By Martin Wolf

We live in a positive-sum world economy and have done so for about two centuries. This, I believe, is why democracy has become a political norm, empires have largely vanished, legal slavery and serfdom have disappeared and measures of well-being have risen almost everywhere. What then do I mean by a positive-sum economy? It is one in which everybody can become better off. It is one in which real incomes per head are able to rise indefinitely.

How long might such a world last, and what might happen if it ends? The debate on the connected issues of climate change and energy security raises these absolutely central questions. As I argued in a previous column (“Welcome to a world of runaway energy demand”, November 14, 2007), fossilised sunlight and ideas have been the twin drivers of the world economy. So nothing less is at stake than the world we inhabit, by which I mean its political and economic, as well as physical, nature.

According to Angus Maddison, the economic historian, humanity’s average real income per head has risen 10-fold since 1820.* Increases have also occurred almost everywhere, albeit to hugely divergent extents: US incomes per head have risen 23-fold and those of Africa merely four-fold. Moreover, huge improvements have happened, despite a more than six-fold increase in the world’s population.

The remainder of this column can be read here. Debate from our panel of economists appears below.

December 19, 2007 6:45am in Climate change | Comment