The interim version of the Garnaut Review (mentioned earlier) includes a numberless graph illustrating what the principle of contraction and convergence in per capita greenhouse gas emissions would resemble:
A few features are especially notable. The first is the relative trajectories in the opening years. States with very high per capita emissions, like Australia and Canada, would have to reduce emissions sharply right from the outset. Rapidly growing poor states like China would be allowed to grow until per capita emissions are comparable to those in relatively low emission developed states, such as the EU. Gradually, everybody’s per capita emissions become lower and more similar.
This approach becomes a lot more politically feasible when you take these lines to represent emission allocations rather than actual emissions. Developing states would have a choice about how to use the extra space allocated for their development. They could opt to use the allocation for their own emissions, allowing the growth of GHG emitting industry; alternatively, they could sell the allocations to more developed states at a globally established market price. That way, poverty reduction and development goals could be served at the same time as total GHG emissions trend towards a sustainable level. The big advantage of allowing global trading is that it should equalize the international marginal cost of abatement. In simple terms, that means that it will ensure that the emissions that can be avoided at the lowest cost will be addressed first, minimizing the overall cost of mitigation.
The Garnaut Review rightly highlights that it would be incredibly politically difficult to establish such an international regime. At the same time, it is probably also right to say that a general approach that embraces contraction and convergence has the best chance of stabilizing global greenhouse gas emissions at a level that avoids dangerous anthropogenic interference in the climate system, and does so in a way that minimizes total costs and manages the distribution of costs and benefits in an acceptably fair manner.
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That does look like a fair sort of progression. The biggest question that jumps out of that graph is “will it be politically acceptable to force Americans to follow their downward-sloping line during the period when people in China are still trending upward?”
This comic will probably serve as a funny reminder of your student days
The comic is accurate and amusing. Anything about the biochemistry of caffeine has appeal to me.
R.K.
Political acceptability is certainly a big problem. That said, contraction and convergence has some hope of (a) solving the problem (b) being feasible and (c) seeming fair.
‘Stabilizing climate requires near-zero emissions’
A new climate science paper calls for dramatic action
Avoiding climate catastrophe will probably require going to near-zero net emissions of greenhouse gases this century. That is the conclusion of a new paper in Geophysical Research Letters (subs. req’d) co-authored by one of my favorite climate scientists, Ken Caldeira, whose papers always merit attention. Here is the abstract:
Current international climate mitigation efforts aim to stabilize levels of greenhouse gases in the atmosphere. However, human-induced climate warming will continue for many centuries, even after atmospheric CO2 levels are stabilized. In this paper, we assess the CO2 emissions requirements for global temperature stabilization within the next several centuries, using an Earth system model of intermediate complexity. We show first that a single pulse of carbon released into the atmosphere increases globally averaged surface temperature by an amount that remains approximately constant for several centuries, even in the absence of additional emissions. We then show that to hold climate constant at a given global temperature requires near-zero future carbon emissions. Our results suggest that future anthropogenic emissions would need to be eliminated in order to stabilize global-mean temperatures. As a consequence, any future anthropogenic emissions will commit the climate system to warming that is essentially irreversible on centennial timescales.