Thursday, October 4, 2007

At Witz End: Global Warming Questions and Answers

Believers express their feelings, right and wrong. "You can choose to believe anthropogenic global warming on faith, like religion; or you can join the rest of us in seriously questioning it and demanding proof."

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4 comments:

Anonymous said...

If Garth had bothered to check his research instead of posting inaccuracies such as "The Science paper showed that CO2 did not cause the warming that ended the last ice age", he would realise that climate scientists have never claimed that it did.

The most likely cause of the ending of the last ice age was the cyclic variations in the earth's orbit - the so-called Milankovitch cycles.

However, this in no way negates the fact that atmospheric CO2 concentrations casue global warming.

Refering to even the most basic book on physics, he would learn that CO2 is a greenhouse gas because it absorbs and emits certain frequencies of infrared radiation.

I challenge Garth to show that increases in atmospheric CO2 will not cause further heating, or will actually cause cooling.

Garth Godsman said...

Hi Anonymous

Sorry mate, but given the level of the dishonest distortion of what we know about the climate history of the Earth, there are plenty of people who think that CO2 did cause the end of the last ice age.

And had you bothered to read the comments by the researchers involved, you'd see that is not an unknown idea amongst climate scientists and I was repeating what the conclusions they had reached from their results.

"However, this in no way negates the fact that atmospheric CO2 concentrations casue global warming."

Fact? CO2 "causes" global warming? Evidence for this claim please. If you were actually familiar with the literature, you would not be quite so sure about that comment.

"he would learn that CO2 is a greenhouse gas because it absorbs and emits certain frequencies of infrared radiation."

Sigh. Yes, I think we are all aware of the basic laboratory physics of CO2's absorption of certain frequencies of electromagnetic radiation.

But the real world climate outside the laboratory is a very different and much more complex thing, so your simplistic assertions lose any relevance.

Now, one of the features of the physics involved is that the so-called "greenhouse" effect of CO2 declines as more is added to the atmosphere.

"I challenge Garth to show that increases in atmospheric CO2 will not cause further heating, or will actually cause cooling."

I challenge you to quantify the actual contribution of CO2 to the warming experienced over the last century or so, compared to the already natural warming of around 0.5 degree C/century the Earth was already experiencing for at least the last 2-3 centuries.

See, it isn't nearly as simple as you think.

Anonymous said...

Sorry Garth, I have not had time to create myself a blog identity. Just in case you think I am hiding behind an anonymous identity, my email is tcb_charles at hotmail dot com if you're interested.

"Sigh. Yes, I think we are all aware of the basic laboratory physics of CO2's absorption of certain frequencies of electromagnetic radiation."

No, not everyone is aware of it, Garth. But as you so obviously are, then given that fact, I ask you once again: why won't increases in CO2 cause warming?

I admit that I am a humble engineer. Nevertheless, having studied thermodynamics, I know that it is not simple, not have I claimed it to be so. There are numerous feedback mechanisms at play of course.

Global warming is an equilibrium concept. Given you understand the physics behind it, you of all people should know that warming will continue even if emissions are stopped tomorrow. Which means that temperatures we see today in no way necessarily reflect the warming potential of existing CO2 levels. So of course todays temperatures ndon't appear as significant as they should.

Who said it was simple? I didn't...

Garth Godsman said...

Sorry mate, I wasn't having a go at you for the anonymous tag. Plenty of people do that and I don't see why they necessarily should bother with creating a blog identity. So I'm fine with that.

Nobody is saying that increases in CO2 wont cause warming, and I believe some (but not most) of the warming over the last one hundred years has to be attributable to this.

But the point I was trying to make is that the climate is more complex than a lab experiment, in ways that we still do not fully understand, and that feedback mechanisms act in ways that could not only accentuate any such warming, but also negate it.

The failure of the General Circulation Models to get the actual amount of warming in the 20th Century right - they all overestimated it - highlights I think the disjunct between what we know about the effects of CO2 in the real world and what actually happens in the real world.

The Earth has been warming naturally by around 0.5 degree C for several centuries now, (and indeed, research just published says that the warming trend in Siberia started 250 years ago, well before anthropogenic CO2 could be the cause http://www.dailytech.com/Researcher+Global+Warming+Began+250+Years+Ago/article9191.htm ), and this in my view clearly accounts for most of the warming recently.

And as I understand it, given the absorption properties of electromagnetic radiation by CO2 and other gases such as water vapour, most of the possible warming effect of CO2 has already taken place.

If you look at the plot of solar activity with temperature fluctuations, the correspondence is nothing short of remarkable.

The same cannot be said for the correspondence between temperature fluctuations and levels of CO2.