Sunday, 12 December 2010

Is this the end for diets based on winter grain?

Today in West Australia Online, there is news that the predicted bumper wheat crop of New South Wales and Queensland is likely to be decimated by excessive rainfalls. the newspaper claims hope that a spell of dry weather will sooner or later allow the crops to be harvested exists, but I would not become too carried away with such hopes.

The combination of extraordinary heat in the northern hemisphere and quite extraordinary drought in southwestern Australia should alert people to what man-made global warming will do for the human diet in future. It is clear from such old studies as the 1984 “Origin and Evolution of the Mediterranean Vegetation and Climate in Europe” (which unfortunately I cannot get hold of) that mediterranean climates like those of southwestern Australia are absolutely unique to the Quaternary, and that before the Quaternary the transition in rainfall from arid to temperate:
  1. was seasonally uniform
  2. occurred at a latitude where rainfall today is absolutely seasonally uniform on continental west coasts
  3. such a latitude is typically around 45˚ to 50˚ from the equator, or around 15˚ poleward of the current equatorward limit of mediterranean climates
Owing to “super-monsoons” that were far more penetrative and intense than those observed in instrumental records before man-made global warming began to take effect, there was never a dry spell during summer in any humid region before the Quaternary. If man-made global warming is leading in this direction, harvesting of winter crops in the summer will become increasingly difficult. There will also be the risk that in hotter and more humid weather, crops will be more prone to the spread of hot-climate diseases which could lead to the disappearance of winter grain crops.

Then there is the danger that historically very cool or cold regions that could grow winter grain even in a much hotter world would be in demand for housing should those socially progressive nations become in trouble with the collapse of their welfare states from low fertility and their culture’s inhospitality and inability to attract migrants.

All these factors combined could very soon see the world have to change its whole staple food system. Wheat, barley and other mild-climate grains would disappear, to be replaced by less efficient yield-wise but more efficient land-wise hot-climate grain, root and tree crops. In the process, many of our present specialties would disappear, and Australia would be farming foods quite alien to us now!

The question is whether such a system can work given the history of attempts to farm tropical Australia outside of the alluvial and volcanic soils of the Burdekin Delta and most of the Wet Tropics, or whether the variability of climate and resultant high risk in eastern Australia can be better managed in the future is a less hospitable and probably even more variable climate?

No comments: