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Global Climate Destabilisation
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johnhemming2



Joined: 30 Jun 2015
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PostPosted: Tue Nov 22, 2016 10:43 pm    Post subject: Reply with quote

clv101 wrote:
Yeah. Firstly the ice-caps have non-trivial gravitational fields of their own. That's one reason why if you were to melt Greenland totally, raising average sea levels by ~7m, the sea level near to Greenland would actually go down as the ice-sheet's gravitational field would no longer be pulling the ocean towards it.

That does not sound right to me. I accept it is possible that the weight of the ice is pushing Greenland down and that removing that weight could have an effect, but I don't think it would "pull the sea up". In the end this is something that can be resolved mathematically. Can you please tell me where the calculations are for this so that I can see them?
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PS_RalphW



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PostPosted: Tue Nov 22, 2016 11:14 pm    Post subject: Reply with quote

Simple Newtonian maths. All masses attract each other. The 4 km thick ice over Greenland is enough to attract water 7M closer to it against the gravitational pull of the rest of the planet. Gravity is an inverse square law - the planet may be huge relative to Greenland ice , but the ice is closer.

Another feature of gravity is that it gets less the deeper you go down a mine. At the centre of the earth it is zero.
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Little John



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PostPosted: Tue Nov 22, 2016 11:38 pm    Post subject: Reply with quote

Wouldn't gravity still exist at the centre of the earth, except it would operate in apparent reverse?

That is to say, if you imagine, for the sake of a thought experiment, a hollow sphere in the center of the earth, Gravity would operate by apparently pulling you back to the surface of the earth over the entire inner surface of this sphere

edit to add:

ah...no.... I see now.

Because the mass of the earth on the opposite side of the sphere you happened to be nearest to would still be exerting it a gravitational force on you, it would more or less cancel out the pull of the side you were nearest to. Thus, unless the sphere were absolutely huge, the slight difference in gravitational pull between one side of the sphere and the other, depending on where you were, would be negligible to the point of virtual nonexistence.

Thus, zero gravity (or near as dammit zero gravity) anywhere near the centre of the earth as well as the dead centre itself.


Last edited by Little John on Wed Nov 23, 2016 12:00 am; edited 1 time in total
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Little John



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PostPosted: Tue Nov 22, 2016 11:54 pm    Post subject: Reply with quote

Which causes me to consider another thing....

I have always assumed barometric pressure increases the nearer one gets to the surface of the earth because of the weight of the air above it exerting a compression on it. All of which is a function of the gravitational force of the earth. However, if gravity weakens as one moves closer to the center of the earth (underneath its surface), then one might expect barometric pressure, if anything, to decrease, if only by a tiny amount, as one moves down a mine shaft. But, as far as I am aware, it increases. That seems somehow inconsistent with what has been discussed here with regard to gravity


Last edited by Little John on Tue Nov 22, 2016 11:58 pm; edited 1 time in total
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clv101
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PostPosted: Tue Nov 22, 2016 11:55 pm    Post subject: Reply with quote

johnhemming2 wrote:
clv101 wrote:
Yeah. Firstly the ice-caps have non-trivial gravitational fields of their own. That's one reason why if you were to melt Greenland totally, raising average sea levels by ~7m, the sea level near to Greenland would actually go down as the ice-sheet's gravitational field would no longer be pulling the ocean towards it.

That does not sound right to me. I accept it is possible that the weight of the ice is pushing Greenland down and that removing that weight could have an effect, but I don't think it would "pull the sea up". In the end this is something that can be resolved mathematically. Can you please tell me where the calculations are for this so that I can see them?


The image above is from this paper: http://www.nature.com/nature/journal/v517/n7535/fig_tab/nature14093_SF1.html

Also see this for more on sea level rise 'fingerprinting', written by my PhD advisor: http://www.the-cryosphere.net/4/621/2010/tc-4-621-2010.pdf
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clv101
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PostPosted: Wed Nov 23, 2016 12:01 am    Post subject: Reply with quote

Little John wrote:
Which causes me to consider another thing....

I have always assumed barometric pressure increases the nearer one gets to the surface of the earth because of the weight of the air above it exerting a compression on it. All of which is a function of the gravitational force of the earth. However, if gravity weakens as one moves closer to the center of the earth (underneath its surface), then one might expect barometric pressure, if anything, to decrease, if only by a tiny amount, as one moves down a mine shaft. But, as far as I am aware, it increases. That seems somehow inconsistent with what has been discussed here with regard to gravity


There's more pressure as you go down as you're supporting everything above you, plus extra incremental stuff, which will be contributing less and less as you get towards the centre of the Earth.
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Little John



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PostPosted: Wed Nov 23, 2016 12:05 am    Post subject: Reply with quote

clv101 wrote:
Little John wrote:
Which causes me to consider another thing....

I have always assumed barometric pressure increases the nearer one gets to the surface of the earth because of the weight of the air above it exerting a compression on it. All of which is a function of the gravitational force of the earth. However, if gravity weakens as one moves closer to the center of the earth (underneath its surface), then one might expect barometric pressure, if anything, to decrease, if only by a tiny amount, as one moves down a mine shaft. But, as far as I am aware, it increases. That seems somehow inconsistent with what has been discussed here with regard to gravity


There's more pressure as you go down as you're supporting everything above you, plus extra incremental stuff, which will be contributing less and less as you get towards the centre of the Earth.
But, if gravity effectively weakens as one approaches the centre of the earth, then you are not "supporting" more "weight" the further down you go because the gravity that produces "weight" is becoming effectively weaker the further down you go
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Little John



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PostPosted: Wed Nov 23, 2016 12:21 am    Post subject: Reply with quote

Something else has just struck me....

The time dilatation effect due to zero gravity at the center of the earth as compared to the surface of the earth, given the earth has been around for very long time and so any time dilation effect will have accumulated, must mean that there will be a calculable, if very small, difference in age between the surface of the earth and its center. That is to say, the center of the earth will be effectively "older" than the surface.
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woodburner



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PostPosted: Wed Nov 23, 2016 12:51 am    Post subject: Reply with quote

I don't subscribe to this time varying with gravity theory, as I think it applies only if the observer and the object don't get together, the time for both of them will be the same if they meet. This applies to the experiments of clocks going round the world and the experimenters claiming tthe time speeds up or slows down or whatever they want to happen. The differences seem to be no more than experimental error.

The claims remind me of the claims made by the pharmaceutical industry that something is going to kill us unless we take their expensive pills. This in turn smacks of the snake oil salesmen in the early US (where most of the big pharmaceuticals are today. i.e. Someone stands to gain by misleading statements.
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kenneal - lagger
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PostPosted: Wed Nov 23, 2016 4:53 am    Post subject: Reply with quote

But Greenland and West Antarctica are melting at the same time so the 1.2m rise caused by melting at the other end of the earth will cancel out the 0.4 drop and result in a 0.8m rise at each pole. We're in for a 0 + 1 aggregate which will equal 1m rise. So if Hansen et al are right, we will end up with somewhere near 5m of his predicted 5m rise by 2100. Not as bad as the 6m many places will get!
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johnhemming2



Joined: 30 Jun 2015
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PostPosted: Wed Nov 23, 2016 7:53 am    Post subject: Reply with quote

clv101 wrote:
johnhemming2 wrote:
clv101 wrote:
Yeah. Firstly the ice-caps have non-trivial gravitational fields of their own. That's one reason why if you were to melt Greenland totally, raising average sea levels by ~7m, the sea level near to Greenland would actually go down as the ice-sheet's gravitational field would no longer be pulling the ocean towards it.

That does not sound right to me. I accept it is possible that the weight of the ice is pushing Greenland down and that removing that weight could have an effect, but I don't think it would "pull the sea up". In the end this is something that can be resolved mathematically. Can you please tell me where the calculations are for this so that I can see them?


The image above is from this paper: http://www.nature.com/nature/journal/v517/n7535/fig_tab/nature14093_SF1.html

Also see this for more on sea level rise 'fingerprinting', written by my PhD advisor: http://www.the-cryosphere.net/4/621/2010/tc-4-621-2010.pdf


Thanks for that. I have glanced at it but it appears to be an issue of the "weight" or "gravitational field" from the ice pushing greenland down rather than the ice pulling the sea up (and not the land). ([the former of] which is entirely reasonable and the detailed calculations would depend on a number of factors).

Obviously the molten water which is actually more dense spreads all over the seas whereas the ice is concentrated on the one location.
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emordnilap



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PostPosted: Thu Dec 01, 2016 1:33 pm    Post subject: Reply with quote

A very good piece from Brian Davey

Quote:
...the necessary [CO₂e] reductions barely affect a very large proportion of the worlds population. The austerity has to be carried by the elite. Perhaps 1% of the global population accounts for 50% of all emissions and if we take the top 5% we are talking about the top 60% of emissions. It is above all the carbon intensity of the lifestyle of the global elite that is taking us all to climate hell and it is the lifestyle of this elite that needs to be tackled.


Yet another (as if one were needed) argument for a cap-and-share system of emissions control. Here it is in a nutshell, for those few on this forum who have not considered such a system:

Quote:
You could do it like this. All fossil fuel sales would be banned unless first authorised by a permit. The number of permits, which would be denominated in carbon units, would be limited and reduced rapidly year on year.

In order to acquire some of the limited numbers of permits, the fossil fuel sellers would have to obtain them. As is obvious, the permits would be very expensive to buy if the cap were tight enough. The fossil fuel sellers would pass on the permit cost to their customers so that the price of fossil fuels would rise, perhaps very considerably. The prices of goods made with large amounts of fossil fuels would also rise. This would not be at all popular and would particularly hit people with a carbon intensive lifestyle, which, as we have seen already, is largely the very rich. However, poor people would be hit too. That is why it would be necessary that the large amount of money raised when permits are sold, should be recycled back to the population on a per capita or some other equitable basis. It might also be necessary to do more to help the high carbon poor in countries like the USA but that is a detail that I will not go into here.

This will achieve what Kevin Anderson wants to see, that is, a scheme that cuts the carbon intensive lifestyle of the rich most, while making a very large number of poor people better off, at least in the early stages of the process. The reason that they will be better off is that if the revenue from carbon permit sales is recycled back to the public on a per capita basis, then everyone, rich or poor, will get exactly the same amount of the revenue from permit sales. However, the poor tend to have a less carbon intensive lifestyle. Although prices for their lifestyle will rise, they will still get more from their share of the carbon permit revenues than they will pay extra in rising prices.

The 1%, however, will be paying a huge amount more because, directly and indirectly, their energy intensive lifestyle accounts for 50% of all carbon emissions and carbon will have become very expensive. Despite this, they will only be getting back the same share from the carbon permit revenues as everyone else.


The piece is too long for comfort and should be split up; nonetheless, further down the story, the Clean Development Mechanism (CDM) is demonstrated to be as much a scam as the Emissions Trading System (ETS) was/is. Now is the time to replace them with a sensible, simple and equitable system such as outlined above.
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emordnilap



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PostPosted: Thu Sep 07, 2017 10:36 am    Post subject: Reply with quote

A relevant reader's question in The Guardian: Just how heavy could rain become in the warming world? gets some extremely informative responses - and the trolls don't seem to have infected it (yet).
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Potemkin Villager



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PostPosted: Thu Sep 07, 2017 3:30 pm    Post subject: Reply with quote

emordnilap wrote:
A relevant reader's question in The Guardian: Just how heavy could rain become in the warming world? gets some extremely informative responses - and the trolls don't seem to have infected it (yet).


I personally like "I think that the only safe answer here is 'lots'. The planetary weather system is an extremely complex system meaning that it has many variables, many of which are currently unknown."
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RenewableCandy



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PostPosted: Sun Sep 17, 2017 5:35 pm    Post subject: Reply with quote

clv101 wrote:
johnhemming2 wrote:
clv101 wrote:
Yeah. Firstly the ice-caps have non-trivial gravitational fields of their own. That's one reason why if you were to melt Greenland totally, raising average sea levels by ~7m, the sea level near to Greenland would actually go down as the ice-sheet's gravitational field would no longer be pulling the ocean towards it.

That does not sound right to me. I accept it is possible that the weight of the ice is pushing Greenland down and that removing that weight could have an effect, but I don't think it would "pull the sea up". In the end this is something that can be resolved mathematically. Can you please tell me where the calculations are for this so that I can see them?


The image above is from this paper: http://www.nature.com/nature/journal/v517/n7535/fig_tab/nature14093_SF1.html

Also see this for more on sea level rise 'fingerprinting', written by my PhD advisor: http://www.the-cryosphere.net/4/621/2010/tc-4-621-2010.pdf

All that is in *addition* to the rebound that the land would experience, and that places like Scotland are apparently still experiencing from the last Ice Age.
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