Last Glacial
Maximum
Chapter 12
Bao, Mario, Ariel, & Keiyro
12-1 Project CLIMAP
CLIMAP (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 CLIMAP
Major 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 reached
2. Ice centered on marine ice sheets
3. Thickness and height of ice sheets
12-3 Glacial Dirt
Glacial outwash: sediment deposits from
glacial meltwater
12-3 Wind
Wind reworks and
carry deposits
-Deposits can be
worldwide
-Na+ and Cl- ions
(salt)
12-4 COHMAP
COHMAP (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 Approach
1. Assemble records of changing conditions
that drive climate
-Over last 21,000 years
2. Ran model simulations of climate
3. Climate data produced was tested against
climate reconstructions
12-5 Pollen: A Climate Indicator
Precipitation 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 Models
A model that
simulates the
vegetation that can
exist in a region
12-7 Glacial Ice Sheets
Ice sheets affected
atmospheric flow
Massive, icy plateaus
blocked/redirected
the flow of air
12-8 Northern Ice Sheets
Most dramatic
climate changes
experienced by
regions closest to
ice sheets
12-8 Changes in North America
Lakes 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 Eurasia
Climate was far
harsher and colder
Less trees and
vegetation
European Steppe
12-8 Europe Comparison
12-8 Permafrost
Permafrost:
permanently frozen
soil and rocks due
to the cold
Evidence of
permafrost in Asia
12-9 Away from the Northern Sheets
Climate changes less
dramatic
More affected by
CO2 and methane
gas
ITCZ Biomass
12-9 Glacial Tropics
Oceans 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 Cooling
CLIMAP reconstruction based on planktic
fauna/flora in oceans
Evidence shows ocean temperatures cooled
by an average of 1.5°C
12-10 Alkenones
Alkenones: 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 Cooling
CLIMAP estimated tropical cooling to be small
and
Critics estimated tropical cooling to be large
Which side was right?
12-12 Medium-Small Cooling
Errors of CLIMAP
-Dissolved CaCO3
samples
-Latitude and Plankton
adaptability
12-12 Medium-Small Cooling
Discrepancies between land and ocean
temperature changes
-Lowering of sea level
-Greater land response to climate forcing
12-12 Medium-Small Cooling
Temperature drop estimated to be 3°C
Models capture effects of greenhouse gases
-Useful in forecasting future climate changes