The linked article & website (with free pdfs) discuss the Oslo principles legal approach to internalizing the externalities associated with climate change:
http://www.theguardian.com/commentisfree/2015/mar/30/climate-change-paris-talks-oslo-principles-legal-obligationshttp://www.yale.edu/macmillan/globaljustice/news.html#oslo2015http://www.yale.edu/macmillan/globaljustice/Oslo%20Principles.pdfhttp://www.yale.edu/macmillan/globaljustice/Oslo%20Principles%20Commentary.pdfExtract: "
The Oslo Principles on Global Climate Change Obligations Launched by Expert Group Including GJP Director Thomas PoggeIt may seem that, in the absence of explicit treaties, states have no legal obligations to curb their greenhouse gas emissions. Yet, if emissions continue on their present trajectory, the harms they cause will reach catastrophic proportions, putting the human rights of billions of people in jeopardy. International human rights law is legally binding on states, which are, therefore, not free to continue business as usual. But how much do human rights and other sources of law, in particular tort law, require each state to do to reduce emissions, even in the absence of a specific treaty? A group of legal experts from around the world has answered this question, producing a set of Principles, setting out existing obligations regarding the climate, along with a detailed legal Commentary. These documents may help judges decide whether particular governments are in compliance with their legal obligations to address climate change. The principles may also serve many other purposes; for example, they may strengthen the bargaining position of poor countries by pointing to far-reaching obligations of wealthy countries."
The following quote cites the legal requirement for the application of the "Precautionary Principle":
"
Precautionary Principle: There is clear and convincing evidence that the greenhouse gas
(GHG) emissions produced by human activity are causing significant changes to the climate and that these changes pose grave risks of irreversible harm to humanity, including present and future generations, to the environment, including other living species and the entire natural habitat, and to the global economy.
a. The Precautionary Principle requires that:
1) GHG emissions be reduced to the extent and at a pace necessary to protect against the threats of climate change that can still be avoided; and
2) the level of reductions of GHG emissions required to achieve this, should be based on any credible and realistic worst-case scenario accepted by a substantial number of eminent climate change experts.
b. The measures required by the Precautionary Principle should be adopted without regard to the cost, unless that cost is completely disproportionate to the reduction in emissions that will be brought about by expending it."