We discuss and comment on the role agriculture will play in the containment of the CO2 problem and address protocols for terraforming the planet Earth.
A model farm template is imagined as the central methodology. A broad range of timely science news and other topics of interest are commented on.
Friday, April 27, 2012
Slip Sliding Greenland Ice Sheet
It is quite reasonable to conclude the the
Greenland ice sheet is generally stable.It has stood up to far worse for far longer and not collapsed.Yet a rapid collapse is possible andthis ice sheet has less precipitation than
was present before the Pleistocene Nonconformity.This may mean that it is capable of
substantial further collapse.
This needs to be considered.Greenland is practically land bound and is
producing only a small amount of sea ice however dramatic it may be.It is mostly producing melt water and that
has accelerated over the past decade.It
is reasonable that a third of the sheet is in a slow motion collapse during
What perhaps is missing are deep channels
to allow the invasion of the sea itself as occurred in the Arctic.
The real question then is whether the
surface of the ice sheet is in fact descending over time in various areas.It seems that satellite work could establish
that and that it needs to be monitored.We still have to wait fro averages to be worked out to see what might be
study shows Greenland may be slip-sliding away due to surface lake melt
by Staff Writers
Boulder CO (SPX) Apr 18, 2012
This is a surface or
"supraglacial" lake on the Greenland Ice Sheet. Credit: Konrad Steffen,
University of Colorado.
Like snow sliding off a roof
on a sunny day, the Greenland Ice Sheet may be sliding faster into the ocean
due to massive releases of meltwater from surface lakes, according to a new
study by the University of Colorado Boulder-based Cooperative Institute for
Research in Environmental Sciences.
Such lake drainages may affect
sea-level rise, with implications for coastal communities, according to the
researchers. "This is the first evidence that Greenland's 'supraglacial'
lakes have responded to recent increases in surface meltwater production by
draining more frequently, as opposed to growing in size," says CIRES
research associate William Colgan, who co-led the new study with CU-Boulder
computer science doctoral student Yu-Li Liang.
During summer, meltwater pools
into lakes on the ice sheet's surface. When the water pressure gets high
enough, the ice fractures beneath the lake, forming a vertical drainpipe, and
"a huge burst of water quickly pulses through to the bed of the ice
sheet," Colgan said.
The researchers used satellite
images along with innovative feature-recognition software to monitor nearly
1,000 lakes on a Connecticut-sized portion of the ice sheet over a 10-year
period. They discovered that as the climate warms, such catastrophic lake
drainages are increasing in frequency. Catastrophic lake drainages were 3.5
times more likely to occur during the warmest years than the coldest years.
During a typical catastrophic
lake drainage, about 1 million cubic meters of meltwater - which is equivalent
to the volume of about 4,000 Olympic swimming pools - funnels to the ice
sheet's underside within a day or two. Once the water reaches the ice sheet's
belly that abuts underlying rock, it may turn the ice-bed surface into a Slip
'N Slide, lubricating the ice sheet's glide into the ocean. This would
accelerate the sea-level rise associated with climate change.
Alternatively, however, the
lake drainages may carve out sub-glacial"sewers" to efficiently route
water to the ocean. "This would drain the ice sheet's water, making less
water available for ice-sheet sliding," Colgan said. That would slow the
ice sheet's migration into the ocean and decelerate sea-level rise.
"Lake drainages are a
wild card in terms of whether they enhance or decrease the ice sheet's
slide," Colgan said. Finding out which scenario is correct is a pressing
question for climate models and for communities preparing for
sea-level change, he said.
For the study, the researchers
developed new feature-recognition software capable of identifying supraglacial
lakes in satellite images and determining their size and when they appear and
disappear. "Previously, much of this had to be double-checked
manually," Colgan said. "Now we feed the images into the code, and
the program can recognize whether a feature is a lake or not, with high
confidence and no manual intervention."
Automating the process was
vital since the study looked at more than 9,000 images. The researchers
verified the program's accuracy by manually looking at about 30 percent of the
images over 30 percent of the study area. They found that the algorithm - a
step-by-step procedure for calculations - correctly detected and tracked 99
percent of supraglacial lakes.
The program could be useful in
future studies to determine how lake drainages affect sea-level rise, according
to the researchers. CIRES co-authors on the team include Konrad Steffen, Waleed
Abdalati, Julienne Stroeve and Nicolas Bayou. The study is being published
online by the journal Remote Sensing of the Environment. The study was funded
by the Arctic Sciences Program of the National Science Foundation.