Methane and supervolcanoes

This recent headline from ScienceNews says it all:

Methane may not warm the Earth quite as much as previously thought

There is much about the environment - and society - that we just do not know. Yet our policies are formulated as if we do know. We think climate change is mostly a result of our pumping greenhouse gases into the atmosphere. That may well be the true but, even now, we find that we don't know as much as we thought about the relative contribution of each greenhouse gas. In this instance, the original estimate was 30 percent off the latest estimate. But we are making policy as if the role of each greenhouse gas in climate change is certain and fixed. 

Not only is the science about each gas's relative contribution uncertain; so too is our knowledge about other determinants of climate change. Yet we enact policy as if we know everything. It's risky; especially as not only is our knowledge of the physics of climate change incomplete, so too is our ability to forecast the future. Eruption of a supervolcano is unlikely but:

[T]his gigantic eruption sent the world into a decade-long volcanic winter and caused the climate to be cold and dry for thousands of years after that. The resulting famine is theorised to have reduced the ancient human population down to just a few thousand individuals. Source

Lesser events, as well as surprises in the physics, could invalidate some or all of our efforts to deal with climate change. Policy should account for such gaps in our knowledge, and not only in environmental matters. Society is also too complicated for a policy approach that assumes that relationships are known and fixed. So, for example, reducing crime rates or increasing literacy is not simply a question of more funding for already-existing bodies. In my view, it's more a matter of putting in place incentives that reward people for achieving our goals, whoever they are, and however they do so. The risks of unanticipated events and failed approaches should be borne by those taking on the task.

Social Policy Bonds are one way of addressing the complexity of society and the environment. They reward the achievement of desirable outcomes, rather than the supposed means of achieving them. They set up incentives to reward promising approaches and - importantly - to terminate failing approaches. They transfer the risk of failure from the bonds' issuers (usually government) to investors in the bonds. They encourage investors to keep an eye on events as they unfold, and to respond to them appropriately. So, for example, investors in bonds targeting climate change would react to the research referenced above (if they did not carry it out themselves) by refining their attempts to deal with methane emissions. Under the current regime, nobody has incentives to change the assumptions on which existing models are based.