Global Warming. 8-Feb-18 OLLI Science in Current Events 1

Transcription

1 Global Warming 8-Feb-18 OLLI Science in Current Events 1

2 Muir glacier, August Feb-18 OLLI Science in Current Events 2

3 Muir glacier, August Feb-18 OLLI Science in Current Events 3

4 Science belief Why is there debate about these scientific topics? Climate change Vaccines Evolution But no debate about other scientific topics? Germ theory Relativity (general, special) Aerodynamics (airplanes, helicopters) Chemistry DNA Nuclear physics (bombs, stars, nuclear power*) Quantum theory, atomic physics (iphones) Radiation (microwaves, light) Thermodynamics (ovens) *nuclear power debate about safety, not about science. 8-Feb-18 OLLI Science in Current Events 4

5 Questions What questions can we ask about climate change? Is the Earth Warming? If yes, what is causing it? If no, is there a conspiracy? If humans are causing it, what can we do about it? what should we do about it? Would it hurt the economy to act? 8-Feb-18 OLLI Science in Current Events 5 5

6 8-Feb-18 OLLI Science in Current Events 6

7 Is Earth warming? Today The basic science: Radiation heating/cooling The Greenhouse effect Heat versus temperature Along with a few other pieces of information 8-Feb-18 OLLI Science in Current Events 7

8 Radiation Definition: the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization. Radiation carries energy Energy example: slow/fast car, slow/fast bus Different types: EM or subatomic particles High-energy radiation causes ionization 8-Feb-18 OLLI Science in Current Events 8

9 Electromagnetic Spectrum 8-Feb-18 OLLI Science in Current Events 9

10 Infrared heat radiation IR camera The Predator could see Arnold in the infrared 8-Feb-18 OLLI Science in Current Events 10

11 Things radiate energy Radiation Hotter -> more radiation Most radiation in the infrared 8-Feb-18 OLLI Science in Current Events 11

12 Electromagnetic Spectrum microwave Non-ionizing. Energy too low to break atomic bonds 8-Feb-18 OLLI Science in Current Events 12

13 Can cell phones cause brain cancer? Cell phone frequency bands About 10 9 Hz (1 GHz) 8-Feb-18 OLLI Science in Current Events 13

14 Electromagnetic Spectrum microwave Non-ionizing. Energy too low to break atomic bonds Ionizing! 8-Feb-18 OLLI Science in Current Events 14

15 Ionizing radiation Can break chemical bonds Can break DNA strands Mutations! Can be: bad (cancer, birth defects) or good (cancer treatment, polymer creation) Fortunately, for DNA we have autocorrect. 8-Feb-18 OLLI Science in Current Events 15

16 Heated ball Is the Earth Warming Heat IN from the sun (radiation) Heat OUT by radiation 8-Feb-18 OLLI Science in Current Events 16 16

17 Infrared radiation Objects radiate in the infrared It s a way to cool off! Any ideas about what else cools itself by emitting IR radiation? 8-Feb-18 OLLI Science in Current Events 17

18 The Greenhouse effect 8-Feb-18 OLLI Science in Current Events 18

19 8-Feb-18 OLLI Science in Current Events 19 19

20 Venus Venus Diameter 94% size of Earth 70 million miles from Sun (Earth 93 million mi) Radiation from the Sun is almost 2x Earth If no greenhouse effect Venus temperature about 90 F Temperature on Venus is about 800 F Runaway greenhouse effect Atmosphere 90x denser than Earth Mostly CO 2 8-Feb-18 OLLI Science in Current Events 20 20

21 8-Feb-18 OLLI Science in Current Events 21 Phys 150 Lecture 20 21

22 Earth Temperature would be about 26 F without greenhouse effect. Observed temperature about 57 F Thanks to greenhouse effect. 8-Feb-18 OLLI Science in Current Events 22 22

23 Global cooling? Newsweek magazine, April 28, 1975 To scientists, these seemingly disparate incidents represent the advance signs of fundamental changes in the world s weather. The central fact is the earths climate appears to be cooling down. 8-Feb-18 OLLI Science in Current Events 23 23

24 8-Feb-18 OLLI Science in Current Events 24 24

25 Temperatures versus CO 2 CO 2 concentrations track temperatures correlated Cause? Effect? Hypothesis is that warmer temperatures release CO 2 from oceans. CO 2 concentrations lag behind temperature changes. Could natural global warming be happening on top of manmade CO 2 increase? Could this be a feedback effect? 8-Feb-18 OLLI Science in Current Events 25 25

26 19-Oct-2015 Phys 192 Lecture 7 26

27 19-Oct-2015 Phys 192 Lecture 7 27

28 19-Oct-2015 Phys 192 Lecture 7 28

29 19-Oct-2015 Phys 192 Lecture 7 29

30 Climate models Use knowledge of physics, chemistry Heat, radiation, convection, evaporation Slice the Earth and atmosphere up into lots of slices Use massive computers to simulate climate evolution with various inputs Compare to recent history to improve the modeling.

31 Questions What questions can we ask about climate change? Is the Earth Warming? If yes, what is causing it? If no, is there a conspiracy? If humans are causing it, what can we do about it? what should we do about it? Would it hurt the economy to act? 8-Feb-18 OLLI Science in Current Events 31 31

32 Questions What questions can we ask about climate change? Is the Earth Warming? That the climate is warming is unequivocal. 8-Feb-18 OLLI Science in Current Events 32 32

33 Questions What questions can we ask about climate change? Is the Earth Warming? yes If yes, what is causing it? Humans adding CO 2 to the atmosphere Not: volcanos Not: solar cycles Exceedingly likely: additional feedback from water 8-Feb-18 OLLI Science in Current Events 33 33

34 Questions What questions can we ask about climate change? Is the Earth Warming? yes If yes, what is causing it? CO 2 from us If no, is there a conspiracy? If humans are causing it, what can we do about it? what should we do about it? Would it hurt the economy to act? These are questions that involve science, technology, policy and politics. 8-Feb-18 OLLI Science in Current Events 34 34

35 A few other facts of interest regarding climate change 11-Nov-2010 Phys 150 Lecture 23 35

36 question If the Arctic Sea ice were to completely melt, the global sea level would rise by A. 0 m B. 1 m C. 7 m D. 20 m 11-Nov-2010 Phys 150 Lecture 23 36

37 question If the Arctic Sea ice were to completely melt, the global sea level would rise by A. 0 m - yes B. 1 m C. 7 m D. 20 m 11-Nov-2010 Phys 150 Lecture 23 37

38 question If the Arctic Sea ice were to completely melt, the global sea level would rise by A. 0 m - yes B. 1 m C. 7 m if Greenland Ice Sheet were to melt D. 20 m - Antarctic Ice Sheet projected to remain frozen 11-Nov-2010 Phys 150 Lecture 23 38

39 Why sea level rise? Only melting ice currently on land would contribute to sea level rise. Much bigger effect from thermal expansion of water. warm things are bigger, even water! 11-Nov-2010 Phys 150 Lecture 23 39

40 Summary Basic science of climate change is well understood. Arguing the basic science is not constructive. There is still room to debate the details (e.g. the subtle details of the models.) There is still uncertainty in the projections. But remember the details and the uncertainty in projections don t change the broad and fundamental conclusions There remains much to debate (policy, politics, modeling details) but unfortunately we instead spend our time arguing about the wrong questions. And we didn t even discuss geoengineering 11-Nov-2010 Phys 150 Lecture 23 40