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John D

I agree Dave that the status quo of economic growth cannot continue. The world economy is like a big spinning top. It needs a certain minimum momentum (growth) or it will wobble and fall over. Its wobbling quite a bit now.


The arctic has been warming faster than the models have predicted. Due to the too many unknowns of feedback loops from melting permafrost, clathrates, and albedo, they are often simply left out of the models to make estimates more conservative. Also, there could be C02 growth from fossil fuels in a stagnant economy, as economies move to cheaper fuels. Natural gas prices won't stay cheap, oil is expensive, and we're already seeing a rise in coal use. Also, extraction of natural gas by fracking and oil sands, etc., is more carbon intensive. Sure you can dismiss their rosy projections on emissions and economic growth, but there's other issues with the modelling and projections as well.

Dave Cohen

Gee Remi,

Re: Sure you can dismiss their rosy projections on emissions and economic growth, but there's other issues with the modelling and projections as well.

Thanks for telling me all that. I wouldn't have known about any of those issues otherwise! ;-)

-- Dave


At the risk of telling you something else you don't (effing) already know ;-)

From NY Times - Global warming: “Anyone who thinks that there is not a dramatic change in weather patterns is denying reality,” NY Governor Cuomo said. “We have a new reality, and old infrastructures and old systems.”

That horse bolted so long ago, it's evolved into an eight-legged equino-hound.


PS - Dave, you're gonna love this:


Dave Cohen


Re: at the risk of telling you something else you don't know...

I am always glad to be told something I don't know on the extremely rare occasions when that occurs. Remi's comment wasn't one of those, but that wasn't my objection.

It was more the tone of the comment I objected to. The content was mostly OK otherwise. When he said--

there could be CO2 growth from fossil fuels in a stagnant economy, as economies move to cheaper fuels

That's simply asserted nonsense.

But I often see comments like that one: but you didn't talk about X or Y!

That's right, I want to say to them, I didn't talk about X or Y. It's a blog, stupid!

I could write a book, but I don't see any publishers stepping up to make it worth my while.

-- Dave


The publishers will come knocking on Dave Cohen's door when the last piglet has flown over the sub-tropical Arctic Ocean and Exxon is supplying tapped farts as the very latest in natural gas.


I don't know, Dave, I like to think you are right about us not being able to increase emissions significantly, but with all the talk about coal lately and the tremendous amount that China seems to find and burn every year... I just don't know. Add in more developing countries with high growth rates and it looks pretty bad. Even China isn't talking about recession, just slowing growth - so still more coal burned every year. Going from 10% growth to 7% growth when you have one of the world's largest economies already still means lots and lots of fossil fuels burned.

I like to think the worst case isn't possible, but there are a lot of "worse than worst case" things going on, like the faster than expected arctic melt. The world economy is not great, but if there is a way to burn enough of whatever to make it keep running, I get the feeling someone will burn it.

Mike Roberts

Just got round to reading this.

I do wonder if the emissions proxy is losing some of its usefulness. I'm not entirely convinced that there is any significant real economic growth in the world right now but emissions have risen significantly for the last three years in a row. Countries will try anything to get back on the growth path and will be willing to use dirtier and dirtier fuels as resources for that.

Chris Korda


I've been following your blog for over a year now, patiently waiting for a suitable opportunity to comment. That opportunity has finally arrived.

There are two fundamental sources of climate scenarios. One you're obviously already familiar with: the IPCC and its related bodies. The IPCC is an international consensus, and thus its scenarios reflect what all the nations of the world can agree is plausible and politically palatable. More importantly, the IPCC scenarios assume good faith: nations are presumed to respect international protocols and meet their agreed emissions targets. Consequently the IPCC tends to produces best-case scenarios. This inherent optimistic bias is exacerbated by the IPCC's scientific component, because the language of science is generally cautious, understated, and conservative. Exaggeration is considered a serious crime in science, second only to faking data.

The other source of climate scenarios is the International Energy Agency (IEA) and its US equivalent, the Energy Information Administration (EIA). These agencies have a very different approach. Essentially they forecast emissions by totaling up all the energy "plays" that fossil fuel corporations (or their state counterparts in command economies such as China's) already have on the books. This is possible because energy companies routinely plan ten to twenty years ahead, which they're obliged to do because energy plays necessitate strategic planning, infrastructure and investment on a monumental scale. Energy infrastructure is so expensive and depreciates so slowly that once it's in service or even beyond the planning stage, it's essentially guaranteed to remain in service for its lifetime. Put simply, you don't build a supertanker (or a port, or a pipeline) and then decide not to use it.

To summarize the difference between the two sources of information, IPCC projections represent what nations say they're going to do, while IEA projections represent what energy companies are actually in the process of doing, i.e. the facts on the ground.

The most recent projections from the IEA and EIA are both based on the same data: The 2011 Integrated Energy Outlook (IEO2011). In its simplest form, "The IEO2011 Reference case projects about 1 trillion metric tons of additional cumulative energy-related carbon dioxide emissions between 2009 and 2035" (US EIA IEO2011, p. 143). This is equivalent to following the IPCC's worst-case RCP8.5 scenario until 2035, as this annotated version of the RCP8.5 emissions graph demonstrates:

Contrary to your out-of-hand dismissal, RCP8.5 represents what the world's energy companies and equivalent state actors are actually in the process of doing, until at least 2035. This was discussed extensively at RealClimate on October's open thread. IPCC's 2007 AR4 presented several scenarios, and in practice we tracked or exceeded the worst scenario (A2). Similarly AR5's scenarios other than RCP8.5 are merely wishful proposals, due to the IPCC's structural biases outlined above.

One might wonder from which nations this additional teraton of fossil CO2 will emanate. Inconveniently, the emissions growth will come from non-OECD countries, especially China, and mostly from burning coal, as demonstrated by IEO2011 figures 115 and 116, reproduced here for convenience:

In other words, in CO2 terms, America is already a sideshow. China, India and other non-OECD countries plan to increase (NOT decrease) their fossil fuel consumption in order to approximate an OECD standard of living, and we're in no position to dissuade them, other than by setting a good example, which we're consistently failing to do. For more on this subject see my blog (Metadelusion):

One also might wonder what temperature change the additional teraton of CO2 commits us to. Estimating this accurately turns out to be a non-trivial undertaking, which may partially explain why AR5 doesn't include any temperature data, unlike AR4. With the assistance of RealClimate contributors, I have attempted to project the temperature change that would result from each of the RCP scenarios, using the method outlined in Hansen et al.'s 2011 paper "Earth’s energy imbalance and implications". The results are available here:

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