Can someone tell, if double CO2 compared to pre-industrial times is a realistic assumption for prediction our climate?

TIA, chris

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pre-industrial was about 280 ppm. Current CO2 is about 379ppm and increasing by about 2 ppm per year. We haven't got to double yet and I hope we don't because it looks far too dangerous.

Doubling CO2 is really a commonly used technique which can then be used to scale the response to smaller changes in CO2 rather than being realistic in itself.

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> pre-industrial was about 280 ppm. Current CO2 is about 379ppm and increasing
> by about 2 ppm per year.

Wow, that's a lot. Considering that in about 100 years we will have double CO2 and that Kyoto is only about stopping the increase *of the increase* of CO2 in atmosphere is frightening.

thx for the answer, chris

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I can't find Novacek(2000) on Google Scholar, but I thought that temperatures were are most 7C higher than now. The permian mass extinction had a global warming of about 6C (but off a higher base?) see http://faculty.weber.edu/dbernal/Benton%20and%20Twichett%202003.pdf

From that paper:

> Climate modellers have shown how global warming can reduce ocean circulation
> and the amount of dissolved oxygen to create benthic anoxia

citing http://www.whoi.edu/science/GG/people/kbice/Hotinski_etal_2001.pdf

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Apparently the Chinese are planning to build 500 new power stations by 2030. Assuming that most of these turn out to be coal-fired, and that plenty of other countries also want, indeed need, more electricity, and will produce most of it from fossil fuel, then the rate of increase in CO2 emissions must surely continue to rise.

It's not just a question of improving living standards for the poor among the present world population. I believe that the UN predicts that world population will increase from the present 6 billion to 8.9 billion by 2050. That's an increase of nearly 50%. Have I understood this right?

Whatever the exact increase in population, it means that CO2 emissions will continue to rise before they level off.

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From what I've read the Chinese are planning to massively increase the number nuclear power stations, but that the proportion of nuclear electricity generation will remain roughly constant. Almost all the rest will be coal. They also have had a large hydro program, but IIRC they have now exhausted most of their hydro potential.

I think your population figures are correct, the UN has a history of over projecting population, mainly because they underestimated the drop in fertility due to better education and economic prospects for women in developing countries.

I think its not so much the increase in living standards among the poor, they seem always to be with us :-( but the relatively well off in countries like India and China becoming much wealthier. Suddenly the factory worker goes from owning a bike to owning a car and a farmer from mainly natural methods to mechanisation and application of large amounts of fertilizer.


&gt; Whatever the exact increase in population, it means that CO2 emissions will
&gt; continue to rise before they level off.

If all predictions were that easy many climate modelers would be out of a job. I think that if we are to limit CO2 growth to double preindustrial levels we need to start taking drastic action now. Each year brings us 2.2ppm closer to a doubling, a rate that is increasing and accelerating, and CO2 emissions increasing, so the cuts will have to be more drastic as they start from a higher base. Realistically I can't see much movement in CO2 reduction before 2012 when Kyoto 2 might be in place. By then global CO2 emissions may be 7-15% higher (mainly depending on world economic growth) and the CO2 level pushing 400ppm.

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The earth's carrying capacity for mankind depends on how people live and whether everyone has access to a similar standard of living. If everyone on earth had a similar life-style to present-day Europeans and North Americans regarding space heating, transport modes and food preferences, with current technology, I can easily imagine that the carrying capacity has already been exceeded, however it is measured.

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My research so far about the <a href="http://en.wikipedia.org/wiki/Paleocene-Eocene_Thermal_Maximum">Paleocene-Eocene Thermal Maximum</a> PETM, suggest that a 7C rise in temperature occurred at high lattitudes, or 5-10C rise or <a href="http://poseidon.palaeoz.geomar.de/files/AandO/Kroon_ODPLegacy.pdf">proto-Atlanticthe entire water column warmed by up to as much as 15 to 19C</a>, figure 2 there shows deep water warming above surface in the southern ocean. It was probably caused by <a href="http://www.giss.nasa.gov/research/briefs/schmidt_02/">an Ocean Burp</a>.

The climate was <a href="http://www.deas.harvard.edu/climate/pdf/bowen_2004.pdf">humid</a>

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