The surprise is that groundwater
removal can account for the additional sea level gain observed since 1961. It is not obviously large, but it is
persistent. Add in the thermal expansion
and a little melt water and we have the equation balanced. It all works out to a couple of inches at
best.
Of course the plainly alarmist predictions
are also making an appearance here but how two inches is predictive of two
meters escapes me. Perhaps the water
will carry a heavy load of mud.
In the meantime, we have an important
clarification that will improve the credence of the underlying work which is necessary
to get rid of the spurious..
Climate scientists say they have solved riddle of rising sea
by Staff Writers
Paris (AFP) May 20, 2012
Massive extraction of groundwater can resolve a puzzle over a rise in sea levels
in past decades, scientists in Japan
Global sea levels rose by an average of 1.8 millimetres (0.07 inches)
per year from 1961-2003, according to data from tide gauges.
But the big question is how much of this can be pinned to global
warming.
In its landmark 2007 report, the UN's Nobel-winning Intergovernmental Panel onClimate Change (IPCC)
ascribed 1.1mm (0.04 inches) per year to thermal expansion of the oceans --
water expands when it is heated -- and to meltwater from glaciers, icecaps and
the Greenland and Antarctica icecaps.
That left 0.7mm (0.03 inches) per year unaccounted for, a mystery that
left many scientists wondering if the data were correct or if there were some
source that had eluded everyone.
In a study published in the journal Nature Geoscience,
a team led by Yadu Pokhrel of the University of Tokyo say the answer lies in
water that is extracted from underground aquifers, rivers and lakes for human
development but is never replenished.
The water eventually makes it to the ocean through rivers and
evaporation in the soil, they note.
Groundwater extraction is the main component of additions that account
for the mystery gap, according to their paper, which is based on computer
modelling.
"Together, unsustainable groundwater use, artificial reservoir
water impoundment, climate-driven change in terrestrial water storage and the
loss of water from closed basins have contributed a sea-level rise of 0.77mm
(0.031 inches) per year between 1961 and 2003, about 42 percent of the observed
sea-level rise," it says.
The probe seeks to fill one of the knowledge gaps in the complex
science of climate change.
Researchers admit to many unknowns about how the oceans respond to
warming, and one of them is sea-level rise, an important question for hundreds
of millions of coastal dwellers.
Just a tiny rise, if repeated year on year, can eventually have a
dramatic impact in locations that are vulnerable to storm surges or the influx
of saltwater into aquifers or coastal fields.
In its 2007 Fourth Assessment Report,
the IPCC said the oceans would rise by between 18 and 59 centimetres (seven to
23 inches) by the century's end.
But this estimate did not factor in meltwater from the mighty Greenland and Antarctic ice sheets.
A study published last year by the Oslo-based Arctic Monitoring and
Assessment Project (AMAP) said sea levels would rise, on current melting
trends, by 90 cms to 1.6 metres (3.0 to 5.3 feet) by 2100.
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