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Global Warming - Is it real, and if so is it caused by humans?
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Of course the model for AGW is more complete. More resources, funding and attention is being directed towards it in order to establish the lucrative carbon taxation system. That doesn't mean that the alternative is not a plausible alternative, no matter how much you twist it around.
I'm not trying to twist anything. I'm trying to make clear that there is a distinction between plausibility and likelihood.
Imagine that we have a bag with 9 black balls and one which is an unknown colour (which may also be black) . Other than (potentially) the colour, there is nothing to distinguish the 10 balls - they are the same size, weight, texture, etc.
I can't see into the bag, but reach in and take out a ball at random.
It is entirely plausible that the ball will be white.
Addressing Angry Troll's choice of wording, it is also impossible to say for sure what colour the ball will be.
The point I'm driving at is that there seems to be a tendency by those who are uncertain to express the argument in language which attempts to level this playing pitch....to hide the notion that 9 times out of 10, I can expect to draw a black ball, and to really hide the notion that if the ball isn't black, we've got absolutely nothing to tell us what colour it might be.
So yes...its plausible that its white...but its far more likely that its black.
Its impossible to say for sure that the ball I draw will be black, but its possible to say that there's (at least) a 90% likelihood of that.
So if anything, I'm not trying to twist words at all. I'm trying to point out the limitations we (should) reach by not twisting them.0 -
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The relationship between global temperatures and shifts in the PDO are definately something that need to be looked at more closely. Anyone with an interest in climate change has heard about how, in the early 70's, scientists were sounding the alarm bells about Global Cooling. Around 1977 the PDO changed to its positive phase, and suddenly we had scientists talking about Global Warming.
PDO cycles change roughly every 30 to 40 years, but thats not set in stone. NASA believe that the cycle has changed back to its negative phase over the past 18 mths, so its going to be interesting to see how global temps react over the next 3 to 4 years.
PDO is an interesting area, and something I wouldn't ever have heard of if it weren't for climate skeptics. However, its not the "smoking gun" as it were in the recent dramatic rise in global temperatures. It can account for short term fluctuations in temperature, but does not explain the long term warming trend over the last half century. There is no long term trend in PDO, its nuetral over the longer term.Here's a graph that illustrates my point a bit better.
The cause of global climate change has a number of variable and we can't just pin it down to one thing. But when we look at the net forcing(solar, aerosols, greenhouse gases, etc) v global temperatures we do see a fairly strong correalation.
As for what should we expect over the coming years with regard to a cooling phase in the PDO? Well scientist think that we should see anthropogenic climate change to be offset by it for a few years and then the warming trend will continue.
From a 2007 paper by Smith et al http://www.sciencemag.org/cgi/content/abstract/317/5839/796We present a new modeling system that predicts both internal variability and externally forced changes and hence forecasts surface temperature with substantially improved skill throughout a decade, both globally and in many regions. Our system predicts that internal variability will partially offset the anthropogenic global warming signal for the next few years. However, climate will continue to warm, with at least half of the years after 2009 predicted to exceed the warmest year currently on record.0 -
PDO is an interesting area, and something I wouldn't ever have heard of if it weren't for climate skeptics. However, its not the "smoking gun" as it were in the recent dramatic rise in global temperatures. It can account for short term fluctuations in temperature, but does not explain the long term warming trend over the last half century. There is no long term trend in PDO, its nuetral over the longer term.Here's a graph that illustrates my point a bit better.
The cause of global climate change has a number of variable and we can't just pin it down to one thing. But when we look at the net forcing(solar, aerosols, greenhouse gases, etc) v global temperatures we do see a fairly strong correalation.
There is a rough trend visible in the PDO graphs, of a negative period from around 1940-1973, a positive period from 1973 to about 2007 and we are now at the beginning of a negative period.
This ties in well with the global temperature record during the time, and adding in the ever high solar activity during the 20th century, you get a general upward trend, perhaps slightly enhanced by CO2.
The PDO changes the amplitude and atmospheric interactions of ENSO events, which affects global temperatures. You only need to look at 1998 to see what a big effect El Nino can have.
Here's a paper that might interest you http://www.cdejager.com/wp-content/uploads/2008/11/solaractivandclimate-nethjgeosci.pdf0 -
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