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Syndicate
Not at the same time though. Combustion is a form of oxidation, but the natural breakdown of methane in the atmosphere is not combustion. In any case, water vapour from evaporation dwarfs that from any other source.
That's exactly my point. As methane breaks down in the atmosphere its greenhouse potential drops but does not disappear since its products, particularly CO2, are also greenhouse gases.
Which brings us back to the beginning. I don't see why we've gone round and round on this.
Quite true, and since atmospheric water vapour is limited by atmospheric temperature and pressure, it is a feedback rather than a forcing. It is increasing only because of the warming forcing produced by increasing CO2. The current increase in methane is also a feedback in the current instance.
But there is one place that added water vapour from combustion is a factor: in the upper troposphere and lower stratosphere from air traffic. In this case, however, it instantly condenses into cloud trails, which reflect incoming sunlight, and thus have a cooling effect.
I think that the cooling effect may be overestimated. A crystal stays there for how long?
And a crystal does not reflect like a mirror. It absorbs too, Light bounces all over the place, in fact.
And there is the whole chemical effect of the ice water and vapour up there. Water is one of the favoured solvents in science. One of the best places to speed up chemical reactions.
i think people do a simple measurement of direct energy transmitted to earth and assume the rest is reflected.
It isn't. Lots still gets here by indirect means.
The air could be a tenth of a degree warmer over a 2 thousand sq mile area or the wind could be a quarter of a mile per hour faster and we would not be able to detect the difference.
It is all energy and it still gets to us.
It's not estimated, it was actually quantified in the days immediately after 9/11 when air traffic was grounded over North America and then resumed.
Source
(footnotes omitted)
A week or so with no flights is not a quantification of anything. Nothing reached equilibrium in that amount of time. All we know is that the days were hotter and the nights were colder in that time. There was not enough time for long term effects to be seen. For instance, more evaporation in the days would change cloud patterns and perhaps even weather systems over the long term. I think people are reading way too much into that little snapshot of change. The system had not even approached its new equilibrium in the tiny period.
Interesting..., but even more worrying:
http://www.bloomberg.com/apps/news?pid=20601124&refer=home&sid=a61C3MoVAAMA
And the collection of papers on Pliocene climate in the Royal Society journal that the Bloomberg report is based on:
http://journals.royalsociety.org/content/l67121161284/?p=20082f4a58b144e...
Perhaps it wasn't quantified, but not only were the days hotter and nights colder, but more daytime solar radiation was reaching the surface. This would be expected to have some impact on temperature.
Are there any studies what an ice-free arctic ocean in summer will do to Ocean currents?
What is the main motivator for the Gulfstream, is it Coriolis or are it the density differences in the Ocean waters, or maybe even the prevailing winds? I imagine the Gulfstream supplies a lot of energy into the Arctic. If it were to come to a halt would it be enough to prevent the melting of the Arctic ice in the summer.It would be interesting to see if there could be developng a slow occilation between an ice-free arctic ocean and no Gulfstream, and an iced over arctic ocean with a gulfstream. If that were to happen how long would it then take for it to dampen into a new equilibrium.
Sunday Times, May 8, 2005
Yes there are Bubbles... I'll see if I can find the links again, but there are several ocean current research projects on-going... The prominent one I was following was from a Japanese - Russian project that was monitering Northern Atlantic and Arctic currents. My personal faveorite for most of this information is http://nsidc.org/ although I'm not sure what they have on ocean currents.
Transplant (on a different forum I beleive) had posted information on Ice Buoys that were tracking the movement of ice across the arctic... You might be interested in that as well. Heh, likely the last few years we can track that... Give it another 10 and there won't be ice to track.
May as well repeat it... The Earth has a fantastic ability to handle yearly variations in temperature, simply through the process of converting ice to water or water to ice and the amount of energy that requires (1 gram of ice melting is the equivlent of 1 gram of 'air' rising some 82 degrees C(estimated, but thats close). Once the ice cube in our northern drink finishes melting, we'll start to see the more abrupt changes. Fortunately, I think we should have another 5 years of burying our heads in the sand before we're confronted with that.
Just to put it out there as another snowball effect... The warming trend appears to be weakening trade winds across the globe. The winds as they travel across the ocean act to cool off the air considerably by evaporating water (same theory as the ice melting above). Weaker winds results in less of this evaporation, which is less of a cooling effect... Meaning we'll be in for warmer ocean temperatures in regions that these winds are weakening and ocean temps can easily be tied to the strength of hurricanes.
I'm sure there are. Try google scholor @ http://scholar.google.ca/
For one thing, much of Earth's ocean currents and weather are driven by the temperature differential between the tropics and the polar regions. Warmer polar regions can't help but mean major shifts in global weather patterns.
The answer is in the name of the mechanism: thermal-haline circulation. See: http://en.wikipedia.org/wiki/Thermohaline_circulation
As the warm gulfstream surface current travels north it looses a huge amount of both mass and heat through evaporation, becoming colder, more saline and more dense, in the process making northern Europe much warmer than it otherwise would be.
When the current meets cold but much less saline (thanks to the annual Arctic ice melt) and much less dense arctic water it sinks to the bottom of the ocean, where it continues as a global deep-sea current that eventually upwells in the Southern Ocean, Indian Ocean and North Paciifc to complete the loop.
Have scientists determined how much of the global warming is due to sun activity?
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Eleutherophobics of the World...Unite!!!
Yes they have. And they've determined that the sun trumps capitalism.
They hate us for our freedoms for sure. Recite aloud and often in the preying mantis position followed by "ohm padne ohm"
Very enlightening (and pertinent) answer.
Not.
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Eleutherophobics of the World...Unite!!!
Perhaps capitalists can finally get out of widgets and commodities, and fossil fuels, and banking and financial skullduggery, and make a grab for public services, health care, and perpetual phony war on terror? Maybe they can globalize that last item on the list without effin it up.
I've said it before, Fidel, but it's worth repeating: You are the master of non sequitur posts.
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Eleutherophobics of the World...Unite!!!
What would you prefer I said, that global warming is inevitable? And so capitalists everywhere should be off the hook for dumping billions of tons of CO2 and other crap into the air around the world? How about some climate science quotations from George Carlin to lighten things up a little. You're too tense, Sven.
Yes... To some degree atleast, although it's extremely hard to get a baseline (like the 'sun has put out more energy today than it did 1150 years ago' denial arguement... Show me our detailed records of the sun from 1150 years ago plz. Hell, show me detailed sun activity records that go back 50 years). We can get pretty accurate measurements as to how much sunlight reaches a certain area, but our history to compare it to is badly lacking (same difficulties with hurricanes).
Check realclimate.org for articles along those lines, I recall one article that actually had it caluculated to an energy per square meter value... The amount that CO2 is capable of trapping and the changes there are exponentially larger than the changes in sunlight reaching earth, so as a final answer, I think 'nearly insignificant' is correct. Though it's a hard question to answer, if you follow the global dimming and atmospheric warming discussions, the better question to ask is where in the atmosphere is the sunlight is being asorbed/reflected... There is far less sunlight reaching the planets surface.
Bubbles... I avoided this at first, but might as well try:
I'd be speculative of my answer to this... but here goes :P You are right with the degree of energy that this system circulates. Water has an incredibly high specific heat capacity... Meaning it takes a lot of energy to raise it by one degree celcius compared to anything else (depending on the air make-up, 1 degree change in waters temp could be a 5 degree change to the same mass of air... If you go by volume, the amount of energy to heat a litre of water 1 degree would increase the temperature of a liter of 'air' by about 4000 degrees).
So the amount of energy transferred by these water currents operates on a level well beyond anything the air currents could transfer. Assuming a full halt in the system can occour, the arctic would be in for a pretty quick deep freeze while the tropical waters quickly warm. No clue what this would do to air currents, but I'd imagine we'd see some extremely windy days... Even then, it couldn't transfer the heat required to keep the system balanced. So you've got an equatorial zone with no method of losing heat and the arctic radiating much more than it receives... Unsure how extreme that could get, 50 degree tropics? 30 degrees? If you go with studies on fossils, there was a time where tropical waters were 50-60 degrees celcius (same time a 'tropical arctic' would have existed)... I'd imagine thats the high end of the extreme. Reforming of ice would restore the balance required for the gulfstream, but no clue if it'd restart on it's own and resume what it once was.
Funny enough, any of these events would not have much effect on the average global temperature really... Just the tropics would hit one extreme while the arctic hit the other extreme.
Then again, I'm not sure if we have a good explaination for El Nino and La Nina (although we know how to identify it and the effects it'll have, the cause is pretty much unknown)... To suggest anyone has decent knowledge of what will happen when a system we don't understand starts dramatically changing is beyond me.
Look up Atlantic conveyor and thermohaline circulation.
You might want to rethink:
"Funny enough, any of these events would not have much effect on the average global temperature really... Just the tropics would hit one extreme while the arctic hit the other extreme. "
http://www.whoi.edu/page.do?pid=12455
http://www.pik-potsdam.de/~stefan/Lectures/ocean_currents.html
I hope you all had a nice time the last few days.
It has been a bit hectic here, with kids and visitors coming over. This by way of a poor excuse for not responding sooner on your replies.
I have been reading a bit up on the possible effects the increase in greenhouse gasses could have on Ocean currents. Not unexpectedly it seems to be a very complex issue.
All that fresh meltwater coming from the Antarctic and Greenland is likely to have an effect on the Ocean currents. It is difficult to see how they could not be changed by this. Also a rising sea level and a melting of the ice in the summer between the Canadian arctic islands is going to change the currents there. I am not sure if that would result in a north or south flow. But with a warmer Arctic Ocean it might end up in an increased south flow of warmer water down Davis Straight. Could add to the interference of the Gulf Stream.
GV:
Heh, a bit snide of a comment GV, though why would I expect less?
Wanna consider the question I was trying to answer and expand on your comment a bit? Or should I respond in kind with "look up Atmospheric waves, ocean basins, and... umm... speed of solar wind?"
ETA for bubbles.... The second link you've posted goes to a 1997 lecture. We've learned alot in the past 10 years, which often makes dated material irrelevent today. Although in this case, it looks like the article is still accurate. This information is still quite relevant:
well, other people reach other conclusions:
http://tinyurl.com/8p7d83
Easily one of the most important stories of 2008 has been all the evidence suggesting that this may be looked back on as the year when there was a turning point in the great worldwide panic over man-made global warming. Just when politicians in Europe and America have been adopting the most costly and damaging measures politicians have ever proposed, to combat this supposed menace, the tide has turned in three significant respects.
First, all over the world, temperatures have been dropping in a way wholly unpredicted by all those computer models which have been used as the main drivers of the scare. Last winter, as temperatures plummeted, many parts of the world had snowfalls on a scale not seen for decades. This winter, with the whole of Canada and half the US under snow, looks likely to be even worse. After several years flatlining, global temperatures have dropped sharply enough to cancel out much of their net rise in the 20th century.
"cancel out their net rise in the 20th century" after "several years flatling"?
This is the bean counting world equating statistical results with events on the ground. Not net effect but "net rise"?
And who has found global termperatures "flatlining"?
Please tell me I'm reading this wrong, that I'm not doing a Rip Van Winkle.
"Funny enough, any of these events would not have much effect on the average global temperature really... Just the tropics would hit one extreme while the arctic hit the other extreme. "
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You can confidently draw the above conclusion from the quoted material you provided, Noise?
Umm... My answer was in speculation to Bubbles question... I had included 'I'd be speculative of my answer to this... but here goes :P" in that post as well. So there was no quoted material, tis my speculation.
If you want the reasoning... The circulation stopping wouldn't affect the average temperature of the world, just the distribution of the energy... Total doesn't change, where it's located does. Admittadely the forming of new ice around the arctic would add energy to the system, but would be counteracted by the amount of water vapor forming in the tropics.
Make sense? It was a speculative answer to a question posed by Bubbles that none of us seemed to wanted to try to answer.
Heh, Dave... That article is painful.
Global temps haven't plummeted. We've had a slightly below average north american season (isolated mostly to the west), while the majority of the globe has consistantly been 4-5 degrees warmer than the baseline (1969-1990 I think?).
The snowfall arguement is funny to... Snowfall comes from freezing rain... The act of water freezing would release energy ;) If anything, increased snowfall reflects there is additional humidity in the air from warming temperatures.