Before you start shouting at your magazine, don’t worry, you’re not going to read that I think climate change isn’t happening or that human beings aren’t contributing to it. However, I am going to try to show that the version of climate change that we are always being shown may not be all that we should be thinking about.
If you look at the timescale over which human-influenced climate change has been happening – and compare it with geological time – it is such a tiny period. However, people do not live over geological time periods, so it is natural that we concentrate on the present, with little regard for the past. In fact, with today’s human influenced climate change taking up all of the limelight, anyone would think that climate change was solely a human invention and that before the industrial revolution, the climate had been stable. But this is not the case.
A quick glance at Fig. 1 shows massive changes in average global temperature across the millions of years of geological time. The y axis of the graph shows change in average world temperature when compared to today, with the last 150 years’ average world temperature shown as 0oC of change. Immediately, one huge change in temperature can be seen to have occurred between 400 and 300mya, when global temperatures dropped from approximately 6oC above today’s average to about 1oC below. Then, following subsequent fluctuations, both up and down, there was another huge change in average global temperature between approximately 55mya, during the Eocene, and 500,000 years ago, during the Pleistocene. In these cases, global average temperatures fell from approximately 6oC above to 2oC below today’s average global temperature.
It would appear that the world’s temperature then settled down somewhat, but if we examine the graph more closely, we discover two more y axes with different scales to that on the far left. These y axes show that what look like smaller fluctuations as time goes on are actually just as large as the fluctuation between 400 and 300mya. For instance, between approximately 55mya, during the Eocene, and approximately 34mya at the very beginning of the Oligocene, global average temperatures dropped from approximately 12oC above today’s average to only about 1oC above. Then, between 6mya and 500,000 years ago, there was a steady drop in temperature, from 2oC above to 6oC below. Since then, the majority of the time has been spent well below today’s average, with only the increasingly small scale of the graph’s x axis creating the appearance of stability.
So, large changes in the Earth’s climate have taken without man’s influence and will continue to take place whether or not man causes them. This we cannot avoid. However, man – like most other creatures – thrives on stability and relatively small changes in average global temperature will cause us huge difficulties.
Currently, we’re all concerned, to various degrees, about global warming, but it is global cooling that worries me. If we look at the Earth’s average temperature during the Quaternary, over the last 2myrs, huge temperature fluctuations can be seen to have occurred in regular cycles. At a closer resolution, as seen in Fig. 2 over the last one million years, evidence from myriad sources and techniques shows an approximate 100,000 year cycle, with 80,000 to 90,000 years of the cycle being cold or glacial, and 10,000 to 20,000 years being warm or interglacial. From Fig. 2, it can be seen that during this time, the cold periods have been the norm, with the warmer interglacials being mere quick spikes within these. An interglacial is what we’re in now; and we’re due a glaciation.
Of course, it cannot be argued for sure that the sequence of glacial and interglacial periods will carry on in this vein. For instance, before the Quaternary, the climate was more stable and now man’s influence may have an effect. But if you compare our impact on our planet to the celestial dynamics of the Earth’s tilt and wobble, and its orbit around the sun, our meddling may end up proving quite insignificant.
Everyone knows of the prime concerns associated with global warming – principally that the world’s low lying areas will become flooded, along with many of the world’s large urban areas; that climates will change, and that we will have more extreme weather. But what if global cooling occurs?
Looking at the northern continents, at the last glacial maximum (when the ice caps extended their furthest south), all of Northern Ireland and about two thirds of Southern Ireland were covered. Scotland was under ice, as was nearly all of Wales. The ice sheet extended into the English midlands and over the whole of Scandinavia, while North America was at least half covered by its own ice sheet (see Fig. 3).
There must have been much hardship among people and animals when a glacial period began. All would have had to migrate south to warmer areas, into habitats already occupied. There would have been fewer natural resources to go round and the areas that humans and animals migrated to may not have fully suited them.
Just imagine if a glaciation were to happen now. All human traces in the above mentioned areas would be obliterated by hundreds of metres of ice, crushing, scouring and destroying. Everything that man has striven to build and create would be wiped out. Extending south from the great ice sheets would be hundreds of miles of permafrost, where the soil would be permanently frozen. Again, the effect on our infrastructure, buildings, everything, would be catastrophic. And a much reduced ecosystem would survive.
If you currently live in an area that was glaciated, you are probably well versed in the glacial features in the landscape that evidence this extreme cold. ‘U’ shaped valleys, moraines, corries, boulder clays and so on are clear to see if you know what to look for. If your area fell into the permafrost zone, evidence is harder to find, but you may still be able to some in the sediments at the surface. For instance, ice wedges can sometimes be observed, where water worked its way into cracks and froze, forcing them apart. This would then allow more water in and the action would be repeated over and over again. These wedge shaped cracks eventually became filled with sediment when the ice finally melted, leaving a ‘fossil’ ice wedge. Looking at one of these wedges ‘in the flesh’ makes you realise just how different your neighbourhood was in the not-so-distant past (see Fig. 4).
If another glaciation occurs, all inhabitants of areas covered by ice caps or turned to tundra will be forced to migrate south, but would the southern regions of the Northern Hemisphere be able to support them? And would the people already living there accept them? My guess for both is ‘no’. It seems ironic to think of Americans streaming across the border into Mexico or anti-immigration Brits looking to move wholesale into other peoples’ lands. I envisage huge conflicts, almost certainly a World War III based on a genuine need for ‘living space’. And man will be governed by the same rules that all organisms live by. If you have overproduced and your environment can no longer support you, your numbers will be reduced. A chilling thought.