Posts
With
Glaciers Undergoing Collapse, Sea Level Rise to Flood More Than 1,500
of Indonesia’s Islands, Capital City Over Next 50 Years
(Satellite
rendering of the vulnerable Indonesia Archipelago — a system
composing 17,000 islands. Image source: Commons)
26
February, 2014
From
a climate-wrecking human warming spurring the melting of glaciers and
ice sheets to the thermal expansion of the world’s oceans, sea
level rise, to some degree or another over the next century is a
given. How rapid this expansion progresses and how much land it
devours will ultimately depend upon the amount of heat trapping gas
we belch into the atmosphere and how sensitive the Earth’s climate
system is to our increasingly traumatic insults.
Current
conservative assessments from the Intergovernmental Panel on Climate
Change (IPCC) estimate a total of 90 centimeters (nearly 1 meter)
additional sea level rise before the end of this century. Today’s
rate of sea level rise gets us to about 30 centimeters over the same
period, so the IPCC is projecting that the pace of rising seas will
more than triple over the coming years and decades.
Despite
the fact that the rate of sea level rise and related glacial melt
would have to rapidly uptick to meet the IPCC estimate, it remains a
conservative case.
Temperatures, over the next century under business
as usual fossil fuel emissions or a moderate mitigation scenario, are
likely to increase by between 5 and 9 degrees Celsius. This range of
global heating is enough to eventually melt all or nearly all the
glacial ice on Earth. So the heat forcing to the world’s glaciers
is expected to be extreme, a blow at least equaling the temperature
change between now and the last ice age. A temperature change that
took 10,000 years to complete now crammed into an exceptionally brief
period from 1880 to 2100.
Under
such an outrageous pace of warming, a warming that could propel Earth
to near Permian and PETM temperatures within 85 years, it is likely
that the rate of sea level rise could be double or more that of IPCC
predictions, possibly equaling or exceeding peak rates of sea level
rise during the end of the last ice age at 10 feet per century. So
the range of increase may well be between 1 and 3+ meters, making the
IPCC case quite an underestimation if business as usual fossil fuel
emissions continue.
(Survey of scientist projections of sea level rise in centimeters by 2100 under a high emissions scenario (RCP 8.5). Note that a majority of scientists project sea level rise in the range of 1 to 3 meters by 2100 with some scientists projecting as much as a 3 to 6 meter rise over the same period. Image source: Real Climate’s Excellent November Report on Sea Level Rise)
Stresses
to glacial systems are already extreme even at the current human
forcing of 400 ppm CO2, 1835 ppb methane, and at rising levels of a
host of other greenhouse gasses. Current
CO2 levels alone, during the Pliocene, were enough to establish seas
as much as 75 feet higher than today.
A fact that raises the question — if we already have 15-75 feet of
sea level rise locked in, how swiftly will that rise occur? And the
answer to that question depends on how rapidly the world’s largest
glacial and ice sheet systems respond to human greenhouse gas
forcing.
Very
Large Glaciers Already on the Move
In
a recent study one of the world’s largest ice sheets, the Pine
Island Glacier, was found to be undergoing the first stages of an
irreversible collapse.
In other words, over the coming decades, the Pine Island Glacier
(PIG) is due to complete an unstoppable slide into the Southern
Ocean. And loss of the Pine Island Glacier alone commits
the world to about 1 meter of additional sea level rise.
Unfortunately
PIG is the first of many glacial systems from West Antarctica to
Greenland that are likely to suffer the same fate. For from these
vulnerable regions, mass losses from glacial melt have more than
doubled over the past decade. In total, by
2008, about 90% of the world’s glaciers were in retreat.
And since that time, warming has continued to advance with melt
episodes becoming ever-more predominant.
Melt
lakes, many larger than 5 kilometers across, form over Western
Greenland, August 4, 2013. Summer of 2012 saw Greenland mass loss hit
600 cubic kilometers. Image source: Lance-Modis.
Greenland,
for example, has exhibited increasingly severe melt stress over past
summers with large stretches of lakes, many measuring 5-10 kilometers
wide, forming over an ever-less-stable ice sheet. A
towering ice sheet that boasts an average altitude of two kilometers,
Greenland’s vast glacial system contains an immense volume of
frozen water.
But as great and mighty as this mountainous pile of ice may seem,
human caused warming continues to deliver a series of ever-more
damaging blows. By 2012 Greenland
had experienced a record wasting with 97 percent of its surface area
showing melt during July and over 600 cubic kilometers of ice lost
throughout the entire year.
Yet as warmth continues to advance poleward, the 2012 melt season is
likely to seem tame with far greater annual losses in store.
So
there are many reasons to believe the IPCC estimates for glacial melt
rates and related sea level rise, as with Northern Hemisphere sea ice
losses, are too conservative and that science, in general, is still
coming to grips with a dramatic and geologically unprecedented pace
of change. That said, even IPCC findings are becoming increasingly
stark.
Indonesia
to Lose 10% of its Islands by Mid-Century
For
if only the very conservative IPCC estimates bear out, we are still
likely to see dramatic loss of lands and displacement of human
beings.
A
glaring example appears in new report from Maplecroft’s
Climate Change Vulnerability Index
which found that more than 1,500 islands in Indonesia would disappear
after just a half meter of sea level rise. The study also found that
the same amount of sea level rise would flood up to half of the
capital city of Jakarta. Meanwhile, the 90 centimeters of sea level
rise projected by the IPCC for the end of this century would put 42
million people along the coastline at risk of losing their homes.
Ancha
Srinivasan, principal climate change specialist with the Asian
Development Bank (ADB) noted
in an interview that:
This
archipelago’s biggest threat is rising sea levels, where 42 million
people living three kilometres from the coast are vulnerable if
estimated sea level rise reaches up to 90 centimetres by the end of
the century.
Indonesia
is composed of over 17,000 islands, many of which are low lying or
feature sprawling and vulnerable coast lines. It is located in a
region of the world where ocean levels are among the most rapidly
rising. It is among a growing number of islands and low-lying coastal
regions that are under increasing threat from what would seem even a
modest change in sea level.
But
as we went at length to illustrate above, Indonesia and other regions
may be lucky to see only a 90 centimeter rise. So these projected
impacts, though seemingly stark, may be at the low end of what we are
likely to experience. Add just one more meter and most of Jakarta is
flooded while 42 million of Indonesia’s people are almost certain
to be members of a vast global migration away from the world’s
coastlines.
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