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Forum » SpaceEngine » Off-topic Discussions » Totally off-topic thread (Talk about anything.)
Totally off-topic thread
WatsisnameDate: Friday, 08.03.2013, 08:00 | Message # 676
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I've already gone over all of that from like, page 30. Page 28, even.






Edited by Watsisname - Friday, 08.03.2013, 08:02
 
midtskogenDate: Friday, 08.03.2013, 08:36 | Message # 677
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Quote (Watsisname)
I've already gone over all of that from like, page 30. Page 28, even.

Yes, we've touched sensitivity before. I understood the discussion between Aerospacefag and you that Aerospacefag suggests that the feedbacks could work the way that they stall or even reverse the effects of the underlying driver, but I'm not sure whether you're actually making a case against that.

Has global warming stopped? Depends on the perspective. When this argument was presented by sceptics some years ago, the counter argument was that an exceptionally strong el niño year was cherry-picked as a starting point and at least 15 years was needed to establish a trend. Now that more than 15 years have passed and the el niño is sliding out of the 15 year window, the argument has turned more into that we need more than 15 years. I agree, and the sceptics have been lucky that the temperature still doesn't seem to move much. I think I'll wait for hindsight before passing a definite judgement on that.





NIL DIFFICILE VOLENTI


Edited by midtskogen - Friday, 08.03.2013, 08:38
 
WatsisnameDate: Friday, 08.03.2013, 09:02 | Message # 678
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One may say global warming has stopped if their perspective is that of complete ignorance. Read post #669.






Edited by Watsisname - Friday, 08.03.2013, 09:06
 
midtskogenDate: Friday, 08.03.2013, 10:13 | Message # 679
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Read post #669.

What exactly is the difference between a pause and a plateau in a temperature graph? Apparently, someone saying that it has paused is ignorant, and someone saying it has plateaued has physics on his side. I need to get that explained. I can't see that either wording implies any kind of momentum more or less than the other.





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WatsisnameDate: Friday, 08.03.2013, 10:40 | Message # 680
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The difference, is everything I went to the trouble of explaining immediately after that statement but somehow you completely ignored. Here, I'll quote myself with big text for you again.

Quote (watsisname)
Global warming has not paused. Global average air temperature has plateaued, but this makes up only a tiny fraction of the heat content of the Earth system, and is easily masked by other processes, such as atmosphere-ocean interactions. Taking such things into account, the signal of global warming is just as strong as ever. It is the earth's oceans that store the vast majority of heat, and indeed the total ocean heat content continues to rise.


edit:
So yes, looking at global air temperature and concluding that global warming has stopped is extremely ignorant, because you limited yourself to an extremely narrow view of the earth system (atmosphere is very small component of total heat capacity -- oceans make up more than 90% of it, so the fact that the oceans are warming is a big deal.) and ignored heat transfers between the different components of said system. This is extremely basic atmospheric science -- the atmosphere is coupled with other systems.

You could also look at the response from the upper atmosphere, since global warming causes the upper atmosphere to cool, as I explained in a follow-up post.







Edited by Watsisname - Friday, 08.03.2013, 10:57
 
midtskogenDate: Friday, 08.03.2013, 11:06 | Message # 681
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Calm down, no need to shout. I'm just wondering if there was a reason why you said temperature has plateaued, not paused, if that meant something.

I totally agree that the air temperature, happened to be measured about 2 metres above the ground, is a poor measure stick for the total heat content. Or for the Earth's general health for that matter. Yet it's what being used in politics. But using arbitrary things as a basis for decisions is nothing new in politics.





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WatsisnameDate: Friday, 08.03.2013, 11:16 | Message # 682
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Please forgive me, my patience has just been very low.

Pause and plateau mean basically the same thing there. The important note is that global air temperature and global warming are not completely equivalent. Rather, global air temperature is one small subset of global warming. It would indeed be nice of politicians understood this as well.





 
midtskogenDate: Friday, 08.03.2013, 18:59 | Message # 683
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On the other hand we have 100+ years of direct observation of this small subset. A challenge for science is that we don't have a long record of the global ocean heat content by direct measurement. Without such data we have no direct evidence for what the long term natural variability of the heat content is making it hard to quantify the human impact.




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WatsisnameDate: Friday, 08.03.2013, 19:14 | Message # 684
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Therefore this enormous increase in global heat content currently can be disputed as being due to other factors, global warming theory is wrong, we're all being stupid, etc. rolleyes

No, actually we can reconstruct ocean temperature very well. Marine fossils, sediments, corals, etc. Not to mention that if/when the heat content of the ocean changes this has enormous and observable effects on the rest of the earth system. This isn't some realm of dark and murky science. It's understood much better than you may think.

edit: In short, 'indirect' does not equate to 'lack of data or understanding'.







Edited by Watsisname - Friday, 08.03.2013, 19:31
 
midtskogenDate: Friday, 08.03.2013, 19:43 | Message # 685
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Quote (Watsisname)
Therefore this enormous increase in global heat content currently can be disputed as being due to other factors, global warming theory is wrong, we're all being stupid, etc.

That's a non sequitur, of course (yes, I saw the smiley).

Quote (Watsisname)
No, actually we can reconstruct ocean temperature very well. Marine fossils, sediments, corals, etc.

Links? Ocean temperature can vary quite a bit locally over time, but globally things level out, so you need a lot of data.

Quote (Watsisname)
Not to mention that if/when the heat content of the ocean changes this has enormous and observable effects on the rest of the earth system.

Absolutely, but the interpretation is not trivial. For instance, if air temperatures dropped, was it cooled by a cold ocean, or was there a transfer of heat from the air to the ocean?

Quote (Watsisname)
edit: In short, 'indirect' does not equate to 'lack of data or understanding'.

No, but it adds a level of interpretation.

Edit: I think satellites is the way to go to get a good view on Earth's heat balance. Unfortunately, there is very little of fossil satellites or sediments of decayed satellites to reconstruct historical records.





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Edited by midtskogen - Friday, 08.03.2013, 20:14
 
WatsisnameDate: Friday, 08.03.2013, 20:27 | Message # 686
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I know, there just seems to be this persistent theme of 'if we don't have direct measurements, then what we do have must be highly questionable", which would be a very gross oversimplification of the true level of knowledge that we possess. Knowledge =/= interpretation, because ideas must be tested against evidence.

Quote
Links?

None specifically; I thought this was just common knowledge. I'd suggest to try browsing the literature. You may search google scholar for terms such as
"ocean heat content reconstruction"
"ocean temperature reconstruction marine fossils sediments"
"ocean temperature isotopic"
"ocean temperature atmosphere coupling"

and see what you find. There's a lot of information out there.

Quote
Absolutely, but the interpretation is not trivial. For instance, if air temperatures dropped, was it cooled by a cold ocean, or was there a transfer of heat from the air to the ocean?


Nope, not trivial at all, and it could be either or both; depending on the particular circumstance. I'm sure you may find very interesting examples in the literature.

When it comes to the current era, it is very clear that the total heat content is increasing because of an enhanced greenhouse effect from human activities. There are subtleties to this when it comes to specific earth systems, because of heat transfer between them, but these do not lead to the conclusion that the enhanced greenhouse warming has stopped. I think that is a good way of tying together this topic.







Edited by Watsisname - Friday, 08.03.2013, 20:47
 
midtskogenDate: Friday, 08.03.2013, 21:07 | Message # 687
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None specifically; I thought this was just common knowledge.

If reconstructions of global ocean heat content for the past millennia are common knowledge, I have missed it. Every time I've heard reconstructions based on corals, sediments etc the scope has in for a specific areas, sometimes for previous geological periods, not reconstruction of global heat content. To get the global figures you must sort out local changes that are just due to changing currents or whatever with local effects.





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WatsisnameDate: Friday, 08.03.2013, 21:51 | Message # 688
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Yes, and the assimilation of knowledge gathered from study of the components leads to an understanding the whole. This may be seen by the literature.

This is similar idea as with reconstructing earth geologic history. One cannot simply figure it out from scratch all at once; one must instead look at all the pieces and put them together.





 
midtskogenDate: Saturday, 09.03.2013, 07:15 | Message # 689
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Easier said than done. How many apples are there in the world? The evidence is out there, and individual apples are easy to count.

It's not my habit of thinking that somebody who knows these things well surely has found a hockey stick (or whatever) for global heat content, or if not, surely would have since all they have to do is to piece together every sample there is and collect the rest themselves from the world's remaining ocean beds, so I don't have to wonder. Or that if I expect something to be this or that way, I can simply google it until I find a paper that says it, and then I don't need to understand why, since somebody else has done that.





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WatsisnameDate: Saturday, 09.03.2013, 07:28 | Message # 690
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I'm sorry, I don't have any idea what you are trying to tell me. Can you clarify? I feel as if you're extremely skeptical about a vast field of study yet not actually trying to learn about it despite being provided with means of doing so. This confuses me greatly.




 
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