The once and future global The once and future global cooling: lessons from cooling: lessons from

prehistoryprehistory

Gregory J. RetallackGregory J. Retallack

University of OregonUniversity of Oregon

Eocene-Oligocene paleosols Badlands National Park, South Dakota

Grassland expansion changed the world Grassland expansion changed the world Since 35 Ma, 0-25% of land, but not AntarcticaSince 35 Ma, 0-25% of land, but not Antarctica

Crumb structure (mollic epipedon) in tall grasslandpaleosol (Mollisol) Dayville, OR: late Miocene (7 Ma)

Grassland soil (Mollisol) Lake Nakuru National Park, Kenya

Smell the grass

cis-3-hexenalcarbon gray, hydrogen white,

oxygen red

QUATERNARY RECORD 1: PALEOSOLS

Quaternary Palouse Loess,eastern Washington

Paleosols near Kahlotus, WA, data from Busacca (1998)

Paleosols near Dayton, WA

QUATERNARY 2: SOIL TYPESPalouse Loess near Clyde, Washington, alternation of

interglacial deep-calcic grassland and glacial

shallow-calcic sagebrush23.7 ka

36.1 ka

40.1 ka

46.2 ka

Mt St Helens ash S

Mt St Helens ash C

thermoluminescence dates from Busacca (1998)

Earthworm fabric in 46 ka Nix grassland paleosolTaenidium (cicada) burrow

in 40 ka Tlal sagebrush paleosol

Also in paleosols,are fossil mam-mals (Rensberger

& Barnosky, 1993), & phytoliths

(Blinnikov et al 2002)

Modern dry grasslandnear Benge, Washington

Modern sagebrushnear Denio, Nevada

QUATERNARY 3: ECOSYSTEM SHIFTS

Longview Ranch, Oregon, with green Oligocene paleosols in hill

CENOZOIC 1: PALEOSOLS IN DEEP TIME

CENOZOIC 2:JOHN DAY FM OLIGOCENEWell dated (Ar/Ar, paleomagnetic) fossiliferous sequence

CENOZOIC 3: SHRUB/GRASS TRACES

Taenidiumcicada burrowof sagebrush

Edaphichniumearthworm chimney

of grassland

Pallichnusdung beetle nests

of grassland

Blocky structurered forested

paleosol (Alfisol),Painted Hills, OR:Oligocene (31 Ma)

Crumb structure(mollic epipedon)in tall grassland

paleosol (Mollisol)Dayville, OR:

late Miocene (7 Ma)

Crumb structure (mollic epipedon)in short grassland paleosol (Mollisol)Kimberly, OR: mid-Miocene (19 Ma)

Merychippus seversus Dayville, OR: mid-Miocene (16 Ma)

CENOZOIC 4: VEGETATION FROM SOIL

PHYTOLITHS-36-0 Ma abundant grassland phytoliths (Strömberg, 2002, 2004)

PEDOGENIC δ13Ccarb

-40 Ma of 20-40% C4(Fox and Koch, 2003)

PALEOSOLS-bunch then sod grasslands at warm- wet times-dry times expanded sagebrush (not grassland)

CENOZOIC 5: VEGETATION

Red forested non-calcareous paleosols (Alfisols) pass upwards into brown

calcareous grassland paleosols (Andisols) by mid-Oligocene (30Ma)

Painted Hills, Oregon

Paleoprecipitation estimated from paleosol Bt (blue)

or Bk (red) follows decline in atmospheric CO2

CENOZOIC 6: CLIMATE FROM SOIL

Chesapeake impact structure35 Ma (from Voytek, 2005)

Columbia River Basalts, Oregon, Washington (17-15 Ma) (Camp and Ross 2004)

Steinheim Crater, Germany 15 ma (3.8 km) by E. Stabenow

CLIMATE 1: TRANSIENT SPIKES35 Ma (Priabonian) and 16 Ma (Langhian)

transient spikes of warm-wet CO2

due to impacts and flood basalts

Ethiopian flood basalts 35 Ma (from Wood and Guth 2010)

PRO. Mountain uplift promotes weathering and albedo (Ruddiman and Raymo 1988)

CON. Physical not chemical weathering, metamorphic CO2

CLIMATE 2: HIMALAYAN COOLING?

PRO. Thermal isolationices Antarctica, consumes H2O, raises albedo (Kennett 1978)

CON. Warms mid-latitudes,minor reductions ofatmospheric H2O,CO2 and albedo

CLIMATE 3: ANTARCTIC CURRENT?

CLIMATE 4: GRASSLAND EXPANSION? Grasslands not due to drying, expanding into wetter regions-from 35-0 Ma expanded from 0-25% of land

Mollic and near-mollic paleosol records from 3 continents (Retallack 2001)

COEVOLUTION 1: GRASSES-GRAZERS

from Retallack 2007

BIOLOGICALMECHANISM-adaptation toothers not toenvironment

-grasses bestwithstand

grazers

-grazers bestcope with phytoliths

and growthof grasses

Paratomarctus euthos middle Miocene, Valentine

Formation, Gordon Quarry, Nebraska

Hesperocyon gregarius 32 Ma

Canis meso-melas (living)

Mesocyon sp. 27 Ma

Tomarctus euthos 16 Ma

5 cm

from Radinsky 1969

Prorean gyrus

COEVOLUTION 2: PACK HUNT & HERDS

-prorean gyrus found in pack hunting wolves and dogs, not foxes

-prorean gyrus appears in boro-phagine dogs of Nebraska 19 Ma

Agate Springs, NE: Miocene (19Ma)by Jay Matternes

bear dog den (Daphaenodon)

cursorial, hypsodont, tridactyl(Parahippus tyleri) Dung cake of ruminant

Mollisol paleosol

Silica husk of grass

(Panicum elegans)

- pack hunting- running escape- prey herding- hypsodont grazing- siliceous grasses- dung cakes- weedless sod- mollic soil

COEVOLUTION 4: DUNG AND SOD

y = 1.7492Ln(x) - 8.4142R2 = 0.7439

0

2

4

6

8

10

12

0 500 1000 1500 2000 2500 3000 3500 4000

Mean annual precipitation (mm)

So

il o

rgan

ic c

arb

on

(kg

/m2 )

Australia from Wynn et al. 2005, Africa from Zinke et al 1984

COOLING 1: CARBON STORAGE - organic C like net primary productivity increases with precipitation-grasslands rule strategic zone (300-1200 mm mean annual precip.)

African grasslands

Australian woodlands

COOLING 2: TRANSPIRATION

- grasslands have moist soil, dry air

-woodlandshave drier

soil (20-30%),moist air

-water vapor is a green-house gas,

although easily rained out

Nairobi National Park, Kenya Kakamega Forest, Kenya

COOLING 3: ALBEDO - grasslands light (albedo 15-19 %), covered by snow (albedo 40-85%)

-woodlands dark (albedo 8-13%) hard to cover with snow

CARBON FARMING 1: MOTIVATION - global warming due to CO2 could be offset by C storage in farm soils

-tests already underway in Australia, baseline soil C assay, then carbon

credit payment for gains

CARBON FARMING 2: TECHNIQUES 1. CELL GRAZING Pen cattle with electric for each days grazing: grazing takes out weeds leaving sod grasses.

2. PASTURE CROPPING Drill seed and raise crop through sod: prevents soil oxidation by plowing.

3. CONTOUR COPPICING Plant trees at inflexion point in slopes: prevents gully erosion.Electric fence and cell grazing, Horsham, Victoria

There’s some good news beneath the horizon,

Next to swamps, grassland soils have more carbon,

Since these are the soils that we already use

We can manage soil carbon and curb soil abuse,

It was just coevolution, a process by which we got sod.By grazing so hard on grassy sward,The Ice Age no longer seems odd.Still we have coevolution, a way that we can go forthAnd use the soil against big oilTo try to cool the Earth.

CONCLUSIONS

Grassland soil (Mollisol), Dionysiou, central Greece.