Simon Redfern at Nanyang Technological University, Singapore summarises his co-authored study that says methane emissions are four times more sensitive to climate change than that estimated in the latest IPCC report, which was only published in February 2022. The study follows the observation that, despite the pandemic stalling the world economy, methane emissions have reached new highs. Not because methane emissions have risen but because natural methane removal has decreased, says Redfern. It seems climate change is causing a runaway effect. Wildfires, more common as the world warms, may be slowing down how methane is removed from the atmosphere. Plumes of carbon monoxide from wildfires are using up hydroxyl oxidising agents in the air, leaving less to react with and remove methane.
Eliminating emissions of COā is high up the environmental agenda ā but the world should not lose sight of the threat from methane. There has been a disturbing recent surge in atmospheric methane, which is more thanĀ 25 times more potentĀ as a greenhouse gas over the course of a century than COā.
Anthropogenic methane emissions account for roughly 60% of the total and come mainly from agriculture, in particular beef and dairy farms and paddy fields, as well as from oil and gas wells and coal mines, and from sewage treatment plants and landfills. Methane is also emitted naturally from wetlands, sometimes known as marsh or swamp gas, which makes up the remaining 40%.
The latestĀ reportĀ from the Intergovernmental Panel on Climate Change (IPCC) showed that methane is responsible for around one-third of the estimated 1.5Ā°C of global warming (sulphur dioxide emissions have contributed aroundĀ 0.5Ā°C of cooling, so total warming is now just over 1Ā°C since pre-industrial times), with around half due to COā.
Scientists have puzzled over the fact that methane emissions have not only grown rapidly since 2007, but have been increasing at an even faster rate in just the past two years. Despite the pandemic, when lockdowns and stuttering industrial activity might have dampened many sources, methane emissions increased by theĀ highest amount on recordĀ in 2021. The amount of methane in the atmosphere justĀ keeps on growing.
![](https://energypost.eu/wp-content/plugins/lazy-load/images/1x1.trans.gif)
Methane leaks from oil and gas extraction sites / IMAGE: Calin Tatu/Shutterstock
The past four decades ofĀ temperature and rain dataĀ ā which indicate that the Earth is not only delivering more methane to the atmosphere, but removing less of it ā may hold the answer. InĀ a new study, my colleague Chin-Hsien Cheng and I showed that climate change has increased the rate at which methane accumulates in the atmosphere, trapping more heat and causing the Earth to warm more and faster and, potentially, releasing more methane in a vicious cycle. This indicates that climate change has an effect on methane ā ultimately increasing the amount of it in the atmosphere ā that is up to four times greater than estimates in theĀ latest IPCC report, which was only published in February 2022.
Wildfires gobbling up methane scrubbers
To explain why atmospheric methane keeps growing, we need to understand how the input and removal of methane to and from the atmosphere is balanced. Even if inputs from gas leaks and coal extraction fall, as may be expected during an economic slowdown, the total annual increase can still rise if the removal rate decreases by even more, or becomes less efficient.
Our study suggests increasing methane emissions may be due to unexpected and complex linkages. For example, wildfires, which are becomingĀ more commonĀ as the world warms, may increase atmospheric methane ā not necessarily by adding more, but by slowing down how it is removed from the atmosphere.
The hydroxyl radical, a powerful oxidising agent found in air which is composed of an oxygen and hydrogen atom (ā¢OH), has been called the detergent of the atmosphere because it cleanses the air of harmful trace gases. Methane is removed by an oxidation reaction with hydroxyl radicals, and this reaction is by far the most important way that methane disappears from the atmosphere.
Wildfires burn carbon-rich wood and plant matter and typically generate carbon monoxide (CO) in the smoke. This gas reacts strongly with hydroxyl, becoming oxidised to form COā. On average, a carbon monoxide molecule remains in the atmosphere for about three months before it is oxidised, while methane persists for about a decade. So, plumes of carbon monoxide from wildfires swiftly use up the hydroxyl ādetergentā, leaving less to react with and remove methane.
![](https://energypost.eu/wp-content/plugins/lazy-load/images/1x1.trans.gif)
Fires consume the atmosphereās methane ādetergentā / IMAGE: Artsiom P/Shutterstock
These results are shocking, as they highlight one way the effects of climate change on the Earth system have been underestimated. The world cannot ignore the worrying sensitivity of methane emissions to increasing global temperatures given the strength of methane as a greenhouse gas.
What can we do?
Methane emissions must not go unchecked. But which sources do we have the greatest ability to reduce? Reducing how much methane seeps from landfills and fossil fuel extraction is important. Cutting back on how much beef and dairy products you eat willĀ certainly help too.
But changes in farming practises, such as banning the burning of vegetation, adjusting what cattle are fed and regularly draining rice paddies haveĀ all been identifiedĀ as routes to lowering how much methane reaches the atmosphere.
But to protect the atmosphereās natural ability to remove methane, the world must redouble efforts to slow climate change and its assault on the natural world.
***
Simon Redfern is Professor in Earth Sciences, Nanyang Technological University, Singapore, and Emeritus Professor of Mineral Physics, University of Cambridge
This article is republished fromĀ The ConversationĀ under a Creative Commons license. Read theĀ original article.