Factors which may exacerbate the effects of global warming.

It is a common argument used by those opposed to taking a responsible stance on global warming, to say that the climate has warmed before and that it did not cause mass extinctions then, so why worry. But even leaving issues like degrees and speed of warming aside, it still has to be said that such arguments fall down to a large extent, because of course the world today is not the same place it was in the distant past, due to many other contributing pressures which may make the effects of warming worse.

Soil loss, is an old environmental concern which goes right back into prehistory, but seems to have become less fashionable today. Yet the fact is, that where large parts of the worlds human population lives, you only get one layer of soil ever, when it is gone it is gone. And when we turned to agriculture and began widespread deforestation, it is estimated that the rate of soil loss increased to a hundred times the background rate. There is strong evidence of this from lake sediments where the onset of human changes to the environment are often clearly visible, with a increase in deposit of a hundred times easily measured. This famously happened in the subtropics and Mediterranean regions where deforestation resulted in the lose of vast areas of cultivatable land in classical times, though there is some evidence that the effects may have been overstated. Yet it still moves forward, and it means that without forest or crop cover the ground absorbs much more solar energy in many places, and it is much harder to regrow forests as carbon sinks, plus it creates more demand for agricultural land to feed our growing populations and more fossil fuels to make those lands produce more.

The other factor is the fragmentation of habitats, in the past whenever climate change took place, plants and animals were able to move slowly to new areas. Following the climate zones they preferred as those zones moved. But today the human population has craved up many of those natural corridors with urban and agricultural developments, and most habitats are fragmented. Making the migration of many organisms especially micro- organisms and plants in some cases almost impossible.

There are of course many other factors at work, which add to the problems. But I wanted to highlight these too especially, because they are real, but in recent years they seem to have gone out of fashion as concerns, in the face of our justified preoccupation with global warming itself. Yet no one factor ever works alone..