What is the future for the planet, and for climate? Gazing into crystal balls is a pastime that humans have a fascination for. It is also one in which they have a dismal record. A generation or two ago, there were predictions of cities made of glass or plastic, clothes of aluminium or asbestos, flying cars, the fall of nationalism and the rise of world government, the demise of religion, and robots taking over our tasks and ushering in an age of universal leisure for all. So much for all that. When we move, then, to the almost limitless complexities and intersecting feedbacks of Earth’s climate system, one might be forgiven for throwing in the towel straight away. This is a system, we must eternally remember, of which we have only partial understanding, even as we see today’s weather patterns spin off from it. Go back into the deep past, and that climate and those long-vanished weather patterns leave only traces in strata that are, in large part, invisible to the naked eye. And of the future, of course, we have no samples, no deep boreholes, no fossils: the canvas is blank—indeed, as yet there is no canvas at all. Yet, from those ancient stratal traces we can construct a picture of events that is both vivid and (within our levels of uncertainty) true. There is no reasonable doubt that 20,000 years ago massive ice sheets spread out from the poles—or, that 125,000 years ago there was a climate on Earth as temperate, within a degree or so, as the one we enjoy today. So, there are patterns, real patterns that we can use as guides to help us try, with the utmost caution and scepticism, to create pictures, scenarios, sketches of the climate of the future. One might imagine alternative futures—or create them—particularly with the help of those elapsed realities. For instance, one might take that striking five-million year slice of climate history put together by Lorraine Lisiecki and Maureen Raymo (see Ch. 8 ).
Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods
