THE PX2720 UNIVERSITY OF WARWICK Second Year Examinations: Summer 2006 Physics Paper 7 GLOBAL WARMING
Answer TWO questions. Time allowed: 1 hour Read carefully the instructions on the answer book and make sure that the particulars required are entered A maximum of 25 credit marks will be awarded for each question. The nominal mark assigned to each part of a question is indicated by means of a bold figure enclosed by curly brackets, e.g. {2}, immediately following that part. This mark scheme is for guidance only and may be adjusted by the examiner. Calculators may be used for this examination.
The following information may be used: Stefan-Boltzmann Constant
; 6 10-8 Wm -2 K -4
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PX2720 GLOBAL WARMING 1. (a) The flux density of solar radiation in the vicinity of the Earth's orbit is about 1370 Wm -2 . Explain why if the Earth absorbed all the incident solar radiation, then the mean temperature of the Earth (as observed from space) would be expected to be about 275 K. {6} What causes the radiation absorbed to be less by about 30%, and what are the strongest contributors to this? {3} Explain why the mean surface temperature is significantly higher than the apparent temperature of the earth as observed from space. {4}
(b) (c) (d)
The figure above shows Global average temperature (relative to the 1979-90 average) for both the surface (upper figure) and the stratosphere (lower figure). (i) Explain how the decreasing trend of temperature with time in the lower figure relates to global warming effects. {4} (ii) Scientific opinion is that even if the atmosphere were to be stabilised at its current composition, surface temperatures would continue to rise for some time. What is the reason for this and roughly how long would you expect the present level of rise to continue? {4} (iii) Sketch how these curves would to have evolve for the earth to reach steady state in this way. {4}
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PX2720 2. (a) (b) Give a brief overview of what basic physics (but not all the detailed meteorological processes) is included in typical Ocean-Atmosphere General Circulation Models. {6} Give at least two pieces of evidence that such models are a valid guide to predicting climate changes. {4}
(A)
(B)
(C) The figure above shows climate projections from the IPCC report of 2001. (c) (d) (e) (f) What is represented by the various different scenarios? [You are not expected to be able to identify them individually.] {4} Why do carbon dioxide concentrations (panel (B)) not decrease by 2100 in any case shown? {3} What is represented by the lighter gray shaded region for predicted temperature in panel (C)? {2} Compare the range of temperature rises to:
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PX2720 (i) the magnitude of historical temperature changes (ii) and policy targets today. {3} (3}
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PX2720 3. (a) (b) (c) (d) (e) (f) Over the next century atmospheric carbon dioxide is likely to reach twice its prei...