Climate and Climate Change

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Global mean temperature change for 1/yr CO2
increase with subsequent stabilisation at 2xCO2
and 4cCO2. The red curves are from a coupled
AOGCM simulation (GFDL_R15_a) while the green
curves are from a simple illustrative model with
no exchange of energy with the deep ocean. (IPCC
2001)
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Climate model predictions of 21st C. temperatures
based on several scenarios of fossil fuel
consumption
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the IPCC-DDC scenario IS92a (GS greenhouse gases
and sulphate aerosols) for the years 2021 to 2050
relative to the period 1961 to 1990
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Major Uncertainties

• Rate of ocean heat uptake
• Magnitude (and long term direction) of marine and
  terrestrial carbon sources and sinks
• Feedback between warming, cloud cover, and
  planetary radiation balance
• Aerosol radiative properties

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A land sink for carbon?

• Terrestrial plants uptake 8-33 of fossil fuel
  emissions (about the same as ocean biotic uptake)
• Plants under-saturated with carbon dioxide.
• Nitrogen and sulfur deposition increased by
  fossil fuel combustion
• Global warming could increase NPP

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Potential effects of CO2 enrichment

• Increased photosynthesis
• Decreased stomatal conductance
• Increased water use efficiency
• Changes in tissue chemistry
• lower N
• Increased secondary compounds (e.g., phenolics)

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Photosynthesis and plant water balance
Absorption depends on soil water soil water
osmotic potential root osmotic potential
soil temperature, oxygen Transpiration depends
on leaf water, temp. air temp, humidity
leaf shape, resistance
H2O
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Water use efficiency

• C3 plants 1-3 g CO2 intake / kg H20 loss
• 20-35C optimal
  temperature
• C4 Plants 10-40 g/kg
• 30-45 C
• CAM Plants 20-40 g/kg
• 20-35 C

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Climate and the distribution of photosynthetic
pathways
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Schlesinger and Lichter 2001
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Andrews Forest Clearcut
Andrews Forest Succession yr. 33
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Figure 1-2 Global terrestrial carbon uptake.
Plant (autotrophic) respiration releases CO2 to
the atmosphere, reducing GPP to NPP and resulting
in short-term carbon uptake. Decomposition
(heterotrophic respiration) of litter and soils
in excess of that resulting from disturbance
further releases CO2 to the atmosphere, reducing
NPP to NEP and resulting in medium-term carbon
uptake. Disturbance from both natural and
anthropogenic sources (e.g., harvest) leads to
further release of CO2 to the atmosphere by
additional heterotrophic respiration and
combustionwhich, in turn, leads to long-term
carbon storage (adapted from Steffen et al.,
1998).
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CLIMATE CHANGEStoring Carbon on Land, R. J.
Scholes and I. R. Noble Science 294, Number 5544,
Issue of 2 Nov 2001, pp. 1012-1013.
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Risks associated with global warming

• Sensitivity
• Adaptive capacity
• Vulnerability

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Spatial variability of annual trends in
temperature and precipitation since 1976 relative
to 1961 to 1990 normals (ref. 1, modified). a,
Temperature (C per decade) b, precipitation (
per decade)
Walther et al. Nature 2002
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A warmer world. Shown here are projected changes
in surface air temperature, relative to
19902000, for the decade 202030.
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http//atlas.gc.ca/site/english/maps/climatechange
/potentialimpacts/coastalsensitivitysealevelrise
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Mitigation and Adaptation Approaches

• Emissions control
• Carbon sequestration
• Geo-engineering
• Adaptation
• Relocation
• Modify farming practices
• Modify water consumption patterns
• Flood control infrastructure

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Per capita greenhouse gas emissions (EPA)
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http//earthtrends.wri.org/text/ENG/maps/184_lg.ht
m
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Costs

• Direct
• Partial equilibrium
• General equilibrium
• Nonmarket
• http//www.unep.org/Documents/Default.asp?Document
  ID192ArticleID2758
• http//www.rff.org/environment/climate.htmissue2
  0briefs

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From Kolstad and Toman 2001
Vs. 5-185/ton for sequestration
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Estimates of the damage costs of climate change -
Part II. Dynamic estimatesTol RSJENVIRONMENTAL
RESOURCE ECONOMICS 21 (2) 135-160 FEB 2002
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Context of the UN Framework Convention on Climate
Change (FCCC)

• FCCC (adopted May 92, entered into force March
  94) requires developed (Annex I) countries to
• Limit anthropogenic emissions of greenhouse gases
  
• Protect and enhance greenhouse gas sinks and
  reservoirs
• 3 elements to Kyoto Protocol to the FCCC, adopted
  December 97
• Emission reduction targets, 5 collectively below
  1990
• Economic flexibility mechanisms, e.g. trading
• Estimating and reporting, 6 greenhouse gases
  (CO2, CH4, N2O, HFCs, PFCs, SF6)

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Global CO2 emissions (A), and annual change in
CO2 emissions (B), 2000 to 2100, leading to
stabilization of atmospheric CO2 at 450 ppm by
2100 for a scenario consistent with the Kyoto
Protocol (magenta) and a scenario with a 10-year
delay (green). Three carbon-cycle
parameterizations are used (see text) best guess
(thick solid lines), strong uptake (thin solid
lines), and weak uptake (thin dashed lines).
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Bush Administation Policy

• Cutting Greenhouse Gas Intensity by 18 Percent
  Over the Next 10 Years
• A New Tool to Measure and Credit Emissions
  Reductions
• Protect and Provide Transferable Credit for
  Emission Reductions
• Reviewing Progress on Climate Change and Taking
  Additional Action if Necessary in 2012
• Funding for Climate Change-Related Programs

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WRI analyis as cited in Parker CRS report