*[Enwl-eng] Why methane is so scary

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      Rising levels of methane in the atmosphere may be a sign that a great 
transition in Earth’s climate has begun. That’s the scary conclusion of new 
research that applies a geological perspective to this aspect of the climate 
crisis.

      You’re reading the Imagine newsletter – a weekly synthesis of academic 
insight on solutions to climate change, brought to you by The Conversation. 
I’m Will de Freitas, energy and environment editor, covering for my 
colleague Jack Marley, who is on holiday but probably still worrying about 
geological perspectives on the climate crisis. This week, we’ll focus not on 
carbon dioxide but on the other main greenhouse gas: methane.

      There’s less methane in the atmosphere than CO₂ and it doesn’t last as 
long, but it is much more potent as a greenhouse gas. After CO₂, methane is 
the second biggest driver of global warming and no other gas comes close.

      But over the past decade or two, methane has been rising fast. Here’s 
Euan Nisbet, an earth scientist at Royal Holloway University of London and 
author of the new study:

      “Imagine accelerating a car with your foot flat down. The car speeds 
up but eventually air resistance equals engine power and the car hits 
maximum speed. In 1999, it looked like methane had reached a similar 
equilibrium between its sources and sinks. Then in late 2006, the amount of 
methane in the air climbed fast. Even more unexpectedly five years later, 
the rate of growth sped up again. During the 2020s the growth rate has 
become yet faster, faster even than during the peak of gas industry leaks in 
the 1980s.”

      Nisbet says this growth is likely down to livestock, landfills and, 
most significantly, wetlands.

      In fact, a group of researchers, led by Judith Rosentreter of Yale, 
published research showing aquatic ecosystems are responsible for half of 
global methane emissions. This includes natural, human-created and 
human-impacted aquatic ecosystems. As they put it, everything “from flooded 
rice paddies and aquaculture ponds to wetlands, lakes and salt marshes.”

      Here’s how it works: “Most of the methane emitted from aquatic 
ecosystems is produced by micro-organisms living in deep, oxygen-free 
sediments. These tiny organisms break down organic matter such as dead algae 
in a process called "methanogenesis”. This releases methane to the water, 
where some is consumed by other types of micro-organisms. Some of it also 
reaches the atmosphere.“

      Nisbet says an increase in these emissions is one impact of climate 
change: "increasing rainfall has made wetlands wetter and bigger while 
rising temperatures have boosted plant growth, providing more decomposing 
matter and so more methane.”

      Rosentreter and colleagues also point out that human-impacted aquatic 
ecosystems – rivers polluted with fertiliser, aquaculture farms, rice farms 
and so on – “increase the amount of organic matter available to produce 
methane, which causes emissions to rise”. They say that “globally, rice 
cultivation releases more methane per year than all coastal wetlands, the 
continental shelf and open ocean together.”

      There are solutions. Rosentreter and co suggest restoring salt marshes 
and mangroves, reducing the amount of fertiliser washing into rivers and 
wetlands (which leads to algal blooms and more methane when that algae is 
broken down), and “managing aquaculture farms and rice paddies so they 
alternate between wet and dry conditions”.

      Nisbet also cites “plugging leaks in the oil and gas industry, 
covering landfills with soil, reducing crop-waste burning”.

      There should be some relatively easy wins, as just 13% of human-made 
emissions from agriculture, energy and waste are properly regulated, 
according to a study published earlier this year by Maria Olczak at Queen 
Mary University of London.

      “Within almost every sector there are major methane sources that have 
been largely overlooked”, she writes. “These include the digestive gases of 
cows and other livestock, methane from the ventilation shafts of coal mines, 
high-emitting sources in the oil and gas sector (so called super-emitters), 
and from abandoned mines and oil and gas wells.”

      Fixing those leaks from the oil and gas industry could actually pay 
for itself, says Jim Kane of Rice University in the US. He cites a report 
that suggests “a one-time investment of $11 billion would eliminate roughly 
75% of methane leaks worldwide.” Investments in infrastructure and repairs 
would “not only reduce warming”, he writes, “but they would also generate 
profits for producers”.

      There are more leftfield solutions too, such as feeding seaweed to 
cows. “The native Australian red seaweed Asparagopsis has been shown to 
markedly reduce methane production in cattle, when added to their diet”, 
says Catriona McLeod from the University of Tasmania’s Fisheries and 
Aquaculture Centre.

      But back to the really scary part. In Nisbet’s new study, he looked at 
periods over the past few million years when Earth’s climate has flipped 
from ice age to warmer interglacial periods. He notes that: “With each flip 
from a glacial to an interglacial climate there have been sudden, sharp 
rises in atmospheric methane, likely from expanding tropical wetlands.”

      His worry is that something similar is happening now. The rapid growth 
of methane since 2006 is “comparable with records of methane from the early 
years of abrupt phases of past [shifts to interglacial conditions], like the 
one that warmed Greenland so dramatically less than 12,000 years ago.”

      “In the past, this took Earth out of stable ice age climates and into 
warm inter-glacials. But we are already in a warm interglacial. What comes 
next is hard to imagine”.

      When you spend your days editing the latest academic research on 
climate change it can be tempting to zone out a bit, to not let individual 
bits of bad news affect you too much. But this piece really shook me. My 
colleague Jack, who worked on the story, described it as the scariest he had 
ever edited.

      Nisbet’s article is our most read of 2023. If you’re one of the many 
people who have already read it, perhaps you could share it with someone 
else?

      - Will de Freitas, Energy and environment editor


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      Rising methane could be a sign that Earth’s climate is part-way 
through a ‘termination-level transition’

      The last time methane in the air rose so fast, Greenland warmed by 
10°C within decades.

      Read more


       Half of global methane emissions come from aquatic ecosystems – much 
of this is human-made

      Scientists previously underestimated aquatic methane emissions. We 
must use this new information to stop methane derailing our attempts to 
stabilise the Earth’s temperature.

      Read more

       Methane must fall to slow global heating – but only 13% of emissions 
are actually regulated

      Major sources, like oil and gas 'super-emitters', are almost entirely 
neglected by regulations.

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       Why fixing methane leaks from the oil and gas industry can be a 
climate game-changer – one that pays for itself

      130 countries have signed a pledge to cut methane emissions by 30%. 
Success could have a swift impact on global warming.

      Read more

       Can seaweed save the world? Well it can certainly help in many ways

      Seaweed is in the spotlight for so many reasons. It all sounds too 
good to be true. So can this wonder weed live up to expectations and fulfill 
its promise to save us from ourselves?

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      From: Imagine newsletter
      Sent: Wednesday, August 23, 2023 8:02 PM
      Subject: Why methane is so scary

 
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