Physics of Technology PHYS 1800

1. Physics of TechnologyPHYS 1800 Lecture 24 Climate Change

2. PHYSICS OF TECHNOLOGYSpring 2009 Assignment Sheet *Homework Handout

3. The Flow of Heat • In radiation, heat energy is transferred by electromagnetic waves. • The electromagnetic waves involved in the transfer of heat lie primarily in the infrared portion of the spectrum. • Unlike conduction and convection, which both require a medium to travel through, radiation can take place across a vacuum. • For example, the evacuated space in a thermos bottle. • The radiation is reduced to a minimum by silvering the facing walls of the evacuated space.

4. Ein Eout Heat Flow and the Greenhouse Effect What heat-flow processes are involved in the greenhouse effect?

5. temperature OUT IN energy Energy Balance (Conservation of Energy)

6. Energy Balance (Energy Conserved) IN OUT Constant Temperature (Equilibrium)

7. Energy Balance (Excess Energy) IN OUT Warming

8. Energy Balance (Energy Deficit) OUT IN Cooling

9. Ein Eout IN Solar Input Source: NOAA

10. lmax Energy density (J/cm3) Wavelength (mm) All bodies at T>0 K emit EM radiation. This process is called blackbody radiation. The hotter the body, the more intensity and the higher the average frequency of the emitted light. Observations: Blackbody Radiation Problem Blackbody radiation spectrum depends only on the temperature of the surfaces of the object. Stephan-Boltzmann Law: Wien’s law The peak wavelength is

11. IN Solar Input Wien’s law Stephan-Boltzmann Law: The peak wavelength is For a solar radius of 7·108 m, and radiating surface area of 4/3 π r2, the solar irradiance is JSun= W . The peak of the solar spectrum is at ~0.450 um wavelength (in the green). This corresponds to a solar temperature of ~5800 K.

12. IN Solar Input Power Density at Earth’s Radius Power Input for Earth The energy density at the average Earth radius is The total power intercepted by the Earth is

13. Ein Eout OUT Visible Reflection Infrared Emission Infrared Trapping

14. Ein Eout OUT Visible Reflection Table 1. Surface Albedos

15. Ein Eout OUT Stephan-Boltzmann Law: Infrared Emission Here use the surface area of the Earth and the equilibrium temperature of the Earth.

16. Ein Eout OUT Infrared Trapping This is the greenhouse effect. First solve the equilibrium problem without this term and then with it.

17. Ein Eout OUT Without Infrared Trapping

18. Ein Eout OUT Measured average T is ~ 298 K = 25 C Difference due to greenhouse effect is ~12 C With Infrared Trapping

19. 600 Projected Concentration After 50 More Years of Unrestricted Fossil Fuel Burning 500 Paleo climate 400 300 280 260 240 CO2 Concentration CO2 [ppmv] 220 200 180 Temperature 600,000 500,000 400,000 300,000 200,000 100,000 0 Years Before Present

20. 600 Projected Concentration After 50 More Years of Unrestricted Fossil Fuel Burning 500 Paleo climate 400 300 280 260 240 CO2 Concentration CO2 [ppmv] 220 Glacial 200 180 Temperature 600,000 500,000 400,000 300,000 200,000 100,000 0 Years Before Present

21. triggers feedbacks Sun

22. Mercury Venus Earth Mars 333° F +855° F 59° F -67° F

23. triggers feedbacks Sun

24. 600 Projected Concentration After 50 More Years of Unrestricted Fossil Fuel Burning 500 Paleo climate 400 300 280 260 240 CO2 Concentration CO2 [ppmv] 220 200 180 Temperature 600,000 500,000 400,000 300,000 200,000 100,000 0 Years Before Present

25. 600 Projected Concentration After 50 More Years of Unrestricted Fossil Fuel Burning 500 Paleo climate 400 300 280 260 CO2 Concentration 240 CO2 [ppmv] 220 200 180 Temperature 600,000 500,000 400,000 300,000 200,000 100,000 0 Years Before Present

26. 600 Projected Concentration After 50 More Years of Unrestricted Fossil Fuel Burning 500 400 Today’s CO2 Concentration 300 280 260 CO2 Concentration 240 CO2 [ppmv] 220 200 180 Temperature 600,000 500,000 400,000 300,000 200,000 100,000 0 Years Before Present

27. MODELS

29. triggers feedbacks Sun

30. 1980

31. 2007

32. 600 Projected Concentration After 50 More Years of Unrestricted Fossil Fuel Burning 500 400 Today’s CO2 Concentration 300 280 260 CO2 Concentration 240 CO2 [ppmv] 220 200 180 Temperature 600,000 500,000 400,000 300,000 200,000 100,000 0 Years Before Present

33. After 45 More Years of current energy use patterns 600 500 400 Today’s CO2 Concentration 300 300 280 260 CO2 Concentration 240 CO2 [ppmv] 220 200 180 Temperature 600,000 500,000 400,000 300,000 200,000 100,000 0 Years Before Present

34. ground observations satellite observations balloon data sea surface temps WARMING continental ice sheet retreat polar ice cap retreat mtn. glacier retreat permafrost melt ice cores coral reef cores tree rings BIOLOGICAL DATA ocean sediment cores

35. A Preponderance of Evidence

36. These folks agree ... • National Academy of Sciences (United States of America) • Royal Society (United Kingdom) • Royal Irish Academy • Academié des Sciences (France) • Deutsche Akademie der Naturforscher Leopoldina (Germany) • Accademia dei Lincei (Italy) • Royal Swedish Academy of Sciences • Royal Society of Canada • Russian Academy of Sciences • Royal Flemish Academy of Belgium for Sciences and the Arts • Science Council of Japan • Chinese Academy of Sciences • Indian National Science Academy • Australian Academy of Sciences • Academy Council of the Royal Society of New Zealand • Academia Brasliiera de Ciências (Brazil) • Caribbean Academy of Sciences • Indonesian Academy of Sciences • Academy of Sciences Malaysia Source: IPCC TAR

37. And these folks... • American Meteorological Society (AMS) • American Geophysical Union (AGU) • NASA's Goddard Institute of Space Studies (GISS) • National Oceanic and Atmospheric Administration (NOAA) • National Center for Atmospheric Research (NCAR) • State of the Canadian Cryosphere (SOCC) • Canadian Meteorological and Oceanographic Society (CMOS) • Geological Society of America • Geological Society of London

38. And these folks... • American Association for the Advancement of Science (AAAS) • American Physical Society / American Institute of Physics • American Chemical Society