Climate Adaptation National Research Flagship Andrew Ash Flagship Director September 2008

Transcription

1 Climate change, rivers and water resources Climate Adaptation National Research Flagship Andrew Ash Flagship Director September 2008

2 Talk Outline Evidence for climate change Projections for the 21st century Potential impacts and vulnerability Adapting to climate change

3 Climate has always been variable. Ice ages occur every 100,000 years due to wobbles in the Earth s orbit temperature ( o C) Carbon dioxide and temperature last 420, 000 years CO 2 (ppm) , , ,000 years before present 100,000 0 The present CO2 level is unprecedented in at least the past 420,000 years and it is expected to rise to ppm by the year 2100

4 In the past 200 years, concentrations of greenhouse gases have continued to increase, and the Earth has warmed Carbon dioxide and temperature last 1000 years temperature ( o C) Cape Grim and South Pole Law Dome ice cores temperature change CO2 (ppm) years before 2000 AD

5 In the past 100 years, global average surface temperatures have risen 0.7ºC

6 Observed changes in rainfall For the world s land surface there has been a slight increase in rainfall over the last 100 years Trends are spatially variable

7 Observed changes in rainfall - Australia

8 Runoff and river discharge At global scale: increased runoff at high latitudes lower runoff at mid-latitudes In Australia: Modelled Annual Inflows - current conditions Perth Annual Inflow (GL) GL/yr Long-term Average Inflow ( GL/yr) GL/yr GL/yr MDB Average Inflows during Drought Periods

9 Our Water Status SWA: multi-decadal hydrological drought Murray Basin: lowest 5-year sequence of flows in 114 years in Murray River Melbourne: driest 10-year period on record Water restrictions: 16 of 24 cities (P>50,000)

10 Glaciers, snow and ice

11 Attribution - causes of warming since 1750 Cooling Warming Mostly due to greenhouse gases Large uncertainty about the cooling effect of aerosols The effect of changes in solar activity is 20 times smaller than that of increases in greenhouse gases IPCC 2007

12 Causes of climate change - most of the observed warming over the last 50 years is attributable to human activities Temperature change ( o C) Australia s mean temperature since 1910 Eight climate models with additional GHGs in the atmosphere Climate models without additional GHGs in the atmosphere Karoly & Braganza (2004)

13 2007 IPCC projections: Temperature

14 Future projections in climate - rainfall December-January-February (DJF) Precipitation increase in 90% of simulations Precipitation increase in 75% of simulations Precipitation decrease in 90% of simulations Precipitation decrease in 75% of simulations

15 Future projections in climate - rainfall June-July-August (JJA) Precipitation increase in 90% of simulations Precipitation increase in 75% of simulations Precipitation decrease in 75% of simulations Precipitation decrease in 90% of simulations

16 Extreme events

17 Current and future rate of sea level rise unprecedented during modern civilisation

18 2030 projections for south-eastern Qld Average annual temperature Estimate of change +1.3 o C Uncertainty +/- 0.6 o C Sea level rise +17cm Average annual rainfall -3.5% +/-11% No. of hot days per year(>35 o C) Extreme rainfall intensity +5 (near coast) +50 (inland) 30% For risk assessment, it is important to consider extreme scenarios, even though they may have low probability (this is why we have insurance).

19 Could be an under-estimate World CO 2 emissions to 2030 (GtC) *from fuel combustion and cement production 20.0 New economic growth path Highest IPCC emission scenario A1 A1F1 A1T A2 B1 B2 New growth path Source: Sheehan, Jones et al. (forthcoming 2008) Global Environmental Change.

20 And temperature records support this high level of emissions Rahmstorf et al.

21 Climate change impacts on rivers and water resources Impacts on rivers and water supplies a combination of rainfall changes, increasing temperatures, evaporation and in coastal areas, sea level rise Effects will be most noticeably expressed through a combination of changes in trend and extreme events Stationary Climate & Coping Range Changing Climate Vulnerable Coping Range Vulnerable

22 Global impacts on water resources High latitude increase in water availability and floods Mid-latitudes to suffer a decrease in water availability, with Northern Hemisphere affected by declines in glacier melt and earlier snowmelt (increased floods) Tropics little change to a modest increase in water availability Erosion events increase due to extreme precipitation Declines in water quality Coastal wetlands affected by salt water intrusion

23 Impacts in Australia water security As a result of reduced precipitation and increasing evaporation, water security problems are projected to intensify by 2030 in southern and eastern Australia IPCC 2007

24 National Runoff Changes in 2030 (vs. 1990) Skill Weighted 2030 Changes of <±10% Signal of increasing rainfall in north Signal of declining rainfall throughout the rest of the continent 2070 Modest rainfall increases in the far north persist Declines of 20 to 40% in the southern interior Larger reductions projected for coastal Western Australia

25 Impact of climate on MDB water availability MDB: median impact is an 11 percent reduction in available water ~2500 GL/year on average 2,000 1,500 6,000 Historical climate Median 2030 climate 4,500 1,000 3, , Barwon-Darling Moonie Eastern Mount Lofty Ranges Wimmera Campaspe Loddon-Avoca Warrego Paroo Gwydir Namoi Lachlan Border Rivers Condamine-Balonne Macquarie-Castlereagh Ovens Goulburn-Broken Murrumbidgee Murray Average water availability (GL/y)

26 Impact of Climate Change on Flooding Nerang Catchment Currently 4500 properties are flood prone - $140M damages 20% increase in rainfall 7000 properties - $235M

27 Ecosystem impacts rivers and wetlands Temperature and rainfall changes will lead to changes in species composition of freshwater habitats with flow on implications for estuaries and fisheries By 2050, 80% loss of freshwater wetlands in Kakadu for a 30 cm sea level rise

28 Adaptation The international community is too late with effective mitigation to avoid significant impacts. It may yet fail to put in place substantial mitigation, in which case the challenge of adaptation to climate change will be more daunting. As a nation, Australia has a high level of capacity to plan for and respond to the impacts of climate change that is, its adaptation potential is high. Garnaut Climate Change Review July 2008

29 We are adapting all the time. Businesses re-position themselves in response to opportunities and risks Governments change policies and programs to better achieve broad societal goals These decisions are taken all the time in the absence of complete information Climate change is no different Our aim is to help make adaptations more effective and efficient in the face of uncertain climate changes

30 Both top-down and bottom-up approaches needed for adaptation Policies (e.g. river management -MDB) Technologies (e.g. infrastructure, recycling) Behaviours (e.g. water use) Adaptive capacity and management

31 Adaptation for rivers and water resources needs to be considered in the context of other drivers: demographic changes land use and land use change environmental management food security

32 Adaptation - no regrets options a priority water use efficiency, especially in agriculture water demand management Building ecosystem resilience to better cope with climate change by reducing current stresses e.g. sediments and nutrients moving into streams

33 Current water shortages driving major new investments in adaptation Dams Desalination Groundwater Recycling Much harder to achieve meaningful responses in terms of river ecosystem health

34 Systems analysis is imperative Northern Australia Forestry plantations

35 Conclusions Climate change is real and underway Climate change will continue in the 21st century Impacts most acutely felt through additive effects (e.g. rainfall, temperature) and extreme events Adaptation to climate change a key driver "Fail to plan = Plan to fail" Need to manage with uncertainty - scenario and risk management approaches to planning Planning will require anticipating change and wide dialogue as to how to manage this change

36 Climate Adaptation Flagship Andrew Ash Flagship Director Phone: Andrew.Ash@csiro.au Media enquiries: Louise Matthiesson Communication Officer CSIRO Climate Adaptation Flagship Phone: Mobile: louise.matthiesson@csiro.au Website: Thank you Contact Us Phone: Enquiries@csiro.au Web: