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Old 12-03-2012, 12:40 PM   #181 (permalink)
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Neil earlier you posted the chart showing that the volume of ice in september has been halved since the 1980s. From all that ice melt we have effectivly gained 0 sea level rise.
You have proven that the sea level rise scare is over hyped.
Why so worried?

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Old 12-03-2012, 12:46 PM   #182 (permalink)
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Taking the equations from

Radiative forcing - Wikipedia, the free encyclopedia

dF=5.35*Ln(C/Co)

dT = 0.8*dF

dF = change in forcing

C = current concentration CO2 (I'm using 2005) 315ppm

Co = orriginal concentration CO2 (I'm using 1958) 380ppm

dT = change in temperature (using 1958 to 2005) 0.64C



I am hoping they made an actual physical measurement and didn't just run that through a model and call it good. This shows that for a doubling of CO2 we get a change of forcing of 3.39w/m^2, which is different from the IPCC value of 3.7w/m^2.

Using the "measured" value changes the equation to

dF = 4.89 * Ln(C/Co)

Filling in for CO2

dF = 4.89*LN(380/315) = .91w/m^2 for the measured 1958-2005 change in CO2.

That should give us a change in temperature of

dT = .8*0.91 = 0.73C which is 0.09C higher than observed.

Correcting for observed gives us a climate sensitivity of 0.696

Now we can calculate for future warming.

Forcasting a rise to 600pmm.

dF = 4.89*Ln(600/315) = 3.15w/m^2

dT = .696*3.15 = 2.19C


That is assuming all warming is due to CO2 with no influence from the sun.

Neil: A lot of the changes that are happening faster than we expected are because they are in the colder climates. One of the things the equations above do not take into account is the fact that in the colder climates a small change in the energy ballance causes a greater change in temperature than it does in warmer climates. The warmer climates will hardly change at all, while the coldest climates will warm by probably 10C or more.
 
Old 12-03-2012, 01:09 PM   #183 (permalink)
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Oilpan: Thats the north polar ice, which is sea ice, which will not effect sea level. Its the ice that is on land that will affect sea level.
 
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Old 12-03-2012, 01:40 PM   #184 (permalink)
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Quote:
Originally Posted by oil pan 4 View Post
Neil earlier you posted the chart showing that the volume of ice in september has been halved since the 1980s. From all that ice melt we have effectivly gained 0 sea level rise.
The Arctic ice is almost entirely pack ice, floating on the ocean surface, so that melting it doesn't change sea level at all. Honestly, I thought stuff like this was supposed to be covered in grade-school science classes.

You are right that sea level rise has been over-hyped, though you're right for the wrong reason. It may, like the recent hurricane Sandy, be a personal & economic disaster for those humans who built close to the sea, but the biosphere would adjust quite easily. (Just as it did to the Pleistocene changes in sea level.)

No, the real problem is that photosynthesis is dependent on temperature Photosynthesis C3 shuts down at about 105F, C4 at about 130F. Once tropical land & ocean temperature reach these levels, there goes a lot of the food supply. And of course, since tropical vegetation will no longer be participating in the carbon cycle, but instead will be rotting or burning, there's another big CO2 feedback spike.
 
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Old 12-03-2012, 01:52 PM   #185 (permalink)
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Quote:
Originally Posted by TheEnemy View Post
That is assuming all warming is due to CO2 with no influence from the sun.
You seem to be forgetting that there are a lot of feedback effects at work. To list just a few:

1) Water vapor also is a greenhouse gas. The amout of water vapor in the atmosphere depends on temperature (and other factors which don't change here). When added CO2 increases the temperature by dT, that increases the amount of water vapor, which increases the temperature by several times dT.

2) Dark land/sea surface absorbs more heat energy than reflective ice cover, so melting the Arctic ice increases warming.

3) As the Arctic land mass warms, melting the permafrost, additional amounts of methane & CO2 are released.

4) A large amount of CO2 is dissolved in ocean waters. The solubility is inversely dependent on temperature. As ocean waters warm (because you've removed that nice radiant barrier insulating ice cover), they hold less CO2, which goes into the atmosphere, increasing warming.

Quote:
That is assuming all warming is due to CO2 with no influence from the sun.
Which, as has been pointed out numerous times, is the case. The sun's output has not changed significantly for as long as we have accurate measurements.
 
Old 12-03-2012, 02:03 PM   #186 (permalink)
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The calculations I did are supposed to account for those feedbacks. If you look at the wiki artilce the full equation is dT = (lamda)dF where lamda is the climate sensitivity, and accounts for feedbacks.
 
Old 12-03-2012, 02:07 PM   #187 (permalink)
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The study of the melting tundra I posted earlier indicates that this will contribute a HUGE amount of GCG - it will add ~39% to the total as we go, over the next several decades. Lots of methane and lots of carbon dioxide are already coming out of the decomposing organic material that used to be frozen. If there is no oxygen present when it breaks done, then we get methane, and if there is oxygen present we get carbon dioxide. The methane is at least 7X more insulating than carbon dioxide; though after a relatively short time (about 7 years?) the methane becomes carbon dioxide - which basically lasts "forever". The only way it is naturally sequestered (weathering?) it takes millions of years to go away.

On ocean level rise - most of it so far has come from the water being warmer i.e. less dense which means it expands. A small amount of the rise so far does come from land ice melting i.e. glaciers and now that Greenland has started to melt faster and faster, we will be seeing accelerated rate of ocean level rise.

In the past 100 years, we have had a bit less than 1 foot of rise - but in the next 100 years we will see at least 2 more feet and maybe 3 or 5 feet. When Greenland completely melts - which it seems inevitable that it will - that will raise the level by about 20 feet. And another complication is that the gravitational pull of the ice itself will disperse, so the ocean level will shift around and the increase will not be "even".

So if Sandy does all the destruction that it did with "just" 1 foot of rise, can you image what it would do with another 2 feet? What about more? Can you imagine what will happen when all the people who live on broad coastal plains get pushed back by a mile - or what about 10 miles?

If you you are not already worried, then you need to learn more.
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Last edited by NeilBlanchard; 12-03-2012 at 02:20 PM..
 
Old 12-03-2012, 02:14 PM   #188 (permalink)
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Quote:
Originally Posted by NeilBlanchard View Post
The study of the melting tundra I posted earlier indicates that this will contribute a HUGE amount of GCG - it will add ~39% to the total as we go, over the next several decades. Lots of methane and lots of carbon dioxide are already coming out of the decomposing organic material that used to be frozen. If there is no oxygen present when it breaks done, then we get methane, and if there is oxygen present we get carbon dioxide. The methane is at least 7X more insulating than carbon dioxide; though after a relatively short time (about 7 years?) the methane becomes carbon dioxide - which basically lasts "forever". The only way it is naturally sequestered (weathering?) it takes millions of years to go away.
So what concentration of CO2 do you think we will achieve before we stabilize?
 
Old 12-03-2012, 02:32 PM   #189 (permalink)
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I think the science indicates that ~350ppm was the threshold for the Arctic ice to stay put. We passed that in about 1987-88.

We had 391.03ppm at Mauna Loa in Hawaii in October 2012. This level "breathes" up and down by ~5-6ppm in the northern hemisphere due to all the trees and other land plants that grow and then either drop their leaves or die each year. The level peaks in about March and hits it's minimum in about October.
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Old 12-03-2012, 02:40 PM   #190 (permalink)
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Quote:
Originally Posted by NeilBlanchard View Post
I think the science indicates that ~350ppm was the threshold for the Arctic ice to stay put. We passed that in about 1987-88.

We had 391.03ppm at Mauna Loa in Hawaii in October 2012. This level "breathes" up and down by ~5-6ppm in the northern hemisphere due to all the trees and other land plants that grow and then either drop their leaves or die each year. The level peaks in about March and hits it's minimum in about October.
That wasn't what I asked, in the comming decades what do you think the atmosphere will stabilize at by the time we shift our energy sources over? 500, 600, 700ppm?

 
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