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a Volcano Slowly Awakening at the Top of our Earth From
Baffin Bay to the Laptev Sea, Arctic Methane Monster Releases
Troubling Outbursts
(Initial methane out-gassing shows a tell-tale methane overburden in the troposphere near Arctic ocean and tundra methane sources in 2011. Just one of many signs of what may be a very large, impending methane eruption. Image source: NASA/AIRS.)
25
February, 2014
The
most dangerous of volcanoes have a number of identifiable behaviors.
They
tend to lay dormant for hundreds, thousands, or tens of thousands of
years. Then, slowly, as heat and pressure beneath the Earth builds,
they begin to awaken. First they tremble a bit. Then they emit a
growing volume of noxious gas. Then, they begin a series of
mini-outbursts in an ever more violent build-up to an explosive and
destructive grand eruption.
The
lost residents of Pompeii, were they here today, could tell us what
such an event is like.
Now
consider that a volcano-like thing also exists beneath the world’s
frozen oceans and lands near the roof of our world. A thing that
probably hasn’t erupted in over 45 million years. A thing that has
had this immense period of time in which to build up an enormous
highly toxic and explosive reserve of frozen and sequestered methane.
A thing that is at least as large as the boundary circumscribed by
the Arctic Circle. A vast and extraordinarily dangerous monster of a
thing. A kind of climate super-volcano.
For
ever since the Earth began its long fall into cooling at the end of
the Eocene, methane has been freezing at the bottom of the world’s
oceans, sequestering in the frozen earth. As world land and ocean
temperatures fell, the methane formed into clathrates or was bound up
in organic permafrost and was, ever-after, locked away. There it lay
patiently, waiting for the time when it would be, once again,
disturbed by a return to warmth.
And
that time of dangerous and explosive reawakening, increasingly, seems
to be now.
Footprint
of the Vast Volcanic Monster: Shallow Seas, Deep Seas, Permafrost
Of
these volatile methane concentrations, some of the most prolific and
the most vulnerable reside in the Arctic. Some, which lay sequestered
within the shallow sea bed near the East
Siberian Arctic Shelf, have been the subject of much controversy
during recent years. Scientists like Natalia Shakhova and Peter
Wadhams have issued repeated warnings that these methane stores could
be vulnerable to a rapid release as sea ice retreats and waters warm.
It is estimated that as much as 1400 gigatons of methane lay
sequestered under Arctic submarine permafrost in the ESAS. A massive
store that, if disturbed even in part, could provide an immense
amplifying feedback to human-caused warming.
But
the Arctic submarine permafrost isn’t the only zone in which large
volumes of methane lay hidden. The Amundsen Basin, one of the deepest
trenches in the Arctic Ocean, in the Laptev Sea is a known emitter of
methane from sub-sea sources. A region near Svalbard both stores and
emits large volumes of methane. And, recently, high rates of methane
release have been observed near Baffin Bay. A complete catalog of
these stores has not been adequately assessed. But, in combination,
it is likely that they at least approach the total volume of stores
in the vulnerable East Siberian Arctic Shelf (ESAS) zone.
Ominous
Rumblings from the Rapidly Warming Deeps
These
stores are deeper beneath the ocean surface and so are not generally
thought to be as vulnerable as the shallow sea reserves in the ESAS.
But this thinking may be in error as Arctic waters display a
temperature inversion in which surface waters near the ice pack are
colder than deeper waters far below.
In
addition, wide zones of deep water in the Arctic have displayed rapid
warming over the past few decades. As an example, bottom waters in
the Greenland Sea, an area between the east coast of Greenland,
Iceland and Svalbard, were shown in a September
2013 study
to be warming 10 times faster than the rest of the world’s deep
ocean system. According to the report:
Recent
warming of the Greenland Sea Deep Water is about ten times higher
than warming rates estimated for the global ocean. Scientists
analyzed temperature data from 1950 to 2010 in the abyssal Greenland
Sea, which is an ocean area located just to the south of the Arctic
Ocean.
(Deep
Water Warming in the Greenland Sea since 1950. Image source: Science
Daily.
Image credit: Alfred Wegener Institute, Helmholtz Centre for Polar
and Marine Research.)
In
other regions of the Arctic and through the rest of the global ocean
system rapid ocean bottom warming has also been observed. Recent
studies by Kevin Trenberth have found that heat accumulation in the
deep ocean, during recent years, has outpaced that of warming at or
near the surface.
And because this warming occurs adjacent to frozen methane stores on
or beneath the sea floor, it is a very, very dangerous development.
To
the point of an observed rapid warming of the deep ocean, it is
important to note that there are a number of mechanisms that
transport heat into the abyss worldwide. But in the Arctic, this
transfer system is amplified and particularly intense. Fresh, cold
surface waters tend to deflect warmer, saltier waters funneling in
from more southerly latitudes toward the Arctic Ocean bottom. As
glacial ice melts in Greenland, as storms within the Arctic intensify
and become more prevalent, and as fresh water runoff from the
continents surrounding the Arctic basin increases, fresh
water content at the surface grows and widens, creating a kind of
fresh water wedge that expands southward and deflects warmer, saltier
water toward the ocean bottom.
And
there, the warmer waters can go to work releasing the massive volumes
of methane stored in frozen clathrates near the ocean floor.
Large
Mid-February Methane Belch
Methane
released from deep water clathrate stores has a long journey before
it reaches the atmosphere. The methane passes through the water
column, where a portion of it oxidizes into CO2. Microbes near the
methane source and throughout the water column devour a portion of
the methane as an energy source. But eventually, if the pulse is
large enough, the methane finds its way to the surface and releases.
Such outbursts are, likely, only a fraction of the initial bottom
release. So a large expulsion into the atmosphere may well be a hint
that something even more powerful and energetic is going on down
below.
Over
the past decade, deep water regions have shown at least as much
atmospheric venting as the East Siberian Arctic Shelf. And this year
has been no exception with troubling outbursts continuing in a zone
from Baffin Bay to Svalbard to the Laptev Sea. These outbursts have,
in part, contributed to increasing atmospheric methane concentrations
at a rate of around 7 parts per billion each year since 2007 after an
8 year period during which global methane levels had plateaued at
around 1790 parts per billion. By comparison, pre-industrial global
methane levels were around 750 parts per billion during the 1880s.
Today, they average around 1835 ppb (Mauna Loa). Should very large
outbursts emerge, the rate of atmospheric methane increase would be
expected to dramatically steepen. And though we haven’t yet seen
these kinds of outbursts, more minor, but still large and concerning,
continue to occur with troubling frequency.
This
past week, according reports from Methane
Tracker
and Sam
Carana,
two particularly large and troubling ocean to atmosphere methane
outbursts were observed in this region — one over the Laptev Sea
and the other over Baffin Bay. The Baffin Bay outburst occurred in a
zone where water depths ranged from 1,000 to 2,500 meters (middle to
deep ocean) and the Laptev outburst likely occurred from the deep
waters and precipitous slopes of the Amundsen Basin which plunges as
deep as 4,400 meters (extraordinarily deep ocean) and extends almost
directly under the North Pole.
(Methane
belching from Laptev Sea and Baffin Bay on February 22nd with highest
reading spiking to 2383 ppb, about 500 ppb above the global average.
Image source: Methane
Tracker
and Sam
Carana.
Data source: composite methane data collection from SIO, NOAA ESRL,
U.S. Navy, GEBCO. )
From
these outbursts, 10,000 foot methane concentrations of 2383 ppb were
observed. These readings are about 500 ppb higher than the global
average and represent an extraordinary local spike for the Arctic.
The
outbursts occurred in a region where the fresh water wedge was most
recently active — areas where sea ice keeps expanding then melting
and retreating as warmer, saltier waters encroach. Regions where the
warmer water column would be continuously flushed toward ocean bottom
zones containing methane hydrates.
If
we were to continue with the volcano analogy, we could well consider
the most recent Laptev and Baffin Bay outbursts to be a series of
minor but intensifying eruptions.
The most recent in a string of troubling and increasingly more
volatile activity from the methane volcano rumbling at the top of our
planet.
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