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Moderated Global Warming Discussion

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aleCcowaN said:
... A reference value for the '80s is a yearly loss of 40 GT.
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Thank you for the quick reply.

I understand that the slopes of the two data sets are equivalent, but why is there a systematic difference in the measured values on the y-axis?

I am not disputing this data in any way, I am merely curious.
 
seycyrus said:
Thank you for the quick reply.

I understand that the slopes of the two data sets are equivalent, but why is there a systematic difference in the measured values on the y-axis?

I am not disputing this data in any way, I am merely curious.
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I'm not sure nor worried. The background plot is more recent and the team closer to the source data, so it can contain some changes in the algorithm, or corrections, like after each strong earthquake in any part of the world, moving the Earth's axis of inertia. There's such kind of difference during 2008 about the time the M8.0 Sichuan earthquake killed 70,000 and left five millions homeless.
 
It is always a good idea to understand any disparities between data sets that are meant to be measuring the same thing.

I do not understand why an earthquake would affect satellite measurements that measure shifts in the earths gravitational field.

EDIT: These are yearly measurements, correct?
 
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By yearly measurements, I meant a year's worth of data, averaged.

Hopefully with earthquakes and other such influences removed.
 
macdoc said:
Not sure I understand - why would you remove earthquake data.?

This might give you some insight

http://www.ouramazingplanet.com/1887-japan-earthquake-altered-earth-gravity.html
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it would certainly affect individual stations when comparing satellite and ground station data (either tidal guage or gps station used to monitor uplift). Also changes to the Earths axis will affect the orbital parameters of the satellite, minutely admittedly, but enough to have to recalibrate the system.
 
Mikemcc said:
it would certainly affect individual stations when comparing satellite and ground station data (either tidal guage or gps station used to monitor uplift). Also changes to the Earths axis will affect the orbital parameters of the satellite, minutely admittedly, but enough to have to recalibrate the system.
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The rotational axis doesn't change, what changes is the principal axis of inertia and the value of the moment of inertia. That's why earthquakes have consequences not only in the shape of the planet (we have to remember that a Greenland 1 mm bulgier implies some 2GT more of ice that it's not) but in the duration of the day. The figures in the article of Wikipedia about leap seconds show those changes with earthquakes and the following adaptation. One can see clearly there the earthquakes of Sumatra (2004), Sichuan (2008) and Chile (2010) affecting the rotation of the Earth.
 
Halsu said:
A good talk, thanks for the link!
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Seconded. Steve Schneider has long been a personal hero of mine. RIP big fella
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it would certainly affect individual stations when comparing satellite and ground station data (either tidal guage or gps station used to monitor uplift). Also changes to the Earths axis will affect the orbital parameters of the satellite, minutely admittedly, but enough to have to recalibrate the system.
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why would you "recalibrate" - it there to measure changes - there is no "baseline" - beyond that of the original survey. I think it's a neat bit of science the way it's done and certainly is offering a lot of insight into the slowly heaving planet. I understand tho the satellites are in need of replacing??
 
aleCcowaN said:
The rotational axis doesn't change, what changes is the principal axis of inertia and the value of the moment of inertia. That's why earthquakes have consequences not only in the shape of the planet (we have to remember that a Greenland 1 mm bulgier implies some 2GT more of ice that it's not) but in the duration of the day. The figures in the article of Wikipedia about leap seconds show those changes with earthquakes and the following adaptation. One can see clearly there the earthquakes of Sumatra (2004), Sichuan (2008) and Chile (2010) affecting the rotation of the Earth.
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Sorry, I was being inexact.

in terms of my use of the word recalibration, if a tidal guage has provided a record of sea level change, but then gets a 10mm uplift due to an eartquake, then an offset has to be applied to subsequent measurements to keep them comparable to the previous record (otherwise it looks like there was a sudden drop in sealevel rather than the station being raised). The GPS satellites are continually requiring recalibration as their orbit velocities are affected by local gravitational changes, atmospheric drag, etc. These changes in velocity cause small changes to their clocks due to relativistic effects (yes, the onboard clocks are that accurate!)
 
But these are a pair of satellites ( so what affects one affects the other ) designed to measure the changes you want to "calibrate"
Their reference point is each other and then they track the gravitational anomalies. Drag would not impact the differential between them and gravity changes is what they measure.
This nothing like a tidal gauge measurement which measures a supposed fixed point that could change with say an uplift.
The reference for these is each other.
 
Perpetual Student said:
When I look at this list LINK, the situation seems to be hopeless. If, say, the USA, second on the list, were to undertake a massive effort to reduce emissions and for example, reduced them by half, that would accomplish very little in global terms, but would come at an enormous economic cost. It seems it would be wiser to spend the money preparing for the consequences of rising sea levels, etc.
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No, three-five degrees centigrade average global increase and you will not be able to grow maize in most of the midwest, maybe some soya. But given the already barely adequate levels of rain during the summer and the increase in temps, you can not just irrigate all of the fields in iowa and illinois.
 
I can't get embedded videos to work on this forum but encourage everybody to watch this:

http://youtu.be/vT6H7HPWkqUa

It's an appeal for crowdfunding of the Dark Snow Project - a project to measure the loss of albedo on Greenland and identify whether soot from industry and wildfires are driving a dangerous new feedback.

It's sad that scientists now have to resort to appealing to the internet to get funding but that's the reality - anyone with a few bucks to spare could do worse than to spend it on this:

http://darksnowproject.org/
 
A gem from that denier site

"Since I started the fb group There is no greenhouse effect, it has become increasingly obvious that there is good reason for the sceptics infighting.
The reason, and this has been admitted by several different main stream sceptics, is that they do not know what the actual GH "theory" is......
Unbelievable as such, but it appears true.


If they knew what the GH theory was they wouldn't be there :)
 
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