Transcript IAN MILLER: Longterm_Role_carbon

Plankton,
and Plants,
and
Tectonics!
Oh My!
The role of the longterm carbon cycle in
Earth’s climate.
Ian M. Miller
Curator of Paleontology
DMNS
WIPS March Meeting, 2008
Earth’s Climate
The average of weather and the combination of…
Solar Energy (distance from the Sun, intensity)
Atmosphere (composition & currents)
Oceans (composition, currents, & geology)
Ice (extent on land and sea)
Continents (location, elevation, & geology)
Plants & Animals (on land & in the seas)
Climate Change
At four (or five) time scales…
Modern time:
Anthropocene (last ~200 yrs—industrialization)
Holocene (last ~10,000 yrs—human civilization)
Deep Time:
Pleistocene (last ~1.8 million yrs—icehouse)
Previous 4.5 by (almost always a greenhouse)
Phanerozoic (542 Ma to ~10 Ka)
Climate Change
At three scales of climatic cycles…
Geologic:
Long-term carbon cycle (millions of yrs)
Milankovitch:
Earth’s orbital dynamics (400,000,
100,000, 40,000, and 20,000 Ka)
Sub-Milankovitch: (amplify longer cycles)
Short-term carbon cycle (~100’s to 1,000’s yrs)
Solar/Sunspot cycles (~10’s to ~1000’s yrs)
Climatic oscillations (2-7 yrs: El Nino La Nina)
Climate Oscillations:
Climate Oscillations:
During “Normal Years” or La Nina
Warm water in the western Pacific causes low pressure and high rainfall;
pressure system drives tradewinds from east to west;
tradewinds drive warm water to the west;
causing cold water to rise off South America and flow west.
South
America
Climate Oscillations:
During “El Nino”
Warm water shift to the eastern Pacific causes drought in western Pacific;
low pressure over the warm eastern Pacific causes heavy rains
and inhibits upwelling along the coast of South America.
South
America
The Ice Record: Milankovitch
Orbital Eccentricity
(~100,000 yr cycle)
Orbital Tilt (~41,000 yr cycle)
Orbital Precession (~23,000 yr cycle)
The Ice Record: Milankovitch
The Ice Record: Milankovitch
Brook, 2008 Nature
Carbon THE greenhouse gas
The Ice Record: Milankovitch
Brook, 2008 Nature
Short-term carbon cycle: ~10’s
to 1000’s of years
Respiration:
CH2O + O2 → CO2 + H2O + energy
Photosynthesis:
CO2 + H2O + light energy → CH2O + O2
Icehouse Earth
Sea Ice
Continental Ice
at the poles
Green River Fm: Greenhouse World
Courtesy K. Johnson
Courtesy K. Johnson
Fossil Lotus
Courtesy K. Johnson
Living Lotus
Courtesy K. Johnson
Lowland rainforest, Panama
Lomonosov
Ridge
Azolla (floating fern)
The Arctic Sea 50 million years ago
Courtesy K. Johnson
Geologic
cycles:
Climate
through
the
Phanerozoic—
carbon is
the culprit
Royer et al., 2003
Long-term Carbon Cycle: rocks
Two generalized reactions…
Photosynthesis/Respiration
CO2 + H20 ↔ CH2O + O2
Weathering/Precipitation
CO2 + CaSiO3 ↔ CaCO3 + SiO2
Long-term carbon cycle: rocks
Berner, 2001
A Carbon Thermostat
• Fluxes in and out of the major reservoirs
are relatively constant leading to an
equilibrium in atmospheric CO2—there are
negligible changes in fluxes during the
Pleistocene.
A Carbon Thermostat
• Fluxes in and out of the major reservoirs
are relatively constant leading to an
equilibrium in atmospheric CO2—there are
negligible changes in fluxes during the
Pleistocene.
• In geologic time, negative feedbacks serve
to regulate the equilibrium.
– High CO2, more warming, more plant growth,
less CO2, less warming…
No sinks: Runaway
Greenhouse Effect
• 97% carbon dioxide
• 3% nitrogen
• Water & sulfuric acid
clouds
• Temperature:
>800°F – more than
twice as hot as
Mercury
Venus
No sources:
Snowball
Earth
~650 Ma
Long-term carbon cycle: sinks
Berner, 2001
Photosynthesis (sink):
CO2 + H2O + light energy → CH2O + O2
Swamp Forests of the Paleozoic
Photosynthesis (sink):
CO2 + H2O + light energy →
CH2O + O2
Weathering (sink):
CO2 + CaSiO3 → CaCO3 + SiO2
Precipitation (sink):
CO2 + CaSiO3 → CaCO3 + SiO2
Precipitation (sink):
CO2 + CaSiO3 → CaCO3 + SiO2
Long-term carbon cycle: sources
Berner, 2001
Georespiration (oxidation, source):
CH2O + O2 → CO2 + H2O
Georespiration (thermal decomposition):
CH2O + O2 → CO2 + H2O
Georespiration (thermal decomposition):
CH2O + O2 → CO2 + H2O
Georespiration (mantle source):
CH2O + O2 → CO2 + H2O
Long-term carbon cycle: sources and sinks
Berner, 2001
How do long-term carbon flux
changes alter the climate?
• The ice age and the oxygen maximum
during the Late Carboniferous.
• Draw down of CO2 leading up to the
Pleistocene minimum.
Climate
and
Carbon
through
the
Phanerozoic.
Royer et al., 2003
Paleozoic Swamp Forests
CO2 and O2 through the Phanerozoic
Berner, 2003
Extant
Dragonfly
Permian
Dragonfly
Climate
and
Carbon
through
the
Phanerozoic.
Royer et al., 2003
Subduction (source) then
Weathering (sink)
Subduction then Uplift
Cenozoic Deep Sea Climate Record
Time, Ma
The Ice Record
Brook, 2008 Nature
IPCC 2001 Temperature Curve
Georespiration (thermal decomposition):
CH2O + O2 → CO2 + H2O
>100 times faster than volcanoes
Berner, 2001
1946 – 1950
svs.gsfc.nasa.gov
1956 - 1960
Temperature
svs.gsfc.nasa.gov
1966 - 1970
Temperature
svs.gsfc.nasa.gov
1976 - 1980
Temperature
svs.gsfc.nasa.gov
1986 - 1990
Temperature
svs.gsfc.nasa.gov
1996 - 2000
Temperature
svs.gsfc.nasa.gov
2002 - 2006
Temperature
svs.gsfc.nasa.gov
Minimum Sea 1979
Ice 1979
September,
Minimum Sea 2005
Ice 2005
September,
September, 2007
The Long-term carbon cycle and
Earths climate:
Carbon cycles:
Long-term carbon cycle (millions of yrs)
Driver of long-term climate changes
Responsible for Icehouses/Greenhouses
Short-term carbon cycle (~100’s to 1,000’s yrs)
May exacerbate short-lived climate events
e.g. Milankovitch cycles
Doesn’t play a role in long-term climate
Long-term carbon cycle and today:
Burning fossil fuels is like setting off volcanoes >100 times
faster than present eruptions rates
Running a global experiment, which in not analogous to
glacial-interglacials.