I do have a different science related question, though. Does the hard data conclusively prove that the current trend towards global warming is manmade? Is it not possible that what we are experiencing is a purely natural fluctuation in global temperature? I saw that Al Gore's environmental horror film was banned from classrooms in Great Britain on grounds of scientific inaccuracy. Was this purely political, or did he overstate the case?
Ah, another can of worms!
A couple of answers:
First, the data absolutely do NOT conclusively show that any trend in the global climate is manmade. There has been a body of work that contradicts the anthropogenic causes and this cannot be disputed to the degree that it's "known" one way or another.
As a physical scientist who has spent my professional career and adult life seeking the carrot-on-a-stick of scientific objectivity, I can earnestly say that the ENTIRE 'anthropogenic global warming' drama has been a lesson in how not to conduct science and how not to communicate science to the 'public.' It has now been so politicized that pretty much no one in either camp will objectively look at any of the data and seek "the truth" that that data has to tell.
What we are "experiencing" can well be part of natural cycle, and I've posted about this in detail before. To get at something resembling 'fundamental truth' in this issue, you have to step back a little bit and examine some science history.
A big part of the case for anthropogenic climate effects rests on the following syllogism:
Premise 1: "Natural" geological change is slow...takes a long time.
Premise 2: We are observing rapid changes in a number of global parameters.
Conclusion: Therefore, man is causing the changes.
Now, this is a logically valid argument, but it is not sound. Valid means the conclusion follows from the premises, whereas sound means the premises are true.
A valid argument, logically:
All cows are purple
Bill is a cow
Therefore, Bill is purple.
Valid, but not sound.
The problem with the AGW syllogism is Premise 1, though Premise 2 is certainly debatable. Premise 2 gets all the press, and that's because Premise 1 is accepted as "conventional wisdom," especially by those making the argument as if it were, indeed, logically sound.
Let's put Premise 2 aside. I'll even accept for the moment, for the sake of argument, that it is true. Do we now have a sound argument?
No. Premise 1 is false. And this is very easy is to show. The problem, however, is the number of people that wrongly accept Premise 1 as true. Even in the face of a tremendous body of evidence to the contrary, this notion of 'natural geological change is slow' persists.
In the 1990's, Spencer Weart (if I recall correctly) published an article in Physics Today,
the 'trade rag' of the American Physical Society. In the article, he outlined some of that body of evidence, which included things such as forest regions completely switching from evergreen to deciduous in a span of decades, ocean currents completely reversing in less than a century and very large scale temperature fluctuations on very small time scales. All of these were pre-Industrial Revolution or indeed, pre-human civilization completely.
He went on to describe how all of this was known around the turn of the 20th century, but for some reason, several key scientists of that time denied the evidence available and "bulldozed" through the notion that geological change MUST be slow. He who writes the textbooks controls the beliefs of the next generation, and once that idea was accepted as "truth," it stuck. Now, 5 generations later, it is indeed, taken as 'established fact.'
Again, this 'truth' was in direct denial of the testable, measurable evidence available even at the time it was posited.
There have been a LOT written on this topic over the past few years. A number of geological 'events' that you and I were taught took "millions of years" to happen, now have bodies of evidence suggesting that those timescales were overestimated by several factors of ten...enough to lead to very different 'modes of thought' on the nature of geological change.
Indeed, ask the Japanese just how long "island shaping" geological change must take.
So, the truth of Premise 1 is certainly in question.
Is that alone enough to falsify AGW?
No. Man could be a driver on top of natural events. Or, those natural events could be in a period of quiet. Indeed this seems to be the case, at least with temperatures.
Part of the problem with historical global temperature 'data' is that it is ALL what is called proxy data...the temperatures are not measured directly but some "proxy" is used for temperature. Whether the proxy is trapped CO2 in ice cores, tree rings, sea levels, etc. there MUST be some mathematical manipulation that leads to "temperature" from the measured proxy.
A few years back, McIntyre and McKittrick, vile and hated as they are, published an incredible piece of work. They used the 'global climate model(s)' that was used to 'reproduce' Mann's Hockey Stick, but used a random driver rather than any real proxy data. In other words, they fed the mathematical model a random stream of numbers, and REPRODUCED THE HOCKEY STICK.
This shows that the math used to model the hockey stick data is pure, unadulterated crap.
But again, this alone does not falsify man-made causes of climate change. But it does call into question ANY conclusion based on those particular models.
One fact that cannot be denied is that the mathematical modeling of temperature proxies show HUGE temperature fluctuations in the historical record, and these fluctuations occur on VERY SHORT time scales.
Finally, I note that another idea in the global warming debate that is pure bunk is the notion of "consensus." There never was consensus, and there certainly is not now. Two key biases have caused the 'appearance' of consensus in the eyes of SOME people:
publication bias - it's much harder to get a paper published that challenges the cause du jour, and
funding bias - you don't get federal money for a proposal that essentially says "I want to falsify man made causes of climate change.'
It's an interesting phenomenon. But one thing is definitely clear, and can be shown: since this 'debate' has started, there have been scientists that refused to step onto the bandwagon and sing "the party line;" often, they were dismissed as crackpots for this fact alone, when no flaw could be found with their science. Ad hominem is the tactic of a politicized debate, not one of true science.
I hope that's a reasonable overview. I am not trying to answer the question of whether not the conclusion of anthropogenic causes are real, but merely to outline the 'debate' as it exists from a scientist's perspective.