I went to the Sustainable Food Cities Conference in Bristol last week. I’ve written about the thought-provoking session on food poverty I heard here.
I had many interesting conversations there, but some of the themes of the conference seemed to me to be wildly off-beam, possibly dangerously so, given the food security challenges we’re facing.
Unlike the Warwick Climate Forum 2015 I went to earlier this month, the talks and many of the corridor conversations in Bristol about sustainable food supplies for cities were about community food growing, passion and inspiration. 
Don’t think for a nanosecond I don’t think urban food growing a Good Thing. It is. And for all sorts of reasons, some of which I’ve outlined before (see How self-sufficient can Birmingham be? Should we even bother trying?)
But fruit and veg patches, community orchards, even the odd flirt with hens or a few sheep on an urban farm has diddley-squat to do with providing a city population with enough food to eat. Or even supplying enough food for a single allotment holder reliably in the summer and autumn, let alone throughout the year.
It’s widespread, this view that all we have to do is persuade communities to grow their own fruit and veg, experiment with acquaponics, do more than admire architects’ drawings of vertical farms or get local authority procurement officers to tick the right ‘sustainable’ boxes on supplier contracts.
There are, however, people who grapple with the real challenges in growing and distributing enough food for all of us. They work in places like the FAO, the Oxford Martin School, DEFRA, Rothamsted and the BBSRC. And yes, in our big supermarkets and other Big Food companies.
Malthus, but for technology, rules. And yup, the technology both enables us to eat and depletes our soils, pollutes the atmosphere, is unfair in its distribution, wastes a load, makes us unhealthily fat, etc etc . . . and may well not enable us to feed all the world’s growing population. But Malthus rules.
This is where, I’d argue, focus should be in any and all conversations about sustainable food for cities.
The New Optimists based What it takes to feed the city (Part 2 of the Birmingham 2050 Scenarios Report) on the then-latest scientific research, and the UK’s Global Food Security Champion, Professor Tim Benton was kind enough to comment on drafts of the report.
Worryingly, though, the research and thinking that characterises these people is seen sometimes as just another perspective, rather than the best evidence we have at the moment, stuff that needs to underpin our decision-making.
So how can we get over to people the scale of things to feed a population? Here’s one way:
Calories are (comparatively) easy to grow, easy to manufacture. Yeah, I do realise we require more than calories for a healthy diet, but calories are a useful illustrator for this argument . . .
If each person on average consumes 2K calories per day, then a city of 1M inhabitants such as Birmingham, needs a supply of two billion calories a day. Today, tomorrow and every day thereafter. (We actually consume over 3K per day on average, but that’s another story.)
All of humanity? All 7 billion of us? 14 trillion calories a day. 5110 trillion calories a year. Sustainable Food Cities starts with a numbers game. It’s the sheer scale of the challenge that we need face.