Transcript Global Warming and Gaia

Global Warming:
Estimating Future Carbon
Emissions
CS 1210
Spring 2004
Coming to a planet near you…
“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
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:
Specified
Atmospheric CO2
Concentration
Climate
Model
Future Climate
• More credible projections will need to do this:
Specified
CO2
Emissions
Combined
Climate and
Carbon Cycle
Model
CO2 Concentration
Future Climate
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
= PAT
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 development
High social and environmental
consciousness
Economic gains invested in social
institutions environment
Massive 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
polity
Note high emissions
for A1FI, lower for
A1T
A1T and B1 have
lowest emissions
No scenarios reduce
CO2 to pre-2000 level
Global warming: possible futures
Uncertainty in
models plus
uncertainty in
emission scenarios