cc: sres@iiasa.ac.at date: Thu, 15 Oct 1998 18:05:48 +0200 from: Arnulf GRUBLER subject: Re: Comments on SRES scenarios to: Bill Hare Dear Bill A few answers to your questions. 1. As stated in the minutes of both the Washington and Laxenburg SRES meetings the A1 marker is represented by the "balanced" technology variant. Oil/Gas, clean coal, as well as "bio-nuc" are alternative equally plausible scenario variants in which technological change and resource accessabiliy go in alternative mutually exclusive directions. Indeed the clean coal and oil/gas intensive variants have much higher emissions than the "balanced" scenario A1, and the non-fossil-intensive scenario have lower emissions. While the final report will preserve this scenario bifurcation, the entire writing team felt it to be a too complex story to be put on the website for a single scenario. Hence, the Washington agreement to develop a "balanced" scenario (progress in clean coal, oil/gas, renewables as well as nuclear). In terms of emissions this results in moderating tendencies. Progress in oil/gas means no C-intensive large-scale synfuels are required. Progress in clean-coal mean that coal can be used without too adverse impacts on local and regional environments. Progress in nuclear and renewables alike result in a regionally/global diversified fuel mix, not requiring overreliance on coal. 2. Variant A1 4 ("bionuc") is entirely plausible because there resource availability is precisely NOT high as in the two fossil-rich alternatives (cf. the storyline text on this). Instead, conventional oil and gas are scarce, clean coal technologies do not get developed, which induces technological change into a post-fossil technological direction. Some might say this is only possible with policies. I would answer that we have left a coal-based steam economy behind us entirely without policy intervention. Hence, I consider the "bionuc" scenario as plausible as the fossil alternatives or the "balanced" marker scenario. 3. I cannot comment in detail on the low sulfur emissions in A2 (perhaps Alex would like to answer you in detail). By looking at the fuel mix some regions go out of fossils which means low sulfur emissions. Other regions stay in coal or fossils which would mean high sulfur emissions. However, A2 is a highly populated world. Food security therefore will be on the top policy agenda. Any environmental impacts like acidification that threatens food security is unlikely to pass unchecked in a 16 billion world. So to me low sulfur emissions appear entirely plausible and consistent. 4. Nuclear in B1. In fact Bert forcefully argued at our Beijing meeting that he and his model are not prepared to forecast nuclear. In fact he uses a generic zero-carbon electricity "backstop" in modeling the B1 marker scenario. This could include anything from wind, PVs, geothermal, nuclear, etc. So your comment points indeed to a reporting problem. Any specific suggestions are welcome. 5. Nuclear in B2. Given that B2 assumes more modest dynamics in both technology (compared to A1) and social and lifestyle patterns (compared to B1) means that: 1. demand is higher than in B1 2. technological change is less radical than in A1 (and B1). This translates into market growth largely for established technologies which means clean coal, and (wether you like it or not) nuclear. It might not seem intuitive, but in all the scenario literature I am aware of, "muddling through" scenarios have generally always the highest nuclear shares. This simply because resource depletion sets in earlier and renewables and other alternative sources are not improving fast enough that they can compete with coal and nuclear. With modest dynamics the choice is therefore largely between coal and nuclear. Evidently this can play out differently in various regions and that's what the scenarios actually assumes. Regions with high population and energy densities and no indiginous coal (all the countries outside US, Canada, Australia, South Africa, Russia, China and India) tilt rather towards nuclear, and the coal-rich regions rather tilt towards coal based technologies. The emphasis on regional self-reliance and environmental protection precludes gigantomanic coal trade in the B2 scenario. So there is not much choice left. 6. You may recall, the repeated staements of the SRES writing team in its discussion and in its minutes, that in view of an unpredictable future we consider a priori all scenarios as equally likely. We may have different personal opinions. But there is no scientific way of assigning relative probabilities to a whole complex of interacting developments that characterizes one particular scenario. Therefore it is in my viewpoint not productive to always try to give probability rankings to the scenarios. If you feel that B1 does not look likely from today's perspective, try to imagine yourself in the year 2020. Try to imagine a scenario with an FCCC and COP-4 back in 1980! You would have been hard pressed even in Greenpeace to suggest this as a "most likely" scenario. Still it all happened. So who can decide? Perhaps we all will think in 10 years B1 as most likely, or A1, or B2. The useful answer is not to decide now, but to explore the implications of alternative futures. That's what SRES is all about and that's what we want to recommend to the scenario users: stay away from the use of a single scenario! 7. I conclude with a personal note. As you are member of the writing team I feel it would have been more productive if you could have provided the Greenpeace view in our meetings in Washington, Laxenburg, and more recently in Beijing. If you are too busy, nominate a colleague to substitute you. But I find it a bit funny to conduct the very function of a scenario writing team only in batch, electronic and fax mode. To me it looks a bit unfair to try to be at the same time within and outside the process and to interpret work burden sharing in a very one sided way. We have to respond to your questions, but you are never present to answer some of ours too. Yours truly, Arnulf. Arnulf GRUBLER International Institute for | Email: gruebler@iiasa.ac.at Applied Systems Analysis | Phone: +43 2236 807 470 A-2361 Laxenburg, Austria | Fax: +43 2236 71313