"Given the contentiousness of this topic in the scientific community, it may
even be contentious for me to say that there is no scientific consensus on
the sources of current methane emissions or the potential risk and timing of
significant methane releases from either surface and subsea permafrost. A
recent attempt at consensus on methane risk from melting surface
permafrost concluded methane release would happen over centuries or
millennia, not this decade (Schuur et al. 2015). Yet within three years that
consensus was broken by one of the most detailed experiments which
found that if the melting permafrost remains waterlogged, which is likely,
then it produces significant amounts of methane within just a few years
(Knoblauch et al, 2018). The debate is now likely to be about whether other
microorganisms might thrive in that environment to eat up the methane –
and whether or not in time to reduce the climate impact.
The debate about methane release from clathrate forms, or frozen methane
hydrates, on the Arctic sea floor is even more contentious. In 2010 a group
of scientists published a study that warned how the warming of the Arctic
could lead to a speed and scale of methane release that would be
catastrophic to life on earth through atmospheric heating of over 5 degrees
within just a few years of such a release (Shakhova et al, 2010). The study
triggered a fierce debate, much of which was ill considered, perhaps
understandable given the shocking implications of this information (Ahmed,
2013). Since then, key questions at the heart of this scientific debate (about
what would amount to the probable extinction of the human race) include
the amount of time it will take for ocean warming to destabilise hydrates on
the sea floor, and how much methane will be consumed by aerobic and
anaerobic microbes before it reaches the surface and escapes to the
atmosphere. In a global review of this contentious topic, scientists
concluded that there is not the evidence to predict a sudden release of
catastrophic levels of methane in the near-term (Ruppel and Kessler, 2017).
However, a key reason for their conclusion was the lack of data showing
actual increases in atmospheric methane at the surface of the Arctic, which
is partly the result of a lack of sensors collecting such information. Most
ground-level methane measuring systems are on land. Could that be why
the unusual increases in atmospheric methane concentrations cannot be
fully explained by existing data sets from around the world (Saunois et al,
2016)? One way of calculating how much methane is probably coming from
our oceans is to compare data from ground-level measurements, which are
mostly but not entirely on land, with upper atmosphere measurements,
which indicate an averaging out of total sources. Data published by
scientists from the Arctic News (2018) website indicates that in March 2018
at mid altitudes, methane was around 1865 parts per billion (ppb), which
represents a 1.8 percent increase of 35 ppb from the same time in 2017,
while surface measurements of methane increased by about 15 ppb in that
time. Both figures are consistent with a non-linear increase - potentially
exponential - in atmospheric levels since 2007. That is worrying data in
itself, but the more significant matter is the difference between the increase
measured at ground and mid altitudes. That is consistent with this added
methane coming from our oceans, which could in turn be from methane
hydrates.
This closer look at the latest data on methane is worthwhile given the
critical risks to which it relates. It suggests that the recent attempt at a
consensus that it is highly unlikely we will see near-term massive release of
methane from the Arctic Ocean is sadly inconclusive. In 2017 scientists
working on the Eastern Siberian sea shelf, reported that the permafrost
layer has thinned enough to risk destabilising hydrates (The Arctic, 2017).
That report of subsea permafrost destabilisation in the East Siberian Arctic
sea shelf, the latest unprecedented temperatures in the Arctic, and the data
in non-linear rises in high-atmosphere methane levels, combine to make it
feel like we are about to play Russian Roulette with the entire human race,
with already two bullets loaded. Nothing is certain. But it is sobering that
humanity has arrived at a situation of our own making where we now
debate the strength of analyses of our near-term extinction."
https://www.lifeworth.com/deepadaptation.pdfhttps://www.nature.com/articles/s41558-018-0095-zhttps://arctic.ru/climate/20170809/655109.html