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Pages in this thread: << 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | (show all)   Rate thread Print Thread
HornCyclist
500+ posts
08/25/11 04:02 PM
Re: North pole to melt this year? [re: hornpharmd]

Maybe God dials back the sun when he sees the CO2 getting up there? Like if you were cooking something and turn the burner down when it starts to simmer?

It seems like negative feedback are silly with the historical data then. The natural system is stable, but the changes in CO2 today are not natural. Even if there were negative feedback systems, they aren't going to stem the release of carbon by man. Unless that system is global policy; that might work.








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pasotex
2500+ posts
08/25/11 05:03 PM
Re: North pole to melt this year? [re: hornpharmd]

I tend to agree.




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Ag with kids
5000+ posts
08/26/11 06:34 AM
Re: North pole to melt this year? [re: hornpharmd]

In reply to:

The historic data shows peaks and valleys. Does it actually show negative feedback and, if so, how?




Those peaks and valleys are empirical evidence of overall net negative feedback. Positive feedback would tend to drive the values to diverge. Note, I'm not saying there aren't positive feedbacks. Of course there are. However, the total feedback of the entire climate system has essentially always exhibited a net negative value.

In reply to:

Knowing very little about this, I would guess with the historical models that the rise in temperature or other factors related to the increase in CO2 led to the negative feedback loop.




I'm not talking about historical "models". I'm talking about historical DATA.

In reply to:

If man is producing the increase in CO2, then the changes would not be subject to the same feedback loops.




How the CO2 gets there is generally not a variable in most equations.


It is far more likely that the historic initial rise was caused by the sun. CO2 represents a positive feedback. The negative "feedback" was also the sun.




The sun and CO2 are both positive feedbacks.

In reply to:

Maybe God dials back the sun when he sees the CO2 getting up there? Like if you were cooking something and turn the burner down when it starts to simmer?




Ah…the insults against the Christians start…

Which doesn't bother me, since I'm not Christian...

In reply to:

It seems like negative feedback are silly with the historical data then. The natural system is stable, but the changes in CO2 today are not natural. Even if there were negative feedback systems, they aren't going to stem the release of carbon by man. Unless that system is global policy; that might work.




Net negative feedbacks is what keeps the system stable. A net positive feedback would drive the system unstable.




Eric '90

The face of a child can say it all, especially the mouth part of the face.

Edited by Ag with kids (08/26/11 06:37 AM)

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pasotex
2500+ posts
08/26/11 10:03 AM
Re: North pole to melt this year? [re: hornpharmd]

Peaks and valleys show negative feedback?

You know that this is not necessarily true when there is a variable external stimulus (like the sun and planet's orbit), right?

What is your empirical proof for some paleo negative feedback?




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Ag with kids
5000+ posts
08/26/11 10:30 AM
Re: North pole to melt this year? [re: hornpharmd]

In reply to:

Peaks and valleys show negative feedback?

You know that this is not necessarily true when there is a variable external stimulus (like the sun and planet's orbit), right?

What is your empirical proof for some paleo negative feedback?




When a perturbation occurs, a positive feedback will acerbate that perturbation and tend to drive it to divergence. A negative feedback will act to dampen that perturbation. Hence, the peaks and valleys that occur as perturbations occur (from whatever source) and then are damped out.

If the climate system had a net positive feedback, then it would be expected that there would be many runaway climate events historically, since the feedback of the climate system would make the climate unstable.




Eric '90

The face of a child can say it all, especially the mouth part of the face.

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pasotex
2500+ posts
08/26/11 02:39 PM
Re: North pole to melt this year? [re: hornpharmd]

The sun is variable, no?




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HornCyclist
500+ posts
08/26/11 03:19 PM
Re: North pole to melt this year? [re: hornpharmd]

We understand what positive and negative feedbacks are. There could be a net negative feedback in past temperature/CO2 changes and there could be a net positive feedback. We don't really know because the huge variable of the sun exists. You can't look at the historical data and say "Oh, well the temperature and CO2 eventually came back down, so there must be a negative feedback." Only if the external variables were constant could we determine the existence of a negative feedback loop with the system.

And I didn't intend to insult Christians. I am a Christian. I meant to insult anyone who proposes illogical solutions to problems.






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Ag with kids
5000+ posts
08/27/11 01:54 PM
Re: North pole to melt this year? [re: hornpharmd]

In reply to:

The sun is variable, no? ]




Yep. And?

In reply to:

We understand what positive and negative feedbacks are. There could be a net negative feedback in past temperature/CO2 changes and there could be a net positive feedback. We don't really know because the huge variable of the sun exists. You can't look at the historical data and say "Oh, well the temperature and CO2 eventually came back down, so there must be a negative feedback." Only if the external variables were constant could we determine the existence of a negative feedback loop with the system. &#8232;




Y'all are almost starting to sound like skeptics with your references to the sun…

Are you suggesting that we don't fully understand the sun's effects and therefore the models may not be accurately modeling them?

But, seriously…the sun could be considered either an internal or external variable to the overall climate system depending on how that system was defined. Even if it was considered an external forcing, it can still be defined. However, what the empirical data shows is that, even with the sun involved (because it always has been involved), the climate system has, overall, exhibited a net negative feedback because it has always damped out any perturbations. A net positive feedback should lead to divergent events.




Eric '90

The face of a child can say it all, especially the mouth part of the face.

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pasotex
2500+ posts
08/28/11 06:23 AM
Re: North pole to melt this year? [re: hornpharmd]

Here is a very sobering paper on what paleoclimatology should teach us.

The Link

and here is a summary of the paper:

The Link

In reply to:

The exact value of climate sensitivity depends on which feedbacks you include, the climate state you start with, and what timescale you’re interested in. While the Earth has ice sheets the total climate sensitivity to CO2 is up to 8°C: 1.2°C direct warming, 1.8°C from fast feedbacks, 1°C from greenhouse gas feedbacks, and nearly 4°C from ice albedo feedbacks. The slow feedbacks have historically occurred over centuries to millennia, but could become significant this century. Including CO2 itself as a feedback would make climate sensitivity even higher, except for the weathering feedback which operates on a geologic timescale.

As is explained in Target Atmospheric CO2, 4 W/m2 of greenhouse gas forcing sustained long enough would ultimately return the Earth to an ice-free state, raising the global sea level by 75 metres. The preindustrial level of atmospheric CO2 was ~275 ppm, so 4 W/m2 would be the effect of doubling the CO2-equivalent of all greenhouse gases (CO2e) to 550 ppm, or increasing CO2 to ~450 ppm with other greenhouse gases responding as feedbacks. Currently CO2 is at 390 ppm and rising; CO2e levels are at 470 ppm and counting; implying significant feedbacks are already in the pipeline. However, we may still be able to prevent them if we can get the Earth back in energy balance by reducing atmospheric CO2. In practical terms, that means cutting global CO2 emissions to near-zero as soon as possible.

Contrarians often argue the paleoclimate record shows CO2 and climate change are nothing to worry about. What it actually tells us is the climate system is extremely sensitive to perturbations – and we are running out of time to prevent the global warming we started from spiraling out of our control.


Here are the qualifications of the poster of the summary on the blog:

The Link




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pasotex
2500+ posts
08/28/11 06:53 AM
Re: North pole to melt this year? [re: hornpharmd]

btw has anyone looked at the sea ice extent lately?

The Link




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Ag with kids
5000+ posts
08/29/11 10:17 AM
Re: North pole to melt this year? [re: hornpharmd]

Is that Hansen paper peer-reviewed? I ask because, after just reading the abstract, I'm amazed that it was let through in that way. For a technical paper to say the following things is quite odd - especially a peer-reviewed paper. I've never seen these kinds of things in ANY technical paper I've read...

In reply to:

Thus goals to limit human-made warming to 2°C are not sufficient – they are prescriptions for disaster.




In reply to:

Rapid reduction of fossil fuel emissions is required for humanity to succeed in preserving a planet resembling the one on which civilization developed.




That is extremely sensationalist. It's the kind of thing I would not be surprised to see on the realclimate or skepticalscience blogs, but definitely not something I would expect to see in a technical paper.

It'll take a little longer to read the full paper, though, so give me a bit to look at it.

I also note that, based on the conclusion from the blog, that all mankind is definitely doomed - we WILL destroy the earth. Because his solution is one thing:

In reply to:

In practical terms, that means cutting global CO2 emissions to near-zero as soon as possible.




In practical terms, that is impossible. In realistic terms, it's also impossible - since even if the US were to go to zero emissions, the developing countries wouldn't..than




Eric '90

The face of a child can say it all, especially the mouth part of the face.

Edited by Ag with kids (08/29/11 10:44 AM)

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pasotex
2500+ posts
08/29/11 04:01 PM
Re: North pole to melt this year? [re: hornpharmd]

I did not use the word sobering by mistake.




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Ag with kids
5000+ posts
08/29/11 10:31 PM
Re: North pole to melt this year? [re: hornpharmd]

In reply to:

I did not use the word sobering by mistake.




The use of terminology that suggests "the end of the world" in this subject is completely over the top. However, its use is important to the proponents of changing environmental policy. It's needed to drive an immediacy to action...even if the actions may not actually accomplish anything. But, then, that's not the point for many environmentalists...




Eric '90

The face of a child can say it all, especially the mouth part of the face.

Edited by Ag with kids (08/29/11 10:39 PM)

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pasotex
2500+ posts
09/01/11 10:49 AM
Re: North pole to melt this year? [re: hornpharmd]

And meanwhile arctic sea ice extent is back to being tied with 2007.

The Link

I thought this stuff was going to spring back?






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MojoMan
1000+ posts
09/01/11 02:11 PM
Re: North pole to melt this year? [re: pasotex]

In reply to:

I thought this stuff was going to spring back?




And I remember being told a few years ago that all Arctic sea ice would be melted and gone by now.

FYI, this is around the annual time when the Arctic sea ice is at its yearly minimum. It will increase quite substantially as we move into winter again over the next six months.

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pasotex
2500+ posts
09/01/11 02:14 PM
Re: North pole to melt this year? [re: hornpharmd]

And what is the trend?




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MojoMan
1000+ posts
09/01/11 02:49 PM
Re: North pole to melt this year? [re: pasotex]

Over the next six months? It will be increasing.

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HornCyclist
500+ posts
09/01/11 02:57 PM
Re: North pole to melt this year? [re: hornpharmd]

Mojo, it's the year to year comparison that matters not across the year. That's what the graph showed. The ice extent will go up and down each year, but less up and more down as time goes by.






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MojoMan
1000+ posts
09/01/11 03:06 PM
Re: North pole to melt this year? [re: HornCyclist]

In reply to:

Mojo, it's the year to year comparison that matters not across the year. That's what the graph showed. The ice extent will go up and down each year, but less up and more down as time goes by.




Actually, it depends on what time frame you want to choose. Within the very narrow little window that you seem to want to concentrate on, that might be right, but it is still very debatable.

However, if you want to look at it over the longer term, then:

Going back to the time when the Earth was formed, when it was covered in molten lava, the trend is upwards.

Going back to the last ice age, when ice covered the Northern Hemisphere down to Kansas or some such place, and New York city was covered in ice more than a mile deep, the trend is downwards.

Going forward, we are apparently inevitably headed back into another ice age, regardless of how much CO2 man puts into the atmosphere, so the trend going forward over that period is upwards.

And going forward to the end of the Earth, when the Earth will be an icy rock, that trend is pointing upwards as well.

It is all a matter of perspective. And yours is not the only one.

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HornCyclist
500+ posts
09/01/11 03:38 PM
Re: North pole to melt this year? [re: hornpharmd]

The period im concerned with is the last century when.started admitting.more and more carbon. A blindfold and eadplugs is a perspective but it wont get you very far.









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