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Lecture 11

Lecture 11

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University of Toronto Scarborough
Biological Sciences
Rudy Boonstra

LECTURE 11 November 27, 2007 To survive in the world we have transformed, we must learn to think in a new way. As never before, the future of each depends on the good of all. th This is the last lecture of the year. Your exam I think is on December 11 . It will be a 3 hour exam but probably about 1 hour more than you need. The structure will be similar to the mid- term (short answers and multiple choice). I tried to be more specific this time. You will have questions from both the lectures and the tutorials. Some of the hardest questions were from tutorials. So do your readings and your tutorials. There are 2 readings for the tutorial this week which are listed on the intranet. Make sure to quiz him and read the information. Think about what is going on there. Is the exam cumulative? No, it is from October onwards. (If you didnt write the exam then it will be cumulative so study previous material.) S: The second isnt as much detailed so how do you study for that? This is more general this ? P: It wasnt all numbers but there was a reasonable number. This time I will have to ask about concepts and general principals. That is what I will quiz you on. There are some numbers and I tried to point them out to you. Remember the short answers are almost all on concepts so same deal. S: Rollover for tutorial so there was one that wasnt tested on so will it be tested this time? P: Yes, remember and study it. Those concepts will be included from that tutorial. There will be office hours during our break as well. Next Monday I will be there from 11:00 -> 12:00. th On Monday the 10 I have a meeting so I wont be there then. I will be there on Wednesday say about 11:00 -> 12:00 (normally it is 10:00). Today We will talk a little bit about dealing with the threat of global change. How do we deal with it? We will talk about the process and the potential benefits or how the world is trying to deal with it. We will talk about how the world dealt with the destruction of the ozone layer. The second portion we will talk about mitigation and adaptation techniques. Ozone Depletion Think about this last 3 months or so the picture I painted is a sobering one. Over the years history has seen an enormous climatic change. It is resilient and has taken a hit by meteorites etc. It recovers after time. The dinosaurs left and vertebrates came in. Over the last 10,000 years there has been relatively stability in the system, more over the last 600,000 with a few BGYC58H3F.November,27,, 2007 LECTURE 11 1 www.notesolution.comblips. You get the impression that the atmosphere is sensitive. Our effort to reduce the nature and insult hasnt been particularly encouraging but there is hope. Only when something terrible happens we think about making a change. Dealing with the threat of global change: The good portion is in the stratosphere and that ozone layer made of this molecule prevents UV radiation from penetrating to the surface of the earth and causing negative effects. The negative effects of course are cancer. There are many types of cancers some are malignant and some are not. I have a red haired friend and he is very susceptible to damage and he has some cancer taken off of his face a few times. In addition cortical cataracts (lenses in your eyes are damaged) and that is only for humans and a few other animals. The other things, plants, we know that plankton may be severely affected by radiation in the marine environment. Finally your regular plants have interactions with bacteria and are very susceptible to UV radiation. So all these factors indicate they are bad. So this layer is very thin, about 3 mm thick if you condense it. There is really nothing there but there is enough to prevent biologically damaging UV radiation from reaching us. In 1928 there was an engineer, they have an odd way of looking at things, and he develops a compound called chlorinated fluorinated carbons. Think of a methane molecule and substitute chlorine and fluorine on it you create something incredibly stable. It is non reactive, it is inert. It is inert at the surface of the earth. Apparently a guy called James Lovelock (The Guyat Principle) developed CFCs. So he develops a device in the early 70s to measure this stuff. He calculates and finds out that it is all there and it hasnt gone anywhere. So you can account for all the CFCs in the atmosphere and it is still there. What happens to the stuff? So why? How does this stuff work and what is its ultimate fate? In 1974 in California a professor asked what happens to it (name is Sherwood). He is doing a post-graduate degree. They propose that this stuff (CFCs) float up and hit the stratosphere and the intense radiation of the sun that doesnt hit the earth breaks it apart. Free chlorine will destroy this molecule and it acts as a catalyst and it goes round and round. The hypotheses are that the chlorine in CFCs will destroy the ozone layer and then we get the brunt of the suns rays. Measurement of the Ozone Layer BGYC58H3F.November,27,, 2007 LECTURE 11 2
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