Environmental Engineering Reference
In-Depth Information
expansion (estimated to be 0.2 to 0.6 m per degree C of global warming in
IPCC, 2007a), which would amount to 0.6 to 1.8 m for a long-term warming
of 3°C or 1.2 to 3.6 m for a long-term warming of 6°C.
6.2 LONG TERM SOCIETAL AND ENVIRONMENTAL ISSUES
Over the coming millennia, some impacts of climate change may settle
into new patterns of climate variability with the successful implementation
of stabilization policies that cap cumulative emissions and therefore limit
increases in global mean temperature. Climate variability could then be
distributed around different means (with perhaps different higher moments),
but it is possible that societies could become accustomed to these new en-
vironments. That world would be different than today, but new conditions
could become routine to people living on Earth one or two thousand years
from now. Other impacts, however, could continue for many centuries past
the date of temperature stabilization.
Rising seas and melting glaciers and/or ice sheets easily fit into this sec-
ond category of persistent and growing very long-term significance. Figure
6.3 displays, for example, contours of 1 m of sea level rise for Florida, which
could occur by 2100 based on Section 4.8. In the longer term, much larger
sea level rise is possible over millennia (see Section 6.1). Clearly, increases
in risks from inundation, repeated flooding, and coastal erosion that have
already been documented in some places for modest sea level rise could
therefore continue as the future unfolds and could well be amplified over
the long term depending upon the rate at which they occur as the climate
system changes.
To get a better understanding of what associated vulnerabilities might
look like as the long-term future unfolds, one might contemplate track-
ing widespread migration over recent time away from areas of exacer-
bated climate risk, but attribution would be extremely difficult. As noted in
Wilbanks et al. (2007: Box 7.2), observed environmental migration is often
a temporary reaction to the calamitous ramifications of one extreme event
or another. WDR (2010) reports that displaced people (the estimated 26 mil-
lion people who have moved permanently during recent years) constitute
less than 10% of the world's international migrants and that most of these
people relocate still live within the same country or, at worst, somewhere
in the same region of the world.
IPCC (2007e) reported, in words that were unanimously approved in
the plenary as part of the Summary for Policymakers, that
