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Fw: E-M:/ Fwd: Shift in Great Lakes seasons may reflect global warming trend



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Enviro-Mich message from "Richard H. and Elsie Freye" <rhfreye@wmis.net>
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----- Original Message -----
From: Richard H. and Elsie Freye <rhfreye@wmis.net>
To: Kirk Riley <rileyki@egr.msu.edu>
Sent: Monday, May 29, 2000 12:32 AM
Subject: Re: E-M:/ Fwd: Shift in Great Lakes seasons may reflect global
warming trend


> The long-term figures certainly indicate trends rather than temporary
> weather changes. However, could you come up with figures indicating
whether
> these changes were sudden or gradual? Other indicators such as ice
formation
> & water levels suggest that the changes were mostly recent. Michelle
> Gesmundo reported (4/11/00) that Lakes Mich. & Huron "are about 21 inches
> below the seasonal average & logged the greatest two-year decline-2.9
feet-
> since measurements were first recorded in the 1860s."
>   An article in the March 2000 Science magazine, p. 164 is headed
"Pollution
> keeps rain up in the air";  Particulates prevent precipitation.
>    Here are some figures on Lake level changes:
>    From March 1999 to March 2000 Lake Superior, area 31000 square miles,
> rose .01 meter,
> Lakes Mich.-Huron, area 45300 sq. mi., dropped .35 meter,
> L. Erie, area 9890 sq.mi, dropped .4 meter., L. Ontario, area 7550 sq. mi.
> gained .02 meters. Outflow from lakes Superior and Ontario are
controllable.
>                            Calculated:
>   Altogether the loss in that 1 year was 50119 million cubic meters,
> approximately 137 million cubic meters per day.
>   That approximates 26% of the mean outflow of the Niagara Falls, (519
> million cu meters per day); 18 times the average Chicago Drainage Canal's
> discharge, (7,823,619 cu meters per day), 8180 tanker loads per
> day,(Canadian tanker Imperial StClair" cap'y 16787 cu.meters); or 1500
times
> the calculated
> loss from domestic uses, including factories, etc. ( the fraction of
> domestic water that is not returned).
> ----- Original Message -----
> From: Kirk Riley <rileyki@egr.msu.edu>
> To: <enviro-mich@great-lakes.net>
> Sent: Thursday, May 25, 2000 9:29 AM
> Subject: E-M:/ Fwd: Shift in Great Lakes seasons may reflect global
warming
> trend
>
>
>
> -------------------------------------------------------------------------
> > Enviro-Mich message from Kirk Riley <rileyki@egr.msu.edu>
>
> -------------------------------------------------------------------------
> >
> > Forward of recent posting to environmental listserv.  The message: the
> > Great Lakes seasons--the cycling of water in the lakes--now come a month
> > earlier because of climate change, perhaps global warming.
> >
> > Kirk
> >
> > >X-Mailer: Microsoft Outlook Express 5.00.2615.200
> > >Date:         Wed, 24 May 2000 12:47:11 -0400
> > >Reply-To: Karen Claxon <kclaxon@earthlink.net>
> > >Sender: Environmental Discussion List <ENVST-L@LISTSERV.BROWN.EDU>
> > >From: Karen Claxon <kclaxon@earthlink.net>
> > >Subject:      GW:  Shift in Great Lakes seasons may reflect global
> warming
> > >trend
> > >To: ENVST-L@LISTSERV.BROWN.EDU
> > >
> > >: 24 MAY 2000 AT 07:00 ET US
> > >Contact: John D. Lenters
> > >jlenters@facstaff.wisc.edu
> > >608-278-1680
> > >University of Wisconsin-Madison
> > >
> > >Shift in Great Lakes 'seasons' may reflect warming trend
> > >
> > >Scrutinizing a 139-year record of Great Lakes water levels, a
> > >University of Wisconsin-Madison scientist has discovered a dramatic
> > >shift in the seasonal changes in water levels on the Great Lakes.
> > >
> > >The finding, reported here today, May 24, at a meeting of the
> > >International Association of Great Lakes Research by UW-Madison
> > >climatologist John D. Lenters, is further evidence that the effects
> > >of global warming on natural systems could be far reaching and
> > >significant.
> > >
> > >"The bottom line is that over this 139-year period, the annual rising
> > >and falling of Lakes Ontario and Erie has gotten earlier" by about a
> > >month, Lenters says describing results of an analysis of long-term
> > >trends in Great Lakes water levels.
> > >
> > >The findings, Lenters says, also show that the range of Lake
> > >Ontario's "annual cycle" increased from 17 to 22 inches, a change in
> > >volume equivalent to 90 billion cubic feet of water. While Lake Erie
> > >does not show the same increase, the one month early arrival of
> > >seasonal high and low water levels mirrors that of Lake Ontario.
> > >
> > >In the Great Lakes, explained Lenters, there is an annual ebb and
> > >flow of lake levels influenced by such things as precipitation,
> > >snowmelt and evaporation over the Great Lakes basin. In the spring
> > >and summer, lake levels rise reflecting such things as precipitation
> > >and spring snowmelt. In the fall and winter, lake levels recede as a
> > >result of evaporation of the relatively warm lake water.
> > >
> > >These shifts, says Lenters, are essentially hydrological
> > >representations of the seasons, and "what I am finding is a shifting
> > >of the seasons."
> > >
> > >These shifts are independent, Lenters says, of annual variability in
> > >lake levels that may reflect, for example, a drought year, or a year
> > >when rainfall exceeds normal precipitation averages.
> > >
> > >"At this time, the most likely explanation for the observed trends
> > >appears to be earlier spring snowmelt in association with higher
> > >springtime temperatures in the Great Lakes region," Lenters says.
> > >"Climate is almost definitely responsible, but exactly how it is
> > >responsible is unknown."
> > >
> > >Lenters' analysis was made using records of monthly mean lake levels
> > >from 1860 to 1998 from four stations around the Great Lakes,
> > >including stations along Lakes Superior, Huron, Ontario and Erie.
> > >Lake Michigan is included in the study as part of Lake Huron since
> > >the two lakes are hydraulically connected.
> > >
> > >Large shifts in the water cycles of Lakes Superior and Michigan-Huron
> > >were also found, but for fewer months of the year. The result is a
> > >different and less dramatic seasonal shift for those lakes, says
> > >Lenters.
> > >
> > >"It is not clear why Lakes Superior and Michigan-Huron are behaving
> > >differently, but it may be related to differences in regional
> > >climate, or the fact that Erie and Ontario are the furthest
> > >downstream lakes.
> > >
> > >"If warming continues, we may begin to see the same consequences in
> > >Lakes Superior, Michigan and Huron," he says. "For example, following
> > >the warm El Niņo winter of 1997-1998, all five Great Lakes reached
> > >their annual maximum nearly two months earlier than normal."
> > >
> > >It is likely that the changes observed in the lakes are part of a
> > >larger systemic change spurred by increased levels of carbon dioxide
> > >in the atmosphere and resulting warming trends, according to the
> > >Wisconsin climatologist. Similar long-term shifts in lake ice and
> > >river flow in the Great Lakes and Upper Mississippi basins have
> > >already been observed by scientists.
> > >
> > >
> > >###
> > >Terry Devitt
> > >608-262-8282
> > >trdevitt@facstaff.wisc.edu
> > >
> > >Lenters is a staff scientist in the Climate, People and Environment
> > >Program of the UW-Madison Institute for Environmental Studies. His
> > >work was supported by a grant from NASA's Upper Midwest Regional
> > >Earth Science Application Center.
> > >Note: Until June 6, messages for Lenters can be left at the following
> > >number: 608-278-1680. He will be checking messages several times a
> > >day.
> >
> >
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