|
Can
Crumbling Himalayas Protect Bangladesh From Rising Seas?
By Andrew C. Revkin
Sediment
from rivers is adding land area to Bangladesh. Can this
counter rising seas? Scientists in Bangladesh have been
reappraising forecasts of eventual inundation of sprawling,
crowded delta regions as seas rise in a warming world. According
to several reports, a fresh satellite analysis shows that
new lands formed by sediment carried from the crumbling
Himalayas are adding to Bangladesh's land area - at least
for now.
As
wire stories circulated overnight, I sent out some queries
to sea-level experts and will report back on how this battle
between new sediment and rising seas will play out.
Sea
level is not uniform globally. Juneau, Alaska, is rising,
for instance. The land there is rebounding, freed of the
weight of ice-age glaciers. When I visited Juneau last year,
biologists told me that a fight is brewing over whether
protected coastal wetlands should no longer be protected
once they are dry. (Coastal property owners say the new
land is theirs.)
The
fate of Bangladesh's lowlands will be determined by a mix
of changes in the height of the Indian Ocean, subsidence
of deltas as aquifers are drained and newly deposited sediments
compress, and the addition of all that Himalayan soil.
In
checking out the news from Bangladesh, I noticed that the
Dutch have been advising Bangladeshis to do as the Dutch
do - use engineering to work with the flow of sediment and
accelerate the accretion of new lands. A recent article
in The New Nation - "Can Bangladesh Trap Silt?"
- is worth a look. All of this serves as a useful reminder
that humans are not some static element in the climate puzzle,
but a dynamic, responsive and innovative one - at least
once a human community gets a strong signal that action
is needed.
When
I wrote with James Kanter last year about the report from
the Intergovernmental Panel on Climate Change on impacts
from global warming, I made sure we noted how the consequences
for humans change significantly when adaptation is taken
into account (boldface added):
Without
such adaptations, it said, a rise of 3 to 5 degrees Fahrenheit
over the next century could lead to the inundation of coasts
and islands inhabited by hundreds of millions of people.
But if steady investments are made in seawalls and other
coastal protections, vulnerability could be sharply reduced.
Bangladesh
has already proved to be one of the world's most resilient
countries in the face of flood threats, as Secretary General
Ban Ki-moon pointed out here. It sounds as if the country
is getting geared up to find ways to exploit the eroding
Himalayas as a way to counter the erosion of its coasts.
Adaptation
can buy time and cut losses in the short run. But in the
end, many experts note that unabated greenhouse-gas emissions
essentially mean there will be no new normal climate or
coastline to adapt to - in Bangladesh or anywhere else.
|
