We are creatures of climate change: it made us and it might break us. What do I mean by that? The study of both human evolution and past climate change have both accelerated dramatically recently, and the connections between the two are becoming clearer.
It was almost certainly climate change in Africa from around 5 million years ago that led to the emergence of a line of adaptable, big brained apes. In long-term steady climatic conditions, living things can persist essentially unchanged for many millions of years. But large scale climatic change with mass extinctions produced the great innovations in evolution, such as the emergence of mammals following the Cretaceous collapse that ended the dinosaurs’ reign.
What happened in East Africa from 5 million years ago was less extreme. The climate became drier and the forest thinned, opening up the savannah we are familiar with today as the home of big game. An ape adapted to the loss of a supportive forest habit by learning to live in the open, on the ground. To survive amidst the large predators of the savannah required enormous cunning: the use of fire and tools. Over those 5 million years the African climate was unstable, with wet and dry periods alternating. It is this flux that probably led to the most adaptable species on earth: us.
By around 200,000 years ago an ape with a brain 3-4 time the size of a chimpanzee was established in Africa. I say established but life was precarious, the environment still hostile. Homo sapiens eventually spread beyond Africa. How tough it was know from the timing. They only arrived in Europe around 36,000 years ago.
During the entire period of the evolution of H. sapiens Europe was in the grip of repeated ice ages. At the last glacial maximum, around 20-25,000 years ago, Europe was covered in ice almost to the Mediterranean. Human populations clung on in Southern France and Spain. The Neanderthals, the last proto human before us became extinct at this time. Their last stronghold is thought to have been some caves in Gibraltar.
But 11,600 years ago, the world warmed dramatically, by 6 degrees and the ice retreated. There have been serious climatic setbacks since then but in the last 10,000 years a Northern hemisphere ice-free over much of its landmass allowed agricultural societies to grow and develop.
But instead of recognizing that our great world civilisation owes as much to climatic luck as to our brilliant minds and hard work, we arrogantly refuse to accept the evidence that the climate is fragile and will be tipped by our own activities unless we modulate them.
The Intergovernmental Panel on Climate Change’s forecasts have projected gradual change into the future, but the increasingly detailed record of past climate change shows dramatic changes happening at certain tipping points, over very few years. The one we should be worried about is that sudden 6 degree rise that launched our ascent – it took place in around a single decade!
There is every reason to fear that the next serious climatic change will happen as rapidly as those of the past but our widespread assumption that we have our benign place in the sun as of right is preventing any serious attempt at climatic mitigation. All past approaches to get governments and public opinion on board have failed so a new approach is called for. Most people in the developed world have grown up thinking that our technology can insulate us from the worst that nature can do. Understanding that we have always been at the mercy of the climate and that our benign time is over is the required background knowledge for our next step. We don’t want to be the headline species in the Next Great Extinction.