The World in 2050_ Four Forces Shaping Civilization's Northern Future - Laurence C. Smith [139]
35 The analogy to a closed car or glass greenhouse is imperfect because air circulation is not trapped in a moving atmosphere, but it’s close enough for our purposes here.
36 Svante Arrhenius, “On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground,” Philosophical Magazine and Journal of Science, 5th Series 41 (April 1896): 237-276.
37 For more about Arrhenius and other early research on the greenhouse effect, see R. Henson, The Rough Guide to Climate Change (London: Penguin Books Ltd., 2008).
38 From global weather station data, the average hundred-year linear trend from 1906 to 2005 is +0.74°C (with error bars, between +0.56°C and +0.92°C). From air bubbles trapped in ice cores, we know atmospheric CO2 concentrations averaged ~280 ppm in the preindustrial era (before ~1750 A.D.) versus ~387 ppm in 2009. The first continuous direct sampling of CO2 concentration was begun by Charles “Dave” Keeling at Mauna Loa Observatory in 1958 and continued by his son Ralph Keeling. Carbon dioxide levels have risen consistently every year from ~315 ppm in 1958 to ~387 ppm in 2009. For the latest data, see http://scrippsco2.ucsd.edu/. The 2007 IPCC SRES B1, A1T, B2, A1B, A2, and A1FI illustrative marker scenarios are about 600, 700, 800, 850, 1,250, and 1,550 ppm, by century’s end respectively, with different scenarios reflecting different assumptions about controlling carbon emissions. Such numbers are two to five times preindustrial levels. IPCC AR4 Synthesis Report, Table 3.1. (Full reference IPCC Fourth Assessment Report [AR4], Climate Change 2007: Synthesis Report, Contribution of Working Groups I, II, and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Core Writing Team, R. K. Pachauri, A. Reisinger (eds.), IPCC, Geneva, Switzerland: 104 pp.) available at http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr.pdf.
39 J. O’Neill, S. Lawson, “Things Are Heating Up: Economic Issues and Opportunities from Global Warming,” CEO Confidential, Issue 2007-01, Goldman Sachs, February 8, 2007; J. Lash, F. Wellington, “Competitive Advantage on a Warming Planet,” Harvard Business Review, March 2007.
40 USCAP Press Release, “Joint Statement of the United States Climate Action Partnership,” January 19, 2007, www.us-cap.org/media/release_USCAPStatement011907.pdf (accessed November 20, 2008).
41 From www.us-cap.org/about/index.asp (accessed November 23, 2008). The Web page later showed the withdrawal of several members.
42 Atmospheric CO2 variations have both natural cycles—which fall and rise with ice ages and warm interglacial periods—and anthropogenic sources, which are also substantial but rise much faster. Our current anthropogenic boost is perched on top of an already large natural interglacial peak, thus taking the atmosphere to levels not seen since the Miocene. Over the past 800,000 years of multiple ice age/warm interglacial cycles, including the current interglacial of the past ~12,000 years, preindustrial atmospheric CO2 levels cycled within a range of ~172 (ice age) to 300 (interglacial) parts per million by volume (ppmv). Human activity has now boosted that to ~385 ppmv and we are projected to reach at least 450 ppmv and perhaps as much as 1,550 ppmv by the end of this century. See ice-core record, D. Lüthi et al., “High-Resolution Carbon Dioxide Concentration Record 650,000-800,000 Years before Present,” Nature 453 (2008): 379-382, DOI:10.1038/nature06949; also Urs Siegenthaler et al., “Stable Carbon Cycle-Climate Relationship during the Late Pleistocene,” Science 310, no. 131 (November 2005), DOI:10.1126/science.1120130, and others.
43 Much older Miocene PCO2 now estimated from boron/calcium ratios in ocean core foraminifera, A. K. Tripati, C. D. Roberts, R. A. Eagle, “Coupling of CO2 and Ice Sheet Stability over Major Climate Transitions of