Global Perspective on Climate Change

Transcription

1 Global Perspective on Climate Change Dr. Barrie Pittock, PSM Former Leader of Climate Impact Group, CSIRO Lead Author IPCC Reports, 1995, 1998, 2001 Editor, AGO Climate Change Guide 2003 Author, Climate Change: Turning Up the Heat (in press) Gippsland Talk, 16 September

2 Outline Evidence for climate change Uncertainty and risk Potential global scale impacts Mitigation and adaptation are both needed The challenge of adaptation Gippsland Talk, 16 September

3 On the Balance of Evidence for Global Warming Land-based temperature record Sea-surface temperatures (ships, satellite obs.) Bore-hole temperatures Most glaciers retreating fast Less snow cover (local, satellite obs.) Less NH sea ice (satellite obs.) Tree-line rising Location shifts of birds, fishes and insects (obs. all continents) Longer growing seasons (anecdotal, satellite obs.) Earlier breakup of river and lake ice Gippsland Talk, 16 September

4 Variations of Earth s Surface Temperature over Last 1,000 Years Gippsland Talk, 16 September

5 Glaciers retreating rapidly e.g., Trient glacier, Switzerland, year 2000 Gippsland Talk, 16 September

6 Frequency of Closure of Thames Barrier: Multiple Causation Gippsland Talk, 16 September

7 European Heatwave, 2003 Number of deaths in Paris during heatwave, July-August 2003 Temperatures Deaths Gippsland Talk, 16 September

8 Increases in Disasters 1960s to 1990s 1960s 1970s 1980s 1990s Ratio 1990s/ 1960s # Weatherrelated # Non-weather Economic losses Insured losses Gippsland Talk, 16 September

9 Paleo- record of last 400,000 years Gippsland Talk, 16 September

10 Orbital Variations of Earth Explain Periodicities in Climate Equinox Normal to plane of the ecliptic Solstice Plane of Earth s axial tilt Precession of equinoxes Wobble Sun P Tilt varies obliquity A Orbit Earth s axis of rotation Solstice Equinox Earth Gippsland Talk, 16 September

11 Paleo- record of the last 25,000 years Gippsland Talk, 16 September

12 Internal Components of Climate Models ATMOSPHERE Equation of water vapour Thermodynamic equation Radiation, clouds, particles Equation of motion Evaporation Rain & snow Ocean Sensible heat surface Radiative transfer Surface stress Salt equation Ice equation Thermodynamic equation Equation of motion OCEAN Gippsland Talk, 16 September

13 Cascade of Uncertainty ESTIMATED PROCESS RANGE OF VARIABLE APPLIED UNCERTAINTY GH GAS EMISSIONS GH GAS CONCENTRATIONS CARBON CYCLE MODEL CLIMATE MODEL GLOBAL CLIMATE CHANGE REGIONAL CLIMATE CHANGE SECTORAL IMPACT DOWNSCALING METHOD SECTORAL IMPACT MODELS Gippsland Talk, 16 September

14 Global temperature projections Gippsland Talk, 16 September

15 Warmings for Various Emissions Scenarios Scenario warming at 2100 at 2350 at equilibrium SRES B n/a n/a SRES B n/a n/a SRES A1T n/a n/a SRES A n/a n/a SRES A1F n/a n/a WRE WRE WRE WRE WRE Gippsland Talk, 16 September

16 Changes in Extreme Events Change in phenomena Higher T max, more hot days Higher T min, fewer frosts & cold days Reduced diurnal T range over land Increased heat index affecting comfort More intense precipitation events Increased mid-latitude drought risk Increased TC peak winds Increased storm surge, coastal erosion Increased TC mean & peak rainfall Likelihood in 21 st century Very likely Very likely Very likely Very likely most areas Very likely most areas Likely Likely, some areas Very likely Likely over some areas Gippsland Talk, 16 September

17 Large-scale Discontinuities Type of event Major changes to ocean circulation Melting of Greenland and disintegration of West Antarctic Ice Sheet Accelerated greenhouse gas release leads to more rapid warming Cause Changes to salinity and temperature change stability & overturning Surface melting, meltwater lubrication, loss of ice shelves accelerate outflow Forests & melting tundra become sources of CO 2 & methane Potential impact Heat transport north in N. Atlantic greatly reduced, El Nino & East Australian current change Rapid & irreversible sea level rise, up to several metres over few centuries Greater faster impacts make adaptation more difficult and impacts more severe Gippsland Talk, 16 September

18 The Nub of the Problem Huge fossil CO 2 emissions Land /soil biota Atmosphere CO 2 CO 2 CO 2 sequestration CO 2 Geological formations CO 2 emissions Fossil fuels reduce natural CO 2 removal Shallow ocean Deep ocean artificial CO 2 sequestration CO 2 moves rapidly between atmosphere, biota & upper ocean Slow natural sink Need to equalise emissions & sinks Need reduced emissions & increased sinks Gippsland Talk, 16 September

19 Possibilities for mitigation Efficiency & conservation Hybrid petrol/electric or petrol/hydraulic Buildings Public transport, bicycles More efficient generators & industry Decarbonisation of electricity & fuels Gas for coal & oil Wind, solar, tidal, biomass Carbon capture & storage (artificial sinks) Nuclear power Strengthen natural sinks Gippsland Talk, 16 September

20 Adaptation to Reduce Increased Vulnerability Stationary Climate & Coping Range Changing Climate Vulnerable Coping Range Vulnerable Stationary Climate & Coping Range Changing Climate Vulnerable Adaptation Coping Range Planning Horizon Vulnerable Gippsland Talk, 16 September

21 Generic Adaptation Options Option Bear losses Share losses Modify threat Prevent effects Change use Change location Research & development Educate, inform, change behaviour Comments or examples Do nothing. Occurs if do not anticipate, or cannot adapt. Mutual aid, insurance, govt. relief. Still costs community. Build dams, levees, etc., slow rate of change. Change management, irrigate, pest & disease control. Switch varieties or crops, change cropping to tourism. Move to cooler or wetter region if possible. Requires anticipation and long lead times. Can be slow and costly. Helps anticipatory action. Water conservation, fire prevention, change design rules. Gippsland Talk, 16 September

22 Conclusions Climate change is happening. It is likely to increase. Uncertainty inevitable, but risk is certain. Without large emissions cuts, global warmings of 3ºC or more likely (>50% probability) by Risk of major global & local impacts. Adaptation thus necessary. Requires anticipation, will cost, & has limits. Gippsland Talk, 16 September

23 My book, due out October 2005, CSIRO Publications (see handouts) Gippsland Talk, 16 September