Livestock and fossil fuels could increase global heat in 4C | Climate change

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Livestock and fossil fuels have pushed global emissions of potent methane from greenhouse gases to the highest level ever, putting the world on track for dangerously high heat levels from 3C to 4C.

Since 2000, odorless and colorless gas emissions have increased by more than 50 million tonnes per year, equivalent to 350 million cars or twice the total emissions of Germany or France, according to the latest study by Methane Budget produced by a global team of scientists.

The results, published in Earth System Science Data and Environmental Research Letters, show that more than half of the methane in the atmosphere now comes from human sources. Of this share, livestock, agriculture and landfills account for about two-thirds, while the fossil fuel industry, made up of oil, gas and coal, makes up the rest.

Methane comes just behind carbon dioxide for its contribution to global warming; the gas is released in much smaller amounts but is 28 times more powerful at trapping heat over a period of 100 years.

In 2017, the last year for which data is available, the planet’s atmosphere absorbed nearly 600 million tonnes of methane, up 9% from the first years of the century when concentrations were relatively stable.

Rob Jackson, professor at Stanford University School of Earth, Energy & Environmental Sciences, California, chairs the Global Carbon Project and edited one of the articles. He said human activities since the industrial revolution had increased the amount of methane in the atmosphere by 2.6 times, compared to 1.7 times for carbon dioxide.

Methane being more powerful than CO2 and its shorter lifespan in its climate effects, it should be at the center of emission reduction efforts, said Jackson.

« CO2 is still the beast to kill, but the second most significant is methane warming. Acting aggressively on methane can save us time to fight CO2 and shave half a degree from the maximum temperature, “he said. “I am optimistic about the opportunities to find super methane emitters using drones and satellites. But it is more difficult to reduce the emissions of a billion burping cows and a billion sheep, where food choices and manure management are important. “

The change is markedly different depending on the sector and location. Methane emissions from agriculture increased by almost 11% during the study period, while those from fossil fuels increased by 15%.

At the regional level, the largest increases – from 10 to 15 million tonnes per year – were recorded in Asia, Africa and Oceania, mainly due to agriculture. In the United States, most of the increase of 4.5 million tonnes over the past decade has been attributed to hydraulic fracturing and other forms of drilling, pipeline and consumption of petroleum and gas.

Europe was the only continent to register a decline thanks to strong measures to reduce manure and industrial emissions. The Arctic has also seen little change, suggesting that fears of methane release from melting permafrost were not realized until 2017.

The authors said there could be no global stabilization of methane emissions unless governments took swift action.

Marielle Saunois, of the University of Versailles Saint-Quentin-en-Yvelines, France, who was the main author of the article in Earth System Science Data, said that there were solutions that did not necessarily require a reduction in consumption. “Policies and better management have reduced emissions from landfills, manure and other sources here in Europe. People also eat less beef and more poultry and fish, ”she said.

Coronavirus blockages would have had less impact on methane emissions than on CO2 and nitrogen dioxide, since agriculture was not as affected by the measures as transport and industry.

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