Seriously?! The Bern model is used for studying the relationship between anthropogenic carbon emissions and atmospheric CO2. It is not the assumption all observed increases in CO2 is anthro.
Try again.
I think you will indeed read this description of the model in some of the online definitions that are attempting to make a short statement or explanation. From what I have learned this is an inaccurate explanation of the Bern Model, an early model going back to at least 1994.
I took the time to look it up, the actual equation that is. Sorry I'm not good at typing equations without special scientific software so I won't attempt. What I concluded after examining the equation for the Bern Model is that it's E(t) term is defined such that one attributes all of the increase in CO2 to anthropomorphic CO2 since a baseline concentration was reached in the recent pre-industrial era . This is an assumption not inherent in the model, but in the way it is being applied and interpreted. No terms are present to take into account additional sources which also add to the baseline, i.e., the constant pre-industiral value. These additional terms could be added to the model however.
The Bern model can be used to model the rates of disappearance of a pulse of CO2 by partitioning the pulse. In the common case, the partitioning is between various sinks which have been assigned time constants. In one application, all of the increase of CO2 is assumed to be instantaneously added to the atmosphere. Then one calculates how much of the additional CO2 from the pulse is left after time "t" has elapsed. (This is valid for the case where the pulse addition is over a time period short compared to the time constants of the sinks.) If the time constants are wrong than the result is wrong.
It is obvious to me now why the Bern model fit the scenario of the Bombtest era C-14 emission. And why Pettersson chose to use the Bern model to model disappearance of bomb C-14 (I asume he used the IPCC's time constants) and then compare the model's prediction of the disappearance of the C-14 pulse to the actual disappearance that could be very accurately followed by C-14 counting.
The Bern Model is wrong of course, like all the other present day climate models that seek to make valid predictions about the distant future. Petterssons analysis shows Bern to not be merely wrong, but wrong in the extreme! Bern was an early attempt to simplify a very complex problem. Nothing wrong with that, but now it is time to jettison it and move on to more realistic, less wrong models. The IPCC should not use this model any longer. Obviously its predictions of residence time for CO2 in the atmosphere are wrong and its assumption that all the additional CO2 in the atmosphere since the beginning of the industrial age is anthropomorphic in origin is way off target, as are the current IPCC time constants for the various CO2 sinks. Pettersson, with his elegant analysis of the C-14 counting data, shows us that.
Furthermore i could not find where the model takes into account any possible concentration dependence of the sinking reactions. It looks to me like it is assumed that all of these sinking paths are treated as though they were zeroth order, i.e. have no concentration dependence. I seriously doubt this is the case for all the reactions.
Another thing i've noticed in my recent exploration of the climate fiasco is that it is very common to see obviously imprecise experimental values expressed with three and four significant figures. To scientists, this is comical and reminds me of that anecdote about Dulong (of DuLong and Petit) who gave experimental results in a 19th century discussion of specific heat capacity to seven decimal places. When questioned whether this was warranted, he responded that he saw no reason that if the first few decimal places were wrong why the others could not all be correct! Of course that was before the development of statistics and the concept of significant figures.
