the year 2020, which was supposed to be a low-activity year due to the lockdowns and travel restrictions across the globe, carbon dioxide is of course the most high-profile and most talked about reason behind the global warming and climate change that has gripped the entire world.

And over the decades as awareness about the unprecedented phenomenon has spread, carbon dioxide has almost exclusively been identified as the villain of the piece and that the magic pill to the current crisis lay in cutting carbon emissions. There is no denying that carbon dioxide is extremely harmful to the global climate and is responsible in large part for the warming of the globe that has been on since the industrial revolution three centuries ago. But carbon has become an easy target for both, the climate activists and businesses, due to several reasons.

First is that it is a high visibility gas as it is released from several human actions and is all pervasive around the globe. Be it transport, power or construction, carbon dioxide is one of the most noxious by-products of the process. Also, it is released in huge quantities, the largest of all gases causing global warming. And household items like the fossil fuels account for an overwhelming chunk of carbon emissions. As a result, the amount of carbon dioxide present in the atmosphere has risen to an annual average of 412 parts per million – 48 pc higher than before the industrial revolution.

While the carbon emissions are a serious issue and need to be cut drastically if global warming has to be slowed, but focusing just on carbon itself is also no solution to global warming. For, besides carbon dioxide, there is a multitude of other gases that are called greenhouse gases or the gases that cause global warming and many of them are far more lethal than carbon. These include gases called F-gases or fluorinated gases such as HCFCs and HFCs that are used in several industries including solvent, foams and cooling and chilling industries – notably the ubiquitous refrigerators and air conditioners. As global warming rises, the demand and the need for both domestic appliances is set to explode, adding to the burden on a saturated atmosphere. Though these gases are released in minuscule quantities as compared to carbon, their global warming potential is up to 35,000 times that of carbon. Together, they account for nearly 3 pc of the total global warming.

None of these gases existed before the human intervention and hence are even more dangerous to the environment. In 2016, 150 nations had met in Rwanda and signed the Kigali Amendment promising to cut HFC consumption by 80 pc by the year 2047. However, as in the case of other GHGs, emissions of these gases are also rising fast across the globe for various products such as aerosols and cooling systems and the Kigali Amendment target is likely to be missed with a wide margin, if things go on as currently.

But beyond F-gases, another danger to the atmosphere comes in the form of methane, the second-most pervasive greenhouse gas after carbon dioxide. Methane is produced by a variety of activities with agriculture, livestock raising, human and animal wastes, landfills, energy use, peat soils and biomass burning, all contribute to methane emissions. According to NASA, from 2007-17, wetlands contributed 30 pc of global methane emissions, with oil, gas, and coal mining and transport accounting for 20 pc. Agriculture, including flatulence and belching by ruminating animals and their manure, made for 24 pc of total methane emissions and landfills led to 11 pc.

As in CO2, methane emissions, too, have been rising rapidly across the globe. As per Global Methane Budget, in 2017, total global emissions were just short of 600 million tonnes, about 9 pc more than the average in the years 2000-2006. By the end of 2019, the concentration of methane in the atmosphere reached around 1875 parts per billion (ppb) over 2.5 times the levels before industrial revolution. Globally, the largest emitters of methane include China, the United States, Russia, India, Brazil, Indonesia, Nigeria, and Mexico. These nations by themselves are believed to be responsible for nearly 50 pc of the global methane emissions due to human activities.

While at 600 million tonnes per year, methane emissions pale in front of the 32 Giga tonnes of CO2, but methane’s global warming potential is far higher than that of carbon. Scientists estimate that over a period of 20 years, per unit of mass, methane is 84-86 times stronger than CO2 in global warming and up to 34 times more powerful over 100 years. As a result, methane is responsible for a fifth of the total global warming as against 65 pc for CO2 emissions through fossil fuel and industries.

Also, methane is often a precursor to ozone, which itself is another greenhouse gas and hence despite the shorter life of methane as compared to carbon, its impact in global warming is much higher, per unit, and methane emissions also need to be curbed if humanity is to achieve its stated goal of arresting global warming.

Besides methane, there are some other gases that lead to greenhouse effect on the planet. These include nitrous oxides, mainly released due to fertilisers and fossil fuel burning. For global warming, N20 is about 300 times as lethal as CO2 and it lasts for about 120 years in the atmosphere. As in all other GHGs, emissions of N2O have also risen sharply over the past 30 years. Its global concentration levels increased from 270 parts per billion (ppb) in 1750 to 331 ppb in 2018 and the growth has been the quickest in the past five decades because of human emissions. Nitrous oxide accounts for 6.2 pc of the total greenhouse gas effect in the world.

While dealing with carbon remains the top priority, it is time to take these gases also into account and plan limiting their production and emissions as well.



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