On Climate, Ethics Must Trump Economics
Scientific evidence alone in not enough. Sometimes it fails to persuade even scientists, imagine if it can nudge ordinary people. We need a whole array of strategies to face down widespread prejudice and biased beliefs. And you need to bring politicians into the equation. This is true for CO2 emissions, but also for cancer therapy, or any science policy.
In the case of climate change, we are in the process of realizing that policy stances have hardened and polarized according to party preference rather than scientific evidence. The latest IPCC report is starkly clear about the time we still have at our disposal to mitigate climate change. We don't have a lot and wasting it in partisan strife could prove fatal. The key argument should be that we have a narrow window of opportunity: the next fifteen years will be decisive. The comparison with an insurance policy is straightforward: if you wait too long to sign it, it could well be worthless. In fact, over the next decade and a half we have to start cutting greenhouse gas emissions, which have conversely grown at a rate of 2.2% p.a. over the last decade, thus doubling the rate of growth with respect to earlier decades. This means that we have gotten worse exactly at the time we should have gotten better. But we still have an option ahead of us, if we stop investing in fossil fuels.
If we take the virtuous path to climate mitigation we will incur a cost, but such a choice is likely to keep the growth of mean global temperatures under +2°C with respect to pre-industrial values. If we don't take this road, given the inertia characterizing atmospheric phenomena, and the irreversibility of investment plans for next decades, we are likely to induce a jump in global temperature higher than the critical +2°C threshold.
But what does it mean to reign in emissions in practice? All energy-intensive sectors (industry, agriculture, transportation) must do their part in cutting emissions. And in addition to supply-side interventions, there should be policies targeting demand through technological innovation. And if these moves proved fatal also for those corporations (and countries) who have built their might on fossil fuels, such a loss would be at least partly compensated by economic and employment growth in other industries (e.g. the IT management of energy demand).
The transition out of coal and oil would still be costly, though. The IPCC is projecting scenarios that factor in aggressive decarbonization policies, and calculates their cost in 1-4% of forsaken consumption from here to 2030. Opinions about how humans are actually capable to halting climate change on the planet vary widely. Economists are trying to give a market-based, thus efficient, answer to the question, but in the end the civilizational response that prevails, will do so for ethical reasons and cultural reasoning, rather than simple cost/benefit analysis. Although the latter would be preferable, most of the potential impacts of climate change are hard to calculate in monetary terms (and some of them cannot even be presently imagined), so that a purely monetary evaluation of the problem risks missing the point.
No matter your take on the issue, our civilization will have to take a stance. It will have to decide soon whether to continue in risky behavior that is altering the global ecosystem or, conversely, accept the fact that economic growth is constrained by ecological limits. If the latter position should prevail in younger generations, then having forsaken a small fraction of growth to make this feasible for them is going to look really smart in the near future.