Hansen on climate change over centuries

Following my recent post, a number of commenters suggested that I ought to respond more directly to the arguments of James Hansen and others for a CO2 target of 350 parts per million, as opposed to the 450 ppm that forms the basis of much current policy discussion. I’m using this paper as a basis, and take the following two points as its central claims

* To avoid unacceptable risk of passing a point of no return beyond which explosive feedbacks (icecaps melting etc) are inevitable, we should aim to reduce CO2 concentrations to 350 ppm by 2100. This is below current levels and won’t be achieved simply by ending net emissions
* We can achieve part of this (maybe a reduction of 60 ppm) through reforestation, biochar and similar measures
* Further reductions will require expensive technological solutions, estimated cost $200/tonne or $20 trillion to remove 50 ppm. Given a maximum point around 450 ppm and 50 ppm from reforestation, that’s about the amount required.

What then should we do? In particular, how much should we be willing to pay now, to avoid high costs in the second half of this century?

Read More »

Various links

A few things where I’ve had a direct or indirect interest

* This study of media bias by econobloggers Andrew Leigh and Joshua Gans has unsurprisingly attracted interest from the media and econobloggers (Andrew gives some links). The striking (if not particularly surprising) finding is that the ABC as a whole is to the right of most newspapers. One aspect of it was how much the media cited public intellectuals identified as partisan by the fact that they were commonly mentioned in favorable terms in Parliament by one side, but not by the other. Interestingly, I didn’t pass this test. I had about 30 favorable mentions, of which about 30 per cent were from the Coalition.

* My Senate submission on deposit guarantees got a good run in this SMH piece, which opens with a look at the incidence of John Dillinger’s bankrobbing exploits, as described by Johnny Depp. Since been romantically linked with Angelina Jolie, I’m keen for more brushes with fame.

* Back when I was doing my Pure Maths degree, I studied fixed point theorems. One implication of the standard Brouwer fixed point theorem is the hairy ball theorem which implies, among other things, that there must always be a place on earth where the wind isn’t blowing. I said at the time that I aimed to get a research grant to test this theoretical result in practice, by travelling round the world and moving on whenever the wind blew. Today, my fellow-student and major source of technical advice for this blog, Martin Ellison, advises me that I’ve missed my chance. These guys have found the spot, in remotest Antarctica.

Gov 2.0

Gov 2.0* is an interesting exercise in trying to use new communications technology (Web 2.0) to promote the public good. Blogger and economist Nicholas Gruen is running the show (or playing a big role anyway) and is looking for tenders on a variety of issues. Take a look.

* To anticipate the standard joke, I’ll be waiting until the 2.1 release.

Bookblogging: The end of the Great Moderation, What next?

In any book on policy thinking, the easy bit (not all that easy!) is to write about what’s wrong with existing ideas, in my case the zombie ideas I’m writing about. The chapter plan for my book includes, in each chapter, a section on “What next”. As regards the Great Moderation, which was essentially an interpretative claim about the data, it’s not really clear what to include. I’m leaving the details of macroeconomic thinking and policy for another chapter and writing about how society should handle risk. Comments and criticism appreciated as always.

I’m in the process of setting up a site at wikidot.com where the whole draft will be presented in wiki format. But I’ve been travelling and haven’t managed to get it going yet.
Read More »