1 Geologic Perspective on Climate El Nino The last 1,000 Years: Natural Variability? The Ice Ages...
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1 Geologic Perspective on Climate El Nino The last 1,000 Years: Natural Variability? The Ice Ages and their cause The world the Dinosaurs inhabited The role of Greenhouse Gases in Climate Change
Transcript of 1 Geologic Perspective on Climate El Nino The last 1,000 Years: Natural Variability? The Ice Ages...
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Geologic Perspective on Climate
El Nino The last 1,000 Years: Natural Variability? The Ice Ages and their cause The world the Dinosaurs inhabited The role of Greenhouse Gases in Climate Change
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Normal Pacific Circulation
http://elnino.noaa.gov/index.html
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El Nino Pacific Circulation
http://elnino.noaa.gov/index.html
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2002 El Nino Sea Surface Temperature Animation
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2004 El Nino Sea Surface Temperature Animation
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Current El Nino Sea Surface Temperature Animation
http://www.cdc.noaa.gov/map/clim/sst_olr/el_nino_anim.shtml
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Fig. 15.16
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Effects on North America
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Sources of past climate information Historical records Tree rings Sediments
Marine and lacustrine Corals Ice cores
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The Last 1,000 Years
Crowley, Fig. 1
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The Last 18,000 Years
Crowley, Fig. 2
LastGlacialMaximum
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Iowa 16,000 Years Ago?
Graphic from Illinois State Museum
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Ice on the Retreat!
Graphic from Illinois State Museum
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The Last 160,000 Years
Crowley, Fig. 3
Interglacial
Glacial
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CS Fig. 15.15
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The Milankovitch Theory
Changes in the amount of solar insolation reaching the Earth at 65°N latitude during the summer drive the waxing and waning of the ice sheets
• Low summer insolation = glaciers build up• High summer insolation = glaciers melt
http://earthobservatory.nasa.gov/Library/Giants/Milankovitch/milankovitch_2.html
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GreenhouseGas Concentrations
Crowley, Fig 4See Fig. 15.14
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The Last 800,000 Years
Crowley, Fig. 5
More often glacial (cold) than interglacial (warm) in last million years !!
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The Last 100 Million Years
Crowley, Fig. 6
ICEHOUSEWORLD
GREENHOUSE WORLD
GH:~200 My~350 My~500 My
IH:~290 My~450 My ~680 My~750 My~950 My~2300 My
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The Geologic History of Ice Ages
Source: http://www.lakepowell.net/sciencecenter/paleoclimate.htm
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Lush but Dangerous World
Crowley points out that if we burn all of the fossil fuelthat is available to us, most of which is in the form of coal, CO2 levels would likely rise to those associatedwith the Cretaceous period, ~150 to 65 million years ago.
The Cretaceous had:- no ice- vegetation all the way to the poles- cold-blooded animals (dinosaurs)
If all the ice were to melt, sea level would rise 70 m (~200 ft)
