It’s certainly possible that there could be unexpected ecological consequences that are more severe than anyone realizes, but that could be true of any number of other things happening that have nothing to do with global warming. In general, it’s best to err on the side of caution, I think.

What’s clear right now, reading the Stein Report is that our CO2 is warming the earth, and that we have to plan for a minimum 3-4C rise in global temperatures and a 1-2m sea level rise over the next 100-200 years. It’s also clear that further CO2 emissions can make the problem even worse and we should take any low or no cost measures necessary to reduce those emission.

Whether we should adopt more severe restrictions at heavy cost is another question, and I think the jury is still out. 1% of GDP per year adds up to a lot of resources in 100 years. Which means we can afford to bank up a lot of remediation capital if we don’t make any high cost changes to our current activities.

I have zero patience for the people who’ve been blowing smoke and putting out a bunch of nonsense over the last 20 years while the scientific community has been coming to a better consensus. But the question of whether it’s costlier to reduce emissions now, versus remediate later is a legitimate one and shouldn’t be ignored.

1% of GDP doesn’t sound like much, but for a bangladeshi it’s the difference between maintaining the current level of poverty and being 2.7 times better off in 100 years. That’s a gigantic cost, and it’s the reason I don’t expect any country not already rich to be down with any costly emission reduction programs. It’s a huge tragedy of the commons problem, and only about 1/5 of the world is wealthy enough that it makes any rational sense to worry about it.

The primary goal, it seems to me, is to get the whole world to a place where giving up 1% of GDP for 100 years isn’t the difference between starvation and comfort.

To quote Duran Duran, it’s about as serious as a nuclear war.

It’s true that, on the assumptions and timescale they are using, it is more of a WWII-level problem, a limited nuclear exchange that destroyed 10% of the world’s cities, than a global-apocalypse, everyone dies, thing.

As such, it is something that will slow progress down, not, in itself, bring on a new dark age, cause future historians to write ‘western civilisation came to an end in the date they called 2074 AD’.

Two caveats:

they could be wrong, either the environmental effects, or the secondary political consequences, could be much worse.

a longer timescale may well show more radical effects, if the problem is not solved in the next century.

What are you claiming? Do you expect the positive economic effects of addressing climate change to out weigh the negative ones? Are the positive gains over the short term or the long term? What counts as short term and what counts as long term?

It seems to me that we have invested huge amounts into building economic systems based on the burning of fossil fuels. Implementing a new model will cost us both the capital investment to create non-polluting energy sources on a massive scale and the forgone economic benefit of using the energy system we have already invested in to accrue economic benefits from the burning of the world’s remaining viable fossil fuel reserves.

The point of the Stern report is that climate change is going to cost a lot more to future generations (i.e. humanity over the long run) than near and long run investments in abatement. But any investment we make now will not result in a benefit to us in terms of reduced climate change effects. The climate effects we will feel in our lifetimes have already been determined by past burning and the burning we will have to continue to do even if we make a full on effort for new energy sources. And any benefits we will receive in our lifetime from a full on reformation of our energy systems will surely be outweighed by the costs of creating a completely new system and loss from abstaining from using fossil fuels.

This does not mean that I do not think we should make radical changes, but I am a bit tired of all the win win comments about addressing climate change.

As there are other SRES scenarios that produce vastly greater GDP per capita figures than A2, I find the whole thing rather off.

Why base a calculation of trade offs between mitigation and business as usual on the scenario that produces the least future GDP per capita, is a medium high emissions scenario and has a vastly (to my mind) over inflated population level of 15 billion?

Watched a decent movie this weekend, Secuestro Express which ended with a line about the third world:”You have two choices. You either kill them, or invite them to dinner.”

I ask myself, would I rather give up 10% of what I have to kill them, or 50% of everything I have to save them?

Expressing this in monetary terms is difficult, but one way of doing it is to look at how much we’re already forgoing in consumption to protect the environment, then observing that much of this will turn out to have been wasted if we don’t do something about climate change.

a tacit assumption there of a contrast between economic effects (serious, bottom line, measurable in dollars of output) and other “airy-fairy” effects (environomental loss etc).

Yes, I know what you mean. At the same time there is a pronounced resistance on the part of environmenatlists to put any economic value at the environment—- corresponding to a proposition that it is infinitely valuable, and that we must do anything to save all of it at any cost whatsoever. This position has the rhetorical advantage of letting you paint any other position as cold-hearted money fixation.

How does this compare to the cost of the invasion of Iraq?

Personally I think the way forward is to innovate in terms of useful boondoggles: at the moment government members round the world are keen to divert funds to their own constituencies in the form of military bases, bridges to nowhere, oil projects, etc. If there were equivalents with positive environmental externalities, they would very readily be funded.

So with some slow down offset by benefits, just guess at 2% of GDP per year. Which would put the US in recession right now. What, 100 billion dollars? That is assuming expenditures balanced around the globe, which isn’t correct, the developed nations will likely have to far outspend the underdeveloped nations. So take it up to 3% minimum of US GDP. Per year, for fifty years.

Ready for your revolution?

When economists have their methodological hats on, they typically deny that economics should be construed as dealing in cash outcomes rather than, say, preference orderings of states of the world. And they are right to do so, insofar as it is a true that you can pack anything into a utility function. But the everyday rhetoric of economics —including as used by many economists—reverts to the cruder approach as somehow more “serious”. (Broome’s book was an important exception to this.)