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20 November 2009
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The IPCC, in their 2006 AR4 reports, have made forecasts as to the
effects of climate change to the end of this century. For this they have
used four basic scenarios, some with variations, and extrapolations of
the different climate models derived from past experience. These are
based on potential demographics and the degree of globalisation of
economics. None of them have taken into account changes in fossil fuel
use from global initiatives, such as the Kyoto Protocol or its proposed
successor, nor does it appear that account has been taken that oil and
natural gas supplies may approach exhaustion.
From these, they have speculated that the global average temperature will
rise by somewhere between 1.1°C and 6.4°C by 2090-2099, relative to
1980-1999. Similarly, they speculated a sea level rise of 0.18 m to 0.59 m,
assuming there were no major dynamic ice flow changes. (These figures have
already been suggested as being either too conservative or not conservative
enough.) They have also looked at potential changes in precipitation
patterns.
I'm sorry, although their ranges are wide enough to cover most
possibilities, I cannot consider these forecasts as being based on science,
which is why I have used the word "speculated" twice in the previous
paragraph. This is not theoretical nor even hypothetical; it is educated
guesswork with sufficient margin to take care of most eventualities.
I look forward to reading how much these guesses have changed in the 2010
Fifth Assessment Report (AR5) which will be published in 2011. I'll make my
guess that there will be considerable differences.
Please allow me to make my forecast for the average global temperature
rise over the last decade of this century. It will be 3.282156°C and I
challenge anyone to scientifically prove that my guess is any worse than
anyone else's. I'll sum this up, more seriously, by suggesting that the most
accurate assessment of the future climate, with our current knowledge, is
best expressed in a 5-character symbolic 'word':
?????
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