When asked to give examples of sustainability challenges, I avoid obvious examples such as climate change and the collapse of oceanic fisheries, focusing instead on public healthcare and pension provision. In both areas, we see growing intergenerational tensions.

Take China. The Center for Strategic and International Studies in the US warns that by 2050 China will have more than 438 million people aged over 60 and that more than 100 million of them will be 80 or over. By the mid-century China will have only 1.6 working-age adults to support every person aged 60 or above, compared with 7.7 as recently as 1975. As a result, Shanghai is now encouraging eligible parents to plan for a second child.

The ruling Communist Party largely decides on such matters in China. In democracies, one industry often overlooked when it comes to long-term thinking is the insurance sector. London is the world's second-largest insurance centre, employing more than 300,000 people. So how is the industry doing on sustainability issues?

It depends where you look. In the US, the Obama administration is struggling to get a grip on the healthcare industry. Critics warn that insurers push up healthcare costs, refusing to pay out when many patients get sick—and, even more troubling, "buying" politicians through lobbying and other even less savoury practices.

Even so, healthcare and pension issues pale when compared with climate change—which, in a recent Ernst & Young survey, topped the list of 10 strategic threats to insurers. In Europe, happily, reinsurers such as Munich Re and Swiss Re are taking climate change seriously and pressuring those they insure to do so, too. But Shanghai's relaxation of the one-child policy signals a potential collision between rival interests of decision-makers.

To relieve the pressure on younger generations forced to shoulder a growing burden in terms of pensions and care of the elderly, governments may encourage population growth, but this risks destabilising our climate. Insurers and politicians have yet to spotlight this tension publicly, but hopefully it is only a matter of time.

John Elkington is co-founder of SustainAbility (www.sustainability.com) and Volans (www.volans.com).