The right to properly manage their cod and other fish stocks is why Iceland went ot war, twice, against a nuclear power. After the herring catch crashed they feared the same would happen with cod and this was key to national survival !  (Fish were 90% of exports then, 2/3rds today).

Best Hopes,

Alan

Now, such calculations are obviously difficult and uncertain, largely because the greater part of the impacts are far in the future. Greenland's not going to melt down tomorrow, but if it does eventually, that's going to be extremely expensive. The future is inherently uncertain so this makes the necessary extrapolations and calculations doubly difficult.

A number of researchers have attempted to put a numerical figure on it anyway, and there has been considerable variation in their results. Here is a paper from 2005 that surveyed over 100 such studies:

http://www.uni-hamburg.de/Wiss/FB/15/Sustainability/enpolmargcost.pdf

The median calculated impact, across all the studies, was $14 per ton of carbon. This is considerably lower than the $100/tC we often see bandied about. The paper also notes: "Interestingly, studies that are peer-reviewed have lower estimates and smaller uncertainties." In other words, the higher-quality studies generally have lower estimates, and the more extravagant estimates come from low-quality studies.

A $14/tC Pigovian tax corresponds to a gasoline tax of about 3 cents per gallon. This is, according to our best estimates and calculations, the correct amount of tax to compensate for the eventual costs of carbon emission, and to cause people to adjust their consumption habits so as to minimize net costs.

Of course, such a low carbon tax would have an almost negligible impact on people's behavior. Maybe some big companies would be willing to make a change in response to a tax of 1% or 2% on energy, but most people won't even notice it. Yet it is the correct level under the Pigou formulation of compensating for negative externalities.

This leads to a paradox, where global warming is a great threat, yet our best estimates of the cost of that threat lead to a policy which will not cause noticeable action to be taken. It is an interesting exercise for the student to try to resolve the paradox. I think the answer should be relatively obvious to anyone who is willing to accept the hard evidence of scientific research without prejudice. But I will refrain from giving my answer here and let others mull over this puzzle.

The necessary tax would be so high, and the perceived inequality so great (only the rich can afford to pay the tax) that the system would break down.

If a tax is meant to change behaviour, what is important is the rate at the margin which influences current purchasing decisions.  You can get a high marginal rate without impoverishing the poor in several ways.

For an easily metered product like electricity you can have a low tariff for an amount sufficient for a frugal household and a high tariff for any extra.  For other carbonaceous products you can provide a credit per citizen/household either in kind, with specific "carbon credits", or cash to help buy basic quantities.  With very high prices this turns into a rationing system.

This is a bit like a carbon-trading system where the credits are distributed amoung the population who then sell them to utilities and industries which require them or use them for personal consumption, but is probably less bureaucratic.

it is quite likely that some emissions of carbon will be incredibly price inelastic.

Gasoline consumption is very inelastic over the short term, but quite elastic over the long term.  It appears likely that carbon emissions are not unlike gasoline consumption (they are even strongly related).  If the carbon tax was escalated on a known schedule over a period of years, people and companies would adapt and plan ahead.

If it paid $50/ton or more, American farmers would probably find a way to sequester carbon as charcoal in the soil (terra preta) and pocket the payment.  The USA produces about 1.3 billion tons of waste biomass alone, sufficient to make about 0.5 billion tons of charcoal; burying even half of that would sequester about 0.8 tons/capita/year (the off-gas from charcoal production plus the remaining charcoal could be used for energy or chemical products).  The sequestration potential increases if high-productivity biofuel crops are added to the mix.

We can do this.