PHYS/ENVS 3070 Homework Assignment #10: Problem #1. Assume that the total coal proved reserves of the world are eventually burned and that 50% of the resulting CO2 is added to the atmosphere. Estimate the resulting increase in concentration of CO2 in parts per million (by number of molecules) in the atmosphere for the world. See section 9.2 of the textbook for the mass of the atmosphere. See chapter 2 of the textbook for the world coal proved reserves, and assume that it is 100% carbon. (4 points) The entire proved coal reserves of the world are given in Table 2.7 of the textbook, and are 984 x 109 tonnes. Note that 1 ton = 0.907 tonnes, and thus this amount of coal is 1.08 x 1012 tons. As we have calculated in previous homework, every ton of coal (assuming 100% carbon content) will produce 3 tons of CO2. Thus, if we assume that 50% of the CO2 ends up in the atmosphere, we get 1.08 x 1012 x 3 x 0.5 = 1.6 x 1012 tons. The entire earth's atmosphere has a mass of 5.7 x 1015 tons (see Section 9.2 of the textbook). If we assume all molecules in the atmosphere have approximately the same mass, then the increase in part per million are 1.6 x 1012 / 5.7 x 1015 = +285 parts per million. One can get a more accurate number by taking into account the differences in the molecular masses. Note that this number is just from coal. Problem #2. The reason that skin cancer can be caused by solar ultraviolet radiation but not by the visible light at the earth's surface is: a. The wavelength of UV is longer, hence it is more destructive. b. There is much more UV than visible light at the earth's surface. c. Once you have a good tan, visible light can do no further harm. d. UV photons have more energy and hence can ionize biological molecules more readily. (2 points) Answer D is correct. Problem #3. What are two changes from the Montreal Protocol that are included in the Copenhagen Amendments (see Figure 10.2 in the textbook for implications). (4 points) There is a nice short "answer to question" page on the NOAA web page: http://esrl.noaa.gov/csd/assessments/2002/qandas15.pdf There are also significant details on the United Nations web page:http://ozone.unep.org/Publications/MP_Handbook/Section_2_Decisions/Fourth_MOP.shtml Problem #4. What do you think are the highest priory changes for the United States of America in terms of global warming (write 1-2 paragraphs). (5 points) There are many good answers here, and reflect different scientific and also moral
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