Dams have been thought a good way of reducing greenhouse gas emissions while satisfying our ever-increasing demand for electricity. Indeed, dams built in cool, dry places probably do reduce emissions per watt compared to fossil fuel generation. So, in 2012 the Intergovernmental Panel on Climate Change (IPCC) said that, taking into account construction and operation, hydroelectric power produces less than 3 percent of the warming of fossil-fuel power plants that burn coal, oil or natural gas. But, as Daniel Grossman writes:
That is true for some dams, such as those built in relatively cool, dry places with relatively little vegetation, which rots and turns into greenhouse gases. But the IPCC report ignored dams built in lowland tropical forests, where luxuriant jungle produces an unusually large amount of emissions. Daniel Grossman, the Sunken Rainforest, 'New Scientist', 21 September
In tropical dams, microbes digesting submerged trees produce methane as well as CO2. An expert based in Brazil says that "hydroelectric dams in
tropical lowlands are a climate disaster."
Why do we continue to make policy about systems that are too complex for us to understand? Partly it's historical. A century or two ago the link between the cause of a social or environmental problem and its effect would be more obvious. Effective policy could be made accordingly. But today the complexities have grown so profoundly that even the direction of causation isn't always clear. Policymakers, though, still make policy based on hunches or scientific knowledge that necessarily becomes out of date.
My suggestions is that, instead of making policy about complex but important issues as if we know what's going on, we should target outcomes, rather than the ways in which most experts currently think is the best way of achieving them. So, instead of targeting, say, 'proportion of electricity generated by renewable resources', we target for reduction the negative impacts of adverse climatic events. A Climate Stability Bond regime would leave it up to motivated bondholders to work out the most efficient ways of achieving our climate goal; and they would do so in ways that both generate and act on the basis of rapidly expanding scientific knowledge. They would have incentives to look more closely and on a continuing basis at, for example, where dams can help achievement of our goal and where they would hinder it.
The Social Policy Bond principle would stimulate, diverse, adaptive iniatives: projects that would take into account the differing and changing circumstances that any single conventional body, such as government at any level, just cannot.
Overwhelming complexity doesn't just affect big global problems. Here, Dr Malcolm Kendrick writes:
[I]n truth, almost all diets are perfectly healthy. Vegetarian, paleo, keto, vegan (with a few essentially nutrients thrown in, so you don’t die), HFLC [High Fat Low Carb], etc. In fact, the only non-healthy diet would be the one recommended by all the experts around the world.Namely, High carb, low fat (HCLF). The ‘eat well plate’, ‘the food pyramid’ – whatever it is now called. Stay away from that, and you will be fine. What causes heart disease (blog) part 65, Dr Malcolm Kendrick, 23 September
Government and their scientist advisors, would serve us better by showing a bit of humility. Targeting outcomes, rather than the ways they currently think we'll achieve them, would be a good start.