BBD BBD says:
“Sigh. This is what I said, and it is perfectly clear: As I understand it, the effect of AGW on the Hadley Cells is to increase precipitation in the tropics, not move it polewards.”
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Look I tried to exit the thread, politely, to let Dikran stop running around in circles.
In relation to your comment as Dikran said
“if [*] the Hadley cells do expand by perhaps 2 degrees. This implies that there is perhaps a 1 degree increase in the “rain band” that might be conducive to the growth of the rainforest.”
That is a 1 degree increase in latitude from the equator.
ie polewards.
It moves the precipitation polewards. Sorry, that is a fact, and would increase precipitation
Your understanding is not supported by the facts.
Izen,
“the position of the ITCZ. That remains at the thermal equator.”
True.
An obvious goalpost move. The sign of a lost argument.
Hadley cells start at the geographic equator for descriptive purposes.
the thermal equator is not identical to that of the geographic Equator, and it moves roughly between the Tropic of Cancer and the Tropic of Capricorn,
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I am so disappointed in the haste and anger to tear down what was merely an observation based on a reasoned thought process with supporting arguments. seems to be purely on the ground that no argument put forward by someone I disagree with could ever possibly be right.
Hence we must ignore the salient points, find examples somewhere to prosecute our case, throw in goalpost moves [thermal equators] and redefine the physics to suit an answer.
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Salient points
AGW causes Hadley cells [defined as starting from the equator] to expand.
The upgoing moist air precipitates over the tropics.
The Hadley cells come down at 30 degrees latitude, now cold dry air causing deserts.
The expansion would cause the Hadley cells to move 2 degrees polewards.
Hence the area of precipitation would be expected to move a degree further polewards.
Hence the tropics [trees] could move further polewards and in fact would be expected to anyway in a warming world.
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Arguments about the Amazon restrictions ignoring the tropics in the rest of the world Both North and South of the equator might look like cherrypicking but hey, this comment says it all.
“BTW if there was any doubt that X’s approach to science, there is always the fact that he only cited the information about the Amazon that supported his argument but he somehow failed to mention the other 97 bits that didn’t:”
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angech, acknowledges his goalpost shift in usual blog style – by walking away.
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No, I gave you and others a chance to let the subject rest.
The fact that others are not piling on in support, well not til now, should have helped you realize that the salient points above, and their relevance to my comments are for once sensible.
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BBD says
“At this point I’m with Dikran”
Good to note there is some scope for change.
“The PETM was a naturally-forced hyperthermal forced by a natural transfer of carbon from sinks to atmosphere [mechanism irrelevant, angech].”
Totally?
Of course the mechanism is important.
“The lag of ~3,000?years between the onset of warming in New Jersey shelf waters and the carbon isotope excursion is consistent with the hypothesis that bottom water warming caused the injection of 13C-depleted carbon by triggering the dissociation of submarine methane hydrates but the cause of the early warming remains uncertain.”
Pangaea split apart due to massive volcanic eruptions.
One could imagine the extra heat from masses of hot lava might have caused heat rise before the CO2 rise.
In fact if the ocean bed ripped apart and all that cold water had a massive heat injection how long would it be before that heat was able to transfer to the surface and into space?
How much CO2 would be released from a warming Ocean ?
Is 2000 gigatons too much to expect from a 5c temperature rise?
How many gigatons of CO2 in the current CO2 level is actually allocated to the ocean warming that has taken place?
Is it ever mentioned in a list. Short answer, No.
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I had hoped to try to retire, whipped [angech says October 12, 2016 at 12:45 pm] BBD.
But in looking at the comments I found a little bit of schadenfreude [2 actually] to relieve my wounds.
One of course was that in arguing for [excessive] stability in the longterm global ocean and air temperatures a lot of commentators have taken the opposite view arguing for extremes of temperature change as being expected, almost normal.
BBD October 12, 2016 at 7:11 am Everything known about palaeoclimate behavior is powerfully suggestive that you are wrong.
BBD October 11, 2016 at 2:35 pm the premise that the earths [overall] ocean and air temperatures are reasonably stable >12C in the last 65Ma alone:
chris October 11, 2016 at 7:29 am.” a large part of Earth surface response to enhanced forcing accrues rather quickly”
BBD says: October 11, 2016 at 12:24 pm The empirical evidence for a rather quick earth surface response is sadly lacking Don’t be silly. look at the 2C rise in 800 ad [graph]
But we cannot be having mega spikes of CO2 all the time
and the planet temp has fallen 12C from 65MA [No super CO2 level] to now, cooling all the way with little temp spikes on the way.
What is the natural cause of a 12C drop from normal CO2 levels to low CO2 levels over 65MA and no, longterm adjustment just doesn’t fit the 8C drop to the current drop.
So anyone using the argument that rapid responses occur naturally rules out the possibility that our current temperature change is just a natural rapid fluctuation that we do not know the answer to.
Taleb has an answer for these Black Swan events, these skewed probability events and explains why we should expect them.
“Also, if we raised ocean temperatures by 5K without some kind of albedo/atmospheric composition change,”
ATTP the premise was that a warming of 5K of the ocean would cause release of CO2 dissolved in the ocean plus water vapor, also a GHG.
You cannot argue that on the one hand such a large amount of CO2 and water vapor would have no effect and would dissipate in 20 years and then say if it came from volcanic outgassing or methane it would last for 200,000 years.
“BBD is correct. We have a mechanism to explain our observed warming. It’s consistent with our understanding of past warming/cooling events”
No it is an observation and the article quoted said that the CO2 rise came up to 3000 years after the warming started.
You have a mechanism, others have a different mechanism, the mechanism is important.
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Andrew Dodds says: October 13, 2016 at 8:48 am
“You have a hypothesis that a flood basalt event will by itself cause a detectable amount of heating.” I’m sure others have had it before me.
“Activity of the NAIP 55 million years ago may have caused the Paleocene–Eocene Thermal Maximum, where a large amount of carbon was released into the atmosphere and the Earth substantially warmed. One hypothesis is that the uplift caused by the NAIP hotspot caused methane clathrates to dissociate and dump 2000 gigatons of carbon into the atmosphere”
Note wording one hypothesis not the hypothesis.
“Lava from 1000K -> 300K @ 2000J /kg/K”
No, setting your own parameters,and using funny temp measures K
Back of envelope Lava flows in large amounts can reach up to 1600C, which would be 1900 K approx Cooling to 0C or if you prefer approx 300K so try 1600C instead of 700C
= .3.2*10^6 J / kg
Yellowstone has a 4000 cubic Kilometer magma chamber and I am sure the NAIP Lava volume is a lot more than 6.6 x 10^6 km3. You seem to be referring to that part of it called the Thulean plateau
Total heat of cooling of lava = 5.6 x 10^25 J
Raise ocean temperature by 1 degree = 5 x 10^24 J
Hence 11C ocean warming (5.6 * 10^25 / 5 * 10^14) possible on your figures.
“The eruptions took place over at least a million years, and many would have been on land.”
” Little is known of the geodynamics of the opening of the North Atlantic between Greenland and Europe” the cause of the ‘North Atlantic mantle plume’ that would have created the NAIP.[13] Through both geochemical observations and reconstructions of paleogeography, it is speculated that the present day Iceland hotspot originated as a mantle plume on the Alpha Ridge (Arctic Ocean)
I’m sorry but this implies most of it happened under the sea.
And as others point out most of it happened in a 20,000 year period though many other smaller events occurred and continue to occur.