The current ice age still
presents the planet with considerable risk of reglaciation, due to
the adverse position of the continents.
The risk of reglaciation - and the crippling effect of the ice age
on the huge northern hemisphere landmass - mean that we must
attempt to put an end the ice age.
The speed of the warming
Rapid change may cause undesirable expenses. So the
question arises of how fast we want to warm the planet up -
and whether the changes should be made faster or slower.
Firstly it needs to be established whether the change is likely
to be gradual or catastrophic.
If the flip from an ice age climate back to a more normal
one is catastrophic, then it may be difficult for humans to control
- since it will most-likely be governed primarily by the inertia of
melting ice, and by other natural processes. In that case, what
humans may be able to influence is how long it takes
before the planet reaches the climate "tipping point" that signals
the end of the current ice age - assuming such a "tipping point" is
still in the future. After such a "tipping point" has been reached,
the climate would be in "free fall" for a while - until it reaches
its new stable point - and attempts to influence it during that
phase would be unlikley to have very much effect.
It has been argued (e.g. by James Lovelock) that positive feedback
effects from melting ice decreasing the albedo will cause
the climate to go into free fall - with global temperatures
increasing suddenly before they stabilise at a new level. Lovelock
also claims that extinction events will compromise the biosphere's
ability to absorb the shock.
I regard this scenario as unlikely. It is important to understand
that the positive feedback effects from melting ice decreasing the
albedo have mostly already happened. The positive feedback
flip from a glacial stage to an inter-glacial warm period is
practically over. Most of the ice sheets have already vanished. The
effects of decreases in albedo from melting ice over the poles are
now approximately balanced by negative feedback - which
arises from increases in temperature producing increasing cloud
There are other possible causes of positive feedback that may
result in chaos-theory-style flips - but the ice-albedo effect
is really the big one.
A more sensible model has the ice age climate as the base line,
and pictures humanity battling against reglaciation and attempting
to raise the temperature. Each degree of temperature rise is
hard won - and if the interventions are halted, the planet
tends to subside back to its ice-ace rest state, due to the
adverse positions of the continents.
Since change is more likely to be gradual than catastrophic, that
leaves humans largely in control of how fast the changes will be -
and perhaps when they start.
Delaying the end of the ice age might seem
attractive to some - in order to give us time to prepare for it.
However, humans like living at the water's edge: they are
drawn there by docks, trade, fishing, and other forces. The longer
we delay planetary warming, the more infrastructure will get
constructed on the existing coastlines - in the "wrong"
place - and the more costly the eventual inevitable damage will be.
Technology will have advanced by the time the move is due, but
probably not by enough to undo the damage of constructing all the
infrastructure in the wrong place.
The best thing to do is to plunge in at the earliest opportuninty -
while our investment in maintaining the life-hostile and
inherently-unstable ice age climate is still relatively
As for the rate of the changes, they will
inevitably be extremely slow. The Greenland ice sheet
has huge inertia - it will take a thousand years to melt it.
The Antarctic looks even more unshiftable: ice five miles thick and
temperatures 37 degrees below zero down at the pole.
This is not good. If it takes 1,000 years to melt Greenland, that's
1,000 years of inconvenience and shifting coastlines. But we can
hardly leave Greenland iced up. It's freezing up a whole continent
- and it may drag us back into a glacial cycle again. I think we
should strive to get the changes over as soon as possible. The
naturally-slow rate of change caused by the thermal inertia of the
huge, thick ice sheets will mean the costs associated with
too-radid change will be minimal.
The risk of reglaciation, and the damage associated with being in
an ice age imply that steps away from the reglaciation "cliff edge"
should be taken as rapidly as reasonably possible.
Since steps to warm up the planet need to be taken, Tundra
reclamation looks like one promising approach.
If these types of technique can be used to help melt the Greenland
ice sheet, it may be possible to eliminate the Arctic ice cap. This
would probably substantially reduce the chances of reglaciation in
the northern hemisphere - where there is the most land at risk -
and would help prolong the growing season and to increase the
extent of the planet's habitable zone.
One of the most obvious interventions associated with Tundra
reclamation involves the planting of trees at high lattitudes.
The effect of trees on albedo in black and white
If evergreen forests can be created in the north, their dark green leaves
will absorb more light - and by shrugging off snow, they will help prevent
sunlight from being reflected back into space.
Trees have local effects on temperature - by reducing albedo and degrading
sunlight into heat.
They also have larger-scale effects on temperature - by temporarily
taking some carbon out of circulation - and by emitting water vapor,
and some methane.
The effect of northerly trees on temperature via reduced
albedo typically outweighs any negative effects of trees as
temporary carbon sinks.
Humans can make a difference in this area with relatively low
They can select the most suitable species, raise them in nurseries,
plant them out with insulating tree guards, and ensure they are
In some areas, even the ultra-low-cost intervention of
sprinkling seeds of an appropriate type on the ground may have a
significant positive effect.
Forests are successfully farmed at lower lattitudes. However,
nearer the pole such activity would probably need subsidising for
it to be viable.
The effect would be local improvements in the habitat - including
local warming effects.
Possibly the use of other plants may be explored in habitats and
regions where trees cannot grow.
The effect of trees on albedo
- Black ground sheets
The dramatic effect of a layer of black soot on temperatures in the
Arctic earlier this century also suggests that black ground sheets
may be an effective intervention.
These would need to be deployed in areas where they do not spend
much of their time buried by snow - or they would not be very
The idea would be to deploy black ground sheets in areas where
there is snow and ice - and then once that has melted and the
ground is exposed, plant trees in that area through the
Unfortunately, the immediate prospects of affecting the Antarctic very much
appear to be rather remote.
Plant aquaculture in the surrounding ocean may eventually have an
impact on it.
I think efforts should probably be concentrated on the northern
hemisphere for the moment, where there is more land, and a greater
chance of success.
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