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The concept of "tipping point" does not apply to the Barnes ice cap.
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I say it does!  The ice cap wasn't melting faster than it was expanding for a very long time, and now it is.  (And what caused approximately 100% of this change, I'm sure, is AGW.)

What I attempted to communicate earlier is that changes in forces (e.g., CO2) within a system (e.g., the icy Arctic) affect different parts of the system (sea ice, ice caps) differently.  Some things are like a canary in a coal mine - are affected obviously and quickly by certain changes - and others are not apparently affected.  Ice caps are affected less than (or more slowly than) sea ice by AGW.  (But a volcano erupting under an ice cap will melt more ice than a similar volcano erupting under the CAB.)

As to figuring out what non-AGW variability is affecting Arctic sea ice, there is "weather" - functionally good-for-melting seasons vs. good-for-keeping-ice-around seasons.  The generic AGW conditions were similar, but the Arctic responses in 2007 and 2012 were very different from 2013 and 2014.  If an 'average' season is half-way between these two pairs, what metric would one use to derive percentages (low points, high points, area, volume, some combination???)?  My biggest problem with this approach is that weather patterns are changing because of AGW.
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Arctic sea ice / Re: The 2017 melting season
« Last post by DrTskoul on March 29, 2017, 11:53:18 PM »
When it comes to these temperature anomalies... which I've been watching since at least November... I really have to wonder how much they matter this time of year (over ice, in particular).

If there's a patch of the arctic where normally it is -40 C/F, but instead due to huge anomalies it is -10 C, so what? It doesn't melt, melt ponds don't happen... I feel like the thermodynamics don't change...  until it gets above freezing.

Do we expect anything to come of these high anomalies, where temperatures still stay below freezing?

Heat flux out of the ice ( if we assume linear force formulation -  flux proportional to ΔT) is a quarter roughly compare to normal... it takes four times as long to thicken at the same level..


... presuming enthalpy remains constant.  The problem is, we have heat flow from depth, such that below a given temperature threshold, the ice won't thicken at all, because heat is replenished at the water/ice interface faster than it can be transferred out of the ice to atmosphere.  At -10C, ice more than 1M thick will actually start melting from the bottom, given enough time.

The implicit assumption was the bottom was at equilibrium... if not then absolutely it can melt. The same way that ice does not initially form until air temperature is below -10...
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Arctic sea ice / Re: The 2017 melting season
« Last post by Neven on March 29, 2017, 11:43:52 PM »
Do we expect anything to come of these high anomalies, where temperatures still stay below freezing?


Yes, earlier melt onset due to downwelling longwave radiation (see here). Or pre-pre-conditioning, as sea ice sailor called it earlier today (half-kiddingly, but aptly).
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The rest / Re: The Trump Presidency (was "Presidential Poll")
« Last post by Neven on March 29, 2017, 11:20:32 PM »
And this last bit from another Jimmy Dore show video published today, is also about Russia and how it detracts from the real problems:

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Arctic sea ice / Re: Arctic sea ice changes: Natural variation vs human influence
« Last post by Archimid on March 29, 2017, 11:18:54 PM »
AndrewB, I agree with you but I was hoping that I was missing something that the "natural variability"  folks know.

An example of what I'm looking for would be something like the PDO. if we assume that the variability of the PDO (its sign, magnitude and frequency) hasn't been influenced by anthropogenic forcings (a big if) then the PDO would be a natural variation. But as you well said, even if the PDO varies naturally it still has to go through the atmosphere to get to teh Arctic, which we already know it has changed due to anthropogenic forcings.

Then you have the Arctic. Since 1979 it has been in decline yet the PDO has oscillated several times. It has been mostly positive for decades and mostly negative for decades. Yet through positives and negatives the arctic decline continues. At most, the natural variability of the PDO is responsible for the rate of melt. During negative cycles the arctic melts slowly and during a positive cycle it melts faster. But it melts either way. Thus 100% of the melt is anthropogenic, but the rate of melt has natural variation in it.
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Arctic sea ice / Re: The 2017 melting season
« Last post by jdallen on March 29, 2017, 11:16:58 PM »
When it comes to these temperature anomalies... which I've been watching since at least November... I really have to wonder how much they matter this time of year (over ice, in particular).

If there's a patch of the arctic where normally it is -40 C/F, but instead due to huge anomalies it is -10 C, so what? It doesn't melt, melt ponds don't happen... I feel like the thermodynamics don't change...  until it gets above freezing.

Do we expect anything to come of these high anomalies, where temperatures still stay below freezing?

Heat flux out of the ice ( if we assume linear force formulation -  flux proportional to ΔT) is a quarter roughly compare to normal... it takes four times as long to thicken at the same level..


... presuming enthalpy remains constant.  The problem is, we have heat flow from depth, such that below a given temperature threshold, the ice won't thicken at all, because heat is replenished at the water/ice interface faster than it can be transferred out of the ice to atmosphere.  At -10C, ice more than 1M thick will actually start melting from the bottom, given enough time.
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The rest / Re: The problem of Corporate Democrats and how to kick them out
« Last post by Neven on March 29, 2017, 11:10:06 PM »
And yet another good one (these are all recent ones, BTW, Jimmy Dore has hundreds of excellent videos), called Cartoon Reveals Exactly How Democrats Gaslight Progressives:

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Quote from Jimmy Dore:

That's the thing that people mistake. They keep saying: 'Well, we've got to get rid of Trump, Jimmy, why don't you get rid of Trump?' We're going to get rid of Trump, but we have to have something to replace him with once we get rid of him. And right now, what we have to replace him with, is more corporatist bullshit, more wars, more bank deregulation, more tax relief for billionaires. Right now, that's what's happening.

(...)

It's the Democrats we have to fight against. We know the Republicans are going to be in the tank for corporations. It's the Democrats who give fealty to the left, but that's just rhetoric. The know all the words, the know all the populist words, like Barack Obama.

(...)

So, this is the problem with the Democratic Party and they need to have something to replace him with. They don't. What they're doing now, is gaslight their own base, which is a losing strategy. As much as 2018 should be a bloodbath for the Republicans, I don't see it happening, because the Democrats are bent on staying shitty.
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Science / Re: Trump Administration Assaults on Science
« Last post by Jim Hunt on March 29, 2017, 11:08:56 PM »
My initial report on today's House Committee on Science, Space and Technology hearing on "Climate Science: Assumptions, Policy Implications, and the Scientific Method“:

http://GreatWhiteCon.info/2017/03/the-house-science-climate-model-show-trial/

My YouTube feed cut out at the point Dana Rohrabacher got rather angry with Mike Mann! Correlation or causation?
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The rest / Re: The problem of Corporate Democrats and how to kick them out
« Last post by Neven on March 29, 2017, 10:57:40 PM »
Another good one, called Keith Ellison Scolds Progressives - 'Buck Up!' and Take it!:

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The rest / Re: The Trump Presidency (was "Presidential Poll")
« Last post by Neven on March 29, 2017, 10:49:29 PM »
But this one fits here, from the Jimmy Dore Show, an 8 minute video called Russia Hysteria Reaches Comical Proportions (click the 'no longer available' link at the bottom if the video doesn't show up):

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