[quote]Zap Branigan wrote:
orinoco wrote:
Zap Branigan wrote:
I don’t believe this is true. The warming has been consistently less than computer projections. That is why the computer models have been revised and downgraded so many times.
http://www.reason.com/news/show/34785.html
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The scariest and most widely cited of the 245 controversial climate storylines mentioned in the IPCC’s Policymakers Summary, released earlier this year, suggested that global temperatures could rise by 4 degrees centigrade by 2100, or about 0.4 degrees per decade. In order to account for the actual, much-lower rates of temperature rise, modelers have inserted a number of cooling factors into their models, particularly sulfate particles produced by burning dirty coal.
The modelers postulate that sulfate particles brighten clouds that cool the surface by reflecting sunlight back into space. Other climatologists think that the sulfate cooling effect in the models is vastly overstated.
The physics of atmospheric warming are uncontroversial, as is the fact that atmospheric carbon dioxide is increasing. Added carbon dioxide should increase temperature, which should increase water vapor (the most ubiquitous greenhouse gas), which should lead to higher average temperatures.
Climate computer models try to replicate this process so as to predict what the earth’s climate will be over the next century. So far, though, the model results do not match the actual temperature trends found in the satellite record. What causes this disparity? Clouds are probably the main cause. It is well known that the computer models are rotten at explaining the effects of clouds on climate.
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Do a google search on “global warming computer modeling” and you will find a bunch of stuff on this topic.
Basically the computer models should be taken with a grain of salt and they tend to predict temperatures higher than actual. The global climate mechanism is still poorly understood.
I recently saw a study that said trees near the poles contribute to global warming because they block the solar energy from reflecting off the snow and out into space. [/quote]
Thanks for taking the time to post that link.
I’ve just read the article and found a few things troubling. For me it seemed a little partisan, as is evidenced by statements that seem to stray a little from just science. An example of this is how the article ended.
'Despite claims from environmentalists committed to global warming catastrophe scenarios and the politicized scientists who run the IPCC, it is clear that the science of global warming is far from settled. As Carl Sagan once said (but didn’t practice), “Extraordinary claims require extraordinary evidence.”
President Bush is wise to insist that global warming alarmists come up with at least better, if not extraordinary, evidence before he commits the country and the world to a perilous, expensive and perhaps needless effort to cut energy use.’
I was also interested to see that the writer of the article is a scientist and an author… the title of one of his books being ’ Global Warming and Other Eco Myths: How the Environmental Movement Uses False Science to Scare Us to Death.’
For me the title of this book points to a man who conflates his political agenda with his scientific opinion.
As for the satellite data that the author of the article seemed to be basing his counter-argument on, I couldn’t view it as there was no webpage at the end of the link.
My own view is that the IPCC scientists are a cautious and conservative bunch…particularly when it comes to their reluctance to include positive feedback loops in their predictions, as the precise temperatures that these would be triggered is unknown.
To me, this is evidence of their cautious nature, as you can’t dispute the fact that the permafrost in Siberia WILL melt, just the precise temp that this will happen. Nor can you dispute the fact that they currently store vast amounts of co2.
Another reason why I think that they are cautious is their reluctance to factor in scenario’s that take into account of the release of the vast natural stores of greenhouse gases - bigger than all the oil and coal reserves of the planet - that will be triggered by rising sea temps.
If these stored methane hydrates located under the sea bed are destabalised by the warming oceans then 10 000 billion tonnes of methane(8 times more potent than co2) will be released(which at a conservative estimate, would raise average global temps by 6 degrees centigrade). The IPCC scientists are aware of this, but still won’t factor it into current predictions of temperature.
Again, these are my own opinions pertaining to why I think - that for the sake of being able to stand up to scrutiny - that IPCC scientists are a cautious and conservative bunch.
[quote]Basically the computer models should be taken with a grain of salt and they tend to predict temperatures higher than actual. The global climate mechanism is still poorly understood.
I recently saw a study that said trees near the poles contribute to global warming because they block the solar energy from reflecting off the snow and out into space. [/quote]
I’d also have to disagree with the conclusions you have drawn here. The warming effect of forests near the poles and other idiosyncracies have been factored into the latest computer models.
Depending on whether you have confidence in the competence and impartiality of the meteorologists at the UK Met Office’s Hadley Centre…you might find this of interest with regards to the accuracy of computer modeling.
Also the following website sheds light on why global warming MIGHT be more serious than previously thought due to the global dimming phenomenon.
Ultimately, whether you’re swayed by the weight of evidence that the IPCC base their conclusions on or not, depends a lot on whether you believe they have an agenda other than that of scientific accuracy and impartiality.
