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