James Fallows, the Atlantic Magazine writer and blogger, says the illustration below is “the most frequently-used chart in modern climate-change thinking.”

Well, it was new to me. But I have to agree, it’s a really useful guide to the most cost-effective measures to deal with greenhouse gases. (You can get a larger version of the chart, along with Fallows’s comments, here.)
Produced by McKinsey & Co and the McKinsey Global Institute, it compares the relative costs of different measures to reduce greenhouse gas (GHG) levels in the atmosphere.
On the chart, the below-the-line items, on the left side, are GHG-reduction measures that save more money than they cost. Most of these are sheer efficiency measures (insulating buildings, switching to more efficient lights).
The above-the-line escalating figures on the right are the rising costs of other abatement measures. The most expensive of them are high-tech “carbon capture and sequestrian” systems, plus protecting forests in heavily-populated Asian countries.
BTW, Fallows is single-handedly trying to stamp out what is surely the most popular analogy used in climate-change debate – the one about the boiled frog. ”You put a frog into a pot of boiling water, and it jumps right out. But if you put it in a pot of nice comfortable water and then turn on the heat, the frog will complacently let himself be boiled.” Rather like human beings on a slowly warming planet. Except, argues Fallows, it aint so.
If you throw a frog into a pot of boiling water, it will (unfortunately) be hurt pretty badly before it manages to get out — if it can. And if you put it into a pot of tepid water and then turn on the heat, it will scramble out as soon as it gets uncomfortably warm.
Even revised, the frog-in-hot-water is still useful. The question is: are human beings smarter than frogs?