Illustration only: not part of the paper
This paper has been out for a few days, and several people have alerted me to it. This new paper by Compo,G.P., and P.D. Sardeshmukh, 2008: Oceanic influences on recent continental warming. in the journal Climate Dynamics, is now in press. See the PDF here
This paper makes some significant claims regarding what is driving the observed climate changes. The emphasis is on the ocean as the main driving component, and the authors recognize that “a combination of natural and anthropogenic influences” may be at work. While they point to the oceans as a significant driver, they don’t offer much to explain what is driving the oceanic change.
Even so, this is a significant work, and I urge my visitors to read it, because it shows that GHG forcing is not the only occupant of the drivers seat. It also clearly illustrates the need to examine such cyclic ocean influences as the PDO and AMO more closely, and to consider them in projections of temperature.
Abstract:
“Evidence is presented that the recent worldwide land warming has occurred largely in response to a worldwide warming of the oceans rather than as a direct response to increasing greenhouse gases (GHGs) over land. Atmospheric model simulations of the last half-century with prescribed observed ocean temperature changes, but without prescribed GHG changes, account for most of the land warming. The oceanic influence has occurred through hydrodynamic-radiative teleconnections, primarily by moistening and warming the air over land and increasing the downward longwave radiation at the surface. The oceans may themselves have warmed from a combination of natural and anthropogenic influences.”
Conclusion:
“In summary, our results emphasize the significant role of remote oceanic influences, rather than the direct local effect of anthropogenic radiative forcings, in the recent continental warming. They suggest that the recent oceanic warming has caused the continents to warm through a different set of mechanisms than usually identified with the global impacts of SST changes. It has increased the humidity of the atmosphere, altered the atmospheric vertical motion and associated cloud fields, and perturbed the longwave and shortwave radiative fluxes at the continental surface. While continuous global measurements of most of these changes are not available through the 1961-2006 period, some humidity observations are available and do show upward trends over the continents. These include near-surface observations (Dai 2006) as well as satellite radiance measurements sensitive to upper tropospheric moisture (Soden et al. 2005).”
Although not a focus of this study, the degree to which the oceans themselves have recently warmed due to increased GHG, other anthropogenic, natural solar and volcanic forcings, or internal multi-decadal climate variations is a matter of active investigation (Stott et al. 2006; Knutson et al. 2006; Pierce et al. 2006). Reliable assessments of these contributing factors depend critically on reliable estimations of natural climate variability, either from the observational record or from coupled climate model simulations without anthropogenic forcings. Several recent studies suggest that the observed SST variability may be misrepresented in the coupled models used in preparing the IPCC’s Fourth Assessment Report, with substantial errors on interannual and decadal scales (e.g., Shukla et al. 2006, DelSole, 2006; Newman 2007; Newman et al. 2008). There is a hint of an underestimation of simulated decadal SST variability even in the published IPCC Report (Hegerl et al. 2007, FAQ9.2 Figure 1). Given these and other misrepresentations of natural oceanic variability on decadal scales (e.g., Zhang and McPhaden 2006), a role for natural causes of at least some of the recent oceanic warming should not be ruled out.
Regardless of whether or not the rapid recent oceanic warming has occurred largely from anthropogenic or natural influences, our study highlights its importance in accounting for the recent observed continental warming. Perhaps the most important conclusion to be drawn from our analysis is that the recent acceleration of global warming may not be occurring in quite the manner one might have imagined. The indirect and substantial role of the oceans in causing the recent continental warming emphasizes the need to generate reliable projections of ocean temperature changes over the next century, in order to generate more reliable projections of not just the global mean temperature and precipitation changes (Barsugli et al. 2006), but also regional climate changes.”
Roger Pielke writes in his blog:
This is a major scientific conclusion, and the authors should be recognized for this achievement. If these results are robust, it further documents that a regional perspective of climate variabilty and change must be adopted, rather than a focus on a global average surface temperature change, as emphasized in the 2007 IPCC WG1 report. This work also provides support for the perspective on climate sensitivity that Roy Spencer has reported on in his powerpoint presentation last week (see).
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MarkW, it’s worse than that.
The non-tree-ring reconstructions of the period 1800-1900 indicate a warming trend. (Coming out of the Little Ice Age, one of the crucial bits eliminated by the Hockey Stick.)
The exact scale of that pre-industrial rise isn’t clear. But there are no declines published reports. The highest I’ve seen is 2.0 C/c. So if you split the range, you’re at 1.0 C/c from truly climactic phenomena.
Another 50%. (Or so.)
“anyone wanna make any wagers about how much of the warming is GHG and how much is natural?”
I’ll say .3-.4F over the last 150 years, with the rest being natural variation.
Leon Brozyna (23:08:35) wrote
“why are the oceans warmer?”
Because they are covered by less low level strato-cumulus cloud. It’s warmer because it’s sunnier. (1)
Palle/’s work is worth looking for on the web (that’s an acute e, BTW); the changes in the earth’s albedo are astonishing, dwarfing minor contributions like CO2.
Why is there less low level cloud? I’m glad you asked that. We spill enough oil on the ocean every two weeks to cover it completely. Waves break less, This suppresses the production of condensation nuclei and reduces cloud cover(2). The water is smoothed. Smoothed water absorbs more radiation and emits less, so it warms(3).
Surfactant does the same thing: you can see wide patches of smoothed water when you fly over the sea and look up-sun.
Rave, froth, cod population crash on the Grand Banks, widening blue deserts, CO2 isotope signal, all explained, all on my site….
JF
1,2,3 research continues, ie this is my guess.
Sorry for the duplication if someone else has already cited this link. The following research is also a blockbuster concerning atmospheric CO2.
http://www.biokurs.de/treibhaus/180CO2_supp.htm
Would someone clarify an apparent contradiction between this paper and others I’ve seen lately? The present article in its conclusion section discusses increased humidity of the atmosphere, and goes on to state that humidity observations include near-surface as well as upper tropospheric moisture. But NOAA’s Earth System Research Laboratory results, as discussed in “The Saturated Greenhouse Effect” by Ken Gregory, show that specific humidity, not relative humidity, has been decreasing each decade since the 1940’s, at all pressures from 700mb to 300mb. This decrease has been related to Lindzen’s infrared iris effect and is touted as a reason for the lack of tropospheric positive feedback the alarmists expected to see in their modeling. Has Compo et al got it wrong, or is there some difference?
“a computerized version of temple priests divining the future through their study of animal entrails.”
I’ve never seen a better definition of a GCM.
Loved the article, hated the typos and grammar errors (the teacher in me). What I read into the paper is an attempt to discuss global warming without alienating the media driven “consensus”. I wholly understand an attempt to write a paper that proposes a different mechanism for an observed event without looking like an enemy of the opposite camp. One must approach these things delicately lest one steps on toes and cuts ones funding out. And that statement comes from experience about how research proposals pass on to the “grant this one” stage. It is a back scratching endeavor that puts Senate and House of Representatives legislative compromises into the kindergarten class.
Evan,
You’re awfully turbo-charged today.
What on earth has put you in this wonderful mood?
It aint even Friday yet!
My mistake, I should have said that specific humidity was decreasing at 400-300mb, not 700-300mb. But my question remains the same. Have the modelers just got a difference of opinion on this “hot spot” issue around 300mb?
Speaking of the sun,
Landscheidt in his famous “New Little Ice Age Instead of Global Warming?” paper, correlated temperature with the aa geomagnetic index, with a 4 to 8 year lag. (The oceans may have played a role in the lag.) He smoothed the aa index, unlike this graph:
http://www.ngdc.noaa.gov/stp/GEOMAG/image/aastar07.jpg
The two year average index for 2006 and 2007 is the calmest since just before weak solar cycles 14 and 15, the first cycles of the 20th century. He predicted a solar minimum around 2030. If I remember the timing, he wrote his paper before the 2003 geomagnetic spike, but with the recent calm years his smoothed curve should not have risen to its prior peak of 1990. He noted the 1990 peak, and with the lag, predicted this decade’s cooler temperatures.
I wonder if the slow conveyor belt and these last two calm geomagnetic years are related?
Thanks stream. To those who asked specific questions; I need to read the paper in its entirety before I try to answer them, so please give me a bit to track down a copy of the Journal.
It’s so much easier when I’m up at school and can just pull them from the EAS department library 🙂
Leon Brozyna:
“I don’t doubt that an AGW proponent would want to jump on this to say that CO2 also causes oceans to warm”
I also have a big problem with this one.
The atmosphere can only warm the sea (or land, for that matter) if it’s warmer than the sea (unless someone’s repealed the 2nd Law of Thermodynamics) and, because of the huge difference in thermal capacity, it will take a long time.
If the atmosphere is warmer than the sea then it must have gotten that way by some other means than the greenhouse effect. The sea can also only warm the atmosphere by any means (conduction or radiation) if it’s warmer than the atmosphere and, also because of the thermal capacity, will continue to warm the atmosphere for a long time.
So, except for coastal areas where air blowing off the land is warmer than the sea, the only real (external) mechanism for warming the oceans is the direct action of sunlight.
Of course you may say that even if the air doesn’t warm the sea, a warmer atmosphere will mean less heat loss, but, because of thermal capacity again, this is insignificant.
If this isn’t so then can someone please explain why
Ron McCarley (11:31:38) :
Are we asking the same question? It looks to me like humidity, whether relative or specific, have been declining. But this paper reports the results of simulation in which it is supposedly rising. Isn’t the model giving results inconsistent with reality?
Basil
Hmm… Boil water with a hair dryer… Technically, you can, just not all at once. You ‘boil’ the surface and eventually the water evaporates out.
As to AGW, etc. AGW doesn’t warm oceans much, if at all. As posted prior, sunlight would be the primary driver for deep ocean temp. If the surface heats up due to IR, it will just evaporate and pull a bunch of heat from the surrounding molecules. That gives us clouds eventually (negative feedback to the ocean heating up).
But, if the air is warmer due to ‘stuff’, then more water vapor is required to form clouds. So… higher air temps due to ‘stuff’ can be in part responsible for increased water temps over time. At times, the system goes unstable and we get a big El Nino/La Nina. During the El Nino, was there a marked increase in cloud cover? During La Nina? Is the cause of La Nina an upwelling of cold water, or a lack of heating water in the past that is now being circulated back to the surface? Interesting problem…
Counters,
The difference between this model experiment and others is that the authors used observed sea surface temperaure. Other models just plugged the physics and let it run.
The next thing they did was to eliminate anthropogenic GHG’s, aerosols and solar forcing. Sceptics have long said that incorrect aerosol calculations were necessary in the models to prevent a runaway greenhouse effect in the models.
You might also notice the models that were used in this experiment were the most prominent in the world.
To Basil @ur momisugly 12:08:34
Yes, I think we are asking the same question. While this paper seems to indicate some willingness to consider aspects that we skeptics have been arguing about, it still seems to cling to the alarmist, water vapor, positive feedback loop caused by CO2, at least to me. I guess good things come slowly. I’m no expert on modeling, but I just wonder if these modeling results might be more pronounced if the water vapor deficiency that we’ve been seeing at 30K feet, and with the lack of cirrus clouds a la Lindzen, were plugged in. I’m real new at the GW game and still learning, but this seems to me to be a significant flaw in this paper. I do love the way, though, that this paper and the IPCC-related group in W. Europe (10 yr. Delay in AGW) are noticing something being wrong with their theory. My apologies on the reference I gave. It wasn’t the one I was thinking of when I wrote the first paper so quick. The paper I quoted was primarily about relative humidity, although it did also discuss the decline in specific humidity around 30,000 ft. and slightly below that.
All I can find are copies of the author’s submitted article. I cannot locate the published journal article from Climate Dynamics. I would appreciate a fuller reference including volume and page numbers, or DOI.
Meanwhile, it is interesting that modelling with observed ocean temperatures and assumed physics appears to give somewhat different outcomes than scenario-based modelling with assumed physics.
Speaking of CO2, does anyone know whats the first six months CO2 level from Mauna Lau look like?
(I’ve looked around for a direct link but haven’t found one)
I remember eading somewhere that early this year the rate of increase had slowed markedly. I’m just wondering if this trend had continued.
Reply: Click here ~charles the moderator
I generally do not read papers about what models say, despite counters’ articulate defence above.
Anyway the obvious flaw in this paper is the ‘assumption’ that increased humidity over land results from increased SSTs despite a lack of clear evidence that SSTs have in fact increased.
There is an altogether simpler explanation for increased humidity over land – irrigation over 600,000,000 acres.
It’s quite a reach to say the oceans are a main driver of climate change, when clearly it would be what causes the oceans to warm or cool to begin with that would be in the climate drivers’ seat, with the oceans simply acting as a major part of the all-important brakes in the climate system, along with GHG’s. They appear to be applying those brakes now, but someone is letting up on the gas as well.
[…] Compo and Sardeshmukh: Oceans a main driver of climate variability – it’s the heat AND the hu… [image] Illustration only: not part of the paper This paper has been out for a few days, and several people have […] […]
Kevin B: In addition to the link jeez provided, I would also refer you to the stupendous CO2 site linked by W F Lenihan @10:40:24 above. Great charts! Even the full moon influences natural CO2 emissions. And CO2 was higher than today in the 1800’s. Very interesting site and new to me. Thanks for posting.
Next, concerning a possible deep ocean heat source, this article mentions the recent and unexpected discovery of hundreds of thousands of new undersea volcanoes. We don’t know enough about this heat/CO2 source to even begin to model it, much less come up with empirical measurements.
steamtracker:
What ‘paradigm’ is that? I hope you’re not referring to the AGW/climate catastrophe hypothesis as the current paradigm. The ‘current paradigm’ is natural climate variability. The relatively new AGW/runaway global warming hypothesis has been put forth, but as you can see throughout these threads, it has been falsified in numerous ways. It would not supersede natural climate variability as the ‘current paradigm’ unless it had withstood falsification. Please correct me if I didn’t understand what you were referring to when you said ‘current paradigm.’ If I misunderstood, I apologize.
Julian Flood:
I would be interested in a citation. Are you referring to covering the oceans with a one molecule thick layer of oil, or some similar miniscule amount? If so, I have two questions:
1. Is that tiny thickness enough to create the calm swathes of ocean you mentioned, and as you stated, to cause waves to break with less force?
2. Since human caused oil spills are now even more infrequent than in past decades, are you taking into account natural oil seepage, which occurs constantly, and greatly exceeds anything humans do?
Finally, Evan, International Talk Like A Pirate Day isn’t until Sept. 19th. Are you practicing up?
Over and out.
leebert:
Greenland has stopped its net melting.
Steamtracker:
the oceans are cooling.
Someone didn’t pay the heating bill obviously. Sorry, no AGW disaster until the bills get paid.
How much would the temperature of an olympic swimming pool increase if you pointed a hairdryer at at for 100 years?
“How much would the temperature of an olympic swimming pool increase if you pointed a hairdryer at at for 100 years?”
Would it increase at all? The entire surface area would be losing the heat as fast as the tiny concentrated point from the hairdryer could heat it.