What do we want?

The Economist, in an article about planetary boundaries, discusses climate change. Do we want to see a reduction in greenhouse gas emissions, or should we focus on “radiative forcing” - the increase in energy delivered to the surface of the Earth over time, largely as a consequence of extra greenhouse gases?

Greenhouse gases are, however, only a problem because of their effect on radiative forcing. If that could be reined back inside [1 watt per square metre above pre-industrial levels] by other means, then the CO₂ limit [of 350 ppm] would no longer pertain. And that might be possible by spraying reflective particles into the upper atmosphere, to bounce sunlight back into space. Such a radical scheme would have all sorts of disturbing side effects, with political ones quite possibly outweighing environmental ones. It is by no means clearly the right thing to do. But it might be. Boundary conditions (subscription), 'the Economist', 16 June

What does 'right thing to do' mean in this context? What do want to achieve? The current policymaking environment allows us to avoid or muddle answers to this question. The result is ad hoc policy, decided on the fly, or not decided at all: just the aggregated effect of private- and public-sector interest groups working towards their own ends.

We need to do better than this. A Climate Stability Bond regime, at the outset, would compel us to clarify what we want to achieve. My suggestion is that we target simultaneously an array of physical, social, biological and financial variables. All targeted variables would have to fall into a specified range, for a sustained period, before the bonds would be redeemed. The variables could include the obvious ones, such as temperature, rate of change of temperature, sea level etc, but also such indicators as numbers of people killed or made homeless by adverse climatic events, species migration, species extinction, ocean acidity, insurance costs and insurance payouts. No longer would we focus (or pretend to focus) on one particular variable ; a bond regime would be versatile enough to target any number of quantifiable variables at the same time. Clarity over exactly what we want to achieve is essential if we are serious about actually achieving it. It's a tragedy that in this, and other, policymaking areas, we end up adopting de facto targets and subordinate all our policymaking to them. And that applies whether it's greenhouse gas levels - or gross domestic product per capita.