Next
year or the year after, the Arctic will be free of ice’
Scientist
Peter Wadhams believes the summer ice cover at the north pole is
about to disappear, triggering even more rapid global warming
21
August, 2016
Peter
Wadhams has spent his career in the Arctic, making more than 50
trips there, some in submarines under the polar ice. He is credited
with being one of the first scientists to show that the thick icecap
that once covered the Arctic ocean was beginning to thin and shrink.
He was director of the Scott Polar Institute in Cambridge from 1987
to 1992 and professor of ocean physics at Cambridge since 2001. His
book, A Farewell to Ice, tells the story of his unravelling of this
alarming trend and describes what the consequences for our planet
will be if Arctic ice continues to disappear at its current rate.
You
have said on several occasions that summer Arctic sea ice would
disappear by the middle of this decade. It hasn’t. Are you being
alarmist?
No.
There is a clear trend down to zero for summer cover. However, each
year chance events can give a boost to ice cover or take some away.
The overall trend is a very strong downward one, however. Most
people expect this year will see a record low in the Arctic’s
summer sea-ice cover. Next year or the year after that, I think it
will be free of ice in summer and by that I mean the central Arctic
will be ice-free. You will be able to cross over the north pole by
ship. There will still be about a million square kilometres of ice
in the Arctic in summer but it will be packed into various nooks and
crannies along the Northwest Passage and along bits of the Canadian
coastline. Ice-free means the central basin of the Arctic will be
ice-free and I think that that is going to happen in summer 2017 or
2018.
Why
should we be concerned about an Arctic that is free of ice in
summer?
People
tend to think of an ice-free Arctic in summer in terms of it merely
being a symbol of global change. Things happen, they say. In fact,
the impact will be profound and will effect the whole planet and its
population. One key effect will be albedo feedback. Sea ice reflects
about 50% of the solar radiation it receives back into space. By
contrast, water reflects less than 10%. So if you replace ice with
water, which is darker, much more solar heat will be absorbed by the
ocean and the planet will heat up even more rapidly than it is doing
at present.
Sea
ice also acts as an air-conditioning system. Winds coming over the
sea to land masses such as Siberia and Greenland will no longer be
cooled as they pass over ice and these places will be heated even
further. These effects could add 50% to the impact of global warming
that is produced by rising carbon emissions.
In
the end, the only hope we have is to find a way to remove carbon
dioxide from the atmosphere once it has got there
The
air over Greenland will get warmer and more and more of its ice will
melt. It is already losing about 300 cubic kilometres of ice a year.
Antarctica is adding to the melt as well. Sea-level rises will
accelerate as a result. The most recent prediction of the
Intergovernmental Panel on Climate Change (IPCC) is that seas will
rise by 60 to 90 centimetres this century. I think a rise of one to
two metres is far more likely. Indeed, it is probably the best we
can hope for.
That
may not sound a lot but it is really very serious. It will increase
enormously the frequency of storm surges all over the world. We may
be able to raise the Thames barrier in Britain but in Bangladesh, it
just means more and more people will be drowned.
Global
warming is generally associated with increased fossil-fuel burning
and consequent rises in levels of atmospheric carbon dioxide. But is
that the only climate problem we face?
No
it is not. We also have the issue of methane. Russian scientists who
have investigated waters off their coast have detected more and more
plumes of methane bubbling up from the seabed. The reason this is
happening is closely connected with the warming of the planet and
the shrinking of the Arctic icecaps.
Until
around 2005, even in summer, you still had sea ice near the coast.
Then it started to disappear, so that for three or four months a
year warm water reached the shallow waters around the shores where
there had been permafrost ground since the last ice age. It has
started to melt with dangerous consequences. Underneath the
permafrost there are sediments full of methane hydrates. When the
permafrost goes, you release the pressure on top of these hydrates
and the methane comes out of solution.
Can
we monitor this methane just as we can monitor carbon dioxide?
Yes,
we can measure methane over large areas using satellites. These have
shown that methane levels that had been fairly flat for most of the
last century have started to rise and are accelerating, often with
little outliers on the graph. There is a scientist called Jason Box
who works in Denmark for the Greenland Survey and he calls these
outliers dragon’s breath. They are not some sort of measurement
caused by dodgy instruments. They are real pulses of methane coming
from offshore flumes.
How
intense is methane as a heater of the atmosphere compared with
carbon dioxide?
It
is 23 times more powerful. However, methane dissipates much more
quickly than carbon dioxide. It gets oxidised so that it only
lingers in the atmosphere for about seven or eight years. By
contrast, carbon dioxide hangs around in the climate system for
about 100 years before it ends up in the sea and is absorbed by
creatures that die and litter the seabed. At least that is what
scientists thought. Today, there are quite a number of researchers
who think carbon dioxide could last 1,000 years in the atmosphere.
So
in the long run carbon dioxide is still going to be worse than
methane in terms of heating the planet because a single methane
pulse will have a disastrous effect but if there is nothing to
follow it on then it will go away. But with carbon dioxide there is
a ratchet effect. All the carbon dioxide we release by burning
fossil fuels just builds up in the atmosphere. We are having to live
with last century’s carbon dioxide. What that says is simple:
there is no such thing as a safe emission rate of carbon dioxide.
That is why I am despondent about us ever being able to cut carbon
emissions.
If
we cannot halt the emissions of carbon dioxide, what can we do?
In
the end, the only hope we have is to find a way to remove carbon
dioxide from the atmosphere once it has got there. Even the IPCC has
admitted that we will have to find a way to extract carbon dioxide
from the air. The trouble is that they don’t just how we can do
that. The most favoured scheme is known as BECCS: bio-energy with
carbon capture and storage. Essentially, you plant trees and bushes
over vast swaths of ground. These grow, absorbing carbon dioxide in
the process. Then you burn the wood to run power plants while
trapping, liquefying and storing the carbon dioxide that is
released.
It
sounds straightforward. Will it work?
I
am a bit suspicious of this technology. BECCS will need so much land
to be effective. Calculations suggest it would need 40% to 50% of
the arable land of the planet to make it work on the scale we will
need and that would not leave enough land to grow crops to feed the
world or to provide homes for a viable population of wild animals
and plants. Other techniques, such as crushing and spreading olivine
rocks, which absorb carbon dioxide, on beaches, will simply not
scale up. They won’t work, so we will have to find some other way
to remove carbon dioxide from the atmosphere directly.
As
far as I can see, it will have to take the form of some sort of
device into which you pump air at one end and you get air without
carbon dioxide coming out the other end. It can be done, I am sure,
but at the moment we do not have such a device. However, without
something like that I cannot see how we are going to deal with the
carbon dioxide that is getting into the atmosphere. We are going to
have to rely on a technology that has not yet been developed. That
is a measure of the troubles that lie ahead for us. I think humanity
can do it, but I would feel much better if I saw governments
investing in such technology.
A
Farewell to Ice: A Report from the Arctic can be ordered on
amazon.com HERE
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