This list from The Guardian rather shows what the problem is:
Road transport (10.5%)
Air transport (excluding additional warming impacts) (1.7% )
Other transport (2.5%)
Fuel and power for residential buildings (10.2%)
Fuel and power for commercial buildings (6.3%)
Unallocated fuel combustion (3.8%)
Iron and steel production (4%)
Aluminium and non-ferrous metals production (1.2%)
Machinery production (1%)
Pulp, paper and printing (1.1%)
Food and tobacco industries (1.0%)
Chemicals production (4.1%)
Cement production (5.0%)
Other industry (7.0%)
Transmission and distribution losses (2.2%)
Coal mining (1.3%)
Oil and gas production (6.4%)
Deforestation (11.3%)
Reforestation (-0.4%)
Harvest and land management (1.3%)
Agricultural energy use (1.4%)
Agricultural soils (5.2%)
Livestock and manure (5.4%)
Rice cultivation (1.5%)
Other cultivation (1.7%)
Landfill of waste (1.7%)
Wastewater and other waste (1.5%)
Assume that we really do want to reduce emissions by 80%. No, go on, just assume it.
OK, there\’s some biggies that would be, not trivial, but at least one can see how they might be reduced. Deforestation for example. But I get 13% of emissions from agriculture as being irreducible (that\’s not including agricultural energy use). Sure, some comes from nitrogen fetilisers: but without those then we\’d need to use manure, which means more animals, and thus more methane from that source instead. I also get 10% from cement, iron and aluminium. No, there\’s not really any way to deal with those either. You\’ve got to use coal (or at least carbon in some form) to make iron, energy to make aluminium and the production of cement is really driving the CO2 off the original mineral. That\’s actually what you\’re setting out to do. Yes, you can substitute for some of the cement, use fly ash for up to 40% of the cement in concrete for example. But fly ash comes from burning coal….
Only 30% comes from all forms of transport, heating, lighting etc: OK, if all of that goes \”green\” then presumably we\’ll not have the 8% from coal and oil/gas extraction. But even if we do end up with a \”zero carbon\” energy generation system, we\’ve still got 23% from those industries, food and metals, that we cannot get to zero carbon.
Which means that we cannot, if we really do have to reduce emissions by 80%, actually manage to do it. It\’s just not possible.
Unless, of course, we follow the more excitable greens and hugely cut the number of people or stop having an industrial culture.
Does this mean that these more excitable greens are therefore correct? Well, no, I don\’t think it does, for I can\’t see any way that the world (which is a euphemism for the 7 billion people in it) is going to agree to give up iron and steel, eating, nor their own of their childrens\’ lives to save the poley bears. Just isn\’t going to happen.
Which means, in the end, that the only viable solution is going to be a method of extracting greenhouse gases: either at their point of production or out of the atmosphere.
Anyone with any ideas? Freeman Dyson seems to think that we could do it through agriculture, stick the carbon in the soil through a change in farming practices. Anything else?
Do you think nuclear fusion technology will be viable any time soon? Within a generation, say?
I agree with Nick. Fusion would do it, if it were cheap enough and then we could use hydrogen power cars etc.
Of course this is a very big IF. I would guess we would have to invent fusion within 10 years to do it by 2050.
I don’t think you’re doing this very carefully. For iron, aluminium, cement, etc, the CO2 is mostly from energy use (heating it up, etc) not from the C required to reduce the ore.
Apart from that, reduction by 80% isn’t really needed anyway. Who (credibly, I’m sure you can find wackos easily) says it is?
Oh, and FD is very clever but clueless on cliamte. Don’t rely on him.
(email conversation)
OK, with iron I agree some is needed. I’d have guessed some energy was needed to melt the stuff too, but I could be wrong. You can tell
fairly easily, though, from the chemical formula, how many tons of coal are needed per ton of iron. And clearly some people are thinking about how to make CO2-free iron: e.g. http://pubs.rsc.org/en/Content/ArticleLanding/2010/CC/c0cc01594f (not idea if that is credible).
Ditto Al: I’m pretty damm sure this uses a *lot* of energy (which is why it is done where there is semi-free elec) to do the electrolysis and melt the ore. I’d bet the C electrodes are a trivial part of the energy use.
For cement, again, I’m pretty sure most of the energy (CO2) is in heating the stuff up. The CO2 given off is small (no?). But just like iron: you could calc that fairly easily. But I can’t be bothered to 🙂
Re iron: OK, I think I’ll abandon my position there. It isn’t quite clear but stuff like http://www.epa.gov/climateleaders/documents/resources/ironsteel.pdf makes it likely that all the CO2, effectively, comes from reducing, which I suppose is exothermic enough to do the melting (A level chemistry is a long time ago).