1. Global impacts of climate change Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis
The main observed temperature changes are:
The globally averaged combined land and ocean surface temperature show a warming of 0.85 [ ] °C over the period 1880 to 2012
“Each of the last three decades have been successively warmer at the Earth’s surface than any preceding decade since 1950.”p.5
Observed changes globally in the distribution of precipitation.
Observed increases in many extreme climate and weather events since 1950.
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2. Change in average surface temperature Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis. p.6

3. Global impacts of climate change Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis
Other observed changes are:
Ocean warming dominates the increase in energy stored
The upper 75m warmed by 0.11 [0.09 to 0.13] °C between 1971 to 2010
Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass.
Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to 0.21] m
(Glacier mass loss and ocean thermal expansion explain about 75% of the mean sea level rise)
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4. Sea level and glacial balance Source: The state of the planet, The Economist, 25 November, 2015

5. Extent of Artic sea ice Source: The state of the planet, The Economist, 25 November, 2015

6. Source: IPCC, 2014 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability, p. 3

7. Consequences of climate change Source: IPCC, 2014 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability
What are the consequences of the changes:
Changing precipitation and melting snow alter hydrological systems and water resources in both quantity and quality
Warming of permafrost and thawing in high latitude regions
Terrestrial, freshwater and marine species have shifted geographic ranges and migration patterns
Only a few species extinctions attributed to climate change
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8. Consequences of climate change Source: IPCC, 2014 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability
What are the consequences of the changes:
Negative impact on crop yields more common than positive impacts
Positive impacts in high latitude
Negative impacts on wheat, maize in many regions
Food security impacts, particularly for poorer communities with less resources for adaptation
Climate related extremes, heat waves, floods, droughts and wildfires illustrate vulnerability
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9. The main observed changes are:
Impacts of climate change in Australia Source: State of the Climate Report, 2014, BOM & CSIRO.
The main observed changes are:
Australia’s climate has warmed by 0.9 °C since
Rainfall average across Australia has increased
Large increases in northwest Australia
Declining trend in southwest Australia
Days and nights of extreme heat have increased
Extreme fire weather has increased
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10. Change in average surface temperature Source: State of the Climate Report, 2014, BOM & CSIRO p.5

11. Change in Rainfall Source: State of the Climate Report, 2014, BOM & CSIRO p.6

12. Projections of future climate change Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis
Projections of climate change are based on scenarios of anthropogenic forcings
(That is the radiative forcing due to human activities)
The magnitude of emissions of greenhouse gases, aerosols and other natural and man-made forcings partly determine future climate
A range of assumptions are made about the magnitude and pace of emission to develop scenarios
These are also based on scenarios of socioeconomic development
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13. Projections of future climate change Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis
The fifth assessment report developed new scenarios called, the Representative Concentration Pathways (RCPs)
Each RPC was developed by an Integrated Assessment Modelling (IAM) group
To summarize:
RCP 8.5 – high emissions scenarios
RCP 6 and RCP 4.5 emissions stabilize (medium emissions)
RCP 2.6 – low emission scenarios
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14. Projections of future temperature Source: IPCC, 2013 In Climate Change 2013: The Physical Science Basis, Ch.12
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15. Projections of future temperature Source: IPCC, 2013, In Climate Change 2013: The Physical Science Basis, Ch.12
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16. How good are these models
How good are these models? Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis
The integrated assessment modelling simulations involve the understanding of interactions between the atmosphere, ocean, land surface, snow and ice, the global ecosystem and other chemical and biological processes.
How good are these models?
The complexity of climate models has progressively increased
Evaluated relative to ability to project past observations
Improvements can be seen in the following figure (see also additional resources)
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17. Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis. Ch. 9

18. Key risks of future climate change Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability, p. 13
Key risks identified from the RPCs:
Risk of deaths or disruption to livelihoods in low lying coastal zones and small island developing states due to storm surges, coastal flooding and sea level rise
Risk of severe ill health for large urban populations – due inland flooding
Systematic risk to extreme weather events (breakdown of key infrastructure)
Risk of mortality and morbidity to periods of extreme heat
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19. Key risks of future climate change Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability, p. 13
Key risks identified from the RPCs:
Risk of food insecurity – drought, flooding and precipitation variability and extremes particularly for poorer populations
Risk of loss of rural livelihood and income due to insufficient access to drinking and irrigation water and reduced agricultural productivity
Risk of loss of marine and coastal ecosystems
Risk of loss of terrestrial and inland water ecosystems, and biodiversity
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20. Key risks of future climate change Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability, p. 13
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21. Climate change impacts on Australia Source: The Garnaut Climate Change Review, 2008, ch.6
The Garnaut Climate Change Review summarized the impacts for Australia:
The review considered both direct and indirect impacts
The ‘direct’ are those experienced within Australia maritime boundaries
The ‘indirect’ are impacts experienced in other countries with consequences for Australia
Two time periods are considered – up to 2030, and from to 2100
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22. Vulnerability – effect of climate change on the Australian population and natural assets
EXPOSURE
To changes in the climate system
Potential impact
from Climate Change
Adaptive capacity
population
nature
VULNERABILITY
To the consequences of Climate Change
SENSITIVITY
To those exposures
The Garnaut Climate Change Review 2008 p 125
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23. Climate change impacts on Australia Source: The Garnaut Climate Change Review, 2008, ch.6
The emissions paths are based on previous IPCC scenarios:
Unmitigated emissions with mean warming of 4.5°C in 2100
Mitigation scenario with emissions stabilized at 550ppm CO2- e* and mean warming of 2°C in 2100
Mitigation scenario with emissions stabilized at 450ppm CO2- e and mean warming of 1.5°C in 2100
In general with no mitigation – impacts on Australia will be severe
Impacts to 2100 summarized in Table 6.3
(*CO2-e = CO2 equivalent greenhouse gas, in terms of GWP)
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24. Source: The Garnaut Climate Change Review, 2008, p.127

25. Source: The Garnaut Climate Change Review, 2008, p.128

26. Climate change impacts on Australia Source: The Garnaut Climate Change Review, 2008, ch.6
The no-mitigation is very costly in the near-term:
Decline in agricultural production – irrigated agricultural in the Murray-Darling Basin to lose half of its output.
decline in precipitation, increased frequency of drought
Effective destruction of the Great Barrier Reef and the Ningaloo Reef (Coral bleaching)
Increasing acidity and warming ocean temperature
Resultant loss of marine biodiversity
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27. Climate change impacts on Australia Source: The Garnaut Climate Change Review, 2008, ch.6
The no-mitigation is very costly in the near-term:
Ecosystems and biodiversity
Declines in biodiversity
Potential species extinction in high-altitude areas and the wet tropics
Coastal wetland inundated with sea water
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28. Climate change impacts on Australia Source: The Garnaut Climate Change Review, 2008, ch.6
The indirect effects:
International trade impacts
decline in terms of trade as China, India, Indonesia and other Asian economics badly affected by climate change
Geopolitical instability
Food security
A number of reasons – reducing crop yields
Infectious disease – where temperature is a factor
Sea level rise – and climate refugees
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29. Risks to human health in Australia
severe weather
severe temperature
disease – vector, food, water
food production decline
air pollution
allergens
mental health
associated cost
The Garnaut Climate Change Review 2008 p 139
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30. Risk to biodiversity in Australia
physiology
phenology – life cycles
population processes
distribution
potential for adaptation
Interactions
genetics
pest species
habitat shift
associated cost
The Garnaut Climate Change Review 2008 p 141
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31. Key regional risks Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability, p. 21
The IPCC summarizes some of the risks for Australia and New Zealand. Use the key above to interpret the risks.

32. Key regional risks Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability, p. 23

33. Tipping points
Some elements of climate are unresponsive to changes until a threshold is crossed, then changes are sudden, severe or irreversible. These thresholds are referred to a ‘tipping point’. (See The Garnaut Review, 2011, p.13)
The IPCC AR 5 WG II, in relation to tipping points suggests (see p.12):
Moderate with warming between 0-1°C
Risks increase disproportionately as temperature increases between 1-2°C
Risks become high above 3°C
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34. Tipping points Source: The Garnaut Review, 2011, ch.1
One tipping point is the acidification of the oceans caused by CO2 dissolving in oceans.
Potential to significantly affect marine organisms and ecosystems such as Great Barrier Reef
Amazon forest is another ecosystem at risk of abrupt change.
Temperature increases change the length of the dry season, intensity of drought and forest dieback
At around 2 °C forest dieback rises rapidly from 20 per cent to 60 per cent
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35. Tipping points Source: IPCC, 2013, Climate Change 2013: The Physical Science Basis, ch.12
Other significant tipping points:
Ice sheets, increase in melt rates not compensated by increase in snowfall rates (unlikely in 21st century)
Long term droughts – can lead to desertification (over long time scales and with persistent drought)
Atlantic thermohaline circulation – a threshold where this occurs causing significant changes in northern hemisphere weather (unlikely but also poor understanding)
Artic sea ice – some studies suggest it might have already reached a tipping point
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