Back in 2020 I made a video focusing on research into levels of global atmospheric methane during
the pandemic lockdown. Scientists already knew there were various sources of methane gas on the
planet and it was kind of assumed that, what with the human species more or less shutting
down for a year, those methane levels would take a bit of a dip, in the same way that
we saw a reduction in carbon dioxide emissions over the same period. So it came as a bit of a
surprise when the researchers plotted their graphs and found the trend line moving in
completely the opposite direction. Methane was on the up, and no one really knew exactly why.
That prompted a deeper dive into the data from all over the world in an attempt to find the
cause of the phenomenon. In December 2022 a new paper was published in the online journal
Nature that shed some light onto the puzzle, and the answer doesn't look all that encouraging!
Hello and welcome to Just Have a Think. So what's all this kerfuffle about methane levels then? Well
as I'm sure you know methane is a greenhouse gas just like carbon dioxide only way more
potent. As a quick recap, greenhouse gases have molecular structures that interact with infrared
light leaving the surface of our planet on its way back out into space. Those molecules can
absorb a photon of infrared light and use that energy to vibrate their atoms. In the case of
CO2 it's the two oxygen atoms either side of the carbon atom that do the vibrating. That
very slightly warms up other molecules in the air like nitrogen and oxygen. Eventually the photon
escapes but there's no guarantee which direction it'll be pointing in when it does. It might carry
on its journey back out of our atmosphere, or it might get bounced back down to Earth again.
A methane molecule is one carbon and four hydrogen atoms. Those four hydrogen atoms can vibrate in
all sorts of different combinations and for reasons that are very much outside the scope
of this video that molecular structure means that over a 20-year time scale methane is 84
times more effective at trapping heat than CO2. It does get broken down much more easily though, as a
result of interactions with things called hydroxyl radicals in the air. So on a 100-year time scale,
which is the time scale used by this IPCC global warming potential chart, methane is only about 28
times more potent than CO2. That's still not ideal though is it? Especially if we're trying to reduce
overall atmospheric greenhouse gas levels by 45 percent within the next seven years.
So where was all the extra methane coming from then? Well, to answer that question
the boffins had to look at all the usual suspects, including production emissions
from oil and gas as well as fugitive emissions from their pipelines, plus emissions from the
waste treatment industry and from agriculture, as well as biological processes in wetlands,
and of course thawing permafrost in the Arctic Circle. What the researchers found
was that as the global human machine ground to a halt methane emissions that were directly
attributable to human activities did actually go down as you'd expect. So that's the reduced
use of fossil fuels and lower agricultural and waste treatment activity that I just mentioned.
The team also registered a significant reduction in air pollutants like hydrocarbons,
carbon monoxide and nitrogen dioxide, which was something that was widely celebrated at the time
and that we covered here on the channel in these pretty astonishing before and after photographs
from some of the most famously polluted locations on Earth. It was undoubtedly fantastic news for
the people and animals that lived in those areas, but as I'm sure you've already guessed, there was
a much more sinister flip-side to this positive environmental clean-up. No doubt many of you
good folks out there will know about the slight dimming effect that air pollution has in those
locations. It keeps local atmospheric temperatures artificially lower than they would otherwise be.
With the particulates vastly reduced, more sunlight was able to get through to the
surface and, as a result, we saw warmer and wetter conditions in the northern hemisphere during 2020.
Those conditions just happen to be perfect for causing methane to bubble up from vast
areas of wetland which potentially sets up one of those extremely annoying feedback loops that
I occasionally refer to. The warmer and wetter it gets the more methane seeps out of the ground,
making the atmosphere warmer and therefore wetter, because for every one degree Celsius of warming
the atmosphere can hold on to seven percent more moisture, which means more methane released and so
on and so on. But on top of that it turns out that those pollutants also contribute significantly
to the creation of hydroxyl radicals in the atmosphere, which are those methane chompers that
I mentioned earlier. Hydroxyls are extremely fleeting and exist in tiny quantities, but
nevertheless they convert about 85 percent of all atmospheric methane into water and carbon dioxide.
Analysis showed that atmospheric hydroxyl concentrations were about 1.6 percent lower
in 2020 compared to the previous year mainly as a result of the huge global reduction
in nitrogen oxide or NOx emissions which come predominantly from the burning of fossil fuels.
When the researchers simulated the effects of these fluctuations they found that a 20% reduction
in NOx emissions could result in a doubling in the speed of atmospheric methane accumulation.
So that seems to have gone some way towards helping our scientists understand the unexpected
rise in methane levels in 2020. What the research couldn't explain is why methane levels continued
to rise even after we came out of lockdown and polluting air particulates returned to their
normal asphyxiating levels in cities around the world. Atmospheric methane concentrations actually
hit a new record in 2021, hitting more than 1900 parts per billion, as we discovered in a recent
video on the subject. That means methane levels are now 2.6 times higher than they
were just prior to the Industrial Revolution. The paper's authors suggest that lower nitrogen oxide
emissions from transport in the United States and India combined with generally less air travel as a
result of ongoing pandemic restrictions may have played a part, but in a recent interview with
Phys.org online professor of Earth Sciences at Royal Holloway University, Ewan Nisbet,
said "As yet we don't have detailed studies, but something very dramatic seems to be going on."
And there are quite a few climate researchers who think that that very dramatic thing may well be
the waking of a potentially catastrophic sleeping giant up in the Arctic Circle.
We looked at the effects of thawing permafrost a few months ago in a video featuring this
beautifully Illustrated interactive website created by the graphics team at Reuters. You
can click up there to jump back to that video and I'll leave a link in the description section to
the interactive Reuters site, which is well worth a look if you get a chance.
About two-thirds of the circumference of the Arctic Circle is basically Russia Canada and
Alaska, much of which is covered in permafrost that for thousands of years has locked up more
than three times as much carbon as all the trees on the planet. But the Arctic is warming at least
three times faster than the global average and that's causing permafrost to start thawing out in
many regions, which means all the infrastructure like roads and houses that's been built on top of
it is now subsiding. That's a big enough challenge in itself. According to a 2018 study in Nature,
69 percent of all Arctic infrastructure could be at risk of damage by mid-century
due to thawing permafrost, and those areas have more than 3.6 million inhabitants.
But it's the methane release that really has the scientists worried. Permafrost contains organic
matter from dead plants and animals and as it thaws out microbes start digesting the newly
available material, and that process releases massive quantities of methane into the atmosphere.
This NASA article, published in September 2022, took a look at the phenomenon of Thermokarst
Lakes in Alaska which form as permafrost thaws out. The state's got millions of these things,
most of which are extremely old and which long ago released any trapped methane. But newer lakes are
now forming more and more rapidly every year. NASA is conducting a research program that they call
the Arctic Boreal Vulnerability Experiment or ABOVE, in an attempt to gain a greater
understanding of how these lakes form and how they affect the atmosphere. It seems that permafrost
thaw can occasionally form chimneys under lakes that allow methane and other gases that were
previously trapped deep underground to escape. Those gases bubble up to the Lake's surface and
release into the atmosphere. As the lake freezes in the winter the gas bubbles can prevent ice
from forming and create pockets of open water that continue emitting methane throughout the season.
Way over in the Laptev Sea and the East Siberian Arctic Shelf methane comes in the
form of underwater hydrates. The water here would normally be at or below freezing point keeping
the subsurface permafrost nice and permanent, but in 2020 Siberian temperatures averaged five
degrees warmer than normal between January and June and the Arctic Shelf waters were several
degrees above freezing for long periods during the year. During that period the International Shelf
Study Expedition analyzed methane hydrates at six monitoring points over a slope area 150 kilometres
long and 10 kilometres wide across the shelf and regularly measured surface methane concentrations
up to eight times higher than normal. They're estimated to be around 1400 billion tons of
carbon locked up in subsea hydrates and the United States Geological Survey lists Arctic hydrate
destabilization as one of the four most serious scenarios for climate change. So perhaps our
little global experiment in switching off human induced pollution and greenhouse gas emissions
during the COVID pandemic inadvertently provided yet another nudge towards a climate tipping
point that apparently continued to accelerate through 2021 and may still be picking up pace
right now. That doesn't mean we shouldn't still be straining every sinew to reach the ambitious
greenhouse gas emissions reductions targets set out by the IPCC though. Using the COVID blip as
yet another excuse for inaction would be a very bad idea indeed. Climate scientists and the vast
majority of global political leaders now agree that moving away from fossil fuel combustion
as fast as possible is absolutely essential to the long-term habitability of our planet.
But unexpected consequences like those we've looked at today will need to be confronted and
factored into the overall mitigation strategy. Now I know you've got your views on this one
so why not jump down to the comment section below and leave your thoughts there. That's
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