If you need another reason to act - think permafrost
Permafrost
is a subject in the climate change debate I have tried to not think
about too much. It is just too scary to think about the vast amounts of
carbon stored in frozen soils, ready to be released if global
temperatures keep rising. But it seems to be time to finally take a
closer look at what is happening in the most northern areas of our
planet.
Areas like the northern parts of Siberia, Alaska, or Canada are cold
enough that most parts of the ground are frozen - that is why it is
called "permafrost"
(Fig. 1). Only the uppermost layer is thawing in the summer, and gives
room for plants to grow. This active layer can be 0.6 to 4 m thick.
Even though some of the plant material decomposes, quite a bit of it
does not. This is because the active layer is frozen during large parts
of the year; and microbial processes that decompose organic material
are significantly slowed down at low temperatures - the soil acts like
a freezer for organic material.
When air temperature increases, then of course the soil warms as
well: the active layer will stay unfrozen for a longer period of time
during the year, and the deeper, permanently frozen area will start to
thaw. At the same time, warmer temperatures increase microbial
activity. Microbial activity, in turn, produces its own heat. With
that, the decomposition of organic materials in the soil will proceed
not only over a larger time span and over a larger area, but also at an
accelerated rate. This positive feedback loop will accelerate with
further warming, and could ultimately trigger an "irreversible process
of thawing."
During decomposition of organic material, vast amounts of CO2 (in the presence of exygen) or methane (in the ansence of exygen) are released, both very potent greenhouse gases.
Is permafrost thawing already? You bet it does. Indeed, in some areas
permafrost has warmed by up to 3ºC within the last decades (see figure to the left).
In some areas, temperatures of the permafrost are getting dangerously
close to above freezing. In fact, in some areas, soil temperature has
already passed the thawing point (see references at NOAA) .
Just how much organic material is stored in the permafrost has so far been "hugely under-estimated." A new report indicates that the amount of carbon stored in permafrost around the North-Pole might bee twice as high as previously thought (CSIRO).
Executive Director of the Global Carbon Project at CSIRO, Dr Pep Canadell, mentioned that
“Projections
show that almost all near-surface permafrost will disappear by the end
of this century exposing large carbon stores to decomposition and
release of greenhouse gases.”
According to these new estimates, a thawing of about 10% of the
Arctic soil would release about 80 ppm CO2. Global temperature would
then increase on abverage by about o.7ºC.
Considering
- that we are already above the CO2 concentration that is considered relatively safe for the future of human civilization (350 ppm CO2)
- that in June 2009 we reached 390 ppm CO2
- that a global increase in temperature above 2ºC will likely cause the passing of irreversible tipping points, and
- that we are already almost committed to a global increase in temperature to 2ºC,
this estimate is extremely worrisom - to say the least.
Even though it is important to clearly understand what will happen
if we do not act in time, let's not worry too much about what could happen in case of inaction. Instead, let's focus on what we need to work towards:
We need a carbon free energy future which is exclusively supported
by truly renewable energies like the sun, wind, water, and geothermy
within the coming decades. Such a "Great Transformation"
will only be possible with vast energy savings through energy
efficiency and through a change in our behavior, wasting much less
energy than we do now. We must not be satisfied with half measures.
Without effective fast action, all our efforts will likely be to no
prevail.
Maiken Winter, reposted and adapted from the Clean Energy Project