Saturday
Apr132013
by 
Bishop Hill
Bishop Hill DIY integrated assessment model
Apr 13, 2013 Climate: WG2 For anyone who has ever longed to write their own economic assessment of climate change, now you can!
Richard Tol has set up an integrated assessment model in Excel, which can be downloaded here.
Reader Comments (54)
There were four bugs. They have now been fixed.
Richard Tol,
Thank you. I will now return to my homework :)
Richard Tol--
Did you miss my comment above regarding problems in the first two of your Excel files? I append part of that comment here to save looking for it:
Comments on the first two Excel files:
MLIAM01_data—carbon dioxide sheet
1) Column A runs backward from 2006 to 13.3 AD (quite precise, that!) then repeats only going backward from 1996 to 1942. Perhaps the reason for this will come clear in time, but meanwhile, as Alexander Woolcott remarked about the famous Time Magazine style, “Backward ran sentences until reeled the mind”.
2) What you call “temperature” is actually temperature anomaly. Might be helpful to state that it was 1961-1990 as I determined by doing a running 30-year average until it was close to zero.
MLIAM01_data—carbon dioxide sheet
1) Column C appears to be another anomaly, only this time a 29-year base period (1850-1878).
MLIAM01_model
1) Plotting your modeled CO2 against observed, the model is a very consistent 10-12 ppm high. See attached Dropbox Excel file. For a model with 5 compartments and 8 free parameters, this appears downright careless. Need I mention von Neumann’s dictum about the elephant’s trunk? Also, why are you starting at 1976, when Mauna Loa started in the 1950s?
https://dl.dropboxusercontent.com/u/75831381/MLIAM01_model--law.xlsx
@Lance
If you plot as X-Y, direction of time is automatically set right.
Greenhouse accounting is quite incomplete, with CO2 from fossil fuels only. Calibrating an incomplete model on part data will not do any good.