as has already been mentioned before, optimum plant growth seems to requires CO2 levels above 1000 ppm so we have a long way to go in that respect. Another thing I find interesting is the fact that the ice cores can be taken in the first place means the ice has not melted through any of the previous cycles, about 8 was mentioned. There is obviously a natural thermostat operating and I believe that thermostat to be water vapour. I also believe that the reason the thermostat operates over the range it does, rather than say the normal difference between summer and winter has everything to do with the solar energy input varying due to variations in the earths orbits and the output of the sun itself. CO2 may have a role in there somewhere, but these other influences are far more powerful. We only have to travel from a temperate to tropical zone to realise how just a slight change in orientation to the sun can have a major influence on the local climate, as it does as we go from summer to winter. The known variations in the orbits and angles of rotation over time are greater than what we experience over the course of a year, and those cycles are measured over 30,000, 40,000, and 100,000 years.
This particular part of South East SA, SW Victoria has only had it's existing climate 3000 years, prior to that between 8000 and 21,000 years ago this area was as dry as what the Mallee is now. 3000 years seems a long time, but 100 years is 1/30th of 3000 years, so if there is ongoing natural climate change we should perhaps be able to see it in our records, and perhaps that is what we are seeing. 1/30th of a year is about 2 weeks, and the one thing the scientists seem to assume is that natural climate change occurs at a regular and constant rate. We know ourselves that at certain times during the year the rate of the ongoing change is hardly perceptible, yet at other times it is so noticeable as to be changing day by day, even if it does seem to slip backwards every now and again Whilst there are certain aspects of our weather that are predictable to a certain degree, there are other aspects that are totally unpredictable, basically because we don't understand all the factors involved, and despite all the data we collect, we simply aren't measuring everything everywhere. I hardly needs to be said that if we haven't got a handle on our weather yet, it is rather arrogant to claim that we know enough about the climate to make predictions that are being sold as fact. It seems to me that as is happening in many different fields, commonsense is being replaced with academic theory.
