CLIMATE CHANGE: what does it mean?

What Does it Mean for Humanity?

Five years ago, when I wrote this book, I was more focused on bringing clarity to the debate, at a time when most discussions on the issue of climate change were largely emotional. Accordingly, I titled the book, Climate Change: What does it Mean? Now that the debate is largely behind us, the question we should be asking is what does climate change mean for humanity?

Human life on earth is said to have begun with homo erectus, about two million years ago, when it branched out on a separate evolutionary path from the other great apes. But during this period, our Earth went through twenty distinct ice ages, each lasting roughly 100,000 years. The last one started about 100,000 years ago, and so the next one should be just around the corner. But that corner could be another century or millennium away. It's well beyond our future and that of our children to concern us.

The question we should be asking is, how did our ancient ancestors cope with the last ice age? It's well known that the great apes and our ancestors originated in Africa, which has been largely unaffected by the ice ages. The northern hemisphere, which contains the largest part of the land mass, was under ice sheets for most of the time and suffered the worst of the climatic changes. So, when our ancestors started migrating out of Africa, about 200,000 years ago, their range of travel to Europe and Asia was at the maximum during the interglacial periods, which typically lasted about 10,000 years. As the ice receded our ancestors moved north, and when the ice descended they moved south.

The last ice age ended about 10,000 years ago and provided our ancestors a period of relative climatic stability. Prior to that, annual average temperatures in the northern hemisphere were marked by wild swings, as much as 15C in a single decade. It was this stable climate that allowed our ancestors to settle down, grow their own food and live in cities. Writing was invented and culture developed. In short, they became civilized!

For the first time in 10,000 years, we're starting to ask the question of whether that period of stability is in jeopardy. We're concerned about temperature changes of 1C over the course of this century, but this pales in comparison with those that occurred in the past.

Anthropologists have estimated that only a few thousand humans remained on earth 70,000 years ago after an event, most likely the explosive eruption of the Toba volcano, in Indonesia, which caused temperatures to drop rapidly around the world, including Africa, were our ancestors managed to survive. If a change of that magnitude were to occur during this century, how many of the eight billion people would survive?

Most people seem to be concerned about increasing temperatures, but we could be facing a sharp temperature drop. The core samples that scientists have taken and analyzed from various locations around the world show that temperatures are just as likely to drop as they are to rise. The events that give rise to sudden temperature changes are known as Dansgaard-Oescher events, named after the scientists who first detected them in the data from Greenland ice cores, but were later detected in all other cores. In the last 100,000 years, 25 such events occurred, averaging one every 4,000 years. While the cause of these large and rapid temperature fluctuations are not known with certainty, they seem to take place with some degree of regularity. Given that we're near the end of the interglacial period, the next Dansgaard-Oescher event could well precipitate a sudden temperature drop. Fortunately for us, we won't be around when it happens, for the human population will be decimated and a new cycle will begin.

In the context of the large temperature cycles reported by Dansgaard-Oescher over the last 100,000 years, our concern about global warming, and the need to prevent it at all costs, is rather moot. There's no question that we have altered our environment in innumerable ways, including unprecedented levels of greenhouse gases, but even greater climatic changes occurred when the human environmental footprint was tiny compared to now.

In the five years since the Paris Accord, many hare-brained schemes have been proposed to save humanity from impending climatic disaster. But the proponents seem to forget that we've been fighting nature continually to alter it to our desires, and the more we fight it, the more damage we cause. Is it possible that we're too smart for our own good? Are we tilting at windmills?