December 2015 will see the definitive meeting of the UNFCCC COP 21 intended to set targets and commitments under the UN treaty establishing UNFCCC and the IPCC, one approved and ratified by the United States (*). Before then, a good deal of back room negotitation and submittal of what are called “INDCs” has been going on. As can be imagined, getting the globe to agree on a far-ranging regulation is a non-trivial thing.

I have been studying climate science for a bit, and following moves to rationalize responsibility for what’s coming and, notably, for the measures needed to avoid the worst. Some of that has been reported on this blog. While I have no delusion that anyone will listen to what I think on the matter, I have thought through questions of climate justice to the point of having specific ideas. Climate justice, for those unfamiliar with the term, deals with three basic matters,

• the disproportionate net effects of climate change on countries because their populations cannot afford to mitigate its effects,
• the disproportionate responsibility of some countries for creating climate change, having built their economies on huge emissions of carbon dioxide through fossil fuel burning, burning of wood to fire iron furnaces, and deforestation, before the serious effects of the practice were appreciated and documented, and
• the disproportional effects of climate change on countries because their situations make them more vulnerable to it.

While no doubt there are many instances of developing and poor countries, such as Bangladesh, who will suffer in the manner covered by the last matter, in the long run it is not clear to me whether they will suffer as much, proportionally speaking, as will countries which depend upon long supply chains for their economies and well being. Nevertheless, it is invariably the case that those nations which do have such dependencies are today among the wealthiest, members of the OECD.

The central question of climate change is how to rebalance the economic externalities of damage to atmosphere, both to allow, in a uniform way countries which suffer the most to have access to the funds and technical help they need to adapt to an Earth with a changed climate, and to convert everyone’s energy and agricultural systems from the present fossil fuel-rich, CO₂-emitting processes, to zero Carbon-emitting ones, or zero net Carbon. I write “net Carbon” because agriculture will never be zero Carbon in itself, so it needs to be offset. Unless Carbon emissions are zero, peak committed warming will continue to increase, despite what observed warming, a short-term phenomenon, or climate sensitivity turns out to be. But the facts are that the countries most responsible for the problem also have the most to lose, by cost, in the transition.

Here I make a proposal. I won’t document it as much as I usually do these things. First of all, as I wrote, this isn’t going to go anywhere. Secondly, the assertions I make are covered by the AR5 report of the IPCC. Should a reader desire a more specific citation, please ask in the comments, and I’ll do my best to identify a specific reference and where the IPCC addressed it.

My proposal argues for the imposition of an tax on Carbon, as countless economists and policy experts have recommended for many years, irrespective of whether they are conservative economists or liberal ones. This would be enforced at import at country borders unless documentation of payment of such tax for all Carbon used in the manufacture of a product were supplied, and, of course, directly on the Carbon content of raw fossil fuels so imported, or extracted from the ground at the source. (In other words, fugitive emissions or Carbon used in flaring would be taxed.) However, for the purposes of climate justice, the Carbon already in atmosphere above the 288 ppm pre-industrial level should also be taxed. That tax should be assessed in proportion to the historical emissions of countries of the world which contributed to it, in accordance with well-established records of their use (not production) of various fossil fuels and known factors of emissions per unit fuel so consumed. It would be nice to penalize countries for deforestation, but records for that are not as well defined or available.

This would assign responsibility for climate change squarely where it belongs. It would also permit the population of Earth to get away with a rate of Carbon tax which was lower than would otherwise be needed to fund the transition to zero Carbon energy, and to mitigate the effects of climate change.

How should the OECD countries where the retroactive Carbon tax would be primarily assigned pay for such a thing? Well, presumably it could be done over time. It would be difficult, and probably improper, to dictate to countries where they should get the monies to pay for such a thing. In the case of countries like the United States, I have a specific suggestion, however, which would be more economically efficient. In particular, I propose the retroactive tax be assigned to fossil fuel companies doing business in the United States in proportion to the share of worldwide business done there and in proportion to their publicly stated fossil fuel reserves averaged over the previous ten years. No doubt such companies would seek to recover the costs of this assessment, and these will find their way into costs of their products. But doing so would keep government out of that part of it. Companies could also choose to reduce their obligations by disowning fossil fuel reserves. This would reduce their on-the-books wealth, but it would address a problem of stranded assets and might be an important tool to avoid a crash in those assets if a steeper tax on Carbon were imposed suddenly.

The monies so collected would be available for independent research and development, with shared intellectual property rights, to find pathways to zero Carbon energy and agriculture. They would also be available to countries in need to mitigate the effects of climate change, and notably weather-related disasters or impacts of sea level rise.

(*) It may be of interest to armchair Constitutional scholars that according to the “treaty clause” of Article II, Section 2, Clause 2, ratified treaties become a part of United States federal law. (See also this summary from the U.S. EPA.)