As the Arctic sea ice melts, be wary of 'Methane Emergency' claims
- 14 Aug 2012, 14:30
- Christian Hunt
Source: NOAA Ocean Explorer
The Arctic summer sea ice minimum is around a month away, and it
seems possible that there will be a new record low in sea ice
extent, along with all the media attention that will
Arctic sea ice is clearly
in long-term decline, and scientists have
been telling us to pay attention to what's happening in the region.
But one group - the Arctic Methane
Emergency Group (AMEG) - argues that sea ice loss
could lead to even more dramatic consequences.
AMEG, a small campaign organisation, suggests continuing sea
ice loss will lead to the rapid release of the greenhouse gas
methane into the atmosphere, destabilising the climate. It
"The Arctic summer sea ice is in a
rapid, extremely dangerous meltdown process... [leading] to an
accelerated rate of Arctic carbon feedback emissions of methane
from warming wetland peat bogs and thawing permafrost."
attention earlier in the year when it argued
that governments must immediately use geoengineering techniques in
the Arctic area to prevent this outcome. The group also
made the same case to the UK
Environmental Audit Committee.
Methane in the Arctic
So with sea ice shrinking, is an Arctic methane bomb the
next big story?
The Arctic is
warming up faster than the global average,
and recent years have seen continuing drops in the amount of Arctic
sea ice - (click here to
see this animated graph):
The loss of sea ice means that more heat is absorbed by
the region, as a smaller ice cap reflects less of the sun's energy
back into space.
Methane is a potent greenhouse gas - much more
powerful than carbon dioxide - and large amounts of
it are stored in the Arctic, trapped in frozen
ground. There's also a lot of methane
buried in sediments under the Arctic
As the Arctic warms, methane currently stored there could be
released into the atmosphere as the permafrost melts, the ocean
warms, and underwater sediments are disturbed.
AMEG is worried that the Arctic will start to release
methane very soon, and very quickly. The organisation points
plumes of methane rising from the Arctic
ocean floor as evidence "suggesting an escalation of methane
emissions could be happening already, even without further warming
of the Arctic."
Newspapers predictably love this story as it
combines a new angle on the Arctic and climate change with the
threat of imminent apocalypse. The scientific literature is much
more equivocal, however.
One recent paper suggests methane plumes may be a result of
continuing and very slow response to its emergence from an ice
age, not due to manmade climate change.
recent review of the scientific literature
on the subject concluded:
"Our current estimates of gas hydrate
storage in the Arctic region are ... extremely poor. It is still
unknown whether future ocean warming could lead to significant
The scientific literature does not appear to suggest that
massive releases of Arctic methane are imminent.
This hasn't restrained AMEG. Its website hosts
"We declare there now exists an
extremely high international security risk from abrupt and runaway
global warming being triggered by the end-summer collapse of Arctic
sea ice towards a fraction of the current record and release of
huge quantities of methane gas from the seabed. Such global warming
would lead at first to worldwide crop failures but ultimately and
inexorably to the collapse of civilization as we know it. This
colossal threat demands an immediate emergency scale response to
cool the Arctic and save the sea ice."
Perhaps unsurprisingly, given such statements, climate
scientists have challenged this argument. Professor Julia Slingo of
the Met Office told the
UK's Environmental Audit
"Our estimate ... is that that we're not
looking at catastrophic releases of methane. I think there is a
lack of clarity in thinking about how that heating at the upper
level of the ocean can get down, and how rapidly it can get down
into the layers of the ocean."
Professor Tim Lenton, an expert in climate tipping points
based at Exeter University,
told the same meeting that methane release
from the Arctic is likely to affect the climate, but over a longer
time period. He said:
"My personal view ... [is that] methane
in the long run and methane loss from these frozen reservoirs will
be a long-term significant amplifier. It might even double
long-term warming, and by long-term I mean thousands and tens of
thousands of years from, say, 3 to 6°C, but ... It plays out
slowly, partly because you have to propagate a warming signal not
just at the bottom of the shelf or the bottom of the ocean, but
through sediments, and that is not inherently a fast process."
Professor Corinne Le Quéré, Director of the Tyndall
told the Ecologist that the presence of
methane plumes in the Arctic needs to be interpreted with care, as
there aren't long term records to compare against:
"We don't know whether these spikes are
natural or not. In the Arctic there are storms, changes in ice
coverage and fluctuations in weather systems so before you can make
this kind of extrapolation you have to look in terms of time and
space, and consider other sources of methane production also."
Methane emissions still important
None of this is to say that Arctic methane might not end up
having an influence on the planet's climate. The scientific
Realclimate suggests that methane emissions
from the Arctic could be a significant long-term contributor to
further warming. Scientists have been arguing for a long time that
the warming of the Arctic is worth paying attention
But enough scientists have challenged the idea that imminent
catastrophic release of Arctic methane could provide a short term
'bomb' effect and destabilise our climate to suggest that the
scientific community isn't buying the argument.