Thursday, May 13, 2010

Professor Asten, climate change and Australia's Aboriginal peoples

A follow up this morning on developments related to one past post on this blog.

Comments on Belshaw's position on climate change focused in part on the question of the extent to which a non-scientist could challenge or must simply accept the views put forward by mainstream science. Here John Quiggin suggested that I seemed to be setting myself as a judge of whether mainstream science should be followed or not.

I said in a later post that in a practical sense the relationship between professionals (I included scientists here) and managers, policy advisers or clients was a complicated and interesting one. By this I was referring especially to the way technical or professional advice was sought, offered, challenged and used. I also said that the discussion provided an opportunity to extend my writing on the issue.

I was reminded of this still to be written post by an interesting piece in the Australian by Michael Asten, a professorial fellow in the school of geosciences at Monash University. I hadn't heard of Professor Asten before, so I did some web searches. It appears that he is one of the better known climate change sceptics. As an aside, am I right in thinking that geosciences is strongly represented among sceptics?

While Professor Asten's article reminded me of my still to be written post, my reaction to the article had nothing to do with that post or indeed about the climate change debate. To explain.

The Medieval Warm Period (MWP) was a period of warmer climate in Northern Europe that lasted from around 950AD to 1250AD. It was followed by what has been called the Little Ice Age, a period of much colder temperatures.

The significance to the climate change debate appears to lie in the question of whether the MWP was global or limited to Northern Europe or perhaps the Northern Hemisphere. It appears that the existence of a global MWP might challenge some of the relationships built into the climate modelling by showing a pattern of temperature changes independent of human activity.

Initially the MWP was assumed to be global. However, this result was later challenged. Quoting Wikipedia (link above):

The IPCC Third Assessment Report from 2001 summarises this research (into the MWP), saying "... current evidence does not support globally synchronous periods of anomalous cold or warmth over this time frame, and the conventional terms of 'Little Ice Age' and 'Medieval Warm Period' appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries" 

Part of the problem with the WMP is the paucity of data for the southern hemisphere. Professor Asten therefore proposes that Australia should take a lead role in the collection and analysis of the necessary data. He concludes:

There is a huge opportunity for CSIRO and the Bureau of Meteorology to extend their recent climate assessment, which was based on 1960-2010 data, to incorporate fossil-shell, cave-deposit and tree-ring records from tropical to Antarctic Australia and territories. This would cost a few per cent of the $652 million allocated on Tuesday to the new Renewable Energy Future Fund. It would make Australia a leader in addressing a great scientific challenge of our time.

I think that this is a very good idea independent of any climate change connection.

One of the things that I did not properly understand when I first did history and prehistory at University was the extent of climatic variation. As an Australian, I was obviously aware of things like floods and droughts. I was also aware that climate had changed over long periods. One could hardly ignore the ice ages! Beyond that, I tended to take climate as a given.

This was a grave error.

To illustrate the scale of the error, consider the low northern plains of Sahul, the pre-historic Australian continent. This was a rich area for the then human population with a mixture of environments. Sea levels began to rise. So fast was this rise across the northern plains that at one point it appears that the sea advanced a metre per annum.

Think about it. You are a sixty year old Aboriginal man. The sea has advanced sixty metres in your life time. Areas that you once knew are now underwater. You don't know why it's happening, just that it is. The widespread prevalence of stories around the world such as Noah and the flood is a not inaccurate description of what happened.

Around 4,000 years ago, more benign conditions on the Australian continent allowed for what some prehistorians have called intensification. Aboriginal populations appear to have increased greatly, technology became more complex, what economists call capital intensity increased. This laid the basis for the Aboriginal society that the Europeans found so much later.

The words capital intensity may sound strange, yet it's an accurate description. Aboriginal groups found the time and gathered the necessary resources to create things such as fish traps, standing nets in the bush, even eel farms. This is capital investment by any standard, investment now in the expectation of future paybacks. Trade also expanded.

This process was not uniform. Bigger populations also increased vulnerability to climatic variation. We know from the analysis of skeletal remains along the Murray River, for example, that people in this densely populated area suffered periodic malnutrition.

Now link all this back to Professor Asten's suggestion.

If we are to write a fuller history of prehistoric life on what is now called the Australian continent, we have to understand climatic change over time. If the Medieval Warm Period occurred in Australia, then it would have affected Aboriginal life. For that reason, I strongly support Professor Asten's proposals independent of any linkages to climate change.  

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