Posted on 03/27/2010 5:44:28 AM PDT by Ernest_at_the_Beach
THE ESTIMATION OF HISTORICAL CO2 TRAJECTORIES IS INDETERMINATE: COMMENT ON “A NEW LOOK AT ATMOSPHERIC CARBON DIOXIDE”
Craig Loehle, PhD, National Council for Air and Stream Improvement, Inc., Naperville, Illinois
Atmospheric Environment doi:10.1016/j.atmosenv.2010.02.029
Figure 2: Projected exponential, quadratic, and saturating models compared to IPCC scenario values. Over the calibration period 1958-2009 the 3 models and data are indistinguishable from each other, but then diverge.
Abstract
A paper by Hofmann et al. (2009, this journal) is critiqued. It is shown that their exponential model for characterizing CO2 trajectories for historical data is not estimated properly. An exponential model is properly estimated and is shown to fit over the entire 51 year period of available data. Further, the entire problem of estimating models for the CO2 historical data is shown to be ill-posed because alternate model forms fit the data equally well. To illustrate this point the past 51 years of CO2 data were analyzed using three different time-dependent models that capture the historical pattern of CO2 increase. All three fit with R2 > 0.98, are visually indistinguishable when overlaid, and match each other during the calibration period with R2 > 0.999. Projecting the models forward to 2100, the exponential model comes quite close to the Intergovernmental Panel on Climate Change (IPCC) best estimate of 836 ppmv. The other two models project values far below the IPCC low estimates. The problem of characterizing historical CO2 levels is thus indeterminate, because multiple models fit the data equally well but forecast very different future trajectories.
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Discussion
Three equally plausible models give very different expectations for future CO2 trajectories under business as usual assumptions. No inference is possible at this time as to which model is “right” because the three models are virtually identical in the CO2 data
period (Fig. 2) and the understanding of the carbon cycle in this context is not precise enough. The factors governing CO2 in the atmosphere may or may not lend themselves to long-term predictability even if they were understood better. It is clear, however, that simply using an exponential model because it fits the data represents an incomplete analysis, as other models fit equally well. The IPCC “best estimate” of 836 ppmv in 2100, which is equivalent to extrapolation of the exponential model, is indeterminateand could just as easily be 569.8 or 672.5 ppmv (or even 747.7 ppmv by Hofmann et al., 2009), as found using equally likely models that fit the same data. These much lower “best estimate” values affect the IPCC “high” estimate, which is derived from the base estimate exponential model by adding a growth term (based on higher economic growth rates and other factors). Because projections of future climate depend on future CO2 (and other greenhouse gas) levels, a future value below the IPCC low estimate would preclude the more extreme climate change forecasts made by the IPCC.
PDF of the entire paper is available at: http://www.ncasi.org/publications/Detail.aspx?id=3282
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. Discussion
Three equally plausible models give very different expectations for future CO2 trajectories under business as usual assumptions. No inference is possible at this time as to which model is “right” because the three models are virtually identical in the CO2 data period (Fig. 2) and the understanding of the carbon cycle in this context is not precise enough. The factors governing CO2 in the atmosphere may or may not lend themselves to long-term predictability even if they were understood better. It is clear, however, that simply using an exponential model because it fits the data represents an incomplete analysis, as other models fit equally well. The IPCC “best estimate” of 836 ppmv in 2100, which is equivalent to extrapolation of the exponential model, is indeter- minate and could just as easily be 569.8 or 672.5 ppmv (or even 747.7 ppmv by Hofmann et al., 2009), as found using equally likely models that fit the same data. These much lower “best estimate” values affect the IPCC “high” estimate, which is derived from the base estimate exponential model by adding a growth term (based on higher economic growth rates and other factors). Because projections of future climate depend on future CO2 (and other greenhouse gas) levels, a future value below the IPCC low estimate would preclude the more extreme climate change forecasts made by the IPCC.
One more Time we see the IPCC at work ....
Much discussion in the comments ....look for Marvin who dismisses the paper....but I believe he is an AGW supporter.
Probably would not give the results they wanted....
Web-info about CO2 and the "Greenhouse Effect" Doom; by Tom V. Segalstad
See post #5.
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DOWNLOAD my ESEF Vol. 1 Chapter (PDF approx. 200 kbytes):
Segalstad, T. V. 1996: The distribution of CO2 between atmosphere, hydrosphere, and lithosphere; minimal influence from anthropogenic CO2 on the global "Greenhouse Effect". In Emsley, J. (Ed.): The Global Warming Debate. The Report of the European Science and Environment Forum. Bourne Press Ltd., Bournemouth, Dorset, U.K. (ISBN 0952773406), pp. 41-50.
DOWNLOAD my ESEF Vol 2 Chapter (PDF approx. 500 kbytes):
Segalstad, T. V. 1998: Carbon cycle modelling and the residence time of natural and anthropogenic atmospheric CO2: on the construction of the "Greenhouse Effect Global Warming" dogma. In Bate, R. (Ed.): Global warming: the continuing debate. ESEF, Cambridge, U.K. (ISBN 0952773422), pp. 184-219.
Great articles across the post. A key question remains. Will the IPCC finally break down and admit they have no conclusive evidence that CO2 causes any appreciable level of global warming. I don’t see it happening. To many powerful banks and industries and private investors involved in this scam of the century to just lay down and die a quiet death.
It still amazes me how they casually toss about curve-fitting as a reliable scientific method for prediction. Try that in the stock market.
I wonder why they include 600,000 years of ice core data on CO2 but omit the current atmospheric CO2 level at the site where those ice cores were extracted.
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