Thanks Keith, REH
----- Original Message ----- From: "Keith Hudson" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, December 16, 2002 12:10 PM Subject: Ice sheets, etc > For those FWers who are interested in the global warming controversy, the > following article from today's Washington Post will be of interest. The > article starts off mentioning two scientific satellites which are being > launched at the same time, but I've only retained info about the climatic > satellite in the following excerpt: > > <<<< > NASA SATELLITES' MISSION TO RUN HOT AND COLD > > William Harwood > > NASA is launching two modest but scientifically ambitious satellites this > week to answer fundamental questions about the forces shaping Earth's > environment, from the surface of the planet to the depths of interstellar > space. > > The Ice, Cloud and Land Elevation Satellite -- ICESat -- is designed to > find out whether the polar ice sheets are expanding or melting, either > scenario a tell-tale sign of environmental change on a vast scale. The > other satellite, the Cosmic Hot Interstellar Plasma Spectrometer, or CHIPS, > will study how the debris from exploding suns cools and ultimately becomes > the raw material for new stars in a galactic recycling program. > > Both satellites are scheduled for launch Thursday atop a Boeing Delta 2 > rocket from Vandenberg Air Force Base, Calif. Of the two, ICESat is the > star of the show, costing $282 million, including data analysis and the > price of the Delta 2 rocket. > > Once operational in a 373-mile-high orbit around Earth's poles, ICESat will > use a sophisticated device known as a laser altimeter to collect precise > elevation data that will help researchers determine the ice-sheet mass > balance, that is, how much new ice forms every year compared with how much > is lost. > > "The ice sheets that cover Greenland and Antarctica today are over two > miles thick in places," said Jay Zwally, ICESat project scientist. "But > very simply, we do not know if they're growing or shrinking. > > "Almost every newspaper article we read says that when the climate warms, > we're going to see the melting of the polar ice sheets and the flooding of > coastal areas. The truth is, we really don't know." > > ICESat is equipped with an instrument known as the Geoscience Laser > Altimeter System, or GLAS. By precisely timing how long it takes a laser > beam to fire, hit the surface and bounce back to a 31-inch telescope, > scientists can determine the elevation of the ice sheets below to an > accuracy of six inches. Firing 40 times a second, GLAS will collect > readings at approximately one-mile intervals. > > Zwally said about three-tenths of an inch of water from the surface of the > ocean ends up in the planet's ice sheets as snowfall. "That's about three > inches every 10 years," he said. "If there was only water going in and > nothing coming out, sea level would drop three inches every 10 years. But > approximately the same amount is coming back out in the form of icebergs > and melting at the edges," he said at a recent news conference. "We don't > know which is greater. The difference is what we call the mass balance." > > Many researchers expect the ice sheets to melt more around the edges and to > grow more in the center. Recent measurements in Greenland using > aircraft-borne instruments show the edges are melting more than expected. > But there is little or no data about what might be going on in the central > regions of the ice sheets. "That's what ICESat will do," Zwally said. > "ICESat will provide precise measurements over the whole ice sheets from > season to season and from year to year." > > It is a complex problem that until now has been fraught with uncertainty. A > United Nations panel on climate change has predicted that over the next 100 > years, the sea level could rise from three to 33 inches. Over time, ICESat > measurements should allow scientists to chart changes in ice-sheet > elevation that are equivalent to a few tenths of a millimeter of sea level > change. > > "For the future, we expect increases in melting and increases in snowfall," > Zwally said. "It's going to be a race between the two of these. We're going > to get more melting at the edges, more snowfall at the center, and just > what the contribution will be is uncertain. It could be either plus or minus." > >>>> > > © The Washington Post > Monday, December 16 > > > -------------------------------------------------------------------------- -- > ------------ > > Keith Hudson, General Editor, Handlo Music, http://www.handlo.com > 6 Upper Camden Place, Bath BA1 5HX, England > Tel: +44 1225 312622; Fax: +44 1225 447727; mailto:[EMAIL PROTECTED] > ________________________________________________________________________
