Atmospheric Research Climate Hazards & Risk Assessment Roger N. Jones AIACC Kickoff Meeting Nairobi February

Atmospheric Research What is a hazard?

Atmospheric Research Typology of extreme climate events

Atmospheric Research Frequency of exceeding heat index threshold

Atmospheric Research Current climate

Atmospheric Research Future climate - no adaptation

Atmospheric Research Future climate with adaptation Policy Horizon

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 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 Uncertainty Uncertainty and probability can be expressed in two ways: 1. Return period / frequency-based 2. Single event

Atmospheric Research Return period / frequency-based probability Recurrent event Where a continuous variable reaches a critical level, or threshold. Eg. Extreme temperature (max & min), Extreme rainfall, THI >72, >78, 1 in 100 year flood Discrete event An event caused by a combination of variables (an extreme weather event) Eg. tropical cyclone/hurricane/typhoon, ENSO event

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. That it will occur IPCC (2001) suggests that climate change is occurring with a confidence of 66% to 95% 2. What form will climate change 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

Atmospheric Research Uncertainty explosion

Atmospheric Research CO 2 emissions and concentrations

Simulated global warming: A2

Atmospheric Research Global warming

Atmospheric Research Mean sea level in the 20 th century Church et al. (2001)

Atmospheric Research Sea level rise projections for one emission scenario (IS92a) Church et al. (2001)

Atmospheric Research SRES sea level rise to 2100

Atmospheric Research Placing thresholds within scenario uncertainty A B

Atmospheric Research Impact thresholds

Atmospheric Research Complex system undergoing change Pre-adapted state Vulnerable state M1 M2 M3 M4

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

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

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

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 Probabilities of flow changes climate view

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

Atmospheric Research Risk analysis results Macquarie 2030

Atmospheric Research Characterising risk 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? Agree or disagree?

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 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 Characterising the risk of global warming 0ºC 1.4ºC 5.8ºC Most likely Least likely Warming | Risk Scenario 1 Scenario 5 Scenario 3 Scenario 4 Scenario 6 Scenario 2

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.