I previously argued (1, 2, 3) that we can expect peak CO2 emissions around 2050. Copenhagen summit draft calls for peaking before 2020. Now it's not entirely impossible, but I would say it's quite unlikely.
Here's a quick list of my assumptions, and how timing of the peak, size of warming, and likelihood of geoengineering would change if they were wrong:
- Economic development of poor countries - faster development means more emissions. As this is the main driver of energy demand for the next few decades in my analysis, much slower development of poor countries will indeed move the peak a lot earlier. The consequence of slower growth is economic genocide, and it's far worse than anything climate change could do, with or without geoengineering. It's not a theoretical possibility, economic genocide is happening right now.
- Correctness of climate science - putting Climategate fraud accusations entirely aside, IPCC has ridiculously wide confidence intervals. Their A1 scenario which is closest to what I describe here expects likely temperature growth to be between 1.4C and 6.4C by 2010, and their likely means merely a 66% confidence interval. If you know anything about science, "95% confidence" turns out to be wrong more often than not, and these estimates are merely scenarios conditional on countless assumptions, not actual forecasts. So what IPCC is saying is essentially "it will get hotter, we have no idea whatsoever by how much". If warming turns out to be on the low end of IPCC estimates, we'll likely see slower adoption of technologies to reduce CO2 emissions, and no geoengineering. If warming turns out to be on the high end of IPCC estimates, we'll likely see faster adoption of emission-reducing technologies, and massive scale geoengineering will be as inevitable as I predict. This is not as relevant as it seems as timing of CO2 peak depends on decisions we'll make in the next few decades, long before we find out 2100's warming.
- Technological progress - faster technological progress can result in lower emissions. If we get breakthroughs in cheap solar energy, battery technology, algae biofuels and such, it might result in much faster peak, maybe even before 2020. But I wouldn't rely on this, a lot of money was spent on these technologies and progress has been slow - what we need is not just some incremental progress which we'll undoubtedly see, but huge breakthroughs and really fast.
- Multicentric world - if we had a world government, we could just take a vote, set up whichever emission caps or taxes we wished, problem solved. If we had a small number of important powers like we do now, we could get them to agree on some flawed solution. But the world seems to be evolving towards multicentricity - right now only US, EU, and China matter, plus maybe Japan, India, and Russia a bit - but in the future other countries will probably count a lot too - and the more players you have, the harder it will be to reach meaningful agreement.
- Economic development of rich countries - CO2 emissions per capita don't increase significantly past certain level of income, so it won't matter much either way.
- Demographic growth - faster growth means more emissions, but uncertainty about 2050 population isn't that high, so it can only have modest effect.
- Attitude towards nuclear energy - if people become more supportive of nuclear energy, it will reduce CO2 emissions somewhat.
- Policy of US, China, India, and the entire developing world - matters a lot, as they are current and future main emitters, they have a lot of demographic and/or economic growth ahead, and it's highly uncertain what their policies will be.
- Policy of EU - matters very little, as EU is already highly efficient for GDP it has, has little economic or demographic growth, and it can be relied on to do further reductions no matter what others will do.
PoliticsAnd regardless of those, the most important factor is politics - global warming is a very unusual situation in which not only everybody's emissions affect everybody equally (straightforward externality / tragedy of commons), but also everybody's current emissions only affect people living in far future. We're asking for 2009's Americans to make significant sacrifices for the sake of 2100's Bangladeshis. 3000's Bangladeshis even, as IPCC says that "anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium".
Let's take an outside view, and make a reference class forecast - in situations in which current sacrifices of people living in one country could make a difference to people living in entirely unrelated country a century ahead - how often were the sacrifices made? To the best of my knowledge the answer is a reliable never. It just doesn't happen. If one country like EU now (and to not that significant extent) were to sacrifice money to limit its emissions, others would just take advantage of cheaper fossil fuels due to reduced demand and burn more of it.
In theory a global carbon emission market could be established, but good luck getting everyone to agree on allocation of emission rights, or income from their sales. The more severe the cuts, the more expensive will emission rights get, and the worse will the fight be. If we allocate most rights to rich countries, poor countries will correctly complain that it hinders their economic development. If we allocate most rights to poor countries, it will amount to massive transfer of wealth from the rich to the poor, and good luck getting voters to agree to that.
We're talking about tens of trillions of dollars. It's not a metaphor, just the proposed American system is estimated to be valued $80bln / year - $80bln times 40 years and 5x (world emissions / American emissions), it will be worth $16 trillion, and growing as supply gets restricted and demand grows due to economic development. How will these tens of trillions of dollars in either emission rights or auction profit receipts be allocated? Yes, good luck with that.
The alternative is not caring about greenhouse gases emissions, and geo-engineering the temperature growth away if need be.