In my blog last week, ‘30,000 Generations’, I wrote about a vision I cherish for long-term human survival, a vision which present global society seems, implicitly, not to have. Of course human could survive if only a few thousand people survived a future crisis, and there have been bottlenecks in the Homo sapiens population before, but I’m sure most people would like to imagine a future where humanity survived without major disruptions.
Today I’m going to write about the most obvious issue that has the potential to affect human survival, anthropogenic global warming.
This is the increase in global temperatures caused by the recent increase in carbon dioxide in the atmosphere. This carbon dioxide is the result of human activities (‘anthropogenic global warming’) . The temperature anomaly due to this from about the 1970s onwards is already approaching 1°C and will continue to increase in the short-term even if CO2 emissions are curtailed. Already many scientist are predicting that the International Panel on Climate Change (IPCC)’s higher estimates of temperature rise (with upper ranges over 3°C) are more likely than lower ones.
Any temperature rise is bad news and the higher the temperature rise the worse the news is.
I don’t propose to dignify global warming denialism with much of mention in this post. Clearly the science has been settled for about 15 years and the only thing more definite in this area than the fact of anthropogenic global warming is the refusal of governments across the world to do anything about curbing emissions. This has been one of the most depressing aspects of life in that period: the clear perception of a problem, the almost complete lack of a response to this problem.
What I want to do in this post is to discuss a couple commonly-heard arguments against a far-reaching policy response to anthropogenic global warming.
The first is ‘the climate has always changed in the past’. True, but whenever it does it causes species to go extinct. Homo sapiens survived an increase in temperature of more than 10°C at the end of the last ice age, but in that time there were only a few tens of thousand of us, we had the entire world at our disposal and we were very mobile. Also, and obviously, the temperature increase was from a global temperature much lower than present, to something like present levels, not from recent average temperatures higher again.
We should also note that we don’t know what the cost was of this adaption process, the archaeological record for the period is so sparse that it couldn’t tell us, for example, if 90% of humans perished.
A better example of what a change in temperature can do is the beginning of the Little Ice Age in Europe. This is a period which began to have its strongest effects in the early C16. The earlier part of mediaeval times in Europe had seen the Mediaeval Warm Period (strongest 950-1250 CE), a period much beloved of denialists because they can argue it was both global and warmer than the present (in fact it was neither). After some centuries of fluctuating weather the Little Ice Age began with a drop of a couple of degrees. Within a century and a half Europe had seen the Reformation and a series of famines, epidemics, and wars (including the 30 Years War) which reduced the European population by a third.
The second is ‘we can adapt’. Again this may be true, but what we need to ask is what form will this adaptation take? will it be a smooth ride with little disruption, or a series of agonising catastrophes with humanity surviving in a few small pockets?
The problem is that global agriculture is not sustainable in its present form even without global warming. Pre-modern agriculture is many parts of the world was not on the European model of continuous cropping of permanently cleared land, but was ‘swidden’, or shifting cultivation, where land was cleared, cultivated until its fertility dropped, then abandoned to natural vegetation again. The traditional northern European model of soils of high fertility, carefully maintained with organic inputs (manure, composting) is not one that necessarily suits soils in other parts of the world which are of lower fertility, and where and heat and high rainfall can leach nutrients quickly.
The area of the world under cultivation and grazing has increase five-fold since the C18 and there is very little further land suitable for cultivation available.
Modern agriculture globally, especially since the ‘green revolution’, is crucially dependent on high levels of inputs, fertilisers and pesticides, and on mechanisation. The productivity of much of the agricultural land of the world would be rapidly be degraded without these inputs, and even with them, cannot be sustained in the long-term. All these inputs are dependent on the petrochemical industry, and this industry is precisely the one which is responsible for the levels of CO2 emissions. Oil is running out. Furthermore, absurd acreages of the world’s cultivated land are also being diverted to crop production for ethanol to replace fossil fuels when the correct course of action should be to develop electric-powered transport as soon as possible. Finally, soils around the world are losing carbon to the atmosphere as a result of unsustainable cultivation.
When we add in global warming we have a further problem: we don’t know how much the temperature will rise by, in what timeframe, and we don’t know for certain what effects a temperature rise will have in particular places. As it is agriculture is being asked to enter a period of change of unknown duration and effects with the other problems listed above remaining unresolved.
In some areas warmer temperatures may be a good thing, I imagine farmers are looking forward to growing wheat further north in Scotland and Scandinavia, for example, but elsewhere it may not be easy to migrate agriculture. Everywhere around the world there will be less available water after global warming. Even in areas where rainfall increases this may not necessarily be a good thing, as higher rainfall can erode soils more quickly.
The two main wheat growing areas of the world, the Great Plains of the US and Canada, and the steppes of Ukraine and Southern Russia, are bound on the north by the taiga, a band of infertile acid soils presently covered in pine trees. This vegetation will migrate north with global warming, but it is difficult to see how extensive wheat growing is expected to migrate to an area of infertile soils covered in dead pine trees without some sort of hiatus, and without massive inputs of fertilisers and fuels to power machinery, at time when, as we have mentioned, these are set to become much more expensive and possibly unavailable.
Presently the world population is 6.9 billion, set to rise to 9 billion mid-century. It will be difficult for agriculture to continue to feed a growing population in the face of its own unsustainability (‘peak soil’ as some have called it), peak oil and climate change.
I have reasonable confidence we can adapt to climate change, what I don’t have confidence in is our ability to perpetuate out current global politics arrangements, including population, intact into the future.
Next week, more on population.