Prof. John Beddington at Green Monday

I spent a most enjoyable evening at Green Monday, the monthly networking event organised by the 2degrees network and Green Business Events. Keynote speaker was Professor John Beddington, the goverment's Chief Scientific Advisor. Surprisingly, he talked less about green issues than about urbanisation and food security, although it soon became clear that these issues are closely connected with climate crisis.

Currently, 47% of the World's population lives in an urban environment, and this is expected to increase to 60% by 2030. Meanwhile, the population is increasing by 6 million people per month and migration from rural to urban areas is increasing fastest in the developing world (in fact, migration from urban to rural is the rule in many developed countries). This is partly driven by changing rainfall patterns, which have caused a 20% reduction in agricultural output according to the Hadley Centre.

Efforts to alleviate global poverty are working - which is, of course, a good thing. But there's a trade-off. The World Bank calculated that in 2005 250 million households had an income greater than the equivalent of £8,000 sterling per annum - not a massive amount but well above the poverty line in most developing countries. It predicts that the number in this income bracket will be 2 billion households by 2050. And as these people acquire more disposable income, they will increase demand for certain products.

So what does all this mean? Well, the arrival in the cities of these newly affluent individuals will put increasing pressure on the food and water supply. Water is currently a free good in these areas, but increasing scarcity and demand will make it a tradable commodity and cities will compete against farmers - and the wealthier cities are likely to win. Without sufficient water for irrigation, food production will be compromised in currently fertile areas, accelerating the rate of decline in food production. Demand for food is expected to increase by 50% over the next 20 years; the conflict is clear.

Climate crisis is now a widely accepted phenomenon and the debate has moved on from whether or not it exists to what we should do about it. But even if we fail to prevent global warming, the full consequences could take decades to manifest themselves. Meanwhile, subtle changes in the weather pattern are being exacerbated by urbanisation to create food security issues which are already being felt and which will become critical within our lifetime.