Climate change, rivers and water resources Climate Adaptation National Research Flagship Andrew Ash Flagship Director September 2008
Talk Outline Evidence for climate change Projections for the 21st century Potential impacts and vulnerability Adapting to climate change
Climate has always been variable. Ice ages occur every 100,000 years due to wobbles in the Earth s orbit temperature ( o C) 20 10 0 Carbon dioxide and temperature last 420, 000 years 350 300 250 200 150 CO 2 (ppm) -10 100 400,000 300,000 200,000 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 550-950 ppm by the year 2100
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) 1.0 0.5 0.0 Cape Grim and South Pole Law Dome ice cores temperature change 350 300 250 CO2 (ppm) -0.5 200 1000 800 600 400 200 0 years before 2000 AD
In the past 100 years, global average surface temperatures have risen 0.7ºC
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
Observed changes in rainfall - Australia
Runoff and river discharge At global scale: increased runoff at high latitudes lower runoff at mid-latitudes In Australia: 30 000 Modelled Annual Inflows - current conditions 25 000 Perth Annual Inflow (GL) 20 000 15 000 10 000 5 000 5 400 GL/yr Long-term Average Inflow (11 200 GL/yr) 6 300 GL/yr 4 150 GL/yr MDB Average Inflows during Drought Periods 0 1892 1902 1912 1922 1932 1942 1952 1962 1972 1982 1992 2002
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)
Glaciers, snow and ice
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
Causes of climate change - most of the observed warming over the last 50 years is attributable to human activities Temperature change ( o C) +0.8 +0.6 +0.4 +0.2 0.0-0.2-0.4 1920 1940 1960 1980 2000 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)
2007 IPCC projections: Temperature
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
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
Extreme events
Current and future rate of sea level rise unprecedented during modern civilisation
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).
Could be an under-estimate World CO 2 emissions to 2030 (GtC) *from fuel combustion and cement production 20.0 New economic growth path 16.0 12.0 Highest IPCC emission scenario 8.0 4.0 0.0 1990 2000 2010 2020 2030 A1 A1F1 A1T A2 B1 B2 New growth path Source: Sheehan, Jones et al. (forthcoming 2008) Global Environmental Change.
And temperature records support this high level of emissions Rahmstorf et al.
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
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
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
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
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 3,000 500 1,500 0 0 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)
Impact of Climate Change on Flooding Nerang Catchment Currently 4500 properties are flood prone - $140M damages 20% increase in rainfall 7000 properties - $235M
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
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
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
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
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
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
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
Systems analysis is imperative Northern Australia Forestry plantations
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
Climate Adaptation Flagship Andrew Ash Flagship Director Phone: +61 7 32142346 Email: Andrew.Ash@csiro.au Media enquiries: Louise Matthiesson Communication Officer CSIRO Climate Adaptation Flagship Phone: +61 7 3214 2642 Mobile: 0405 284 102 Email: louise.matthiesson@csiro.au Website: www.csiro.au/org/climateadaptationflagship Thank you Contact Us Phone: 1300 363 400 Email: Enquiries@csiro.au Web: www.csiro.au