Suppose I am right and our grandchildren find that we were greatly exaggerating the risks, and underestimating the benefits of CO2.
Suppose they do indeed experience carbon dioxide levels of 600 parts per million or more, but do not experience dangerous global warming, or more extreme weather, just a mild and decelerating increase in global average temperatures, especially at high latitudes, at night and in winter, accompanied by spectacular global greening and less water stress for both people and crops.
Does it matter that our politicians panicked in the early 2000s? Surely better safe than sorry?
Here’s why it matters. Our current policy carries not just huge economic costs, which hit the poorest people hardest, but huge environmental costs too.
We are encouraging forest destruction by burning wood, ethanol and biodiesel.
We are denying poor people the cheapest forms of electricity, which forces them to continue relying on wood for fuel, at great cost to their health.
We are using the landscape, the rivers, the estuaries, the hills, the fields for making energy, when we could be handing land back to nature, and relying on forms of energy that nature does not compete for – fossil and nuclear.
But there is a further reason why it matters. Real environmental problems are being neglected. The emphasis on climate change as the pre-eminent environmental threat means that we pay too little attention to the genuine environmental problems in the world.
We bang on about ocean acidification when it is overfishing and run-off that is most hurting coral reefs.
We misdiagnose climate change as the cause of floods when it is land drainage and urban development that is the cause.
We claim climate change as the cause of extinctions, when it is invasive species that disrupt and damage ecosystems and drive out rare species.
We say climate change is a threat to air quality, when it is climate policy that has hindered progress in improving air quality.
We talk about losing seabird colonies to warming seas and then build wind farms that slaughter the birds while turning a blind eye to overfishing.
Here’s why I really mind about the exaggeration: it has downgraded, displaced and discredited real environmentalism, of the kind I have devoted part of my life to working on.
I have worked on wildlife conservation projects in India, Pakistan and elsewhere. Climate change is the least of the problems facing birds like the western tragopan, the lesser florican, the cheer pheasant and the grey phalarope, rare species that I once studied and published peer-reviewed papers about.
The climate obsession has used up money and energy and political will that could have been used for getting rid of grey squirrels, for protecting coral reefs, for preventing deforestation and overfishing, for weaning the rural poor in Africa off bushmeat and wood fuel.