Climate change isn’t something for the future: it is already happening. The longer it goes on the easier it will be to notice these changes without having a specialist to measure it. In virtually every population that has been studied in detail, evolutionary changes have been observed.

There has been a morphological change, for example, in the long-winged conehead bushcricket. Previously they could only fly for short distances, to escape predators.

But because it has been getting warmer in the South of England, where they were confined, they have expanded their wings and can now fly for several hours at a time to cooler areas in the North.

It would once have taken them a week to cross a field, now they can fly for several hours at a time.

In the human population — if you ignore the recent, rapid movement of people around the world — you can also see how size and shape have been influenced by the environment. In different countries, indigenous populations have widely varying body sizes and shapes.

Inuit and Eskimo populations have relatively small extremities, short fingers and compact bodies, because that’s the optimal shape for conserving heat. By contrast, Maasai warriors in Africa have long, large limbs. There are also obvious variations in skin colour.

So are the more rapid changes in climate going to reverse or exaggerate these characteristics? I don’t think so. At the moment the interbreeding between human populations is affecting changes in our appearance much faster than changes in climate could do. If you look at the inhabitants of London, for instance, many individuals already show a mixture of traits.

Cultural and technological changes are also having a huge impact. The arrival of air-conditioning in a hot country can lower the temperature in a building by 15C overnight. And medical advances are lengthening our life span. These things are likely to be much more important than the natural environment in shaping us today.

Professor Chris Thomas is a specialist in biodiversity at the University of York

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