NASA RESEARCHERS DOCUMENT
SHRINKING OF GREENLAND'S GLACIERS
Greenland's southeastern glaciers are rapidly thinning and
their lower elevations may be particularly sensitive to potential
climate changes, a NASA study suggests.
"The results of this study are important in that they could
represent the first indication of an increase in the speed of
outlet glaciers," said Bill Krabill, principal investigator at
NASA Goddard Space Flight Center's Wallops Flight Facility,
Wallops Island, VA. An outlet glacier acts as a major ice
drainage region for an ice sheet.
"The excess volume of ice transported by these glaciers has
had a negligible effect on global sea level thus far, but if it
accelerates or becomes more widespread, it would begin to have a
detectable impact on sea level," Krabill said.
In the March 5 issue of SCIENCE, researchers report the
glacial thinning is too large to have resulted from increased ice-
surface melting or decreased snowfall. The researchers believe
the thinning, as much as 30 feet over five years in some
locations, is the result of increasing discharge speeds of
glaciers flowing into the Atlantic Ocean.
Krabill said surface-melt water might be seeping to the
bottom of glaciers. Such seepage may be reducing the friction
between the ice and the rock below it, enabling the glaciers to
slide with less friction across the bedrock and thus allow more
ice to slip off into the ocean, according to Krabill.
"The results of this study are significant because they
provide the first evidence of widespread thinning of low-elevation
parts of one of the great polar ice sheets. The results also
suggest that the thinning outlet glaciers must be flowing faster
than necessary to remove the annual accumulation of snow within
their basins," said Krabill.
"Why they are behaving like this is a mystery," said Krabill,
"but it might indicate that the coastal margins of ice sheets are
capable of responding quite rapidly to external changes, such as a
potential warming of the climate."
Researchers noted that while some internal areas of Greenland
that were surveyed showed ice thickening, areas along the coast
showed ice thinning. "Taken as a whole, the surveyed region is in
negative balance," Krabill said.
In 1993 and 1994, NASA researchers surveyed the Greenland ice
sheet using an airborne laser altimeter flown on a NASA P-3
aircraft and measured the thickness of the entire ice sheet. Ten
flight lines flown in 1993 in Southern Greenland were resurveyed
in 1998. The flight lines in Northern Greenland flown in 1994
will be resurveyed in May 1999. Throughout the study, pilots have
used the Global Positioning System and other navigational
equipment to fly the same flight path some 400 meters above the
icy surface.
The results showed three areas in the South accumulating at
rates up to ten inches per year. These areas located in the
internal sections of Greenland are in regions of high snowfall.
In the outer regions of the ice sheets, the researchers
reported large areas of thinning, with the rate of thinning
increasing rapidly towards the ocean. Most-rapid thinning rates
(more than three feet per year) were observed in the lower depths
of East-coast outlet glaciers, the researchers reported.
The researchers noted that the areas of thinning in the East
also saw warmer than normal temperatures for 1993 to 1998.
"However, we also observe areas of thinning near the West coast,
where many locations were cooler than normal," the researchers
reported.
These surveys have established baseline data sets that will
be extended with information from NASA's ICESAT spacecraft. The
ICESAT satellite laser altimeter will be launched in 2001 to
measure ice-surface elevations in Greenland and Antarctica.
Further information on the Greenland mapping project,
including the technology behind the science, can be found on the
web at:
The Office of Earth Science enterprise, NASA Headquarters,
Washington, DC, sponsors the Greenland and Antarctic ice mapping
projects as part of NASA's ongoing efforts to understand the total
Earth system and the effects of natural and human-induced changes
on the global environment.
Gisteraand het Azell geskakel om te laat weet hoe dit daar gaan. Sy klink
soos die Azell van ouds, altyd iets om oor te lag en te babbel. Sy het al
lekker aangepas en kom goed oor die weg met die twee dogtertjies wie sy
versorg. Sy hou haar tans besig met 'n kursus in rekenaars en leer ook om
te figuurskaats.
Sy vertel dit sneeu steeds en mis die warm weer wat ons tans het, vreeslik.
Johan, was dit jy wat so 'n ruk terug jou brief aan die familie op die
nuusgroep geplaas het oor julle leefwyse en die weer? Ek sal eendag wanneer
ek groot is, oorsee gaan reis, net om die lewenswyses van ander mense te
gaan verken!
Aangesien van die mense op die nuusgroep moeg is van die politiek sal ons
maar oor die weer gesels! :-)
Watter gedeelte van ...south-africa.AFRIKAANS verstaan jy nie??
As jy in engels wil skryf, gaan doen dit in n engelse groep.
Ons is trots op die taal wat ons praat en al praat ons engels, die rede
hoekom ons hier is, is om afrikaans te skryf en lees.
Secret Squirrel wrote in message ...
> I have purposefully ignored this NG for the past few weeks
> however on my return I notice that it is still frequented by a
> bunch of loosers ... including an exiled SAfrican in Canada who
> persistently posts bloody "Kultuuuuuuuuuuuuuuraaaaal" flavoured
> poems, while dreaming of a return to the old National Party
> order.
>
> Get a life you lot ... let's have some worthwhile contributions
> from now on ..... pleeeeeeeeeeez
>
> Squirrel
>
'Ons lag gemiddeld 15 keer per dag. En die goeie nuus is dat lag goed is
vir 'n mens se gesondheid. Dit laat jou jou probleme vergeet, verminder
stres en dit verbeter kommunikasie tussen mense. Dit is egter nie al nie.
Lag is goed vir 'n mens se bloeddruk, dit laat spasmas in jou spiere verslap
en dit verbeter spysvertering. Kortom, daar word gesê dat mense wat gereeld
lag, langer lewe as die suurknolle en bitterbekke wie se lippe amper nie
roer nie.'
Hoe oud is Gloudina al? (met verwysing na die feit dat sy reeds 3 eeue,
'skuus 3 dekades uit die land is) Miskien is sy nie so 'n suurknol of
bitterbek soos beweer word nie!
JONG DAMES DINAMIEK (MAAK MY SIEK)
Uit 'n CD van die "Naaimasjiene."
ons huis is massief en ons kar baie blink
ons swembad is groot en die tuinjong so flink
die dahlias blom mooi en die kinders is soet
hulle hou ons naam hoog as hul oom dominee hoflik groet
en ons eet en ons drink en ons werk en ons bid
en ons slaap en ons swem en ons teel en ons sit
ek sal ons meid regeer en haar hiet en gebied
ek's voorsitter van jong dames dinamiek
laai die kinders af by sport en gaan koer in die boetiek
ek het klas ek het styl ek's ryk ek's chic
by die vroue-landbou-unie en by dames aktueel
bring ek ook my deel en hou ons volk so heel
my man is die bestuurder van santambank
hy's 'n diaken en daarvoor kan ek die Here dank
hy's ryk hy't mag hy't krag hy't geld
en ons sal dit beskerm met trots en geweld
hy's penningmeester van die potjiekosklub
in sy tee gooi ek altyd net suurlemoensap
hy's ook vooraanstaande in die broederbond
in die burgermag skrik hy vir geen bom se lont
hy's voorsitter van die rapportryers en
soggens eet hy pap en roosterbrood en spek en eiers
en ons eet en ons drink en ons werk en ons bid
en ons slaap en ons swem en ons teel en ons sit
my siel is 'n groot blink shopping centre
ek sal altyd vir roomkoek en lemoensap tender
ek lees Tryna du Toit en aanbid vir Bles
en help my kinders met hul kinderkrans-les
ons glo in kuns en ons glo in kultuur
ons koop Tretchikoffs en drink gemmerbier
my oudste seun is in die eerste rugbyspan
en daarom weet ons mos hy's 'n ware man
my jongste dogter is die netbalkaptein
sy's voorbeeldig, sy vloek nie en drink niks wyn
my ander seun staan eerste in sy klas
in kadette marsjeer hy altyd in pas
my oudste dogter is getrou by die KJA
vir geen wulpse kêrel sal sy ooit sê ja
ek is trots op my telge, hulle laat my hart sing
vir die samelewing sal hul hul beste bring
en ons eet en ons drink en ons werk en ons bid
en ons slaap en ons swem en ons teel en ons sit
ons lees die kerkbode en die huisgenoot
ons het 'n vakansiehuis en 'n groot motorboot
my siel is 'n groot blink shopping centre
my steak is altyd sappig en baie tender
my liefdeslewe is sterk en gesond
ek het 'n groot en stewige heerlike mond
ons nagte is wild en vol warm passie
my man is mal oor my kwispelkwassie
sy lyf is fris en bruin en groot
gewyd skiet hy altyd elke skoot
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