Lecture #42. Low Clouds Over the Ocean. Positive Feedback and Clouds. The First Estimate of Surface Warming Due to a Doubling of CO 2 - in 1896!

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1 The First Estimate of Surface Warming Due to a Doubling of CO 2 - in 1896! Original prediction: a doubling of CO 2 would increase temperature between and 6 C. Was attempting to explain ice age If the quantity of carbonic acid in the air should temperature sink to one-half variations. its present percentage, the temperature would fall by about ; a Speculated diminution that fossil to one-quarter would reduce the CO 2 might temperature help to by avert 8. On the other hand, any the next doubling ice age. of the percentage of carbon dioxide in the air would raise the temperature of the earth's surface by ; and if the carbon dioxide were increased fourfold, the temperature would rise by 8. - Sv. Arrhenius, Das Werden der Welten, Lecture #2 What is the dominant source of uncertainty in the blue band? A) What human CO2 emissions will be in the future B) Melting of ice in Antarctica and Greenland C) Positive feedback mechanisms with clouds D) Opinions of different scientific groups E) Changing projections over the last 5 years Positive Feedback and Clouds Low Clouds Over the Ocean What do you notice between these two models?? Consistent? Different? Disproves global warming models When do you call this lying (purposeful deceipt)? the-pros-and-cons-of-nprs-policy-of-not-calling-out-lies 1

2 visualizations-data/ycom-us-2016/ gtonpost.com/news /energyenvironment/wp/20 17/0/28/epawebsite-removesclimate-sciencesite-from-publicview-after-twodecades/?utm_term =.3bc8a0abe1b Politics and rhetoric have a strong influence on the public view of scientific research. Much of this is through specific manipulation of facts and data. Reading Assignment Reading Finish Chapter 12-1 Homework Assignment HW #10 (last one) due Wednesday, May 03, 2016 Examination #3 ( Final Exam ) Monday, May 8, 2017 from 1:30-3:00 pm In our regular classroom G130. See details on the next slide. When money and defense matter, there is often a different story. -- My office hours are Monday 11 am - noon Also available by appointment just me. 2

3 Radiance (Wm -2 (cm)) Examination #3 ( Final Exam ) Monday, May 8, 2017 from 1:30-3:00 pm In our regular classroom G130. This final exam counts the same as the first two exams. This exam focusses on Chapters 9, 10, 12-1; Homework assignments 8-10; and the corresponding Lecture Material (including guest lectures). As with the other exams, this one is open book, and open calculator (but not your phone or other notes). D2L scores now have most of your course information All homeworks (except HW #10 due Wednesday) First two exams Paper #1 Extra Credit #1, #2, #3, # Percentage of clicker questions answers (not yet dropping 5 lectures) Please check your scores and let me know by Friday if there are any discrepancies or issues. The exam will consist of multiple choice questions. Same row seating assignments as before. More Realism Consider a one-dimensional model with atmosphere as a single uniform layer as completely transparent to incoming solar radiation and absorptive of a fraction of the outgoing radiation from the earth s surface (grey body). without an atmosphere with an atmosphere 1 2 S (1 A ) 20Wm O P Planet Solar flux (W m -2 ) Albedo Teff (C) Actual Tsurf (C) Greenhouse effect (C) Earth Venus Mars Venus is the poster child for a runaway greenhouse effect. There is no scientific dispute regarding the greenhouse effect. T s Surface a T a Atmosphere Frequency Dependence of Atmospheric Absorption The absorption spectrum of the earth s atmosphere is definitely frequency (wavelength) dependent. Greenhouse Even though there is a lot (a whole lot) more going on, we have enough to understand the greenhouse effect. The frequency dependence of the earth s emission spectrum is due to the specific energy level structures of the molecular atmospheric constituents K CO H K O 3 H 20 0 Wavenumber (cm -1) 3

4 Greenhouse Short wavelength radiation (visible and some UV) from the sun goes mostly through the glass. Long wavelength radiation (IR) is reflected and trapped inside the greenhouse by the glass. Thus, the equilibrium balance is changed and the greenhouse heats up to a new equilibrium balanced temperature. Note that real greenhouses also reduce convective heat losses. Greenhouse Glass Earth s Atmosphere Greenhouse Gases Gases that absorb light in the IR range are called greenhouse gases. Absorption Concentration Relative Impact CO ppm 373 CH ppm 35 NO x ppm 90 CFC ppm 6 Each gas impact depends on its quantity (ppm) and how much IR it absorbs.

5 Clicker Question Do these lifetimes seem consistent with your general knowledge? A) Yes B) No Longer Term Trends * Carbon dioxide s lifetime is poorly defined because the gas is not destroyed over time, but instead moves among different parts of the ocean atmosphere land system. Some of the excess carbon dioxide will be absorbed quickly (for example, by the ocean surface), but some will remain in the atmosphere for thousands of years, due in part to the very slow process by which carbon is transferred to ocean sediments. What kind of acid is forming in the oceans? A) Citric acid B) Hydrocloric acid C) Carbonic acid D) Super acid 5

6 Sea Level Rise 6