Children today are likely to reach old age in a world that is 4C warmer, where the 10,000-year certainties of the global climate can no longer be relied on, and widespread crop failures, drought, flooding and mass migration of the dispossessed become a part of everyday life.

The greatest concern is that a 4C increase in global average temperatures – a temperature difference as great as that between now and the last Ice Age – would create dramatic transformations in the world, leading to water shortages, the collapse of agriculture in semi-arid regions and triggering a catastrophic rise in sea levels in coastal areas.

Another concern to scientists is the speed of climate change. A study found that a global temperature rise of between 2C and 4C could be so rapid that it would coincide with the expected peak in global population, which is expected to reach nine billion by 2050 before it begins to fall.

This would mean that the problems of water shortages and food production caused by climate change will occur at precisely the same time as the world is having to cope with feeding the greatest number of people in its history. A slower rate of climate change, on the other hand, will see the highest temperature increases occurring after the global population has peaked.

Niel Bowerman of the United Kingdom's Oxford University, who led the study into the rate of climate change, said it highlighted the urgency of having emissions peak in coming years. "Our study shows we need to start cutting emissions soon to avoid potentially dangerous rates of warming within our lifetimes, and to avoid committing ourselves to potentially unfeasible rates of emissions reduction in a couple of decades time," he added.

(Source: Crop failures and drought within our children's lifetimes [Independent])