date: 15 Dec 1997 14:14:53 -0700 from: Tom Wigley subject: MAGICC CH4 results to: Mike Hulme , Sarah Raper Dear Mike and Sarah, I have revised some of the code in MAGICC to improve the CH4 results. There were two glitches. The first was in the initialization of ECH4 to give a balanced 1990 budget. By a fluke, this didn't affect any results because of the specific choice of parameters I had. The second was in the calculated CH4 concentrations. I had tuned the model to match an early set of IPCC results, and these are all somewhat lower than the published values. This required tedious trial and error retuning of the methane model parameters, which I have now done. The new parameters are better, because a single set works for all IS92 scenarios---previously different parameters were required for A,B,E,F versus C,D. With regard to the distributed code, we have to make a choice whether to stick to the old code (which agrees with Ch. 6, but not Ch. 2) or the new code (which agrees with Ch.2). I'm inclined to go with Ch. 2 consistency and the new code. What do you think? I have more things to clean up in MAGICC, so I won't send the new code (for MAG.FOR) until I've done these. In the meantime, here are the header notes from the new code to fill in some details. Cheers, Tom C MAG.FOR C C Revision history: C C 971214 * METHANE PARAMS CHANGED TO GIVE BETTER SIMULATIONS OF IPCC C SAR RESULTS AS PER TABLE 2.5a IN SAR. 1990 TAU SET TO 9.1: C PREVIOUSLY 9.08. IF DELTAU IS SET AT +/- 0.8 (CF. IPCC C RANGE IS +/- 1.8), WHICH MAKES HIGH TAU = 9.9, AND C ITAUMETH IS SET AT 3 (WHICH GIVES UPPER BOUND CONCS FOR C THE ORIGINAL OSBORN & WIGLEY MODEL) THEN OUTPUT AGREES C EXTREMELY WELL PRATHER'S IPCC RESULTS. THIS IMPLIES THAT C PRATHER'S MODEL MUST HAVE A HIGH TAU AND/OR A TAU C SENSITIVITY THAT DIFFERS SUBSTANTIALLY FROM THE CENTRAL C OSBORN & WIGLEY VALUE. C C COMPARISON OF PRATHER IPCC (CH.2) AND CURRENT MODEL (IPCC C VALUES HAVE 17ppbv ADDED BECAUSE THE IPCC VALUE IN 1990 C IS 17ppbv BELOW THE VALUE USED HERE - THIS MAKES THE C COMPARISON HERE MORE TRUE TO A FORCING COMPARISON). C C RESULTS BELOW ARE IN ORDER : OLD VERSION (I.E., NUMBER C USED IN CH.6 OF SAR); NEW VERSION; IPCC (CH.2). NOTE THAT C THE MAIN REASON WHY THE CH.6 VALUES ARE SO DIFFERENT FROM C THE IPCC CH.2 VALUES IS THAT THE PRESENT MODEL WAS TUNED C TO AN EARLY VERSION OF PRATHER'S RESULTS. C C SCENARIO 2050 CONCS 2100 CONCS C IS92A,B 2764 2833 2810 3467 3611 3633 C IS92C 2148 2252 2241 1997 2088 2086 C IS92D 2157 2259 2247 2056 2161 2163 C IS92E 2972 3056 3031 4109 4301 4308 C IS92F 2996 3081 3055 4492 4711 4686 C CH.6 NEW CH.2 CH.6 NEW CH.2 C C C THE TABLE BELOW COMPARES NEW WITH OLD (IPCC CH.6) T & MSL C CHANGES OVER 1990-2100. C C SCENARIO SIMULATION OLD DT NEW DT OLD DMSL NEW DMSL C IS92C LOW 0.8622 0.8747 12.63 12.86 C IS92A MID 2.0308 3.0504 48.94 49.28 C IS92E HIGH 3.5260 3.5601 94.75 95.21 C C 971213 * ERROR IN CORRECTING INPUT METHANE EMISSIONS FOR 1990 C IMBALANCE CORRECTED (SUBSTANTIAL REVISION). THIS WAS FIRST C CORRECTED IN OPT.FOR ON 961024. IT MAKES NO DIFFERENCE C TO THE OUTPUT: OUTPUT IS ONLY AFFECTED FOR NON-ZERO DELTAU. C IN PREVIOUS VERSION OF THE CODE, DELTAU WAS SET TO ZERO. C 971123 * TWO ERRORS FOUND C (1) S90IND=0.0 INPUT CAUSES CRASH. CORRECTED TEMPORARILY C BY RESETTING S90IND=-0.0001 C (2) EQUIVCO2 MISCALCULATED (USED IF NOUT=4 ONLY). C CODE CORRECTED. TABLE 1: FOSSIL CO2 EMISSIONS DATA USED IN CARBON CYCLE CALCULATIONS. MODIFIED IS92a KYOTO EXTENDED KYOTO YEAR ANNEX I NON-I BUNKER GLOBAL ANNEX I GLOBAL ANNEX I GLOBAL 1990 3.907 2.088 0.114 6.109 3.907 6.109 3.907 6.109 1991 3.791 2.270 0.117 6.178 3.791 6.178 3.791 6.178 1992 3.708 2.240 0.136 6.084 3.708 6.084 3.708 6.084 1993 3.631 2.293 0.129 6.053 3.631 6.053 3.631 6.053 1994 3.676 2.484 0.132 6.292 3.676 6.292 3.676 6.292 1995 3.801 2.567 0.138 6.506 3.801 6.506 3.801 6.506 1996 3.869 2.662 0.138 6.669 3.869 6.669 3.869 6.669 1997 3.920 2.758 0.138 6.816 3.920 6.816 3.920 6.816 1998 3.971 2.854 0.138 6.963 3.971 6.963 3.971 6.963 1999 4.022 2.950 0.138 7.110 4.022 7.110 4.022 7.110 2000 4.073 3.046 0.138 7.257 4.073 7.257 4.073 7.257 2001 4.110 3.177 0.138 7.425 4.029 7.344 4.029 7.344 2002 4.147 3.308 0.138 7.593 3.985 7.431 3.985 7.431 2003 4.183 3.440 0.138 7.761 3.941 7.519 3.941 7.519 2004 4.220 3.571 0.138 7.929 3.897 7.606 3.897 7.606 2005 4.257 3.702 0.138 8.097 3.853 7.693 3.853 7.693 2006 4.294 3.814 0.138 8.246 3.810 7.762 3.810 7.762 2007 4.331 3.924 0.138 8.393 3.766 7.828 3.766 7.828 2008 4.367 4.036 0.138 8.541 3.722 7.896 3.722 7.896 2009 4.404 4.146 0.138 8.688 3.678 7.962 3.678 7.962 2010 4.441 4.258 0.138 8.837 3.634 8.030 3.634 8.030 2011 4.478 4.370 0.138 8.986 3.634 8.142 3.598 8.106 2012 4.515 4.480 0.138 9.133 3.634 8.252 3.562 8.180 2013 4.551 4.592 0.138 9.281 3.634 8.364 3.526 8.256 2014 4.588 4.702 0.138 9.428 3.634 8.474 3.491 8.331 2015 4.625 4.814 0.138 9.577 3.634 8.586 3.456 8.408 2016 4.662 4.945 0.138 9.745 3.634 8.717 3.421 8.504 2017 4.699 5.077 0.138 9.914 3.634 8.849 3.387 8.602 2018 4.735 5.207 0.138 10.080 3.634 8.979 3.353 8.698 2019 4.772 5.339 0.138 10.249 3.634 9.111 3.320 8.797 2020 4.809 5.470 0.138 10.417 3.634 9.242 3.287 8.895 2021 4.846 5.601 0.138 10.585 3.634 9.373 3.254 8.993 2022 4.883 5.733 0.138 10.754 3.634 9.505 3.221 9.092 2023 4.919 5.863 0.138 10.920 3.634 9.635 3.189 9.190 2024 4.956 5.995 0.138 11.089 3.634 9.767 3.157 9.290 2025 4.993 6.126 0.138 11.257 3.634 9.898 3.125 9.389 2026 4.993 6.230 0.138 11.361 3.634 10.002 3.094 9.462 2027 4.993 6.334 0.138 11.465 3.634 10.106 3.063 9.535 2028 4.993 6.438 0.138 11.569 3.634 10.210 3.033 9.609 2029 4.993 6.542 0.138 11.673 3.634 10.314 3.002 9.682 2030 4.993 6.646 0.138 11.777 3.634 10.418 2.972 9.756 2031 4.993 6.750 0.138 11.881 3.634 10.522 2.943 9.831 2032 4.993 6.854 0.138 11.985 3.634 10.626 2.913 9.905 2033 4.993 6.958 0.138 12.089 3.634 10.730 2.884 9.980 2034 4.993 7.062 0.138 12.193 3.634 10.834 2.855 10.055 2035 4.993 7.166 0.138 12.297 3.634 10.938 2.827 10.131 2036 4.993 7.270 0.138 12.401 3.634 11.042 2.798 10.206 2037 4.993 7.374 0.138 12.505 3.634 11.146 2.770 10.282 2038 4.993 7.478 0.138 12.609 3.634 11.250 2.743 10.359 2039 4.993 7.582 0.138 12.713 3.634 11.354 2.715 10.435 2040 4.993 7.686 0.138 12.817 3.634 11.458 2.688 10.512 2041 4.993 7.790 0.138 12.921 3.634 11.562 2.661 10.589 2042 4.993 7.894 0.138 13.025 3.634 11.666 2.635 10.667 2043 4.993 7.998 0.138 13.129 3.634 11.770 2.608 10.744 2044 4.993 8.102 0.138 13.233 3.634 11.874 2.582 10.822 2045 4.993 8.206 0.138 13.337 3.634 11.978 2.556 10.900 2046 4.993 8.310 0.138 13.441 3.634 12.082 2.531 10.979 2047 4.993 8.414 0.138 13.545 3.634 12.186 2.505 11.057 2048 4.993 8.518 0.138 13.649 3.634 12.290 2.480 11.136 2049 4.993 8.622 0.138 13.753 3.634 12.394 2.456 11.216 2050 4.993 8.726 0.138 13.857 3.634 12.498 2.431 11.295 2051 5.011 8.806 0.138 13.955 3.634 12.578 2.407 11.351 2052 5.028 8.886 0.138 14.052 3.634 12.658 2.383 11.407 2053 5.046 8.968 0.138 14.152 3.634 12.740 2.359 11.465 2054 5.063 9.048 0.138 14.249 3.634 12.820 2.335 11.521 2055 5.081 9.128 0.138 14.347 3.634 12.900 2.312 11.578 2056 5.099 9.208 0.138 14.445 3.634 12.980 2.289 11.635 2057 5.116 9.289 0.138 14.543 3.634 13.061 2.266 11.693 2058 5.134 9.369 0.138 14.641 3.634 13.141 2.243 11.750 2059 5.151 9.450 0.138 14.739 3.634 13.222 2.221 11.809 2060 5.169 9.530 0.138 14.837 3.634 13.302 2.199 11.867 2061 5.187 9.610 0.138 14.935 3.634 13.382 2.177 11.925 2062 5.204 9.691 0.138 15.033 3.634 13.463 2.155 11.984 2063 5.222 9.771 0.138 15.131 3.634 13.543 2.133 12.042 2064 5.239 9.852 0.138 15.229 3.634 13.624 2.112 12.102 2065 5.257 9.932 0.138 15.327 3.634 13.704 2.091 12.161 2066 5.275 10.012 0.138 15.425 3.634 13.784 2.070 12.220 2067 5.292 10.093 0.138 15.523 3.634 13.865 2.049 12.280 2068 5.310 10.173 0.138 15.621 3.634 13.945 2.029 12.340 2069 5.327 10.254 0.138 15.719 3.634 14.026 2.008 12.400 2070 5.345 10.334 0.138 15.817 3.634 14.106 1.988 12.460 2071 5.363 10.415 0.138 15.916 3.634 14.187 1.968 12.521 2072 5.380 10.495 0.138 16.013 3.634 14.267 1.949 12.582 2073 5.398 10.575 0.138 16.111 3.634 14.347 1.929 12.642 2074 5.415 10.655 0.138 16.208 3.634 14.427 1.910 12.703 2075 5.433 10.736 0.138 16.307 3.634 14.508 1.891 12.765 2076 5.451 10.888 0.138 16.477 3.634 14.660 1.872 12.898 2077 5.468 11.040 0.138 16.646 3.634 14.812 1.853 13.031 2078 5.486 11.194 0.138 16.818 3.634 14.966 1.835 13.167 2079 5.503 11.346 0.138 16.987 3.634 15.118 1.816 13.300 2080 5.521 11.498 0.138 17.157 3.634 15.270 1.798 13.434 2081 5.539 11.650 0.138 17.327 3.634 15.422 1.780 13.568 2082 5.556 11.803 0.138 17.497 3.634 15.575 1.762 13.703 2083 5.574 11.955 0.138 17.667 3.634 15.727 1.745 13.838 2084 5.591 12.108 0.138 17.837 3.634 15.880 1.727 13.973 2085 5.609 12.260 0.138 18.007 3.634 16.032 1.710 14.108 2086 5.627 12.412 0.138 18.177 3.634 16.184 1.693 14.243 2087 5.644 12.565 0.138 18.347 3.634 16.337 1.676 14.379 2088 5.662 12.717 0.138 18.517 3.634 16.489 1.659 14.514 2089 5.679 12.870 0.138 18.687 3.634 16.642 1.643 14.651 2090 5.697 13.022 0.138 18.857 3.634 16.794 1.626 14.786 2091 5.715 13.174 0.138 19.027 3.634 16.946 1.610 14.922 2092 5.732 13.327 0.138 19.197 3.634 17.099 1.594 15.059 2093 5.750 13.479 0.138 19.367 3.634 17.251 1.578 15.195 2094 5.767 13.632 0.138 19.537 3.634 17.404 1.562 15.332 2095 5.785 13.784 0.138 19.707 3.634 17.556 1.547 15.469 2096 5.803 13.937 0.138 19.878 3.634 17.709 1.531 15.606 2097 5.820 14.089 0.138 20.047 3.634 17.861 1.516 15.743 2098 5.838 14.241 0.138 20.217 3.634 18.013 1.501 15.880 2099 5.855 14.393 0.138 20.386 3.634 18.165 1.486 16.017 2100 5.873 14.546 0.138 20.557 3.634 18.318 1.471 16.155