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Global Warming:Estimating Future Carbon
Emissions
CS 1210
Spring 2004
“A world thrown into turmoil by drought, floods, typhoons. Whole countries rendered uninhabitable. The capital of the Netherlands submerged. The borders of the US and Australia patrolled by armies firing into waves of starving boat people desperate to find a new home. Fishing boats armed with cannon to drive off competitors. Demands for access to water and farmland backed up with nuclear weapons. Sound like the ravings of doom-saying environmental extremists? It's actually the latest Pentagon report on how to ready America for the coming climate Armageddon.”
--- www.scoop.co.nz
Coming to a planet near you…
Review: Heat-Trapping Gasses
Water Vapor – most powerful greenhouse gas
Carbon Dioxide
Methane
Chlorofluorocarbons (also involved in ozone depletion)
Review: Climate modeling
All climate models based on heat balance
Zero-dimensional model: Earth as a single point
One-dimensional model: Earth as a set of latitude zones
General circulation models: 4-D grid
Review: Zero-D model
Energy incoming from sun is constant
Energy radiated out depends on T
Adjust T so that Energy out = Energy in
Result: T = zero degrees F!
Difference between model and reality is natural greenhouse effect
General Circulation Models
Uses 4-D grid
Limited by available supercomputer power
Starley pun: need a “Congressional Resolution”
Starley Thompson’s smoking gun
Starley’s Grand Challenge
Existing climate models:
Assumed CO2 levels Climate change
Models we need:
Assumed human emissions CO2 levels and climate change
Moving from Specified to Predicted CO2
• • Currently, projections of climate change do this:Currently, projections of climate change do this:
• • More credible projections will need to do this:More credible projections will need to do this:
SpecifiedSpecifiedAtmospheric COAtmospheric CO22
ConcentrationConcentration
ClimateClimateModelModel
Future ClimateFuture Climate
SpecifiedSpecifiedCOCO22
EmissionsEmissions
Combined Combined Climate and Climate and
Carbon CycleCarbon CycleModelModel Future ClimateFuture Climate
COCO22 Concentration Concentration
Human & Natural Carbon Flows
Natural carbon flows are much larger than anthropogenic flows
Possible indirect effects of human activity on natural carbon flows could be very important
Summary: model uncertainties
Cloud processes (can heat or cool)
Effects on natural carbon flows
How much human-emitted carbon?
Effects of global warming (possibly include THC collapse)
Predicting Human Carbon Emissions
Use the IPAT formula: I = P A T
Future human Population: unknown
Future human Affluence: unknown
Future human Technology: unknown
The IPCC Scenarios
The Intergovernmental Panel on Climate Change (IPCC) attempts to project possible future CO2 emissions
IPCC generated 40 scenarios, grouped into four storylines
Each storyline is a possible general trend of the history of the 21st century
Storylines of 21st Century History
Actual direction will depend on conscious human choices
US has disproportionate influence on future direction of the world
A1 storyline: successful globalization
High economic growth
Investment in education and technology
Incomes of rich and poor nations converge
Scenarios within A1 storyline
B scenario: Baseline (average) case
FI scenario: Fossil-fuel intensive
T scenario: new technologies used (solar, wind, nuclear)
A2 storyline: differentiated world
Differences between rich and poor nations persist
High population growth in poor nations
Many resources devoted to feeding 15 billion people
Few resources devoted to pollution control
B1 Storyline: Global Sustainable Development
Coherent international approach to sustainable developmentHigh social and environmental consciousnessEconomic gains invested in social institutions environmentMassive income redistribution towards income equality
B1 population and economics
Population reaches 9 billion by 2050
Declines to 7 billion by 2100
Lower average income than A1, but higher environmental quality and less poverty
B2 storyline: sustainable focus
Strong emphasis on environmental problems
Decentralized and community-based
Less global planning and tech focus than B1
Strong education and welfare systems lead to small, well-educated population
B2 Population and Economics
Population reaches 10 billion by 2100 (compare to B1, with more coordination)
Slightly less average income than B1
More inequality, but more local control
Emission Scenario Results
Baseline assumptions: no explicit climate polityNote high emissions for A1FI, lower for A1TA1T and B1 have lowest emissionsNo scenarios reduce CO2 to pre-2000 level
Global warming: possible futures
Uncertainty in models plus uncertainty in emission scenarios