2. By the early 18th Century nearly every residence had a cesspit beneath the floors. In the best of homes the nauseating stench permeated the most elegant parlor. Indoor odors were often worse than of the garbage- and manure- filled streets. While noxious fumes were ignored by most people, it was fear of "night air" laden with coal smoke and sulfurous industrial fogs which alarmed the City dweller. Typical cesspit, with access from the street http://www.swopnet.com/engr/londonsewers/londontext1.html

3. Climate Change Week 7 Lecturer: John Todd Ecosystem Processes 16 April 2002

4. Why start a lecture on climate change with a diagram of a cesspit? Disposal of waste has always been a problem for human societies. We are learning the importance of liquid and solid waste disposal; and we have had some success in controlling some waste discharged into the atmosphere. We now need to learn that with so many humans we need to limit all wastes released to the atmosphere.

5. Population

6. We have learnt not to dump solid and liquid wastes into our rivers. But we discharge some 20 billion tonnes of carbon dioxide into the atmosphere each year.

7. Facts and Speculation Changes to atmosphere Impact on radiation Complicating factors Observed warming Uncertainty contributes to lack of action Some possible futures

8. An emotional topic

9. First Some Facts 1.The chemical composition of the atmosphere is changing 2.It is almost certain that human activities are contributing to these changes 3.The average surface temperature is warming 4.But some argue that point 3 is not linked to points 1 and 2

10. Changes to atmosphere Carbon Dioxide CO 2

11. Ice cores allow CO 2 analysis back 400,000 years Now

12. Cape Grim, Tasmania’s ‘baseline’ monitoring station

13. Cape Grim, Tas is one of the important global monitoring sites for climate change gases. Air reaching Cape Grim from the west and south-west has travelled ¾ of the way round the world without passing over land. There are at least 30 gases, released by human activities, increasing in the atmosphere that influence the heat escaping by radiation.

14. Gases that interact with energy flow out of the atmosphere – greenhouse gases Sunlight in Infrared out Wavelength 0.7  10  CO 2 CH 4 N2ON2O 20 o C 25 o C

15. Long time scales The energy reaching the Earth each day is large, so one might expect quick changes But we have seen how massive the atmosphere is 5 x 10 15 tonnes The earth itself is 6 x 10 21 tonnes These numbers are so large they are difficult to comprehend, but the point is, it will take a long time to heat the Earth up and a long time for it to cool off again.

16. Carbon Balance – annual flows 50 3000 7000 600 40,000 700 in atmosphere increasing by about 2 per year Units 10 9 tonnes of carbon 1 5 Burning fossil fuels 3 About 1 unaccounted for 800

17. 1998 hottest ever 2001 second hottest

19. Uncertainties Will climate change lead to more storms, more droughts, more floods? Will feedback processes, such as increased cloud, faster plant growth, etc. off-set the changes? Will other changes accelerate the warming, e.g. less ice and snow, CO 2 release from oceans, melting of tundra etc.?

20. No trends are obvious

21. Tropical cyclones in the Australian Region Source: Bureau of Meteorology Maybe the proportion of intense storms is greater?

22. Some of the uncertainties If it gets warmer, there will be more evaporation. This will alter the water cycle slightly, but we have seen how much energy the evaporation and condensation of water transfers to the atmosphere. How will this change local weather? Will there be more clouds? Will there be more rain?

23. Implications for your professional work Will need informed people in many disciplines who can deal with this issue sensibly. Reduce the emissions of climate change gases. Facilitate adaptation to changes in weather patterns

24. Summary We are altering the chemical composition of the Earth’s atmosphere. The Earth is warming. The impact this will have on the processes we have covered in this series of lectures is unknown –Energy flow/radiation –Global circulation –Weather –Water cycle

25. Exam Atmospheric composition, temperature Radiation balance Global circulation Water in atmosphere Weather Climate change Also examples, but not the topic of a question Provides examples for above three topics Need to understand the basics Possible question Will be one essay question Know definitions of identified words

26. Next Week Professor Jamie Kirkpatrick Weathering and erosion Chapter 13 of Christopherson.