climate change scenarios: global and local

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New Zealand Climate Change 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 University 2 National Institute of Water and Atmospheric Research (NIWA)

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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 Presentation

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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?

3

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

4

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 !

5

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

6

NZ scenarios: temperature

Scenario information provided by B. Mullan, NIWA

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NZ scenarios: temperature

Scenario information provided by B. Mullan, NIWA

8

NZ scenarios: temperature

Inter-model variations in temperature

Scenario information provided by B. Mullan, NIWA

9

NZ scenarios: winter precipitation

Scenario information provided by B. Mullan, NIWA

10

NZ scenarios: winter precipitation

Scenario information provided by B. Mullan, NIWA

11

NZ scenarios: summer precipitation

Scenario information provided by B. Mullan, NIWA

12

NZ scenarios: summer precipitation

Scenario information provided by B. Mullan, NIWA

13

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

15

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

16

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

20

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

22

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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Adaptation needs in various sectorsFigure from IPCC WGII, Chapter 11: Hennessy et al, 2007

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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

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Adaptation needs in various sectorsFigure from IPCC WGII, Chapter 11: Hennessy et al, 2007