Download - Last Glacial Maximum
Last Glacial MaximumChapter 12Bao, Mario, Ariel, & Keiyro
12-1 Project CLIMAPCLIMAP (Climate Mapping and Predictions) Project began in early 1970s
First map of ice-age Earth released 1976
12-1 First CLIMAP Map
12-1 Project CLIMAPMajor Ice Sheets….-Laurentide ice sheet-Cordilleran ice sheet-Scandinavian ice sheet-Barents ice sheet
12-2 How Large Were the Ice Sheets?
CLIMAP reconstruction highly controversial due to:
1. The extent that ice reached2. Ice centered on marine ice sheets3. Thickness and height of ice sheets
12-3 Glacial DirtGlacial outwash: sediment deposits from glacial meltwater
12-3 WindWind reworks and carry deposits-Deposits can be
worldwide-Na+ and Cl- ions
(salt)
12-4 COHMAPCOHMAP (Cooperative Holocene Mapping Project) began in 1980s
Combined data-model approach to examine the last glacial maximum and subsequent changes to interglacial conditions.
12-4 COHMAP Approach1. Assemble records of changing conditions that drive climate-Over last 21,000 years
2. Ran model simulations of climate3. Climate data produced was tested against climate reconstructions
12-5 Pollen: A Climate IndicatorPrecipitation and temperature determine vegetation growth
Pollen is carried by wind, water, insects-Settles into mud and preserved
12-5 Pollen in a Lake Core-Spruce pollen-Oak pollen-Prairie pollen
12-6 Distribution of Spruce Pollen
12-6 Biome ModelsA model that simulates the vegetation that can exist in a region
12-7 Glacial Ice SheetsIce sheets affected atmospheric flow
Massive, icy plateaus blocked/redirected the flow of air
12-8 Northern Ice SheetsMost dramatic climate changes experienced by regions closest to ice sheets
12-8 Changes in North AmericaLakes once occupied deserts in SW U.S
Pacific NW was colder and drier
Climate due to jet stream’s influence
Glacial Lakes
12-8 Changes in EurasiaClimate was far harsher and colder
Less trees and vegetation
European Steppe
12-8 Europe Comparison
12-8 PermafrostPermafrost: permanently frozen soil and rocks due to the cold
Evidence of permafrost in Asia
12-9 Away from the Northern SheetsClimate changes less dramatic
More affected by CO2 and methane gas
ITCZ Biomass
12-9 Glacial TropicsOceans were 1°-2°C cooler
-Based off plankton fossils
Tropics too far away from ice sheets to be affected
-What caused cooling in the tropics?
12-10 Small Tropical CoolingCLIMAP reconstruction based on planktic fauna/flora in oceans
Evidence shows ocean temperatures cooled by an average of 1.5°C
12-10 AlkenonesAlkenones: organic molecules in plant plankton shells
Used in temperature reconstructions
12-11 Large Tropical Cooling The atmosphere cools 6.5°C for every kilometer
4°-6°C cooling shown from drop in ice line of tropical mountains
12-11 Large Tropical Cooling
12-12 Tropical CoolingCLIMAP estimated tropical cooling to be small
andCritics estimated tropical cooling to be large
Which side was right?
12-12 Medium-Small CoolingErrors of CLIMAP-Dissolved CaCO3
samples-Latitude and Plankton
adaptability
12-12 Medium-Small CoolingDiscrepancies between land and ocean temperature changes-Lowering of sea level-Greater land response to climate forcing
12-12 Medium-Small CoolingTemperature drop estimated to be 3°C
Models capture effects of greenhouse gases-Useful in forecasting future climate changes