It's only ever the excuse for economic planning which changes

Time was when that scientific socialism was going to make us all richer though planning - eliminating that waste and competition of undirected free markets. That one worked so well as 1989 showed. Sadly though, the passion for planning remains, it's only the excuses which change:

The Climate Change Act should now become the model for the new sustainable economy act. At its core would be a legal requirement on the government to set environmental limits, and to produce economy-wide plans to achieve them. Over time these limits should include air pollution, soil degradation, resource depletion, plastics pollution and biodiversity loss. All together they would bring the economy within a sustainability constraint.

For each major environmental impact, the act would establish a long-term goal and require the government to set shorter-term targets and plans. So, for example, the 25-year goal of eliminating non-recyclable plastics would be implemented through a series of five-year plans to cut plastic waste by a specific number of tonnes. A long-term goal of restoring biodiversity to, say, a 1980 benchmark would be implemented through successive five-year targets for individual declining species.

The goals and targets would be based on the advice of an expert and independent sustainable economy commission, modelled on the climate change committee, which would in turn report to parliament.

The logical mistake being made here - over and above the one that planning doesn't in fact work - is the failure to realise that the environment is not an absolute good. Sure, we'd prefer not to choke the whales, we'd like not to boil Flipper and we're eager the beasts of the fields  multiply. But how much would we prefer, how much would we like, how eager are we?

That's a balancing match there. For our other consideration - among many others perhaps - is human utility. That we 7 billion of us get to enjoy this life and planet to the maximum amount we can without actually bursting from the joy of it. We therefore need to understand the cost of the varied desirable things.

Fortunately we have a method to do that. Those markets so derided in fact. Yes, it's true, there are some things which markets don't contain - the answer is to put them into markets with Pigou Taxes. Absolutely not to try and plan, even the Stern Review pointed out that that was the wrong way to do it.

Crowbar the price system if we must, but how much pollution, resource use, biodiversity, we have is an outcome of the rest of the world, not a plan which can be imposed upon it.