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Post by kiwistonewall on Feb 24, 2010 4:02:54 GMT
Is there any reliable research done on the effects of tectonics on sea levels? The Earth is slowly growing - maybe 2mm a year in diameter, maybe more. Cause? Sea floor spreading faster than subduction? Spin changes with changes in Ice at poles? etc etc. The Earth is slowly undergoing accretion of meteors & dust in any case. The Geometry of the oceans is always changing. It would be fascinating for an accurate 3d modelling of the sea floor to be done & the changes over time measured. I don't think our systems are quite up to that yet. Still, if the oceans are growing, they would hide the decline (I couldn't help myself) in sea level rises.
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Post by hiddigeigei on Feb 24, 2010 4:03:47 GMT
"... ice melts when it warms..."Under normal pressure, ice melts when it warms to 0 oC. "We do not really know how stable the West Antarctic and Greenland Ice sheets really are." Deep cores in the Greenland Ice sheet suggest it's been around [stable] for quite some time. "He should at the very least cite opposing views in his papers..."Hear! hear! Any one at the IPCC listening?
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Post by hairball on Feb 24, 2010 4:06:02 GMT
Interview from a couple of days ago with Nils-Axel Mörner. Big oil should really get their disinformation act together, the ever-dizzy miss Greenhouse is about the only person who does interviews with sceptics. Streaming only :\ itsrainmakingtime.com/2010/nilsaxelmorner/Oops, put the wrong link up, fixed now.
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Post by steve on Feb 24, 2010 13:28:12 GMT
I cannot see how the earth could realistically be expanding in volume. If sea floor spreads faster than subduction, this pushes up mountains and would result in sea level falls. Or vice versa. At a guess a) this is a small effect b) if it wasn't small, then GRACE would have detected it, in the same way that GRACE is detecting the change in the ice sheet mass balance.
If you google "earth accretion rate" seems to be measured in no more than 10000 kg per year, which would have a tiny impact on sea levels.
hiddigeigei,
Just because the ice sheet has been around for a long time doesn't mean it is insensitive to temperatures that are warmer than now. The last time that temperatures were a bit warmer than now for long periods (the Eemian) sea levels were 6 metres higher.
As for citing of opposing views, I would wonder whether you've read any of the IPCC report, most of which is A says this, but B says that and C says the other.
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Post by woodstove on Feb 24, 2010 15:13:15 GMT
I cannot see how the earth could realistically be expanding in volume. If sea floor spreads faster than subduction, this pushes up mountains and would result in sea level falls. Or vice versa. At a guess a) this is a small effect b) if it wasn't small, then GRACE would have detected it, in the same way that GRACE is detecting the change in the ice sheet mass balance. If you google "earth accretion rate" seems to be measured in no more than 10000 kg per year, which would have a tiny impact on sea levels. hiddigeigei, Just because the ice sheet has been around for a long time doesn't mean it is insensitive to temperatures that are warmer than now. The last time that temperatures were a bit warmer than now for long periods (the Eemian) sea levels were 6 metres higher. As for citing of opposing views, I would wonder whether you've read any of the IPCC report, most of which is A says this, but B says that and C says the other. Know your Holocene, Steve. The last time temperatures were higher than now, according to the great bulk of mainstream climatological papers published on the subject, was during the Medieval Warm Period ending only 700 years ago. The previous warmer-than-now period was likely the Roman Warm Period, again according to the preponderance of peer-reviewed research (as opposed to your rogue-IPCC clan's jottings). Argue about these two periods, as you feel you must. However, no one in their right mind throws out the Holocene Optimum. So saying that the Eemian, which ended 100,000 years ago, was the last time that the ocean-atmosphere system was warmer than today is wrong. I know that you're not trying to win debates, so this is probably a plus. ;D The Greenland and Antarctic ice sheets sailed through the Holocene Optimum, and the Eemian for that matter, intact. I'm sorry, but 6 meters of sea level rise is small potatoes. Only people who hate nature conjure sea level as inherently stable. Sea level has never stopped moving and never will stop moving, no matter how much the nature-haters want it to do so. As for the coming century, I anticipate a continuation of the basically flat sea level of the past century. You need to visit the coast and take in the scenery sometime!
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Post by Maui on Feb 24, 2010 19:16:40 GMT
Heat flow from the Earth into the ocean is the major factor. Look at what we are learning from Enceladus: Attachments:
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Post by Maui on Feb 24, 2010 19:26:24 GMT
I agree with Woodstove, inasmuch as I know sea level has been flat for 43 years at Hookipa beach on Maui, Hawaii. But nearby on the Big Island, some of the land dropped ten feet in a 1970's earthquake. Two milimeters over the whole planet is insignificant.
The important changes humans will experience in the future are not those for which we may prepare, but more like the Haiti earthquake or southeast cold snap: "change" is unpredictable, sudden, dramatic, and sometimes deadly.
Phillip Bose Orcas Island, WA
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Post by scpg02 on Feb 24, 2010 23:03:49 GMT
Heat flow from the Earth into the ocean is the major factor. Look at what we are learning from Enceladus: Wow, very interesting. Thanks for posting it.
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Post by aj1983 on Feb 24, 2010 23:24:44 GMT
I find that hard to believe. I do remember reading somewhere it was very much insignificant. Does somebody have any convincing research that volcanic heat release does have a significant effect on the oceans' heat content?
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Post by Graeme on Feb 24, 2010 23:38:54 GMT
I find that hard to believe. I do remember reading somewhere it was very much insignificant. Does somebody have any convincing research that volcanic heat release does have a significant effect on the oceans' heat content? I don't know anything about this area, but I should point out that there are theories that indicate that an insignifcant increase of CO2 (when viewed as a percentage of the total atmosphere) can have non-insignficant impacts (some proposals claim catastrophic impacts) due to forcing factors. It is possible that the same applies here.
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Post by aj1983 on Feb 25, 2010 1:38:07 GMT
I'm rather interested in what physical mechanism you would hypothesize for this, and what observations you would use to back it up.
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Post by Ratty on Feb 25, 2010 8:38:40 GMT
Be gentle with me and remember that I'm just a broken down school teacher but .... I wonder what effect river run-off, sedimentation, undersea eruptions (and their outflow) have on sea level, if any. I also seem to remember that Earth is visited by something like 40,000 tonnes of space dust annually. Much of that must finish in the oceans.
??
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Post by steve on Feb 25, 2010 10:45:53 GMT
I cannot see how the earth could realistically be expanding in volume. If sea floor spreads faster than subduction, this pushes up mountains and would result in sea level falls. Or vice versa. At a guess a) this is a small effect b) if it wasn't small, then GRACE would have detected it, in the same way that GRACE is detecting the change in the ice sheet mass balance. If you google "earth accretion rate" seems to be measured in no more than 10000 kg per year, which would have a tiny impact on sea levels. hiddigeigei, Just because the ice sheet has been around for a long time doesn't mean it is insensitive to temperatures that are warmer than now. The last time that temperatures were a bit warmer than now for long periods (the Eemian) sea levels were 6 metres higher. As for citing of opposing views, I would wonder whether you've read any of the IPCC report, most of which is A says this, but B says that and C says the other. Know your Holocene, Steve. The last time temperatures were higher than now, according to the great bulk of mainstream climatological papers published on the subject, was during the Medieval Warm Period ending only 700 years ago. The previous warmer-than-now period was likely the Roman Warm Period, again according to the preponderance of peer-reviewed research (as opposed to your rogue-IPCC clan's jottings). Argue about these two periods, as you feel you must. However, no one in their right mind throws out the Holocene Optimum. So saying that the Eemian, which ended 100,000 years ago, was the last time that the ocean-atmosphere system was warmer than today is wrong. Well of course you are missing some potential differences between the characteristics of the Holocene optimum and those of the Eemian and current warming, such as the length of the warm period (which I referred to) and the possibility that Holocene warm periods were not warm throughout the whole year. Do you dispute, then, the evidence that sea levels rose at greater than 1 metre per century during periods of the Eemian. Was the water delivered by aliens, or did it melt from Greenland and/or the WAIS? Only people who hate human civilisation think that a one metre sea level rise within the next one hundred years, with more to come, is "small potatoes".
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Post by steve on Feb 25, 2010 10:58:52 GMT
Be gentle with me and remember that I'm just a broken down school teacher but .... I wonder what effect river run-off, sedimentation, undersea eruptions (and their outflow) have on sea level, if any. I also seem to remember that Earth is visited by something like 40,000 tonnes of space dust annually. Much of that must finish in the oceans. ?? ratty, 40000 tonnes of space dust is nothing as compared with the ocean (10^18 tonnes). Processes such as river runoff, sedimentation etc, are cyclical. The sediment carried by rivers such as the Colorado was originally from the sea bed. While the erosion is occurring in Colorado, somewhere else (the Himalayas and Tibet), the land is continuing to rise (implying that the Indian ocean basin is getting a bit bigger). The GRACE satellite is attempting to observe these processes by monitoring the earth's gravitational field. Such observations would be capable of seeing the net differences one way or another. Apart from the current net flow of land ice into the sea of about 2mm per year, I haven't heard that there are any significant net changes that would affect sea level
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Post by kiwistonewall on Feb 25, 2010 11:47:47 GMT
HAven't heard = We dont know.
The geometry of the oceans (and therefore volume) is changing in unknown ways. Subduction zones create deep trenches. The shape of the Earth is also changing - it never was a sphere! - and that may be due to past (or present) changes in ice cover.
The oceans do not have a static geometry. We haven't got the faintest idea, nor any way of measuring this geometry except to make the crudest estimates.
It is time to admit that human science is still very much in its infancy. We are too ignorant to play God (yet!)
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