class 8, past climates and society
TRANSCRIPT
GEOG5426 Past climates, past societies
By November 3
[Tentative] list of 10 articles related to your region and time period.
November 24
Brief (15-minute) summaries of project topics.
(1) What are the most important features of the modern climate in your region?
(2) What proxies are available in your region, over the time interval specified? How are they related to climate? and
(3) How different were past climates from modern conditions? Why is that important?
Scientists are sometimes like American tourists; [we] think that if we just speak English loud enough,
people will understand us.
“Kevin Finneram, editor in chief
Issues in Science and Technology
Tip #1
Use images, not text
Hear a piece of information, and three days later you'll remember 10% of it.
Add a picture and you'll remember 65%.”
“
John Medina
LOWf re q u e n c y
Tip #2
Design for the back row
Make It BIG
Make It BIG
Lake Winnipeg, Manitoba, Canada• Lake Winnipeg is the 11th largest
freshwater lake in the world
• The lake’s watershed includes territory in Alberta, Saskatchewan, Manitoba, Ontario, Minnesota and North Dakota
• Its tributaries include the Saskatchewan, Red, Winnipeg and Assiniboine Rivers.
• The lake drains northward into the Nelson River and contributes to Hudson Bay.
Photograph of Lake Winnipeg from Gimli, Manitoba
St. George et al., The Holocene, 2010
St. George et al., The Holocene, 2010
Anatomical signatures from riparian trees can be used to extend flood records by several hundred years.
Flood hazards and tree rings
In the Red River basin, shifts in annual precipitation of roughly ten percent altered flood risks significantly during the last 350 years. Geological processes are not affecting flood hazards at relevant timescales.
The current design flood for the Red River valley was produced by an exceptional combination of extensive flooding in the northeastern Great Plains and unusual spring weather across central North America.
Paleoflood Records for the
Red River, Manitoba, Canada
characteristics of D2M ‘hotspots’
Not correlated with major modes
Do not track SST anomalies
Are not synchronized with each other
✘
✘
✘
Tip #3
Get to the point
The secret of being a bore is to tell everything.”“Voltaire
MURDERYOURDARLINGS.
“Sir Arthur Quiller-Couch
”
“I’m more important that the next speaker.”
“I’m more important than this session.”
“I’m more important than my audience.”
What going over time really means
Strive for continual improvement
You must unlearn what you have learned.”“Yoda
MEGADROUGHTintensity at least equivalent to modern multiyear droughts
duration longer than the several years to decade thereof
Seager et al., Journal of Climate, 2008
Red River floods
Red River valley
AP Photo/U.S. Coast Guard, Lt. Brendan Evans
DaKohlmeyer
River diversion
Main channel
Winnipegpopulation: 680,000
Photograph: Greg Brooks
why are Red River floods so severe?
why are Red River floods so severe?
geology &climate history!
Level of Lake Winnipeg (metres)
We do not think that the country below Fort Garry will ever be flooded again for experience shows clearly that each successive flood has indicated far less depth of the plains that its predecessors – a fact fully accounted by the rapid widening of the river channel.
“
”Anonymous, 1861
Brooks (2003) Geomorphology
how o!en does the Red River flood?
Stratigraphy and limnology
Photograph: Greg Brooks
Red RiverManitoba
2008
1875
Photo: Erik Nielsen
Photo: Erik Nielsen
67Photo: Erik Nielsen
Photo: Erik Nielsen
70St.. George and Nielsen, The Holocene, 2003
Normal growth
Flood damaged
St. George and Nielsen, The Holocene, 2003
350 years of Red River floods
The forts now stand like a castle of romance in the midst of an ocean of deep contending currents, the water extending for at least a mile behind them, and they are thereby only approachable by boats and canoes.”
“Francis HeronHudson Bay Company, 1826
St.. George and Rannie, Canadian Water Resources Journal, 2003
74Winnipeg floodway
expansion
GEOG5426 Past climates, past societies
Climate and the collapse of the Mayan CivilizationHaug et al., Science, 2003
Intertropical Convergence ZoneThe region where the northeasterly and southeasterly
trade winds converge, forming an o"en continuous band of clouds or thunderstorms near the equator.
National Weather Service
Photo: f-l-e-x
Photo: Celso Flores
Photo: npa!erson
Haug et al., Science, 2003
Haug et al., Science, 2003
Aztec drought and “The Curse of One Rabbit”Therrell et al., BMAS, 2004
Therrell et al., BAMS, 2004
Therrell et al., BAMS, 2004
photo: Howard Arno!
Therrell et al., BAMS, 2004
Therrell et al., BAMS, 2004
November 10
Statistics in Paleoclimate