MET 112 Global Climate Change Lecture 15

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MET 112 Global Climate Change - Lecture 15

• Climate Change Future Predictions
• Eugene Cordero
• San Jose State University

• Outline
• Scenarios
• Global Models
• Future Predictions

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Climate Change and humans

• Anthropogenic increases in
• Emission scenarios have been developed
• Changes in solar irradiance and volcanic aerosols

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Climate Change and humans

• Anthropogenic increases in
• greenhouse-gas concentrations
• sulfate aerosols due to anthropogenic emissions
• Emission scenarios have been developed
• Changes in solar irradiance and volcanic aerosols
• Unpredictable and difficult to model

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Calculation of Future CO2 Concentrations
CO2
Carbon Cycle Model Simulates atmosphere-biospher
e and atmosphere-ocean interactions
CO2
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Calculation of Future CO2 Concentrations
CO2 Emissions
Carbon Cycle Model Simulates atmosphere-biospher
e and atmosphere-ocean interactions
CO2 Concentration
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Carbon Cycle Models

• Atmosphere/ocean and atmosphere/biosphere
  interactions not well understood
• Model calculations contain uncertainty the
  largest uncertainty

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Carbon Cycle Models

• Atmosphere/ocean and atmosphere/biosphere
  interactions not well understood
• Model calculations contain uncertainty the
  largest uncertainty
• Future uptake of carbon by the biosphere
• Future uptake of carbon by the oceans

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Past and Projected Future CO2 Concentrations
(Back-Up)
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Past and Projected Future CO2 Concentrations
(Back-Up)
(ppm) Parts per million
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• Therefore, stabilizing emissions is not enough to
  reduce the radiative forcing
• Based on above, how much will emissions have to
  decline in to stabilize CO2 at 550ppm?

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Scenarios
Emission Scenarios
SRES (special report on emission scenarios)
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Scenarios
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CO2 emissions for stabilization scenarios
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CO2 concentrations (amount)
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Projected CO2 Concentrations for Various Scenarios

• Note that even the low-emission scenarios result
  in greatly increased CO2 concentrations by the
  year 2100
• Max concentration (of scenarios shown)
• Min concentration (of scenarios shown)

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Projected CO2 Concentrations for Various Scenarios

• Note that even the low-emission scenarios result
  in greatly increased CO2 concentrations by the
  year 2100
• Max concentration (of scenarios shown) 970 ppm
• Min concentration (of scenarios shown) 550 ppm
• (Compare with current value 370 ppm)

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Climate Models

• A climate model is a mathematical representation
  of the physical processes that control climate
• Basically everything that affects climate
• Equations are very complicated
• Some of the largest supercomputers are currently
  running climate models

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Climate Models

• A climate model is a mathematical representation
  of the physical processes that control climate
• Basically everything that affects climate
• Sun, atmosphere (greenhouse gases, aerosols),
  ocean, land
• Equations are very complicated
• Some of the largest supercomputers are currently
  running climate models

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Model Schematic
Changes in greenhouse-gas concentrations and
changes in albedo due to aerosols
Climate Model
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Model Schematic
Changes in greenhouse-gas concentrations and
changes in albedo due to aerosols
Climate Model
Climate change (i.e. temperature, winds etc.)
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Adjustable Parameters

• Climate Models contain a number of knobs to
  adjust the model.
• These knobs corresponds to physical processes
  that cannot be well modeled
• These knobs are set to best fit observations.
• Thus ,models have inherent uncertainties

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Adjustable Parameters

• Climate Models contain a number of knobs to
  adjust the model.
• These knobs corresponds to physical processes
  that cannot be well modeled
• These knobs are set to best fit observations.
• Thus ,models have inherent uncertainties
• Many different models are used (different
  research teams) to develop a consensus.

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General Circulation Models (GCMs)

• The most sophisticated type of climate model.
• Atmosphere/Ocean/Ice GCMs simulate the dynamics
  and thermodynamics of atmosphere/ocean/ice
  interactions.
• These models produce
• Can simulate regional effects

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General Circulation Models (GCMs)

• The most sophisticated type of climate model.
• Atmosphere/Ocean/Ice GCMs simulate the dynamics
  and thermodynamics of atmosphere/ocean/ice
  interactions.
• These models produce
• 3-dimensional simulations
• Can simulate regional effects
• Very computationally expensive to run

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Model Verification Can it be done?

• Before you can trust any of these models, they
  must be verified.
• If your model can simulate the past and present
  climate, then there is a reasonable chance that
  the model can reasonably model future climate.

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Model Verification Can it be done?

• Before you can trust any of these models, they
  must be verified.
• Use past and current climate as a test.
• If your model can simulate the past and present
  climate, then there is a reasonable chance that
  the model can reasonably model future climate.

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Most of the observed warming in the past 50 years
is attributable to human activities
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Future Predictions Temperature
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Notes on Temperature Projections

• Curves represent warming produced for seven
  scenarios by a model with average sensitivity.
• Each bar on right represent range of warming
  produced

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Notes on Temperature Projections

• Projected Warming 2000 2100 ranges from 1.4C
  to 5.8C.
• Curves represent warming produced for seven
  scenarios by a model with average sensitivity.
• Each bar on right represent range of warming
  produced
• by models of differing sensitivies for a specific
  scenario.

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Annual mean temperature change, 2071 to 2100
relative to 1990 Global Average in 2085 3.1oC
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Land areas are projected to warm more than the
oceans with the greatest warming at high latitudes
Annual mean temperature change, 2071 to 2100
relative to 1990 Global Average in 2085 3.1oC
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Annual mean precipitation change 2071 to 2100
Relative to 1990
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Some areas are projected to become wetter, others
drier with an overall increase projected
Annual mean precipitation change 2071 to 2100
Relative to 1990
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Sea Level
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Sea Level Rise
Annual mean precipitation change 2071 to 2100
Relative to 1990
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Model Sensitivity

• Models (like the atmosphere) are sensitive
  systems.
• They can respond differently to the same
  radiative forcing, e.g., a doubling of CO2
• This means that different models give different
  answers to the same problem
• Thus, we use a range of models to determine the
  range of possible future scenarios.

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Model Sensitivity

• Models (like the atmosphere) are sensitive
  systems.
• They can respond differently to the same
  radiative forcing, e.g., a doubling of CO2
• Thus, we use a range of models to determine the
  range of possible future scenarios.

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Main climate changes

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Main climate changes

• Higher temperatures - especially on land
• Arctic shows the largest warming
• Hydrological cycle more intense
• More rain overall
• Sea levels rise
• Why?
• Changes at regional level
• More intense weather (extremes)
• Floods, droughts etc.

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Questions

• Based on the A1F1 scenario, what is the predicted
  CO2 concentration, temperature change and sea
  level change in 2100?
• Based on the A1T scenario, what is the predicted
  CO2 concentration, temperature change and sea
  level change in 2100?

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UNITED NATIONS FRAMEWORK CONVENTION ON CLIMATE
CHANGERio de Janeiro June 1992ARTICLE 2
OBJECTIVE

• The ultimate objective of this Convention .... is
  to achieve, . stabilization of greenhouse gas
  concentrations in the atmosphere at a level that
  would prevent dangerous anthropogenic
  interference with the climate system.
• Such a level should be achieved within a
  time-frame sufficient
• to allow ecosystems to adapt naturally
  to climate change.
• to ensure that food production is not
  threatened, and
• to enable economic development to
  proceed in a sustainable manner.

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Gateway to IPCC data

• IPCC Data Distribution Centre
• http//ipcc-ddc.cru.uea.ac.uk/

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Mean Temperature (2050) relative to
1961-90 A1F A2 B2
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Impact of climate change predictions

• What affect will these predictions have on the
  earth?
• Environment
• Business
• Society