1. Climate Change: The Move to Action (AOSS 480 // NRE 501) Richard B. Rood 734-647-3530 2525 Space Research Building (North Campus) rbrood@umich.edu http://aoss.engin.umich.edu./people/rbrood Winter 2008 January 17, 2008

2. Class News A ctools site for all –AOSS 480 001 W08 This is the official repository for lectures Email climateaction@ctools.umich.edu Class Web Site and Wiki –Climate Change: The Move to ActionClimate Change: The Move to Action –Winter 2008 TermWinter 2008 Term Dramatic Changes in Earth's Polar Ice: Are We Waking Sleeping Giants? Dr. Waleed Abdalati, NASA Goddard Space Flight Center.Dramatic Changes in Earth's Polar Ice: Are We Waking Sleeping Giants? –Exhibit Museum (1109 Geddes) –Friday, 1/18/2008; 07:30 PM to 09:00 PM

3. Readings on Local Servers Assigned –IPCC Working Group I: Summary for Policy MakersIPCC Working Group I: Summary for Policy Makers Of Interest –Kerr: Ice Age TurnaroundKerr: Ice Age Turnaround –Royal Society: Biofuels and Climate ChangeRoyal Society: Biofuels and Climate Change

4. Outline of Lecture Revisit the ice age-temperate cycle (Corrections and clarification) –Role of the ocean –Role of the sun –Sources and sinks of carbon dioxide Greenhouse effect Radiative Balance of the Earth

5. The Conservation Principle The idea that some basic quantities are conserved. –A counting problem. –The amount that you have is equal to the amount that you started with, plus the amount that you acquired (income or production), minus the amount that you got rid of (expense or loss) –This is within in some closed system.

6. Conservation Principle (Developed with idea of money: a budget) What you have = what you had + what you earned - what you spent (M tomorrow - M yesterday )/N = ΔM/Δt = I – eM Δ ≡ Difference i.e.M(t 2 )-M(t 1 )IncomeExpense Change per unit time Continuous equation in limit of small Δt

7. Conservation Principle “in balance” If a quantity is conserved or “in balance” then Change per unit time = 0

8. The first place that we apply the conservation principle is energy Assume that Energy is proportional to T, if the average temperature of the Earth is stable, it does not vary with time.

9. Let’s revisit the ice ages

10. The FIRST two definitions of profess Profess:. To affirm openly; declare or claim. 2. To make a pretense of; pretend.

11. Behavior of water; Phase change Differences for the Future (100-200 years)  ~100 ppm CO 2 (Already)  > 200-300 ppm CO 2 certain  ~ 8-20 C polar T difference  ~ 2-6 C global average T difference These numbers are in reasonable relation. ICE AGE ~200 ppm CURRENT (360 ppm) NEW AGE? ~500 ppm Differences from Past (20,000 years) ~100 ppm CO 2 ~ 20 C polar T difference ~ 5 C global average T difference Time gradient of CO 2 changes, 2 orders of magnitude (100 times) larger.

12. Bubbles of gas trapped in layers of ice give a measure of temperature and carbon dioxide 350,000 years of Surface Temperature and Carbon Dioxide (CO 2 ) at Vostok, Antarctica ice cores  This is one of the points of controversy.  There is a lag between CO2 and T turn around. This has been extended back to > 700,000 years

13. CO 2 and T Variation 350,000 years of Surface Temperature and Carbon Dioxide (CO 2 ) at Vostok, Antarctica ice cores NEED TO EXPLAIN THIS REDUCTION OF CO 2 CO 2 2005 CO 2 2100 360 ppm 460 ppm

14. CO 2 and T Variation 350,000 years of Surface Temperature and Carbon Dioxide (CO 2 ) at Vostok, Antarctica ice cores NEED TO EXPLAIN THIS INCREASE OF CO 2 CO 2 2005 CO 2 2100 360 ppm 460 ppm

15. Increase-decrease of CO 2 in ice age cycles Number of plausible mechanisms that are related to the ocean, and the fact that because of ice freezing and thawing there are always “margins” in the climate that are subject to change. The impact of ice in the climate is very different than liquid and vapor phases of water.

16. Some clarifications A mistake from last lecture –CO 2 and sea water Vostok Ice Core and CO 2 –Vostok and CO2Vostok and CO2 –Role of Ocean in ReversalRole of Ocean in Reversal

17. CO 2 and sea water The amount of CO 2 that is dissolved in water is proportional to –Amount of CO 2 in the air (partial pressure of CO 2 ) The amount of CO 2 that is dissolved in water is inversely proportional to temperature –Warm water absorbs less CO 2 –Cool water absorbs more CO 2

18. Ocean is part of the turnaround

19. CO 2 in mixed layer moved to deeper layers of ocean. SOLUBILITY PUMP BIOLOGICAL PUMP

20. CO 2 in Ocean Figure: Hannes Grobe Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, GermanyHannes Grobe

22. Ice on the ocean OCEAN ATMOSPHERE mixed layer of ocean CO 2 polar chemistry carbonic acid biology plankton, shells, bones tropics polar ICE Ice acts as an barrier between ocean and atmosphere. (Heat, CO 2, etc.)

23. Ice on the ocean OCEAN ATMOSPHERE mixed layer of ocean CO 2 polar tropics polar ICE If ice is gone, could open more water for absorbing CO 2 polar

24. Ice on the ocean OCEAN ATMOSPHERE mixed layer of ocean CO 2 polar tropics polar ICE If ice is gone and there is high CO 2 in sea water under ice could cause large release of CO 2 from the sea. polar

25. Ocean-CO 2 There is a lot of CO 2 in ocean and it moves back and forth between ocean and atmosphere based on pressure and temperature. –In general cold water absorbs more CO 2 than warm water. Warming ocean absorbs less Higher CO 2 in atmosphere “pushes” in more –Sea ice places a barrier on transfer between atmosphere and ocean and loss of sea ice affects balance based on whether or not there is “excess” CO 2 stored in the water.

27. Conservation principle for CO 2

28. What are the mechanisms for production and loss of CO 2 ?

29. CO 2 is increasing in the atmosphere. Burning changes some organic carbon to inorganic carbon. In ocean transfer of CO 2 between CO 2 and calcium carbonate and carbonic acid. In some problems is CO 2 treated as conserved because of time scales of transport and chemical inertness. For the climate problem CO 2 in the environment is increasing. It takes a long time for it to be removed.

30. Carbon and Terrestrial Exchange

31. Carbon and Oceanic Exchange

32. Reduction in CO 2 350,000 years of Surface Temperature and Carbon Dioxide (CO 2 ) at Vostok, Antarctica ice cores THIS REDUCTION OF CO 2 IS RELATED TO BIOLOGY. Dominance of the oceanic sink? CO 2 2005 CO 2 2100 360 ppm 460 ppm

33. Ice Age – Temperate Cycles There is a relation to orbital cycles, which cause slight perturbations in radiative balance of the Earth-Sun system. Something is required to amplify this radiative forcing. –Likely related to oceans and sea ice –Likely related to storage of CO 2 in the ocean

34. Let’s leave the ice ages

35. Two concepts First, the expression of the conservation principle as an equation is a model. Second, in the good practice of science one of the first things to do is to draw a picture.

36. Conservation (continuity) principle Energy from the Sun Energy emitted by Earth (proportional to T) Earth at a certain temperature, T Stable Temperature of Earth could change from how much energy (I) comes from the sun, or by changing how much we emit, related to e.

37. But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F). The Greenhouse Effect (Is this controversial?) SUN Earth Based on conservation of energy: If the Earth did NOT have an atmosphere, then, the temperature at the surface of the Earth would be about -18 C ( ~ 0 F). This temperature, which is higher than expected from simple conservation of energy, is due to the atmosphere. The atmosphere distributes the energy vertically; making the surface warmer, and the upper atmosphere cooler, which maintains energy conservation. This greenhouse effect in not controversial.

38. But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F). The Greenhouse Effect (Is this controversial?) SUN Earth Based on conservation of energy: If the Earth did NOT have an atmosphere, then, the temperature at the surface of the Earth would be about -18 C ( ~ 0 F). This temperature, which is higher than expected from simple conservation of energy, is due to the atmosphere. The atmosphere distributes the energy vertically; making the surface warmer, and the upper atmosphere cooler, which maintains energy conservation. We are making the atmosphere “thicker.” This greenhouse effect in not controversial.

39. Some aspects of the greenhouse effect Greenhouse warming is part of the Earth’s natural climate system. –It’s like a blanket – it holds heat near the surface for a while before it returns to space. Water is the dominant greenhouse gas. Carbon dioxide is a natural greenhouse gas. –We are adding at the margin – adding some blankets Or perhaps closing the window that is cracked open. N 2 0, CH 4, CFCs,... also important. But in much smaller quantities. We have been calculating greenhouse warming for a couple of centuries now.

40. The first place that we apply the conservation principle is energy If we change a greenhouse gas e.g. CO 2, we change the loss rate. For some amount of time we see that the Earth is NOT in balance, that is ΔT/Δt is not zero, temperature changes.

41. Conservation (continuity) principle Energy from the Sun Energy emitted by Earth (proportional to T) Earth at a certain temperature, T Stable Temperature of Earth could change from how much energy (I) comes from the sun, or by changing how much we emit, related to e.

42. The first place that we apply the conservation principle is energy We reach a new equilibrium Changing a greenhouse gas changes this

43. But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F). The sun-earth system (What is the balance at the surface of Earth?) SUN Earth Based on conservation of energy: If the Earth did NOT have an atmosphere, then, the temperature at the surface of the Earth would be about -18 C ( ~ 0 F). What else could be happening in this system? This greenhouse effect in not controversial.

44. Conservation of Energy The heating could change. That is the sun, the distance from the sun,....

45. The first place that we apply the conservation principle is energy We reach a new equilibrium Changes in orbit or solar energy changes this Can we measure the imbalance when the Earth is not in equilibrium?

46. Still there are many unanswered questions We know that CO 2 in the atmosphere holds thermal energy close to the surface. Hence, more CO 2 will increase surface temperature. –Upper atmosphere will cool. –How will the Earth respond? Is there any reason for Earth to respond to maintain the same average surface temperature? Why those big oscillations in the past? –They are linked to solar variability. –Release and capture of CO 2 by ocean plausibly amplifies the solar oscillation. Solubility pump Biological pump What about the relation between CO 2 and T in the last 1000 years? –Look to T (temperature) variability forced by factors other than CO 2 Volcanic Activity Solar variability CO 2 increase Radiative forcing other than CO 2 ? –Other greenhouse gases –Aerosols (particulates in the atmosphere)

47. Radiative Balance of The Earth Over some suitable time period, say a year, maybe ten years, if the Earth’s temperature is stable then the amount of energy that comes into the Earth must equal the amount of energy that leaves the Earth. –Energy comes into the Earth from solar radiation. –Energy leaves the Earth by terrestrial (mostly infrared) radiation to space. (Think about your car or house in the summer.)

48. Radiation Balance Figure

49. Have a good weekend