Understanding Climate Change


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View part of a presentation by Professor Andy Pitman of the UNSW Climate Change Research Centre. The presentation includes the basics about climate change, the causes, effects and impacts of global warming and sea level rise.
Learn about what Australia can expect and even more specifically, what Woollahra residents can expect and more importantly, what we can all do about it.

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Understanding Climate Change

  1. 1. Basics … <ul><li>Climate change is not the same as the greenhouse effect ! </li></ul><ul><li>but greenhouse is global and it’s being amplified by human activity </li></ul>
  2. 2. Temperature <ul><li>Continued greenhouse gas emissions at or above current rates would cause further warming - very likely larger than those observed during the 20th century. </li></ul>2005 2006 2007
  3. 3. What causes greenhouse ? <ul><li>Carbon dioxide </li></ul>
  4. 4. Basic science <ul><li>Warming of the climate system is unequivocal </li></ul><ul><ul><li>atmosphere </li></ul></ul><ul><ul><li>Oceans (to at least 3000m) </li></ul></ul><ul><ul><li>Snow and ice are melting, flora and fauna are changing </li></ul></ul><ul><li>There are no observations that suggest the planet is not warming. </li></ul>
  5. 5. Basic science <ul><li>Continued greenhouse gas emissions will cause further warming </li></ul><ul><li>They would cause changes in the global climate during the 21st century </li></ul><ul><ul><li>very likely larger than those during the 20 th century </li></ul></ul><ul><li>21 st century emissions will contribute to warming and sea level rise for more than a millennium </li></ul><ul><ul><li>due to the long timescales required to remove this gas </li></ul></ul><ul><li>We are committed to at least several more decades of warming and associated changes in temperature, sea level and other impacts </li></ul>
  6. 6. … what does the greenhouse do ? <ul><li>Earth has warmed 0.74 o C in the last 100 years </li></ul><ul><ul><li>unusual and very unlikely to be entirely natural in origin. </li></ul></ul>
  7. 7. Sea level rise <ul><li>Global sea levels rose at an average rate of 1.8 mm y-1 over 1961 to 2003 - faster over 1993 to 2003, about 3.1 mm y-1. </li></ul><ul><li>total 20 th century rise is estimated to be 0.17m. </li></ul><ul><li>Projected globally-averaged sea level rise at the end of the 21 st century in metres is between 0.18 m and 0.59 m. </li></ul><ul><li>if increases in melt from Greenland and Antarctic continue, these projections may increase by a further 10 to 25%. </li></ul><ul><li>Warming of 1.9 to 4.6°C would elimination the Greenland ice sheet and result in 7m rise in sea level if sustained for millennia . </li></ul>
  8. 8. Global warming - Impacts <ul><li>For the next two decades a warming of about 0.2°C per decade is projected. </li></ul><ul><li>Projected globally-averaged surface warming for the end of the 21 st century (2090–2099) ranges from 1.8 to 4.0°C </li></ul><ul><li>Possibility of positive feedbacks accelerating this </li></ul><ul><li>Projected warming will eliminate the Greenland ice sheet and result in 7m rise in sea level if sustained for millennia . </li></ul>
  9. 9. Impacts – less well known <ul><li>no trend in the frequency of tropical cyclones, but hint of an increase in intensity since about 1970 </li></ul><ul><li>frequency of cyclones projected to decrease, intensity expected to increase </li></ul><ul><li>No idea no changes in tornadoes, hail, lightning and dust-storms etc. </li></ul><ul><li>it is virtually certain that acidification will continue and will lead to dissolution of carbonates </li></ul>
  10. 10. Regional projections … <ul><li>What should we expect over Australia ? </li></ul>
  11. 11. Temperatures: mean and extremes Low emissions High emissions
  12. 12. Changes in mean precipitation Low emissions High emissions
  13. 13. What about Woollahra? <ul><li>Climate strongly influenced by: </li></ul><ul><ul><li>El Nino-La Nina </li></ul></ul><ul><ul><li>East coast lows </li></ul></ul><ul><ul><li>Storm activity </li></ul></ul><ul><ul><li>We cannot project how east coast lows may change yet </li></ul></ul><ul><ul><li>We cannot project changes in storm activity </li></ul></ul><ul><ul><li>Considerable effort on El Nino – but remains the greatest uncertainty in projecting the future climate of eastern Australia </li></ul></ul>
  14. 14. What about Woollahra? <ul><li>Not really vulnerable to flood (cf. Lismore) </li></ul><ul><ul><li>Likely more driven by catchment management that climate change </li></ul></ul><ul><li>Not vulnerable bush fires </li></ul><ul><li>Fresh water reasonably secure (cf Wagga) </li></ul><ul><ul><li>But invest now to preserve resource </li></ul></ul><ul><li>Temperature </li></ul><ul><ul><li>unlikely to be the key problem due to moderation by ocean and location </li></ul></ul>
  15. 15. Why is it always seem to be bad news ? <ul><li>Humans have “tuned” their crops, water use, settlements, storm water, ports etc assuming climate does not change </li></ul><ul><li>Of course we can adapt – but that costs time and money </li></ul><ul><li>Climate change may [rarely] exceed the adaptive capacity of a society </li></ul>
  16. 16. What can we do about it ? <ul><li>Adapt to projected changes </li></ul><ul><ul><li>Planning </li></ul></ul><ul><ul><li>Build robustness into social, economic and environmental systems </li></ul></ul><ul><li>Buy time </li></ul><ul><ul><li>Cut emissions </li></ul></ul><ul><ul><li>Renewables, gas replacing coal … </li></ul></ul><ul><ul><li>Increase sinks (plant forests) </li></ul></ul><ul><ul><li>Protect sinks (protect forests) </li></ul></ul>
  17. 18. Conclusions <ul><li>Climate change, driven by humans, is a reality </li></ul><ul><li>The science underpinning this reality is well understood, robust and reliable - large scale impacts of global warming are well understood, robust and reliable </li></ul><ul><li>Hard to be precise about what will happen in a specific location </li></ul><ul><li>Solutions – build robustness into your existing environment … </li></ul>
  18. 19. But satellites don’t show warming Satellite Surface
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