climate change for chile_will steffen

7/29/2019 Climate Change for Chile_Will Steffen

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The Critical Decade 2013Climate change science, risks and responses

Professor Will Steffen

www.climatecommission.gov.au


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Outline of talk

Basics of climate science

Risks of a changing climate

Responding to climate change challenges and

opportunities


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The atmosphere is warming


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Source: IPCC AR4

Where does the excess heat go?


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The ocean is warming


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Changes faster than predicted


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Enhanced Greenhouse Effect


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Warming is occurring worldwide

IPCC AR4 2007

Observed 20thcenturywarmingcan only beexplained byincluding bothdrivers of naturalvariability andthe additional

greenhousegases emitted byhuman activities.


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2,000 year global land temperature

reconstruction


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Climate Change Science: Summary

Warming of the climate system is unequivocal, as is nowevident from increases in global average air and oceantemperatures, melting of snow and ice, and rising sea level.

Numerous changes in climate have been observed at the

scales of continents or ocean basins - wind patterns,precipitation, ocean salinity, sea ice, ice sheets, and aspectsof extreme weather.

It is very likelythat anthropogenic greenhouse gas increasescaused most of the observed increase in globally averagedtemperatures since the mid-20th century.

IPCC AR4 2007


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Decisions: risks and opportunities

Meinshausen et al. 2009

Decision point

Risks


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Extreme weather and climate change


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We are living in a new climate


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Heatwaves

Source: Bureau of Meteorology


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IPCC Special Report on Managing the Risks ofExtreme Events and Disasters to Advance

Climate Change Adaptation (SREX)


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Projected return periodof hot day compared with

late 20th century return

period of 20 years

B1

A1B A2


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Heavy rainfall and flooding

I fl f i h


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Influence of warming on the water

cycle


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Rainfall deciles

1 Aug - 31 Dec 2010

SST anomalies

1 Aug - 31 Dec 2010

SST and rainfall extremes


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Projected return periodof heavy daily rainfall

compared with late20th century return

period of 20 years


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Changing rainfall patterns


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Gray shading: less than 66% model agreement on sign of change

Coloured shading: 66% model agreement on sign of changeStippling: 90% model agreement on sign of change


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Consequences of sea-level rise

Western Australia

Perth region

Torres Strait Islands

I fl f l l t l


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Influence of sea-level on coastal

flooding


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Sea-level rise projections


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J. Hunter 2011

Adapting to sea-level rise


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Polar ice sheets and sea-level rise

Rignot et al. 2011

Source: Shepherd at al. 2012


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Decisions: risks and opportunities

Meinshausen et al. 2009

Decision point

Risks

Opportunities


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Opportunities: New Energy Systems

Silicon wafer

Rear metal

Electron

Solar ThermalSolar Concentrators


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Opportunities: built infrastructure

Mitigation aim for C-neutrality inall buildings. Or generate moreelectricity than is consumed. Sixgreen star (or above) could become

the standard.

Adaptation

Minimise resource use e.g., water Design to minimise impact of extreme heat Build green star communitiesgreen infrastructure Dont build on vulnerable coastlines or flood-prone areas

O t iti i i di id l


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Opportunities: engaging individuals

and communities


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Key Messages

The evidence for climate change is overwhelming andclear. It is beyond reasonable doubt that the burning of

fossil fuels is the primary cause.

We are already seeing the social, economic and

environmental impacts of a changing climate, especially

extreme events. The risks rise as climate shifts further.

Risks to business include climate change impacts, policy

changes, stranded assets, loss of community support.

Opportunities for business include new green industries,

rise of prosumers, networking


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www.climatecommission.gov.au

climate change for chile_will steffen

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