From healthmaps@attbi.com Tue Aug 6 16:19:33 2002 Received: from mailscan6.cac.washington.edu (mailscan6.cac.washington.edu [140.142.33.14]) by lists.u.washington.edu (8.12.1+UW01.12/8.12.1+UW02.01) with SMTP id g76NJTeY017866 for ; Tue, 6 Aug 2002 16:19:29 -0700 Received: FROM mxu3.u.washington.edu BY mailscan6.cac.washington.edu ; Tue Aug 06 16:19:28 2002 -0700 Received: from rwcrmhc52.attbi.com (rwcrmhc52.attbi.com [216.148.227.88]) by mxu3.u.washington.edu (8.12.1+UW01.12/8.12.1+UW02.06) with ESMTP id g76NJSbq026350 for ; Tue, 6 Aug 2002 16:19:28 -0700 Received: from harriet ([12.229.18.75]) by rwcrmhc52.attbi.com (InterMail vM.4.01.03.27 201-229-121-127-20010626) with SMTP id <20020806231926.JLYO22139.rwcrmhc52.attbi.com@harriet> for ; Tue, 6 Aug 2002 23:19:26 +0000 From: "HealthMaps" To: "WAPHGIS" Subject: WAPHGIS: Earth's girth grows Date: Tue, 6 Aug 2002 16:19:38 -0700 Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_005E_01C23D65.100CF0F0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 This is a multi-part message in MIME format. ------=_NextPart_000_005E_01C23D65.100CF0F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit Earth's girth growsDefinitely mapping oriented, and ... health too? In the US our collective girth is growing and now it seems, the same for the planet. Richard E Hoskins ---------------------------------------------------------------------------- ---- updated at midnight GMT search nature science update advanced search Earth's girth grows Our planet's waistline is mysteriously increasing. 2 August 2002 TOM CLARKE Researchers are baffled by the bulge. © NASA After 18,000 years of slimming, our planet has suddenly turned tubby round the middle. Researchers are baffled by the bulge. There are explanations for subtle changes in the Earth's vital statistics, but none of them account for a shift this big, this fast. Soon after the first satellites were launched, scientists realized that Earth is not a perfect sphere. Because it is spinning fast and made largely of slightly flexible rock, it is a bit wider around the equator than from pole to pole. The difference is tiny - Earth's girth is only about 0.3% greater than its height. More accurate measurements of satellite orbits, made using lasers in the 1980s1, revealed that the Earth was, in fact, becoming gradually more spherical. As the ice caps melted after the most recent ice age, their weight was removed from the poles - the poles were rising back to their original position after millennia under pressure. At least, they were until 1998. For the past four years the slimming has reversed, say Christopher Cox at Raytheon, a research and technology company in Lanham, Maryland, and Benjamin Chao at NASA's Goddard Space Flight Center in Greenbelt, also in Maryland2. "You won't notice the difference when you step outside each morning," says Cox. But the sudden change is at least twice as large as the effect of ice-cap melting, he says. "It's a mystery, but probably an explicable one," says Anny Cazenave, an Earth scientist at the National Centre for Space Studies in Toulouse, France. If matter is being redistributed towards the equator, the question is: from where? Cox and Chao reckon that the flip is far to fast to be due to flow in the bulk of the Earth's rock. And there has been no measurable alteration in the weight of atmosphere recently, ruling this out as an explanation. Ice-cap melting as a result of global warming could be releasing more water to equatorial regions, widening the Earth. But the requisite rise in sea level hasn't been detected either. Instead, the researchers think that a flipping of the Earth's magnetic field could be part of the cause. These electromagnetic jerks occur about once a decade, when the Earth's liquid metal core moves. Such a switch occurred in 1999, which could have followed a transfer of molten metal away from the poles towards the equator, Cox and Chao suggest. This is a plausible explanation, says Cazenave. But she argues that "it's probably not the only factor", as Earth's core does not weigh enough. She suspects that a change in ocean currents may be piling more water around the equator than before, adding to the effect. More recent data "strongly implicate the ocean", agrees Cox. One thing is almost certain, says Cox: the planet's weight problem is probably just a passing phase and is not a result of human activity. "We think it's part of long-term natural variation in climate and the oceans, and things will probably return to normal again," he says. "But we could be wrong." References a.. Yoder, C. F. et al. Secular variation of Earth's gravitational harmonic J2 coefficient from Lageos and nontidal accleration of Earth rotation. Nature, 303, 757 - 762, (1983). b.. Cox, C. M. & Chao, B. F. Detection of a large-scale mass redistribution in the terrestrial system since 1998. Science, 297, 831 - 833, (2002). © Nature News Service / Macmillan Magazines Ltd 2002 • Earth could hold more water 8 March 2002 • Stress relief caused Giant's causeway 28 January 2002 • Move any mountain 22 September 2000 • Chemical combat foils superbugs 7 August 2002 • Foaming Rhine riddle solved 7 August 2002 • Seminal maths manuscript unearthed 6 August 2002 • Fish nibbled not poisoned 6 August 2002 ------=_NextPart_000_005E_01C23D65.100CF0F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Earth's girth grows
Definitely mapping=20 oriented, and ... health too? 
 
 In the US our=20 collective girth is growing and now it seems, the same for the planet.=20

Richard E Hoskins

3D"nature
updated at midnight GMT
=20 =20
=20
search nature science update
=20
advanced search=20
3Dnews
3Dcontent=20
3D"by
3Dconferences
3Dservices=20
3D"send
3D"printable
3Dealert=20
3Dhelp=20
3Dfeedback=20
3Dinformation=20
3D"about
3D"about
3Damersham
 <= /TBODY>

Earth's girth = grows

Our planet's waistline is = mysteriously=20 increasing.
2 = August=20 2002=20

TOM=20 CLARKE

Researchers are = baffled by=20 the bulge.
=A9=20 = NASA

After 18,000 years of slimming, our planet = has=20 suddenly turned tubby round the middle.

Researchers are baffled by the bulge. There = are=20 explanations for subtle changes in the Earth's = vital=20 statistics, but none of them account for a shift = this=20 big, this fast.

Soon after the first satellites were = launched,=20 scientists realized that Earth is not a perfect = sphere.=20 Because it is spinning fast and made largely of = slightly=20 flexible rock, it is a bit wider around the = equator than=20 from pole to pole. The difference is tiny - = Earth's=20 girth is only about 0.3% greater than its = height.

More accurate measurements of satellite = orbits, made=20 using lasers in the 1980s1,=20 revealed that the Earth was, in fact, becoming = gradually=20 more spherical. As the ice caps melted after the = most=20 recent ice age, their weight was removed from = the poles=20 - the poles were rising back to their original = position=20 after millennia under pressure.

At least, they were until 1998. For the past = four=20 years the slimming has reversed, say Christopher = Cox at=20 Raytheon, a research and technology company in = Lanham,=20 Maryland, and Benjamin Chao at NASA's Goddard = Space=20 Flight Center in Greenbelt, also in = Maryland2.

"You won't notice the difference when you = step=20 outside each morning," says Cox. But the sudden = change=20 is at least twice as large as the effect of = ice-cap=20 melting, he says.

"It's a mystery, but probably an explicable = one,"=20 says Anny Cazenave, an Earth scientist at the = National=20 Centre for Space Studies in Toulouse, = France.

If matter is being redistributed towards the = equator,=20 the question is: from where? Cox and Chao reckon = that=20 the flip is far to fast to be due to flow in the = bulk of=20 the Earth's rock. And there has been no = measurable=20 alteration in the weight of atmosphere recently, = ruling=20 this out as an explanation.

Ice-cap melting as a result of global warming = could=20 be releasing more water to equatorial regions, = widening=20 the Earth. But the requisite rise in sea level = hasn't=20 been detected either.

Instead, the researchers think that a = flipping of the=20 Earth's magnetic field could be part of the = cause. These=20 electromagnetic jerks occur about once a decade, = when=20 the Earth's liquid metal core moves. Such a = switch=20 occurred in 1999, which could have followed a = transfer=20 of molten metal away from the poles towards the = equator,=20 Cox and Chao suggest.

This is a plausible explanation, says = Cazenave. But=20 she argues that "it's probably not the only = factor", as=20 Earth's core does not weigh enough. She suspects = that a=20 change in ocean currents may be piling more = water around=20 the equator than before, adding to the effect. = More=20 recent data "strongly implicate the ocean", = agrees=20 Cox.

One thing is almost certain, says Cox: the = planet's=20 weight problem is probably just a passing phase = and is=20 not a result of human activity. "We think it's = part of=20 long-term natural variation in climate and the = oceans,=20 and things will probably return to normal = again," he=20 says. "But we could be wrong."
 
References
  1. Yoder, C. F. = et=20 al. Secular variation of Earth's=20 gravitational harmonic J2 coefficient from = Lageos and=20 nontidal accleration of Earth rotation. Nature, 303, 757 - 762,=20 (1983).
  2. Cox, C. M. & = Chao, B. F.=20 Detection of a large-scale mass redistribution = in the=20 terrestrial system since 1998. Science, 297, 831 - 833, = (2002).=20


=A9 Nature News Service / Macmillan = Magazines Ltd=20 2002
3D"related
=95 Earth could = hold more=20 water
8 March = 2002
=95 Stress relief = caused=20 Giant's causeway
28 = January=20 2002
=95 Move any=20 mountain
22 September=20 2000
3D"more
=95

Chemical=20 combat foils superbugs
7=20 August 2002

=95

Foaming=20 Rhine riddle solved
7=20 August 2002

=95

Seminal=20 maths manuscript unearthed
6 August 2002

=95

Fish=20 nibbled not poisoned
6=20 August 2002

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