“‘Sustainable intensification’ is likely to be code for ‘second wave of GM’ with a promise of less land take and more room for biodiversity. But in practice intensification over the past 60 years has been a pretty extensive affair – reflecting growth in population and consumption levels. One can only believe in less land take and less damage to biodiversity if new wave intensification goes hand in hand with a lot of planning and conservation policies that are not to do with food.

Aquaculture is touted as a great form of SI but a lot depends on the fish in question. Much of the time farmed fish need to eat wild fish, which defeats the point of aquaculture as a means to relieve pressure on wild species. Conceivably we could have GM farmed fish engineered to be vegetarian. That might be intensive and sustainable, but whether it would go down well with environmentalists and consumers is another matter. And the same goes for high-rise super-factory farming: it could be sustainable in the sense of being low in carbon, relatively speaking, but it might not be good for animal welfare or waste.

Urbanisation is regularly seen as a positive development for the environment on a global scale, but the idea that concentrating people in cities means less pressure on hinterland environments does not always stand up. So much depends on capacity to import, capacity to grow food in cities, ability of the urban poor to afford food, enforcement of planning rules, etc. Rapid urban growth and urban poverty tend to mean more pressure on food suppliers and biomass in the urban hinterland.

The water issue is enormous. Recent work indicates that the biggest waste water impact in the UK comes from the embedded water in discarded food from households etc. (There is also a big carbon load in waste food).”