“Roger: Thought you would appreciate this.. Joe Romm’s guest blogger, Elizabeth Grossman, writes (without a word of protest from Joe):

“The underestimation of greenhouse emissions occurred, Field said, because the IPCC failed to include in its scenarios the rapid increase in carbon dioxide from Asia’s coal-reliant industrial expansion between 2000 and 2007.
“‘We were too optimistic,’ Field said. ‘There was no decrease in emissions from developed countries and the sharpest increases and overall intensity came from China and India that rely heavily on coal.’
“‘It was assumed that coal would become less important,’ says Ken Caldeira, also of the Carnegie Institution. What happened, however, is that China and India developed rapidly while rising oil prices pushed wealthy nations to use more coal, which is more CO2 intensive in its emissions. Scientists at NASA’s Goddard Space Science Institute concur that the past five years’ sharp increase in atmospheric CO2 is attributable to the steep rise in global coal use, pushed upward by accelerated Asian economic and industrial development.
“‘IPCC scenarios assume an increase in energy efficiency during this period,’ Caldeira says. But that didn’t happen. ‘Efficiency flattened out,’ he says.”

Can it be? That sounds suspiciously like an endorsement of your Nature paper on assumptions about spontaneous decarbonization!”

Just so that you can be completely accurate in the future, we are in 2008 at an estimated 9 GtC emissions from fossil fuels (i.e., not including land use). See the ppt here:

http://www.globalcarbonproject.org/ activities/ AcceleratingAtmosphericCO2.htm

Starting at 9 GtC rather than 8 GtC means instead of BAU being 28 GtC in 2050 (as you have written) then this value is 31 GtC (using your 3.0% rate of increase per year, at 3.3% it is 35 GtC). So you should probably correct this error in the post above and then also tell us where these 3 extra wedges will come from.

My suggestion is to reduce the future baseline to 2.8%, and this will get you 3 free wedges in 2050 under your other various assumptions.

Readers should have a look at Ted Nordhaus’s comment, which is a great summary of the debate:

http://climateprogress.org/2008/04/23/is-450-ppm-politically-possible-part-25-the-fuzzy-math-of-the-stabilization-wedges/#comment-11468

I didn’t change the size of the wedge — I explained why a larger wedge falls out of the analysis logically. I ALWAYS assumed a 4-decade wedge — read my original post.

I never “proposed” a baseline rate of 3.3% for the next four decades! I just noted that was what some people have reported has happened to date.

I haven’t “Assumed that the proportion of future primary energy consumption from coal will more than double” (!) over the next 4 decades. I merely pointed out that this is an inevitable consequence of YOUR assumption that CO2 emissions will continue at their anomalously high rate of 3% per year (or 3.3%) per decade, compared to the rate of the last 3 decades, 1.5% per year.

What I don’t understand is why you don’t realize that if my wedges are delusional, your innovation strategy is doubly so. That seems so obvious. But I’ll deal with it in my next post to spell it out.

You promised a list of technologies that if deployed in the coming decades would lead to net global emissions of 4 GtC. When it was pointed out that your math did not add up you played with your assumptions as follows:

1) Increased the size of your wedge from 1.0 GtC 50 years from now to 1.8 GtC 42 years from now. The shorter time frame means that you need less wedges.

2) Decreased the baseline growth rate that you had first proposed by about 10%. (Recall that you suggested 3.3%, not me.)

3) Assumed that the proportion of future primary energy consumption from coal will more than double (!) over the next 4 decades, representing a 6-fold increase in coal consumption.

I may have missed a few new assumptions. So what you have shown is that a list of practically impossible steps (I know we didn’t discuss this) can be shown to be sufficient to the task of reducing emissions if and only if we accept a wide range of assumptions put in place/modified after the analysis was challenged.

Look, I understand that you believe that it would be feasible for each of your proposed wedges to be implemented with 100% success on the time scale that you propose, and that you further believe that the assumptions required to make your math work out will pan out. But I’d ask that you respect that I doubt your optimism on wedge feasibility and also on the rosy scenarios. On this reasonable people can disagree. So lets agree to disagree.

But I hope that you will understand that my view of the importance of innovation 9as a complement, not replacement) lies in exactly these doubts of the likelihood of success of your proposed strategy. You have said that if we don’t get started by 2012 we’re in deep trouble. Well, that isn’t too far away, and when global emissions are around 10 GtC near 2012, I’d expect that you’ll find an innovation-based approach a lot more appealing. We shall see.

Hmmm. I thought the point of cellulosic biofuels would be to not use cropland, but rather to use land that is not suited to crop production, or to use extra woody and non woody biomass from forests, crop residues, yard waste, etc. In fact, I thought there were technologies being discussed to make biofuels from garbage. this seems like the second post this week that leaves out non-crop plants. What’s up with that?

First, you don’t have to “grant” me supersize wedges. That’s just the way the numbers work out. But I’m glad you accept them.

Second — Your phrase “the full 50 years” is a complete non sequitur. How many times do I have to repeat this point? I’m not defending Princeton’s flawed approach. Quite the reverse. I’m proposing my own approach using their framework. There never was anything magic in their 50 years. I have repeatedly said we need to do this faster than 50 years. You can keep attacking Princeton’s approach all you want if it makes you happy, but it is quite irrelevant to my proposed solution.

Third, let’s not claim we know the carbon emission from 2000 to 2006 so precisely. I think 3% is a pretty damn conservative assumption, given that it is double the rate from 1970 to 2000.

Fourth, finally, I don’t “get” 6 super-sized wedges. I get more than 10. Your assumptions are off. In your 3% growth scenario, probably all of the extra tons (above the 1.5% scenario) are coal.

To elaborate, You can’t take EIA’s fraction of coal today and use it in 2050 — the whole point is that the re-carbonization is occurring because the world is building a disproportionate amount of coal. Thus I would say probably 100% of the extra tons in 2050 are coal. By extra tons, I mean the ones beyond the 15 GtC that we would otherwise have if we stayed at the 1.5% carbon growth of the previous three decades that Socolow had assumed in their BAU. So in the heavily carbonized scenario you are positing, probably some 18 GtC are coal.

And 10 of my wedges are zero-carbon power generation (or generation avoidance), so that works out fine.

As for the double counting claim — This comment is a real non sequitur. Who cares if Pacala’s and Socolow’s more efficient coal plants wedge is double counting? I don’t use that wedge. I only use a few of their wedges. I thought it was clear that I’m only using the framework of their otherwise flawed analysis.

I haven’t made any rosy assumptions. One would have to say that assuming emissions growth of 3.3% per year for the next 42 years is pretty unrosy, though. In any case, you assert “I’ve proposed 12.5 TW for 2050″ but you haven’t shown any analysis to support the 12.5 claim, nor have you shown any analysis why it wouldn’t be adequate.

I didn’t realize this was a game to you. For me, avoiding catastrophic global warming is the most serious thing we could possibly be doing. My math clearly works out. I guess it was overly optimistic of me to assume you would concede my math is right, but at least my readers know that my 14 to 16 wedges are the solution I promised.

You have NEVER proposed your own specific solution , however, so I think people should take your comments with a large grain of salt. If you won’t do that, I’m not sure why I should keep responding to these largely irrelevant potshots at my solution.

To summarize:

At 8.4 GtC in 2008 (which is too low, but OK), at 3% growth to 2050 this results in 29 GtC. If we allow your new and improved super-sized wedges of 1.8 GtC, you get 6 of these, or about 11 GtC. You have 8 remaining regular-sized wedges for another 8 GtC. Thus you are 29 minus 19, or 6 GtC short of your 4 GtC target in 2050.

If you had stuck with your original 3.3% emissions increase that would add 4 GtC, and if we went out th full 50 years add another 7 GtC. This results in another 11 regular sized wedges.

So I count you as still being either 6 or 17 wedges short, depending on assumptions, and granting you these super-sized wedges that you have come up with.

Keep trying, Joe, you are getting closer, here is what I posted over at Climate Progress:

Joe-

Thanks for the exchange. You appear to have identified another case where assumed efficiency gains contribute to the emisisons reductions challenge. If we can find just a few more of these assumptions then there may be no problem left to solve Seriously, here are a few comments:

1. Of your proposed 14 mid-century wedges, only 6 involve the production of energy. Given that the world will need more energy under all scenarios your displacement of coal is therefore limited to 6 wedges, and cannot reach 14 unless you come up with 14 involving the production of energy.

2. According to the EIA currently coal is responsible for about 3.0 GtC of global emissions, or about 36% of the current total global emissions. In 2050 using your data, of the 28 GtC, only 10 GtC would come from coal (using current technologies). So you can’t get 14 wedges from 10, so even if you came up with 14 on the production side you can’t get more than 10. Of course we could assume a faster rate of growth for coal, and then replace all of that (another creative use of assumptions!)

3. If Pacala and Socolow are counting the increasing efficiency of coal plants BOTH as a contribution to the 1.5% per year increase in emissions (rather than a higher rate) and ALSO as a wedge, then they are engaged in double counting. You cannot have both! If this is true then they lose a wedge.

4. You shaved 0.3% off the growth rate from your earlier post. That was worth 4 wedges. Also, you use a 42-year short wedge, rather than 50 as do P&S, that is worth another 7 wedges.

We can play the assumption game all day long. I will grant you that there are indeed a combination of assumptions that you can put together to get your math to work out. You haven’t yet done so, but I’m sure you can.

But playing the assumptions game is why the “emissions reduction” framing is a little bit like balancing future gov’t budgets — it encourages the creative use of rosy assumptions. A more useful strategy would be to talk about how to meet the worlds future power needs using carbon free energy. You’ve proposed 12.5 TW for 2050. This won’t be nearly enough.

Anyway, this post should just about explain everything.

BTW — for the record, I don’t think “the bridge collapse in Minnesota was caused by global warming.” I merely said it was legitimate to ask whether extreme heat events contributed to it, based on what many other people wrote at the time and since.