As the threat posed by global warming intensifies, northern governments are building up their climate change fortifications. From lower Manhattan to the Thames estuary, flood defences are being strengthened to protect people from rising sea levels. Meanwhile, millions of the world's poorest people facing the prospect of more droughts, storms and floods are being left to sink or swim with their own resources.Today the Intergovernmental Panel on Climate Change meets in Brussels to draw up its findings on climate change impacts. It's a document that makes for grim reading. Wholesale reversals in human development are in prospect. Yet the rich countries that bear historic responsibility for the threat are failing to invest in averting its outcome.

It is easy to get swept up in the carbon-cutting euphoria of the past few months. The EU has bold plans for cutting greenhouse gas emissions. Britain has gone one better, setting legally binding targets. Greenhouse gas mitigation is set to dominate the G8 agenda in June. The bad news is that even if all industrial countries deliver on the cuts envisaged by the EU, the chances of keeping below the 2°C dangerous climate change threshold are slim, and more extreme weather patterns are all but inevitable.

Britain is already preparing for the worst. The UK Climate Impacts Programme run by the Department for the Environment has drawn up comprehensive threat assessments. Agriculture is being helped to identify new opportunities created by longer growing seasons and warmer summers. Meanwhile, the Environment Agency has a budget of over £800m for flood defences.

Elsewhere in the world, adaptation to climate change poses more immediate dangers. Last year, drought threatened the lives and livelihooods of over 10 million people in Ethiopia and Kenya. Drought will become more frequent as temperatures rise. In Bangladesh and Vietnam, a one-metre rise in sea levels could displace over 40 million people. Beyond the immediate human suffering, events such as droughts and floods can send whole economies into reverse gear.

So, having created the risks faced by developing countries, what is the rich world doing to reduce vulnerability? Not a lot. The current international effort on aid for adaptation is running at a mere £10m-£15m a year for all developing countries. In the developing world, weather disasters are, in many cases, a one-way ticket to a lifelong poverty trap. Almost 500,000 people in Mozambique are recovering from the devastating floods that swept the country in January. The cost of repairing the physical infrastructure is put at £36m.

Of course, there is no proven link between global warming and specific climate emergencies. But climatologists point to a common climate change thread linking the floods in Mozambique to the recurrent failure of the spring rains in Ethiopia.

Justice and moral responsibility dictate that those responsible for creating the climate change threat invest in containing its consequences. Two years ago the Gleneagles G8 summit pledged to double aid for Africa and other developing regions. That falls far short of what is needed to finance an effective response to climate change. Perhaps the Berlin G8 summit could, for example, look at a levy on carbon trading or airline taxes - linking the agendas for mitigation and adaptation.

Northern governments can do nothing, and wait to deal with the consequences of climate change - the food emergencies, the refugees, the health epidemics and the conflicts - through humanitarian aid, mopping up after the event and calling it charity. Or they can act now in a spirit of global justice, and invest in poverty reduction and crisis prevention.

Kevin Watkins is director of the UN's Human Development Report Office; marisol.sanjines@undp.org

© 2007 The Guardian