Atmospheric Research Representing Uncertainties & Selecting Scenarios Roger N. Jones AIACC Training Workshop on Development and Application of Integrated Scenarios in Climate Change Impacts, Adaptation and Vulnerability Assessments Tyndall Centre, UEA, Norwich UK April

Atmospheric Research Coverage Sources of uncertainties Implications of each for I, A & V How to address each type of uncertainty Risk assessment framework Criteria for selecting scenarios

Atmospheric Research IPCC 1994

Atmospheric Research Uncertainty explosion Global climate sensitivity Emission scenarios Regional changes Biophysical impacts Socio-economic impacts Climate variability

Atmospheric Research Likelihood Probability can be expressed in two ways: 1. Return period / frequency-based (Climate variability) 2. Single event (Mean climate change, one-off events)

Atmospheric Research Return period / frequency-based probability Recurrent or simple event Where a continuous variable reaches a critical level, or threshold. Eg. Extreme temperature (max & min), Extreme rainfall, heat stress, 1 in 100 year flood Discrete or complex event An event caused by a combination of variables (an extreme weather event) Eg. tropical cyclone/hurricane/typhoon, ENSO event

Atmospheric Research Hot cows and heat stress THI between 72 and 78 mild stress THI between 89 and 98 severe stressDEAD COWS! THI above 98 moderate stress THI between 79 and 88

Atmospheric Research Frequency of exceeding heat index threshold

Atmospheric Research Frequency-based probability distributions

Atmospheric Research Single-event probability Singular or unique event An event likely to occur once only. Probability refers to the chance of an event occurring, or to a particular state of that event when it occurs. Eg. Climate change, collapse of the West Antarctic Ice Sheet, hell freezing over

Atmospheric Research What is the probability of climate change? 1. Will climate change happen? IPCC (2001) suggests that climate change is occurring with a confidence of 66% to 90% 2. What form will it take? Uncertainties are due to: future rates of greenhouse gas emissions sensitivity of global climate to greenhouse gases regional variations in climate decadal-scale variability changes to short-term variability

Atmospheric Research Range of uncertainty

Atmospheric Research CO 2 emissions and concentrations

Atmospheric Research Simulated global warming: A2

Atmospheric Research Global warming

Atmospheric Research Risk exercise - estimating joint probabilities Take a gold coin (preferably 1 pound coin) Heads represents low end (1.4°C), tails represents high end (5.8°C) Flip coin 7 times and record the number of heads and tails Which outcome is most likely?

Atmospheric Research What is a hazard?

Atmospheric Research Typology of extreme climate events

Atmospheric Research Current climate

Atmospheric Research Future climate - no adaptation

Atmospheric Research Future climate with adaptation Policy Horizon

Atmospheric Research Linking key climatic variables to impacts Climate variable Impacted activity Performance criteria

Atmospheric Research Cross impacts analysis

Atmospheric Research Cross impacts analysis

Atmospheric Research Characterising vulnerability Presentations in this workshop suggest two ways of characterising vulnerability: 1. In response to a fixed climate hazard e.g. temperature, peak wind speed 2. As a measure where the degree of harm cannot be tolerated, and that can be linked to a given climatic condition (threshold approach)

Atmospheric Research Thresholds A non-linear change in a measure or system, signalling a physical or behavioural change Climate related thresholds are used to mark a level of hazard

Atmospheric Research Thresholds Biophysical Tropical cyclone Coral bleaching ENSO event Island formation Island removal Behavioural Legal/regulatory Profit/loss Cultural Agricultural Critical

Atmospheric Research Thresholds Link socio-economic criteria with biophysical criteria through a value judgement Provide a fixed point against which to measure climate uncertainty Directly link a particular impact to climatic variables Introduce criteria as defined by stakeholders into an impact assessment

Atmospheric Research Critical thresholds A level considered to represent an unacceptable degree of harm This is a value judgement and may be decided by stakeholders, be a legal requirement, a safety requirement, a management threshold etc

Atmospheric Research Metrics for measuring costs Monetary losses (gains) Loss of life Change in quality of life Species and habitat loss Distributional equity

Atmospheric Research Planning horizons

Atmospheric Research Probabilistic structure of climate uncertainties Critical threshold Time Variable(s)

Atmospheric Research What is a risk?

Atmospheric Research What is a risk? Two uses 1. In general language 2. A specific operational meaning

Atmospheric Research Characterising risk UNEP definition risk = hazard + vulnerability vulnerability = exposure + susceptibility to loss risk = f(hazard,likelihood)

Atmospheric Research Placing thresholds within scenario uncertainty A B

Atmospheric Research Impact thresholds

Atmospheric Research Probabilistic structure of climate uncertainties Critical threshold Time Variable(s)

Atmospheric Research Production effects THI between 79 and 88 THI between 72 and 78 mild stress no stress moderate stress mild stress

Atmospheric Research Coral bleaching Caused by SST above a threshold Expels xosanthellae algae Severity related to days above bleaching threshold Corals may recover or die

Atmospheric Research Macquarie River Catchment Burrendong Dam Windamere Dam Major Areas of Abstraction Macquarie R Contributing Area Macquarie Marshes Area ~ 75,000 km 2 P = 1000 to <400 mm. Major dams: Burrendong and Windamere Water demands: irrigation agriculture; Macquarie Marshes; town supply Most flow from upper catchment runoff Most demand in the lower catchment

Atmospheric Research Ranges of seasonal rainfall change for the MDB Summer Autumn Winter Spring

Atmospheric Research P and Ep changes for Macquarie catchment In change per degree global warming

Atmospheric Research Changes to MAF for 9 models in 2030 (%) Based on IPCC 1996 B1 at 1.7°C 0.55°C A1 at 2.5°C 0.91°C A1T at 4.2°C 1.27°C

Atmospheric Research Climate change – flow relationship  flow = a  ( atan (  Ep /  P ) – b Standard error < 2%

Atmospheric Research Sampling strategy The range of global warming in 2030 was 0.55– 1.27°C with a uniform distribution. The range of change in 2070 was 1.16–3.02°C. Changes in P were taken from the full range of change for each quarter from the sample of nine climate models. Changes in P for each quarter were assumed to be independent of each other The difference between samples in any consecutive quarter could not exceed the largest difference observed in the sample of nine climate models. Ep was partially dependent on P (dEp = 5.75 – 0.53dP, standard error = 2.00, randomly sampled using a Gaussian distribution)

Atmospheric Research Changes to Burrendong Dam storage 2030 <60 <70 <80 <90 <95 <100 <50 Cumulative Probability (%)

Atmospheric Research Changes to bulk allocations for irrigation 2030 <60 <70 <80 <90 <95 <100 <50 Cumulative Probability (%)

Atmospheric Research Changes to Macquarie Marsh inflows 2030 <60 <70 <80 <90 <95 <100 <50 Cumulative Probability (%)

Atmospheric Research Probabilities of flow changes - impacts view Range of possible outcomes

Atmospheric Research Critical thresholds Macquarie River Catchment Irrigation 5 consecutive years below 50% allocation of water right Wetlands 10 consecutive years below bird breeding events

Atmospheric Research Irrigation allocations and wetland inflows - historical climate and 1996 rules

Atmospheric Research Threshold exceedance as a function of change in flow (irrigation)

Atmospheric Research Threshold exceedance as a function of change in flow (bird breeding)

Atmospheric Research Risk analysis results Macquarie 2030

Atmospheric Research Risk analysis results Macquarie 2070

Atmospheric Research Bayesian analysis results Macquarie 2030

Atmospheric Research Bayesian analysis results Macquarie 2070

Atmospheric Research Characterising risk as a function of global warming The standard “7 step method” of impact assessment progresses from climate to impacts to adaptation. This infers that we must predict the likeliest climate before we can predict the likeliest impacts. Can we get around this limitation?

Atmospheric Research Characterising risk There is another way. Impacts = function(Gw) Impacts = function(Gw,t,p) p(impacts) = no. of scenarios < threshold = risk

Atmospheric Research Risk exercise - estimating threshold exceedance: sea level rise Recover coin from greedy presenter Heads represents low end (9 cm), tails represents high end (88cm) The group chooses two critical thresholds Flip coin 7 times and record the number of heads and tails Which outcome is most likely?

Atmospheric Research Increasing likelihood of global warming Probability of threshold exceedance Characterising the risk of global warming

Atmospheric Research Characterising the risk of global warming Risks to Many Risks to Some I I Risks to unique and threatened systems II II Risks from extreme climate events Large Increase Increase III Distribution of impacts III Negative for most regions Negative for some regions IV Aggregate impacts IV Net Negative in all metrics Markets + and - Most people worse off V Risks from large-scale discontinuities V Very low Higher Probability of threshold exceedance

Atmospheric Research Long-term planning Short-term policy response 1. Enhance adaptive capacity so that the current coping range expands, reducing present vulnerability. 2. Develop this capacity in such a way that the longer-term risks to climate change are also reduced.

Atmospheric Research Basic principles Pay greater attention to recent climate experience. Link climate, impacts and outcomes to describe the coping range. Address adaptation to climate variability and extremes as part of reducing vulnerability to longer-term climate change. Assess risk according to how far climate change, in conjunction with other drivers of change, may drive activities beyond their coping range. Focus on present and future vulnerability to ground future adaptation policy development in present-day experience. Consider current development policies and proposed future activities and investments, especially those that may increase vulnerability.

Atmospheric Research Foresighting your project Visualise how you will present the results (graph, text, table, animation) Rehearse how you will communicate the uncertainties Anticipate questions upon presentation or review How will you engage different stakeholders?