The latest annual report from the International Energy Agency is well worth consulting directly: Though it's received wide coverage in the general press, that coverage tends to be slanted and unbalanced by comparison with the IEA's own executive summery or even just the excellent press release the agency issued with the report.
The IEA sees itself frankly as setting the stage for the Copenhagen climate conference next month, and contrasts what it calls a reference scenario--what's generally called business as usual--with a 450 scenario. In the reference scenario, temperatures could rise by as much as 6 degrees celsius by comparison with pre-industrial times, whereas the scenario in which carbon concentrations in the atmosphere are limited to 450 ppm would keep the cumulative rise to about 2 degrees.
In the reference scenario, global energy demand increases 40 percent in the two decades to 2030 and fossil fuels continue to dominate supply, with 90 percent of the increase in world demand occurring in the fast-industrializing less-developed countries. In the 450 scenario, fossil fuel demand peaks in 2020, and carbon emissions in 2030 are slightly lower than they were in 2007. Improved energy efficiency would account for more than half the carbon abatement in the 450 scenario, but greater reliance on zero-carbon electricity generation also would play a big role: renewables would account for 37 percent of electric power production in 2030, nuclear reactors 18 percent, and clean coal--coal with carbon capture and storage—5 percent.
The IEA estimates that these adjustments would cost the world $10.5 trillion over two decades, but these expenditures would be largely offset by savings in variety of benefits, including public health. "The challenge for climate negotiators [at Copenhagen] is to agree on instruments that will give the right incentives to ensure that the necessary investments are made and on mechanisms to finance those investments,” said IEA Executive Director NobuoTanaka.