climate change scenarios: global and local
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Climate change scenarios: global and local. NZCCC Adaptation Conference ‘09 Andy Reisinger 1 with Martin Manning 1 , Brett Mullan 2 , David Wratt 2 , Richard Nottage 2 1 Climate Change Research Institute, School of Government, Victoria University - PowerPoint PPT PresentationTRANSCRIPT
New Zealand ClimateChange Research Institute
Climate change scenarios:
global and local
NZCCC Adaptation Conference ‘09
Andy Reisinger 1
with Martin Manning 1, Brett Mullan 2, David Wratt 2, Richard Nottage 2
1 Climate Change Research Institute, School of Government, Victoria University2 National Institute of Water and Atmospheric Research (NIWA)
2
Scenarios: alternative futures
Future climate change depends on future greenhouse gas emissions
Future greenhouse gas emissions depend on socio-economic choices
Figures based on Meinshausen et al., Nature 2009
We cannot predict the socio-economic choices the worldwill make.
But we can ask “what if” any particular choice became reality?
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Scenarios: alternative futures
rapidlydecarbonising world
high carbon world
Future climate change depends on future greenhouse gas emissions
Future greenhouse gas emissions depend on socio-economic choices
Different impacts globally
Different socio-economic drivers: fractured world with uneven development vs.convergent world with strongfocus on multilateralism
Figures based on Meinshausen et al., Nature 2009
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Climate change scenarios: implications
Implications of alternative scenarios:
• (obviously) different climate and impacts for NZ
• but also: different impacts around the world• and also: very different settings for international
policy, technology, sustainability, cooperation
NZ intimately connected with rest of the world through tourism, exports, security, aid, migration, technology and raw materials → flow-on effects !
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Climate change scenarios for NZ
Methodology
• select IPCC models that do the best job in reproducing current/recent climate in Pacific
• select model information for two scenarios– high carbon world (SRES A2)
– rapidly decarbonising world (scale SRES B1 scenario so that global warming is limited to 2°C by end 21st century)
– estimate global warming for two missing model runs
• down-scale models to high resolution over NZ change in seasonal average climate parameters changes in extremes more difficult to model
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NZ scenarios: temperature
Inter-model variations in temperature
Scenario information provided by B. Mullan, NIWA
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NZ scenarios: precipitation
Inter-model variations in precip: south-west South Island
Scenario information provided by B. Mullan, NIWA
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NZ scenarios: precipitation
Inter-model variations in precip: east North Island
Scenario information provided by B. Mullan, NIWA
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Climate change scenarios: sea level
Very rapidly moving area of science:
• IPCC model-based projections: 18-59cm by 2100 …• … but no best estimate or upper limit. Acceleration of
polar ice loss could lead to greater sea level rise.
• Recent studies suggest sea level rise could significantly Recent studies suggest sea level rise could significantly exceed 1m by 2100. Sea level very likely to continue to exceed 1m by 2100. Sea level very likely to continue to increase for many more centuries beyond 2100.increase for many more centuries beyond 2100.
• No convergence yet between recent studies.Uncertainty unlikely to be resolved in the next few years. Potential for rapid rise is a key reason for concern.
Picture: National Oceanic and Atmospheric Administration (NOAA), US
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Climate change scenarios: extremes
Extremes key part of climate change:
• Even a small change in mean climate can result in significant changes in climatic extremes.
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Climate change scenarios: extremes
prob
abili
ty o
f occ
urre
nce
w e t dryaverage
adapted range
damage threshold
expected annualaverage damage / costs
Schematic example: changes in drought risk
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Climate change scenarios: extremes
prob
abili
ty o
f occ
urre
nce
w e t dry
adapted range
expected annualaverage damage / costs
damage threshold
averageaverage
Schematic example: changes in drought risk
change in mean climate
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prob
abili
ty o
f occ
urre
nce
w e t dry
Climate change scenarios: extremes
adapted range
expected annualaverage damage / costs
damage threshold
average
Schematic example: changes in drought risk
change in mean climateand in variability
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Climate change scenarios: extremes
Extremes key part of climate change:
• Changes in means imply altered frequency of extremes.
Key climatic extremes:– extreme temperatures (hot days ↑, heat wave ↑, frost ↓)– heavy precipitation and flood risk ↑– drought risk in eastern/northern regions ↑– less certain: storm surge, storms, extratropical cyclones
Quantitative projections currently difficult:– default: historical variability superimposed on trend– Regional Climate Model (RCM) key advance
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Adapting to climate change
• less of a problem for NZ?
– less warming than rest of world …
• … don’t be too sure about that:
– sea level rise same as global average (if not more)– much smaller budget than larger countries …– … but same complexity and range of issues– decentralised approach to decision-making– high dependence on natural resources and exports– flow-on effect of global changes
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Adaptation processAdaptation is a process involving various stakeholders
Science sectorCouncil/business
CommunityCivil society
Central/local govt
Central govt guidanceand support
Local govt/businesspolicies and plans
Figure by R. Warrick, IGCI (Warrick, 2000)
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Adaptation challenges
When to adapt:• reactive: wait for need/opportunity from climate change
• context-specific: when other pressures create opportunity
• proactive/planned: to avoid unsustainable lock-in
Decisions require social value-judgements:• discounting over time: are we prepared to incur short-
term opportunity costs to avoid longer term risks?
• attitude to risk: how to handle low-probability/high-impact event; who pays if the unlikely event happens?
• sustainability trade-offs: how do we balance economic, social and environmental risks and gains?
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Climate change scenarios: summary
• 2 scenarios to highlight contrasting futures
• pattern of climate change in NZ broadly similar but much more pronounced under high carbon world
• climatic extremes change more rapidly/significantly than averages, and are often more relevant
• adaptation is a complex process involving multiple stakeholders and steps towards implementation
• value judgements are integral part of adaptation
• impacts and adaptation options in NZ depend on climate and socio-economic changes domestically and internationally