Climate Solutions 2: Low-Carbon Re-Industrialisation - WWF Blogs

above. Large-scale changes in climate
conditions can be expected to have a net
detrimental effect on local ecosystems.
This is because climatic conditions shift
beyond the natural range of variability to
which vegetation in these ecosystems
has evolved to optimise growth (i.e.
growth that allows for absorption of
carbon dioxide from the atmosphere).
Some research predicts that the
amplitude and/or frequency of the
ENSO will be significantly increased as
a result of increased ocean heat uptake
(Timmermann et al. 1999). Monsoon
behaviour (such as the Indian Summer
Monsoon and the Sahara/Sahel and
West African Monsoon) appears to be
more difficult to predict under climate
change, though large-scale changes are
possible (Lenton et al. 2008).
4.2.7 Water Vapour
As the Earth’s atmosphere warms,
ocean evaporation increases and this
water enters the atmosphere as vapour.
Like other greenhouse gases, water
vapour traps heat, further contributing
to global warming through this positive
feedback loop (Soden and Held 2006).
A related impact is the loss of cloud
cover in some regions through the
effects of global warming. Clouds reflect
radiation back into space, thus their loss
may provide a positive feedback if land
or ocean surfaces reflect less radiation.
However, this theory is still subject to
debate. This is because clouds reflect
radiation back to Earth, as well as into
space, providing both a warming and a
cooling influence, respectively. Which
of these competing effects dominates
remains a matter of contention and the
subject of further research (Soden and
Held 2006, Lin et al. 2002, Lindzen et al.
2001).
4.2.8 Non-linearity of Positive
Feedbacks
An important point regarding the
behaviour of feedback systems is that
they are unlikely to behave in a linear
way. Because these non-linear effects
are more challenging to communicate,
“society may be lulled into a false sense
of security by smooth projections of
global change”, according to Lenton
et al. (2008). For this reason, work is
currently underway to develop early
warning systems to determine when key
positive feedbacks are reaching critical
thresholds.
Of the tipping elements described above,
Lenton et al. (2008) have concluded
that “the greatest threats are tipping
the Arctic sea-ice and the Greenland ice
sheet, and at least five other elements
could surprise us by exhibiting a nearby
tipping point”.
4.3 Avoiding Runaway Climate
Change
Considerable uncertainty still surrounds
the critical temperature threshold
for climate change tipping elements,
beyond which runaway climate change
would take hold. NASA climatologist
James Hansen and co-workers
suggest that 1.7°C above pre-industrial
temperatures should be regarded as
an appropriate upper limit for human-
The greatest
threats are tipping
the Arctic sea-ice
and the Greenland
ice sheet, and at
least five other
elements could
surprise us by
exhibiting a
nearby tipping
point.
Lenton et al. 2008
Climate Solutions 2: Low-Carbon Re-Industrialisation
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Climate Risk