Boris Johnson demonstrated his neo-liberal credentials once again in his latest Daily Telegraph column by suggesting that the slogan for the G20 protestors (or “the G20 mob” as he prefers to call them) should be “What do we want? Free trade!” My response would be “Jobs, justice and climate” – the banner under which tomorrow’s G20 demonstration in London has been organised.

The dual challenge for the G20 Summit, the main thrust of which is a major fiscal stimulus and banking reform to counter the global recession, is to promote economic recovery without further damaging the environment and to limit the impact of the economic crisis on the developing world.

It is crucial that development assistance should be maintained, at a time when aid and Foreign Direct Investment have fallen and the populations of developing states increasingly rely on money transfers from migrants in the developed world.

Also, the developed world must keep to its commitments made at the 2007 Bali conference on climate change, in preparation for the negotiations over the post-Kyoto agreement in Copenhagen at the end of this year – that is, to trim our own lifestyles while allowing poorer countries to develop without strings and conditions, and assisting them with technology transfer and innovative finance.

As Nicholas Stern and his colleagues have recently pointed out (in An outline of the case for a ‘green’ stimulus), in the developed world the best way to boost employment during a recession while at the same time reducing carbon emissions is to invest in new green industries like renewable energy projects. We should put more money into energy efficiency rather than exporting our waste to the developing world.

Examples already exist. In the USA, Obama’s economic package proposes to put billions of dollars into green jobs. A third of China’s recovery programme is in creating green jobs. And Germany is directing 19 per cent of its recovery expenditure into new green industries.

London needs to show that we can do this as well. With just over 50 per cent of humanity now living in cities, which are responsible for 75 per cent of CO2 emissions, we could make a real difference. The commitment of our current Mayor to the ideology of neo-liberalism is of course a major obstacle here.

That said, the main show at the G20 will be Obama’s first meeting with the Chinese premier. At the end of the day, it’s the G2 who will determine what really happens to the world economy.