Guiding Principles for Climate Legislation

Position: The Citizen’s Climate Lobby favors legislation that will bring atmospheric CO2 levels to between 280 and 350 ppm. To accomplish this, the US must adopt legislation not just with emissions reductions targets, but with “carbon negative” targets and effective mechanisms for meeting those targets by removing CO2 from the atmosphere and sequestering it permanently in a safe way. 
 
Why 280? 280 ppm was the atmospheric concentration of CO2 before levels began to climb at the beginning of the industrial revolution1. We assume that, since writing, agriculture, and essentially all human culture came about with a concentration of between 265 and 280 ppm2, this concentration is a sustainable target for the future of humanity.

Why 350? 350 ppm is the atmospheric concentration scientists calculate we can sustain with acceptable negative effects. This estimate is based on the observation that the Earth was ice-free until atmospheric CO2 decreased to a level of 450 +/- 100 ppm3. 350 ppm is thus outside the error of this observation, and should guarantee that not all of the ice on the planet would melt.

However, the authors of this paper acknowledge that reductions below 350 ppm are likely necessary. There is ~ 80 m (262 ft)4 of sea level rise locked up in the world’s glaciers and ice sheets, and melting just a fraction of it could displace billions of people. For instance, the West Antarctic Ice sheet, which has in recent years shed ice shelves the size of Connecticut and Delaware5, 6, contains enough ice to raise sea level by ~ 8 m4. The Greenland ice sheet, which has moved from losing almost no ice in the 1990’s to contributing 10% of the annual observed 3 mm rise in sea level7, contains enough ice to raise sea level ~6.5 m more4. The US Geological Survey estimates that a rise in sea level of 10 m would displace ~ 25% of the US population8, or ~ 75 million people. Even a 1 m sea level rise would displace nearly 500 million people around the world4.

How long do we have? Current “business as usual” projections predict that global concentrations of CO2 will reach 450 ppm by 20209.  However, these predictions ignore the possibility that the Earth will release large amounts of greenhouse gasses suddenly. Possible sources include methane hydrates on continental shelves, and methane stored in permafrost that is already starting to melt. If only 10% of the methane from the modern clathrate reservoir (which has ~5000 Pg of C) were to be released to the atmosphere in a few years, the radiative forcing would be equivalent to a 10-fold increase in atmospheric CO2 concentrations10.

Resolution: To avoid the risk of an ice-free world that exists at atmospheric CO2 concentrations above 350 ppm, the Citizen’s Climate Lobby advocates for legislation that does the following:

1. Reduces our fossil CO2 emissions to 0.
2. Reduces those emissions in a timely fashion. 
3. Incentivizes the production of renewable energy.
4. Incentivizes public participation in eliminating CO2 emissions.
5. Removes CO2 from the atmosphere and sequesters it safely.

References:

1.     Forster, P., et al. 2007: Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. P. 135
2.    Jansen, E., et al., 2007: Palaeoclimate. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. p. 447
3.     Hansen, J., Mki. Sato, P. Kharecha, D. Beerling, R. Berner, V. Masson-Delmotte, M. Pagani, M. Raymo, D.L. Royer, and J.C. Zachos, 2008: Target atmospheric CO2: Where should humanity aim? Open Atmos. Sci. J., 2, 217-231,

4.     E. Lynn Usery, 2007: Modeling Sea-Level Rise Effects on Population using Global Elevation and Land-Cover Data. From United States Geological Survey Website. http://cegis.usgs.gov/pdf/ aag-2007-508.pdf. Accessed 7/17/09.
5.     Ice shelf bridge on Antarctica collapses. MSNBC, from the Associated Press. Last updated: 4/3/09. http://www.msnbc.msn.com/id/30036283/. Accessed 7/17/09.
6.     Section of Antarctic Ice Shelf Breaks Off. Troubled Times, from the Associated Press. 4/17/98. http://www.zetatalk.com/theword/tword14o.htm. Accessed 7/17/09.

7.     Luthcke, S.B., H.J. Zwally, W. Abdalati, D. D. Rowlands, R. D. Ray, R. S. Nerem, F. G. Lemoine, J. J. McCarthy, D. S. Chinn, 2006: Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations.  Science (314), p. 1286-1289

8.     Poore, R. Z., R.S. Williams Jr., C. Tracey, 2000: Sea Level and Climate. From United States Geological Survey Website. http://pubs.usgs.gov/fs/fs2-00/. Last Accessed 7/17/09.
9.     Sokolov, A.P. P.H. Stone, C.E. Forest R. Prinn, M.C. Sarofim, M. Webster S. Paltsev, C.A. Schlosser, D. Kicklighter, S. Dutkiewicz, J. Reilly, C. Wang, B Felzer, J.M. Melillo, H.D. Jacoby, 2009: Probabilistic forecast for 21st century climate based on uncertainties in emissions (without policy) and climate parameters. J. of Climate.
10.     Petrenko, V. V., A. M. Smith, E. J. Brook, D. Lowe, K. Riedel, G. Brailsford, Q. Hua, H. Schaefer, N. Reeh, R. F. Weiss, D. Etheridge, J. P. Severinghaus, 2009: 14CH4 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources. Science (324), p. 506-508.