Soren wrote on Dec 1
st, 2009 at 10:02am:
I understand all that. What I also notice is that the predictions or the reasoning behind the predictions or both are always changing. As UNPREDICTED new information comes to hand, as the climate unfolds in UNPREDICTED ways, failed past predictions are explained in terms of new predictions. Something unpredicted will always scuttle the previous predictions but it will be co-opted to make a new, firmer, larger, smoother, more jutting, er, I mean more scientific prediction.
"Unforeseen and unpredicetd natuaral variations prevented previous predictions to be fulfilled? Never mind, we assure you that the science is all settled and simple and well in hand this time . The current truth is fully reliable and based on irrefutable science. Look at this graph. See?"
The problem is that most 'skeptics' (your term) conveniently ignore what we know about natural variations. They take the temperature record and say "See- there is no correlation" ignoring the fact that there is natural variation, and that this is very well understood.
If we looks at periods of ten years or shorter, such short-term natural variations can more than outweigh the anthropogenic global warming trend. For example, El Nino events typically come with global-mean temperature changes of up to 0.2 °C over a few years, and the solar cycle with warming or cooling of 0.1 °C over five years.
We can account for the influence of these natural influences, not by some iterative approach, but by measuring the changes, in some cases quite accurately.
The global ocean surface temperatures in 2009 broke all previous records for three consecutive months: June, July and August. The years 2007, 2008 and 2009 had the lowest summer Arctic sea ice cover ever recorded, and in 2008 for the first time in living memory the Northwest Passage and the Northeast Passage were simultaneously ice-free.
This was repeated in 2009. Every single year of this century (2001-2008) has been among the top ten warmest years since instrumental records began.
This trend is set to increase even more as the greenhouse gas induced warming trend and the solar output start to increase in unison in the next few years. Sunspots numbers this month have continued to ramp up from October as predicted.
In Science, we work on the basis of self correction. The overall predictions are refined as time goes on.
In the 1920's, a book was published entitled 100 Authors Against Einstein. His remark was, ‘If I were wrong, then one would have been enough!’ As Stephen Hawking pointed out however, that one opposing scientist would have needed proof in the form of testable results.
These attributes of science can be used in assessing competing assertions about climate change:
Quote:Can the statement under consideration, in principle, be proven false?
Has it been rigorously tested?
Did it appear in the peer-reviewed literature?
Did it build on the existing research record where appropriate?
If the answer to any of these questions is no, then less credence should be given to the assertion until it is tested and independently verified.