Where I live, coal was so abundant near the surface that you could have dug a hole in your garden and found it lying there. This coal was laid down during the carboniferous period when Bristol was somewhere over the Equator and the ecosystem was abundant with life. This coal is fossilised life.

Yet walk a few streets north-west and you find a band of red sandstone. By this time in its geological history, Bristol had drifted north towards the Tropic of Cancer and the area had become desert. No more fossilised life, no more coal – just scorched sand. Carry on further north and carbonate limestones return. The desert receded and life came back.

It is hard to imagine down-town Bristol as a rainforest. When it was rainforest, it would have been even harder to imagine down-town Bristol as a lifeless desert (jokes aside about abandoned department stores).

These changes happened over millions of years. What’s key is that when you are in one state it is very difficult to imagine that it could be anything different.

What if the state we lived in now were a desert-like version of a much richer place? And what if, unlike the geological example, we could help it return to that thriving state?