IPCC AR4

Climate Change – Greenhouse Gases

A. Background• Greenhouse Effect

• Gases absorb heat (long-wave radiation)• Natural Greenhouse Effect

• Mean planetary temperature = 15 oC vs. -6 oC• Enhanced Greenhouse Effect

• Due to GHGs emitted from human activity

B. Greenhouse Gases• Most important GHG is water vapor

• Accounts for ~50% of natural GHE• Historically: Belief that human activities didn’t

affect atmospheric moisture content• Recent evidence that humans affect atmospheric

humidity (Santer et al. 2007, Willett et al. 2007)

Greenhouse GasesGas Sources Residence

Time (y)Radiative Forcing

Influence

(GHGs)

Carbon Carbon DioxideDioxide

FF combustionFF combustion

DeforestationDeforestation

Biomass burningBiomass burning

50-20050-200 11 63%63%

MethaneMethane Rice paddiesRice paddies

Cattle/TermitesCattle/Termites

LandfillsLandfills

FF ProductionFF Production

1010 2121 18%18%

Nitrous Nitrous OxideOxide

FertilizersFertilizers

DeforestationDeforestation

Biomass burningBiomass burning

150-170150-170 206206 6%6%

Halo-Halo-carbonscarbons

Industrial processesIndustrial processes

Electrical transmissionElectrical transmission

Substitution for ozone-Substitution for ozone-depleting substancesdepleting substances

15-65015-650 10,700 – 10,700 – 15,80015,800

13%13%

US EPA

Climate Change – Greenhouse Gases

B. Greenhouse Gases• Some features of CO2/Temperature

relationship don’t correlate well. Why not?• Other factors besides GHGs may influence

global climate

Climate Change – Other Factors

A. Cloud Cover• Reflects incoming radiation• Difficult to estimate in climate models• Effects vary in relation to altitude, thickness,

composition

B. Atmospheric Dust• Important factor in cool period from 1930s to 1960s

• Overwhelmed effects of rising CO2 during this period

• Produced by volcanic eruptions, dust from areas experiencing drought

• Cool period following eruption of Mt. Pinatubo in 1992

• Mechanism behind “Nuclear Winter” scenario

Climate Change – Other Factors

C. Volcanism• Affects water vapor, particles, sulfides, nitrates• Generally leads to planetary cooling

• Theory about extinctions at P/T boundary• Mt. St. Helens and Mt. Pinatubo eruptions caused

planetary cooling, and those were small eruptions

D. Photosynthesis & Transpiration• Affect CO2, water vapor

• As [CO2] rises, some plants• Photosynthesize more rapidly• Grow faster• Incorporate more CO2 into biomass

• Keep their stomata open less

• Transpiration releases water vapor into atmosphere• Less transpiration when [CO2] is higher (stomata)

Climate Change – Other Factors

E. Solar Output• May affect amount of incoming radiation• Solar output varies – sunspots, solar flares

• Sunspots: magnetic storms that appear as dark patches on sun’s surface

• Sunspot cycles of 11, 88, 205 years• During sunspot maxima, solar output ca. 0.1%

higher than normal

http://calspace.ucsd.edu/virtualmuseum/climatechange2/06_3.shtml

Climate Change – Other Factors

E. Solar Output• Researchers have correlated sunspot

minima with “Little Ice Age” in Europe during 17th and early 18th centuries when sun was 0.25% dimmer than normal

• 20th century dominated by sunspot maxima• Some predictions that 21st century will see minima

• Controversial• IPCC (2007): Solar output variation is ~14x less

influential than GHGs

Lean 2010

Global patterns

Regional variation

Climate Change – Other Factors

F. Albedo (Reflectivity)• Earth’s surface varies considerably (mean =

0.30-0.36)• Ice/Snow highly reflective (0.9)• Clouds vary in reflectivity• Land generally less reflective

• Changes in land use affect albedo• Desertification increases albedo• Melting of snow/ice decrease albedo

Climate Change – Other Factors

• Many factors affect global climate in multiple ways

• Ex – Clouds absorb long-wavelength radiation (heat) and reflect incoming short-wavelength radiation (light)

• Net effect = cooling

• Ex – Particles in atmosphere reduce re-radiation of long-wavelength radiation and reflect incoming short-wavelength radiation

• Net effect probably warming at low levels, cooling at high levels (e.g. following a large volcanic eruption)

• Efforts to reduce particulate air pollution facilitate warming

• Uncertainty about impact of many factors

IPCC AR4

IPCC AR4

Climate Change – Effects

A. Negative1. Sea Level• Warming melting of glaciers and ice caps

sea level rise• Warming thermal expansion of water

additional sea level rise• Melting of all ice sea level rise of ~70 m

http://www.epa.gov/climatechange/science/futureslc_fig1.html

Climate Change – Effects

A. Negative1. Sea Level• Since 1880, sea level has been rising at a rate of ~15

cm century-1

• Accelerating since 1940s• Some polar ice sheet loss• Loss of temperate glaciers

• Warming should more atmospheric moisture and precipitation, which should net growth of polar ice caps

• Examples• Bangladesh: Over 20 million people live less than 1 m

above sea level• ~40% of food production tied to flood plains

• AOSIS (Alliance of Small Island States) – Strong concerns about sea level rise

http://vrstudio.buffalo.edu/~depape/warming/east.html

US East Coast –Sea Level Rise1 m 3 m

www.panoramio.com/photo/31807235

http://sealevel.colorado.edu/files/current/sl.pdf

- Sea level rise is not globally uniform

Climate Change – Effects

A. Negative2. Rainfall Patterns• Warming should lead to

• Reduced precipitation at low latitudes• Increased precipitation at high latitudes

• Examples• Reduced snowpack in Sierra Nevada Mountains

due in part to rainfall instead of snow• Drought in many parts of the world

1958-2008

US Global Change Research Progam

Climate Change – Effects

A. Negative3. Storms• Warming should lead to

• More severe storms• Greater storm frequency

http://www.ncdc.noaa.gov/extremes/cei/

Climate Change – Effects

A. Negative4. Ecosystem Changes• Shifting climatic zones could expand ranges of

warmth-tolerant species and contract ranges of warmth-intolerant species

• Colder-living species might be displaced poleward as well as upward in elevation

• Species unable to adapt or move would go extinct• Predicted rates of 16.9 km/decade and 11.0 m/decade

(Chen et al. 2011)

• Within an ecosystem, some species will be more sensitive to climate change than others

• Species composition of ecosystems almost certainly will change

• Changes in CO2 concentrations pH of ocean

Chen et al. 2011

Climate Change – Effects

A. Negative4. Ecosystem Changes• Shifting climatic zones could expand ranges of

warmth-tolerant species and contract ranges of warmth-intolerant species

• Colder-living species might be displaced poleward as well as upward in elevation

• Species unable to adapt or move would go extinct• Predicted rates of 16.9 km/decade and 11.0 m/decade

(Chen et al. 2011)

• Within an ecosystem, some species will be more sensitive to climate change than others

• Species composition of ecosystems almost certainly will change

• Changes in CO2 concentrations pH of ocean

Climate Change – Effects

A. Negative5. Health

• Consistently elevated temperatures can lead to immunosuppression

• Allergies could worsen due to increased pollen production, dust (desertification), mold (humidity)

• Additional human mortality from severe summer heat

Climate Change – Effects

A. Negative6. Tropical Pests and Diseases

• Many tropical diseases are transmitted by animal vectors – insects, rodents

• Vector distribution often is limited by climatic barriers (e.g. mountain ranges)

• Ex: Malaria• Most prevalent vector-borne disease (1-2 million

cases/year)• Transmitted by Anopheles mosquitoes• Warming could lead to

• Broader geographic range (estimate that +2oC could expand range from 42 to 60% of global land area)

• Higher mosquito metabolic rate More food• Faster maturation More rapid reproduction• Faster parasite life cycle

• Potential spread into large urban areas (Nairobi, Kenya; Harare, Zimbabwe) with immunologically naïve pop’ns

• Projections are controversial and highly variable

Climate Change – Effects

B. Positive1. Plant Growth

• Warmer temperatures and elevated [CO2] faster plant growth & greater food production per acre

• Elevated [CO2] should more efficient use of water, reduced runoff and less water pollution

• Enhanced plant growth should remove CO2 from atmosphere faster (Gaia Hypothesis)

2. Agriculture• Expansion of agricultural regions• Longer growing season in areas that currently are

marginal for agriculture

Climate Change – Effects

B. Positive3. Rainfall Patterns

• Predictions of increased rainfall in major agricultural regions, especially in northern hemisphere

• Reduced irrigation required for plants/crops• Increased precipitation (as snow) should cause

glaciers and ice sheets to grow

4. Milder Winters• Severe winters pose a health and safety risk• Fewer expenses associated with less severe

winter weather

III. Climate Change – Projections

• Complexity and uncertainty in climate models

• Unknown response of earth climate system to a forcing function

• Accumulation of GHGs in atmosphere

• What should we do?? And why?• Lomborg

IPCC AR4

Some Responses to Global Climate ChangeSome Responses to Global Climate Change

Deny it altogetherDeny it altogether

Stress scientific uncertainty and do nothing beyond calling for more Stress scientific uncertainty and do nothing beyond calling for more scientific researchscientific research

GeoengineeringGeoengineering

AdaptationAdaptation

MitigationMitigation

VulnerabilityVulnerability

Who is most likely to get hit the hardest—suffer the greatest costs—by Who is most likely to get hit the hardest—suffer the greatest costs—by climate change?climate change?

Global SouthGlobal South

Lower income and marginalized communities and the poorer Lower income and marginalized communities and the poorer sectors of societies (poor pays, not polluter pays)sectors of societies (poor pays, not polluter pays)

Non-dominant groups of people in countries with strong ethnic, Non-dominant groups of people in countries with strong ethnic, religious, and other dividesreligious, and other divides

Women and childrenWomen and children

One Attempt to Sort out the Ethical Dimensions of One Attempt to Sort out the Ethical Dimensions of Global Climate ChangeGlobal Climate Change

As per the title “A Perfect Moral Storm: Climate Change, Intergenerational As per the title “A Perfect Moral Storm: Climate Change, Intergenerational Ethics and the Problem of Moral Corruption” (2006) Stephen M. Gardiner Ethics and the Problem of Moral Corruption” (2006) Stephen M. Gardiner claims that climate change poses nearly insurmountable ethical problems.claims that climate change poses nearly insurmountable ethical problems.

Climate change involves:Climate change involves:

1.1. dispersion of causes and effects in terms of space and time,dispersion of causes and effects in terms of space and time,

2.2. fragmentation of human agency in terms of space and time,fragmentation of human agency in terms of space and time,

3.3. and institutional inadequacy in terms of space and time,and institutional inadequacy in terms of space and time,

4.4. all subject to human corruption. all subject to human corruption.

First and Second Spatial Perspectives First and Second Spatial Perspectives of the Moral Stormof the Moral Storm

1.1. Dispersion of causes and effects of climate change Dispersion of causes and effects of climate change makes it hard to pinpoint moral geographical locations.makes it hard to pinpoint moral geographical locations.

2.2. Fragmentation of human agency makes it difficult to Fragmentation of human agency makes it difficult to respond to climate change. From an individual’s respond to climate change. From an individual’s perspective, it’s rational not to restrict one’s own perspective, it’s rational not to restrict one’s own pollution, while from a collective perspective it’s pollution, while from a collective perspective it’s rational to restrict pollution = tragedy of the commons.rational to restrict pollution = tragedy of the commons.

Third Spatial Perspective of the Moral StormThird Spatial Perspective of the Moral Storm

Institutional inadequacy hampers efforts to respond to Institutional inadequacy hampers efforts to respond to climate change because:climate change because:

1.1. There is no effective global governance system.There is no effective global governance system.

2.2. Some nations might wonder if they will be better or worse off Some nations might wonder if they will be better or worse off because of climate change.because of climate change.

3.3. Effectively mitigating climate change might require deep and Effectively mitigating climate change might require deep and profound changes to economic, political, and social structures. profound changes to economic, political, and social structures.

First Temporal Perspective of the Moral First Temporal Perspective of the Moral StormStorm

Dispersion of causes and effects over time might under-Dispersion of causes and effects over time might under-motivate people to effectively respond to climate change motivate people to effectively respond to climate change because:because:

1.1. Climate change is a resilient and substantially deferred Climate change is a resilient and substantially deferred phenomenon.phenomenon.

2.2. Climate change impacts are seriously back-loaded.Climate change impacts are seriously back-loaded.

Second Temporal Perspective Second Temporal Perspective of the Moral Stormof the Moral Storm

Fragmentation of human agency across time makes it Fragmentation of human agency across time makes it difficult to respond to climate change. From an individual difficult to respond to climate change. From an individual generation’s perspective, it’s rational not to restrict generation’s perspective, it’s rational not to restrict current pollution, while from a collective intergenerational current pollution, while from a collective intergenerational perspective it’s rational to restrict pollution.perspective it’s rational to restrict pollution.

This is an intergenerational tragedy of the commons.This is an intergenerational tragedy of the commons.

Third Temporal Perspective Third Temporal Perspective of the Moral Stormof the Moral Storm

This intergenerational tragedy of the commons has multiplier effects, This intergenerational tragedy of the commons has multiplier effects, namely: namely:

1.1. Inaction now raises transition costs that might make future change Inaction now raises transition costs that might make future change more difficult.more difficult.

2.2. Insufficient action now might make some generations suffer Insufficient action now might make some generations suffer unnecessarily (e.g., climate change harms future generations A, B, unnecessarily (e.g., climate change harms future generations A, B, and C, but current inaction leads to harming future generations D and C, but current inaction leads to harming future generations D and E as well).and E as well).

3.3. Insufficient action now might result in tragic choices for future Insufficient action now might result in tragic choices for future generations.generations.

Moral CorruptionMoral Corruption

Humans are often:Humans are often:

DistractedDistracted ComplacentComplacent UnreasonableUnreasonable Self-deceptiveSelf-deceptive ManipulativeManipulative Selectively attentiveSelectively attentive DelusionalDelusional HypocriticalHypocritical

Because of these human characteristics, and because climate change Because of these human characteristics, and because climate change involves a complex convergence of problems, we will often fall prey involves a complex convergence of problems, we will often fall prey to moral corruption. How will we ever successfully deal with climate to moral corruption. How will we ever successfully deal with climate change? change?

Climate Change and Some Dimensions Climate Change and Some Dimensions of Environmental Equity and Justiceof Environmental Equity and Justice

Distributive Justice: What is a fair or equitable distribution of the burdens and benefits of climate Distributive Justice: What is a fair or equitable distribution of the burdens and benefits of climate change?change?

Intragenerational equity: What steps should be taken to ensure that marginalized and Intragenerational equity: What steps should be taken to ensure that marginalized and vulnerable people within current generations do not disproportionately suffer from climate vulnerable people within current generations do not disproportionately suffer from climate change impacts?change impacts?

Intergenerational equity: What steps should be taken to ensure that future generations do not Intergenerational equity: What steps should be taken to ensure that future generations do not disproportionately suffer from climate change impacts?disproportionately suffer from climate change impacts?

Ecological Justice: What does the nonhuman world deserve?Ecological Justice: What does the nonhuman world deserve?

Compensatory Justice: How should monetary and technological resources be redistributed to Compensatory Justice: How should monetary and technological resources be redistributed to compensate those who shoulder disproportional burdens?compensate those who shoulder disproportional burdens?

Procedural Justice: How should responsibilities about what to do be defined and delegated?Procedural Justice: How should responsibilities about what to do be defined and delegated?

Participatory Justice: Who gets to delegate the responsibilities and decide what to do and how it Participatory Justice: Who gets to delegate the responsibilities and decide what to do and how it should be done?should be done?

Restorative or Transformative Justice: How can responses to climate change be used to restore Restorative or Transformative Justice: How can responses to climate change be used to restore or transform what is fundamentally wrong with North-South and other political, economic, and or transform what is fundamentally wrong with North-South and other political, economic, and social relations?social relations?

Some Possibilities for Burden-SharingSome Possibilities for Burden-Sharing

Historical Responsibility: Each country’s GHG reductions depend on its relative Historical Responsibility: Each country’s GHG reductions depend on its relative contribution to the problem of climate change. Also know as polluter pays or contribution to the problem of climate change. Also know as polluter pays or beneficiaries pay. beneficiaries pay. Common but Differentiated Responsibility: All people bear a common Common but Differentiated Responsibility: All people bear a common

responsibility reduce GHG emissions, but the greatest burden falls to those with responsibility reduce GHG emissions, but the greatest burden falls to those with the ability to pay and to those who have benefitted the most from GHG-producing the ability to pay and to those who have benefitted the most from GHG-producing activities.activities.

Solvency: Costs are distributed among states according to their ability to pay and Solvency: Costs are distributed among states according to their ability to pay and their contribution to the problem of climate change. their contribution to the problem of climate change.

Grandfathering: The world’s wealthier nations make efforts to reduce their GHG Grandfathering: The world’s wealthier nations make efforts to reduce their GHG emissions relative to a baseline year. emissions relative to a baseline year.

Per Capita (Equal Entitlements): Specify the size of the emissions budget, and Per Capita (Equal Entitlements): Specify the size of the emissions budget, and allow for every global citizen to be allocated an equal entitlement to the allow for every global citizen to be allocated an equal entitlement to the atmosphere, with rich countries contracting their annual GHG budgets and poor atmosphere, with rich countries contracting their annual GHG budgets and poor countries increasing their annual GHG budgets to eventually converge with the countries increasing their annual GHG budgets to eventually converge with the rich nations.rich nations.

Some More Possibilities for Burden-SharingSome More Possibilities for Burden-Sharing

Securing Basic Needs: Countries emitting more than what is deemed Securing Basic Needs: Countries emitting more than what is deemed “reasonable” to support a consistent, modest standard of living accept far “reasonable” to support a consistent, modest standard of living accept far higher mitigation costs than countries facing more poverty.higher mitigation costs than countries facing more poverty. Compensatory Equity: Powerless, disadvantaged, and socioeconomically Compensatory Equity: Powerless, disadvantaged, and socioeconomically

vulnerable people who are worst affected by climate change are vulnerable people who are worst affected by climate change are compensated by those who have benefitted the most from GHG producing compensated by those who have benefitted the most from GHG producing activities.activities.

Focus on the Poor: Relative to climate change, improve the situation of the Focus on the Poor: Relative to climate change, improve the situation of the poorest countries of the South, with the long-range intention of mitigating poorest countries of the South, with the long-range intention of mitigating unequal distributions of wealth.unequal distributions of wealth.

Carbon Intensity: Stabilize the climate as cost-effectively as possible while Carbon Intensity: Stabilize the climate as cost-effectively as possible while maximizing global economic growth.maximizing global economic growth.

Performance: Countries who use energy more efficiently are rewarded with Performance: Countries who use energy more efficiently are rewarded with more benefits.more benefits.

http://vimeo.com/3353504