Atmospheric methane concentration at record levels

The 2019 levels are the highest since record-keeping began in 1983
Atmospheric methane concentration at record levels

Global atmospheric concentration of methane has hit an all-time high — to 1,875 parts per billion (ppb) in 2019 from 1,866 ppb in 2018 — according to a new preliminary estimate released by the United States National Oceanographic and Atmospheric Administration (NOAA).

Methane is a powerful greenhouse gas — its potential to cause global warming is over 25 times that of carbon dioxide.

Not only is the 2019 figure the highest since record-keeping began in 1983, the increase during the year was the second-largest single-year leap in over two decades.

While these preliminary numbers will be subject to further analysis before final estimates are released in November, the sheer magnitude of the increase, as well as the fact that the new data merely highlighted existing trends, is a cause of concern.

In a paper published in 2019, NOAA scientists found that the increase in methane emissions between 2013 and 2018 was 50 per cent higher than in the previous five-year period. They had argued that methane emissions would pose a massive challenge to the achievement of the Paris Agreement’s temperature goals.

Wetlands are a key source of atmospheric methane. Warm climate increases the efficiency of microbes that convert organic matter into methane, the 2019 paper stated.

Such climate ‘feedbacks’ are largely beyond human control and are expected to intensify with increasing temperatures.

But there are also anthropogenic sources of methane — leaks from global oil and gas production system are a key source.

Grant Allen, an atmospheric physicist at the University of Manchester, told the Independent that “if we were to stop all natural gas use tomorrow we could reverse this”, as rising methane emissions were the sum total of natural and anthropogenic activity.

A recent study published in Nature found that methane leaks from the fossil fuel industry were underestimated by at least 40 per cent. And the Trump administration rolled back regulations on such leaks, a key polluter, in the US.

Even as some are celebrating the potential fall in global carbon dioxide emissions due to decreased economic activity in the wake of the novel coronavirus disease (COVID-19) pandemic, a report from the International Energy Agency (IEA) has warned that declining revenues in oil and gas industry may disincentivise fixing of leaks.

This, according to the IEA, would be tragic as reducing emissions from oil and gas system remains the ‘lowest of low hanging fruit’ in mitigating climate change; many measures to tackle such leaks would be zero-cost options.

Enteric fermentation in livestock such as cows and sheep are another key source of anthropogenic methane emissions.

Drew Shindell, a climate scientist at Duke University, told Scientific American that the most straightforward measure consumers could adopt to reduce global methane emissions would be reduced consumption of beef and dairy, which may also come with significant health benefits.

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