Population crashes. Mass migration. Vast new deserts. Cities abandoned.

That's the headlines on this week's issue of the magazine New Scientist (28 February 2009). It looks at the latest predictions for the impact of climate change – which are dramatic.

According to researchers such as Syukuro Manabe's team at Tokyo University, we face a future with two dry belts around the Earth, within which human habitation will be impossible.

The belts will develop as a result of a shortage of water. In southern Europe rising temperatures will destroy the glaciers whose meltwater supplies rivers like the Danube and the Rhine. There will be similar effects in other mountainous regions including the Peruvian Andes and the Himalayan and Karakoram ranges.

Warmer temperatures will reduce soil moisture across China, the south-west US, Central America, most of South America and Australia, the researchers say.

All the world's deserts are predicted to expand, and the Mediterranean will have desert regions on its northern side as well its south – deserts reaching up into central Europe.

A warmer world

The changes are characteristic of a world in which the average planetary temperature has risen by 4 degrees C. We are on the way to that. The European Union aims to limit the rise to 2 degrees, but the Intergovernmental Panel on Climate Change (IPCC), whose conclusions are generally regarded as conservative, says that the increase through the century may be between 2 degrees and 6.4. Last August, one of the UK's chief scientific advisers, Professor Bob Watson, warned that we should prepare for a 4 degree increase.

The New Scientist publishes a map which shows what a warmer world may look like – it can be found in interactive form on the magazine's website, along with the full article by Gaia Vince.

One of the big changes on the map of the possible future is the great swathe of green across the north of Europe and America.

The high latitudes are looking like being the best places to live in a warmer world. The huge land masses of Canada and Russia, free from ice, will provide space for many millions of people – as will the ice-free region of Western Antarctica. Scandinavia, the British Isles, Iceland and parts of Greenland will also be habitable – as will the Sahel in Africa, currently semi-arid but predicted to benefit from an intensification of the African monsoon.

Elsewhere in Africa the prospects do not look so good, or in Australia, where habitation will be limited to the far north and west, together with Tasmania. New Zealand, on the other hand, is predicted to have a more habitable climate, and hence a big increase in population and agriculture.

'This will probably be a mostly vegetarian world,' says the New Scientist. 'The  warming, acidic seas will be largely devoid of fish, thanks to a crash in plankton that use calcium carbonate to build shells. Molluscs, also unable to grow their carbonate shells, will become extinct. Poultry may be viable on the edges of farmland but there will simply be no room to graze cattle.'

Switching to solar

One of the main sources of energy would be solar power from vast arrays of solar collectors in the deserts. 'High-voltage direct current transmission lines could relay this power to the cities, or it could be stored and transported in hydrogen – after using solar energy to split water in fuel cells.'

With such technology, there is hope of survival, says the article – 'provided we have the time and willingness to adapt'. It quotes two views on the possible outcome.

'I'm optimistic that we can reduce catastrophic loss of life and reduce the most severe impacts,' says Peter Falloon, a climatic impacts specialist at the Hadley Centre. 'I think there's enough knowledge now, and if it's used sensibly we could adpat to the climate change that we're already committed to for the next 30 or 40 years.'

'I would like to be optimistic that we'll survive, but I've got no good reason to be,' says Nobel prizewinning atmospheric physicist Paul Crutzen of the Max Planck Institute for Chemistry in Mainz, Germany. 'In order to be safe, we would have to reduce our carbon emissions by 70 per cent by 2015. We are currently putting in 3 per cent more each year.'

The author of the New Scientist article, Gaia Vince, is a freelance writer who is travelling the world. Her dispatches on the way are posted up on her own site at www.wanderinggaia.com.