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 [0.65- 1.06] °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. Page 1

Change in average surface temperature Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis. p.6

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) Page 3

Sea level and glacial balance Source: The state of the planet, The Economist, 25 November, 2015

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

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

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 Page 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: 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 Page 8

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 1910 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 Page 9

Change in average surface temperature Source: State of the Climate Report, 2014, BOM & CSIRO p.5

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

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 Page 12

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 Page 13

Projections of future temperature Source: IPCC, 2013 In Climate Change 2013: The Physical Science Basis, Ch.12 Page 14

Projections of future temperature Source: IPCC, 2013, In Climate Change 2013: The Physical Science Basis, Ch.12 Page 15

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) Page 16

Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2013: The Physical Science Basis. Ch. 9

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 Page 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 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 Page 19

Key risks of future climate change Source: IPCC, 2013 Summary for Policymakers, In Climate Change 2014: Impacts, adaptation and vulnerability, p. 13 Page 20

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 2030 to 2100 Page 21

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 Page 22

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) Page 23

Source: The Garnaut Climate Change Review, 2008, p.127

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

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 Page 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: Ecosystems and biodiversity Declines in biodiversity Potential species extinction in high-altitude areas and the wet tropics Coastal wetland inundated with sea water Page 27

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 Page 28

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 Page 29

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 Page 30

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.

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

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 Page 33

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 Page 34

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 Page 35