It’s much easier to solve imaginary problems than real ones, which explains why the current Government is highly concerned about low levels of debt, and relaxed about high levels of greenhouse gas emissions. Since 1950 our national debt has fallen from 100 per cent to 14 per cent of GDP. Our greenhouse gas emissions have risen six-fold over the same time.

Bizarrely, while most politicians understand that current levels of debt are low, they are determined to focus our attention on what might happen in 40 years’ time. The long-run cost of ageing, the long-run consequences of small deficits, the impact of demographic change on labour force participation – if we care about future generations, then we must act now.

When it comes to climate change it seems the opposite is true. If our emissions and the population keep growing, and we double our coal exports, scientists say we will fundamentally change the climate in dangerous and unpredictable ways. But to those politicians, that’s not our problem. That’s a problem for future generations to solve.