Climate and humans: the long view

Professor Clive Finlayson
Director, Gibraltar Museum
BBC News 24 Dec 09;

We seem preoccupied today by looming predictions of imminent climate change.

This is understandable as our lifestyles and lives appear to be coming under threat from this global phenomenon of unprecedented scale.

But if we were to use the deep history of this planet as our yardstick, the unusual thing would be for our climate to remain immutable.

Earth's climate has always been in flux and the last 10,000 years, which in relative terms have been fairly stable, are not the rule.

In those 10,000 years we have gone from hunter-gatherers to farmers, industrialists and travellers in cyberspace, seemingly safe within the cocooned illusion that climatic stability was the way of the world.

Human imprint

And all the time, the deadline for the next climatic downturn, leading to the next Ice Age, was getting closer. It gets closer every day that goes by and our science cannot predict when this will happen. But happen it will.

We became increasingly uneasy as we began to realise that the effects of the industrial revolution had, over the last two centuries, generated new variables that were complicating an already complex multivariate, multi-scale, melee.

The debate then centred on how we could distinguish our own imprint on the Earth's climate from the background gamut of natural factors that generated climatic variability.

And we came to the conclusion, after a long-drawn debate, that our mark could be picked up, appearing like a curved hockey stick on a graph of temperature against time.

The "hockey stick" spoke of warming not cooling. Perhaps a new Ice Age would come, but in a remote future that was not worth considering.

Perhaps our own brand of global warming would counteract it. But the imminent danger would be the warming of the planet.

We should be under no illusion as to the effects of global warming, natural or man-made. It will change the face of the planet even though we don't really know where, when or how, in any kind of detail.

But natural climate change has altered the face of the planet many times before, and in far more dramatic ways. Even the rate of change expected today is not outside the limits of natural change.

Climate swings

The 40-odd thousand years leading up to the last Ice Age included countless wild and sharp climatic oscillations that would have provided the most sensational of world headlines had our Neanderthal cousins had satellite television, mobile phones or internet.

The regularity of drastic climate change would soon have offered little by way of breaking news.

So, in terms of the well-being of our planet, little of what is coming will scare it. It has seen extreme global warming, as when tropical forests covered the poles, and extreme deep freezes, as when icebergs reached the latitude of Lisbon, Portugal - with strays drifting into the Mediterranean.

The difference with this one, and we should be open and honest about it, is that it will affect millions of people. Our own history, and that of our Neanderthal cousins and our predecessors, has been shaped by climate change and luck.

Our population was so small that being in the right place at the right time, or the wrong place at the wrong time, really mattered.

The Neanderthals, who had been so successful in Europe for much longer than we have been around, vanished because of too much global cooling.

Many of our own stock - and this may surprise people - also went extinct because they couldn't handle the climate and its effects.

Several small populations, in Africa, Australia and on the plains of central Asia, scraped through and we are all descended from them.

No living human has experienced the kind of climate change that they had to go through. Most perished but a few survived.

Clive Finlayson is director of the Gibraltar Museum and author of the book "The Humans Who Went Extinct. Why Neanderthals died out and we survived", in which the theme of this article is expanded.