Lessons from the Climate Wars:The Future of the IPCC

Gary Yohe

Woodhouse/Sysco Professor of EconomicsWesleyan University

May 7, 2008

Princeton/GFDL Lecture Series on the IPCC

Outline

• Review some of the major lessons from the Fourth Assessment Report from perhaps a WGII perspective.

• Links to future visions for IPCC– Research and information gaps– Working Group tensions and aspirations– Timing and client-base tensions

• “Integrating” assessments and special reports into a process that more quickly and appropriately informs plenary approved outlines

Portraits of Anticipated Climate Change and Impacts – The TAR (2001)

Anthropogenic warming is ‘unequivocal’

WGI SPM Fig. 3

Portraits of Observed Climate Change

Attribution on Every Continent

EFFECTS ARE BEING OBSERVED NOW: Observed effects in N. America

Emissions are accelerating and Carbon

Dioxide is the largest

contributor

(IPCC WG3)

Unmitigated GHG emissions will continue to

grow over the next few decades (IPCC WG3)

• 25-90 % inc (over 2000 levels) of emissions by 2030, depending on the SRES scenario

Scenarios, simplified:

A1: globalised, high growth world

A2: regionalised, high growth world

(large diffs in income)=BaU B1: lower resource use, global

governance, higher income B2 : lower resource use,

regional variations, lower income

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Summary - Lessons from the Fourth Assessment Report (2007)

• Anthropogenic signals have been confirmed at continental scales.

• A climate change signal has been confirmed for many observed impacts and attributed to anthropogenic sources of warming.

• Climate is changing faster than was anticipated only 5 years ago (in the Third Assessment Report of the IPCC).

• Many of the temperature thresholds for critical impacts are now thought to be lower than anticipated in the TAR (5 years ago). The planet is approaching these thresholds more quickly than thought in 2001.

More Lessons from the Fourth Assessment Report (2007)

• Achieving any concentration threshold cannot guarantee achieving a specific temperature threshold; but achieving a concentration target can reduce the likelihood of crossing those thresholds at any point in time.

• Vulnerability to climate risk will be amplified in areas that already confront multiple stresses (for example, from land degradation, globalization, exposure to disease, etc.)

An Important Corollary from the Fourth Assessment Report

(2007)• Climate change can be its own source of multiple stress.

• Vulnerability to climate can therefore be greater than the sum of the vulnerabilities to each manifestation taken alone.

Making “Dangerous” Operational:

Key Vulnerabilities and Key Risks

• Depending on circumstances, some impacts could be associated with ‘key vulnerabilities’, based on a number of criteria in the literature.

• Assessment of potential key vulnerabilities is intended to provide information on rates and levels of climate change to help decision-makers make appropriate responses to the risks of climate change.

• Fundamentally, risk is probability times consequence.

• Aside: accepting risk allows IPCC to report more than “high confidence” conclusions.

Criteria for “key” vulnerabilities and risks – WGII-Chapter 19

• Magnitude• Timing• persistence/reversibility• the potential for adaptation• distributional aspects• Likelihood• “importance” of the impacts

Risks to Unique and Threatened Systems

As warming proceeds, species extinction and coral reef damage is projected; with significant extinctions for warming above 4oC and widespread coral reef mortality over 2.5-3oC. Increasing vulnerability of indigenous communities in the Arctic and small island communities to warming is projected.Irreversibility, distributional

aspects, likelihood, potential for adaptation

More globally quantified assessment of ecosystem changes are now

available.

Assessing Confidence – TAR 2001

Very high

High

Medium

Low

Confidence Regions

estimated confidencefromliterature review

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Minimum Probability (š)

(n'/n) Proportion

Risk of Extreme Weather Events

Responses to some recent extreme events reveal higher levels of vulnerability than the TAR. There is now higher confidence in the projected increases in droughts, heatwaves, and floods as well as their adverse impacts.Distributional aspects, likelihood,

potential for adaptation, magnitude, timing

Higher Risk of Vulnerability from Extreme Weather – Likelihood times Consequence

Exercising the Risk CalculusVulnerability to Coastal Storms

• Confidence in connection between climate change and their intensities and frequencies continues to vacillate.

• Evidence is that consequences are higher than previously assessed (lower adaptive capacity, etc….).It follows that risk can be assessed

to be higher than previously thought.

Distribution of Impacts and Vulnerabilities

There is increasing evidence of greater vulnerability of groups such as the poor and elderly in not only developing but also developed countries. Moreover, there is increased evidence that low-latitude and less-developed areas generally face the greatest risk, particularly in dry areas and mega-deltas.

Distributional aspects, likelihood, potential for adaptation, magnitude

In all regions the most affected will be: the poor, elderly, young and marginalized.

Selected health impacts of climate change

COASTAL SETTLEMENTS Densely populated “megadeltas”, especially in Asia

and Africa, face particularly high risks.

The most vulnerable people and places can now be identified

• Most vulnerable regions are: – Africa, Asian mega-deltas, small islands, the Arctic

• Most vulnerable sectors are:– water in the dry tropics – agriculture in low latitudes – human health in poor countries – ecosystems at the margins: e.g. tundra, boreal,

mountains or already stressed: e.g. mangroves, coral

In all countries, even those with high incomes, some

are especially at risk: the poor, the elderly, and young

children.

Net Aggregate Impacts

Compared to the TAR, initial net market-based benefits from climate change are projected to peak at a lower magnitude of warming, while damages would be higher for larger magnitudes of warming. The net costs of impacts of increased warming are projected to increase over time.

Timing, magnitude,

distributional aspects

The aggregate impact of climate change is negative ... but its timing

remains unclear

Important regional differences in crop yield response exist

Estimates of the Social Cost of Carbon

Figure 20.3: Cumulative Density Function for the Social Cost of Carbon The distribution is shown for all studies in gray and for studies that use pure rates of time preference equal to 3%, 1%, and 0% in black from top to bottom, respectively. (Source: Tol (2005))

Approaches to Economic Valuation of Impacts – Policy-

maker Discretion

• Discount rate• Equity weighting

• Take-home: Any set of choices designed to move SCC to one end or the other of its distribution can be undone by Mother Nature.

Risks of Large-scale Discontinuities: Long-term or Irreversible Changes

There is increased confidence that global warming over many centuries will lead to large sea level rise. Species extinction is projected within this century.

Magnitude, irreversibility, potential for adaptation, distributional aspects, timing, likelihood

An Updated Burning Embers Diagram

A Major Lesson from the Fourth Assessment Report (2007)

• Adaptation is unavoidable because the planet would be committed to more warming even if emissions of greenhouse gases were halted today.

• Responding to climate change involves an iterative risk management process that includes both adaptation and mitigation and takes into account climate change damages, co-benefits, sustainability, equity, and attitudes to risk.

Adaption is complex because coping ranges and adaptive capacity vary greatly

between regions e.g: in Australia and New Zealand (based on expert judgement)

Pathways to alternative targets

Policy Relevant Information for the Short-term

Moving to the Future:Tensions over Timing between

Clients• Specific research needs – relatively easy, but need

to think about context and priorities; beyond control unless a “science plan” is offered.

• Tension between negotiators’ needs for Copenhagen and IPCC’s necessity to preserve the credibility of its special reports and comprehensive assessments.

• Tensions between Working Groups.• Speeding the pace at which IPCC results are

reflected in “Plenary Approved Outlines”.

Some future WGII-type research needs

• Observed effects: rate, sensitivity, and learning about adaptation• Scaling and mapping impacts against unmitigated climate change

(plugging the gaps: missing regions, exposure fields, and high-end CC)

• ......especially for a range of development pathways• ......especially for a range of mitigation pathways• Effects of weather events (both extreme and other)• Effects of large-scale events• Clarify near-term inflexion-point of benefits/damages• Evaluate interaction of impacts with sustainable development• Evaluate impacts in context of multiple stresses• Much more on costs of adaptation• .....and on capacities, limits and barriers to adaptation

Prioritize in terms of gaps looking through the lens of “key vulnerabilities” and the criteria.

Tensions over Timing

• Negotiators want timely information on “risks” through Copenhagen – a sense of urgency.

• IPCC wants to preserve the integrity of the assessment process – an argument for deliberate and well-vetted processes within an intergovernmental context.

• Thus this tension is created by the IPCC’s context with the UNFCCC and the COP’s.

Reactions with IPCC to the Tension

• Solomon and Manning Editorial (Science, 319:

1457) – Periodic assessments– Preserve the process– Be sure to do the science right

• Working Group II “hindsight meeting” at the NAS in early March:– Agree… but emphasize doing the right science– Inform decision-makers where they work– Use criteria for “key” to prioritize– Suggests need for carefully crafted Special Reports

Tension between Working Groups – Two Examples

• Providing information for the critical time-frames within which decision-makers on the cusp between environment and sustainable development operate – “time slices” for this century.

• Providing (some) information about the range of possible outcomes based on observations even if understanding about and modeling of (including calibration) the underlying process is not well-formed or comforably substantiated.

A Working Group II Aspiration(Source: Executive Summary, Stern, et. al., 2007:

Committed0.6oC

2.0oC target(pre-ind.)

Sea Level Rise Trajectories (AR4)

Source: NECIA/UCS, 2007 (see: www.climatechoices.org/ne/)

NYC : Today’s 100-Year Flood Could Occur Every 10 Years under the Higher-Emissions

Scenario

Credit: Applied Science Associates, Inc.. Source: Google, Sanborn Map Company, Inc.. NECIA, 2007 (see: www.climatechoices.org/ne/).

Return-Times for the Current 100-flood Anamoly in NYC

y = 76.218e-0.1019x

R2 = 0.9764

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A Decision-maker’s Choice Set:

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Perhaps the New Scenarios will Help

• Four different scenarios defined by forcing.• Long-term ensembles through 2200 on major

variables.• Significan downscaling through 2035.• Building both ways after their creation:

– Forward to the impacts that can be cast in socio-economic context.

– Backward to consider “non-implausibility” including along socio-economic dimensions.

• Will not be ready in a timely fashion for Copenhagen or even AR5.

Speeding the Pace

• Speed the pace of incorporating new knowledge into the assessments even if their spacing over time does not change– Learning from experience in bring the

synthesis together – do it sooner.– Exercising self-critiques to see how AR4 and

even TAR could have been better given what we know now synthetically.

– Work to make sure that fundamental insights from AR4 and not SAR form the basis of the Plenary Approved Outlines

Suggested Topics for Special Reports

• The practice of adaptation and mitigation – bring lessons from the ground to the assessment (e.g., risk management is a key to the finance ministries).

• The two-way causal connection (positive and negative) between sustainable development and climate change (e.g., what would Chapter 20 have looked like if it had been done by development economists?).

• What is missing in valuation across many metrics (e.g., is aggregation worth the effort?) (risk profiles can portray relative vulnerabilites in multiple metrics with and without mitigation and/or adaptation)

Suggested Structure for Creating Special Reports

• Special meetings to review critically AR4 material and even TAR from new perspectives – how would the chapters have changed if those perspectives had been applied?

• Smaller writing teams create the new (updated in a sense) chapters based on the literature available then and since with full documentation of– New stuff for negotiators (responding to urgency)– New stuff for the assessment and the contributors to the

assessment (responding to making deliberate progress in IPCC)

• The reports should close with suggestions and perhaps drafts of chapter outlines (for later “synthetic” chapters) or topic templates (for earlier “sectoral” and “regional” chapters) for the AR5.

Thanks for your attention…

Questions?

Extra slides

• An economic case for near-term action

• Downing/Watkiss matrix – what is missing

Risk Management Perspectives to Policy and Framing The Long

Term• Read the charts and pick a level that you

think is “dangerous” – for example, the EU 2 degree target

• Convert to a concentration target based on tolerable risk– 750 ppm means a greater than 80% chance of

exceeding 2 degrees by 2090’s– 650 ppm means a 70% chance– 550 ppm means around a 60% chance– 450 ppm means a 20% chance

Since concentrations depend on cumulative emissions….the

short term response comes into focus

• Once you have a concentration target in mind, you have a long-term perspective.

• For the short-run, you know immediately from basic economic theory (the Hotelling result on exhaustible resources) that doing nothing over the near term cannot be a least-cost strategy.

This is A VALID ECONOMIC ARGUMENT FOR IMMEDIATE ACTION

An Economic Argument for Near-term Action: “Uncertainty is a

Reason to Act”

• The case for adaptation is simple – we are committed to at least another degree of warming over this century.

• For mitigation, can skeptics guarantee that humans are not changing the climate?

• Can they guarantee that the source of climate change is not human influence?

• Since they cannot, then people can define what they think is “dangerous” interference with the climate system.

Another Complication – What is Missing?