From a press release by: National Oceanography Centre, Southampton (NOCS)
Understanding past and future climate
The notion that scientists understand how changes in Earth’s orbit affect climate well enough for estimating long-term natural climate trends that underlie any anthropogenic climate change is challenged by findings published this week. The new research was conducted by a team led by Professor Eelco Rohling of the University of Southampton’s School of Ocean and Earth Science hosted at the National Oceanography Centre, Southampton.
“Understanding how climate has responded to past change should help reveal how human activities may have affected, or will affect, Earth’s climate. One approach for this is to study past interglacials, the warm periods between glacial periods within an ice age,” said Rohling.
He continued: “Note that we have here focused on the long-term natural climate trends that are related to changes in Earth’s orbit around the Sun. Our study is therefore relevant to the long-term climate future, and not so much for the next decades or century.”
The team, which included scientists from the Universities of Tuebingen (Germany) and Bristol, compared the current warm interglacial period with one 400,000 years ago (marine isotope stage 11, or MIS-11).
Many aspects of the Earth-Sun orbital configuration during MIS-11 were similar to those of the current interglacial. For this reason, MIS-11 is often considered as a potential analogue for future climate development in the absence of human influence.
Previous studies had used the analogy to suggest that the current interglacial should have ended 2-2.5 thousand years ago. So why has it remained so warm?
According to the‘anthropogenic hypothesis’, long-term climate impacts of man’s deforestation activities and early methane and carbon dioxide emissions have artificially held us in warm interglacial conditions, which have persisted since the end of the Pleistocene, about 11 400 years ago.
To address this issue, the researchers used a new high-resolution record of sea levels, which reflect ice volume. This record, which is continuous through both interglacials, is based on the ‘Red Sea method’ developed by Rohling.
Water passes between the Red Sea and the open ocean only through the shallow Strait of Bab-el-Mandab, which narrows as sea levels drop, reducing water exchange. Evaporation within the Red Sea increases its salinity, or saltiness, and changes the relative abundance of stable oxygen isotopes.
By analysing oxygen isotope ratios in tiny marine creatures called foraminiferans preserved in sediments that were deposited at the bottom of the Red Sea, the scientists reconstructed past sea levels, which were corroborated by comparison with the fossilised remains of coral reefs.
The researchers found that the current interglacial has indeed lasted some 2.0–2.5 millennia longer than predicted by the currently dominant theory for the way in which orbital changes control the ice-age cycles. This theory is based on the intensity of solar radiation reaching the Earth at latitude 65 degrees North on 21 June, the northern hemisphere Summer solstice.
But the anomaly vanished when the researchers considered a rival theory, which looks at the amount of solar energy reaching the Earth the same latitude during the summer months. Under this theory, sea levels could remain high for another two thousand years or so, even without greenhouse warming.
“Future research should more precisely narrow down the influence of orbital changes on climate,” said Rohling: “This is crucial for a better understanding of underlying natural climate trends over long, millennial timescales. And that is essential for a better understanding of any potential long-term impacts on climate due to man’s activities.”
The study was funded by the United Kingdom’s Natural Environment Council and the German Science Foundation.
Publication:
Rohling, E.J., et al., Comparison between Holocene and Marine Isotope Stage-11 sea-level histories. Earth and Planetary Science Letters (2010). doi:10.1016/j.epsl.2009.12.054
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Readers may be interested in some of these papers on orbital influences:
http://www.people.fas.harvard.edu/~phuybers/
There’s hockey stick stuff (Mann, ‘M&M’, etc.) there too – something for everyone — I disagree with the CO2 ‘funding hooks’ inserted in opening & closing lines of some articles based on my own analyses, but important research needs to get funded somehow – and there are good finds in between opening & closing lines…
Jeff (15:03:31) :
http://climateprogress.org/2009/01/26/noaa-climate-change-irreversible-1000-years-drought-dust-bowls/
The carbon cycle is quite slow at
taking out the carbon in the climate system
Nah. Read this.
The Climate Progress piece you linked to references Solomon et al (2009). The article I linked to, by Prof. Tom V. Segalstad, debunks Solomon.
Good reading.
Leif Svalgaard (16:08:11) :…energy in the cosmic ray flux compared to simple day light? 0.03 W/m2 compared to 1361 W/m2.
Then I vote for natural oscillations instead. Is it so difficult to understand that a system can have substantial oscillations that cover a wide range of timescales even if the external force is constant or nearly constant? Ever heard about reaction-diffusion systems?
Invariant (01:07:40) :
Leif Svalgaard (16:08:11) :…energy in the cosmic ray flux compared to simple day light? 0.03 W/m2 compared to 1361 W/m2.
Then I vote for natural oscillations instead. Is it so difficult to understand that a system can have substantial oscillations that cover a wide range of timescales even if the external force is constant or nearly constant? Ever heard about reaction-diffusion systems?
~
“Natural oscillations,” of sorts. How much more does the sun need to slow down and weaken its magnetic interlock amongst other forces before Earth’s orbit starts slipping?
Why do solar cycles slow down, lengthen and then go thru periods where they speed up?
..”external force is constant or nearly constant?,” nope.
I vote external forces.
rbateman … heh
This assessment, like the others you posted, just doesn’t stand up to scrutiny.
The green economy is going to accelerate the already begun process of cleaning our clocks. Kyoto was a tremendous boon to China. Factories in Europe and North America closed and new, dirtier factories opened in China and other parts of Asia to replace them.
You just can’t make the cost of doing business more expensive and expect the overall economy to improve. Increasing the cost of energy make us less productive and less competitive, not more.
“Carbon” emissions and other greenhouse gases simply are not a problem. There is no climate crisis and the earth is in no more or less peril than it’s been for millions of years.
We should all focus our limited time, energy and money on solving real problems.
Leif Svalgaard (16:08:11) : 0.03 W/m² compared to 1361 W/m².
Carla (05:17:57) : “external force is constant or nearly constant?,” nope.
What would be the magnitude of the external variation in terms of W/m²?
Invariant (08:02:45) :
What would be the magnitude of the external variation in terms of W/m²?
There is the 1.3 W/m2 variation of TSI.
Any other external variation is of the order of a million times less. Now, imagine you have 10 million external variations all working in the same direction, then you have something. Don’t misunderestimate fools’ capacity for conjuring up something like this.
Anthony-
Is there any way to set things up that we can send a message directly to someone who has made an earlier Comment? I am thinking of a behind-the-scenes system that does not require revealing the e-dress of the original commenter. I fear that many comments on comments are never seen by the original writer because of the need for original commenter to come back later to a topic and look for additional comments.
A case in point is that I wanted to send an encouraging comment on the comment by Douglas DC (14:31:28): “…..as one who wouldn’t pass an Aryan test…..a white greenie’s biggest fear is healthy, happy_prosperous_ dark skinned people”.
I just wanted to point out that Hitler was misinformed. “Aryan” is from the same origin as “Iran”, whose people are not quite as light skinned as the average western European (as is also true of real “Caucasian” people from the Caucasus region).
IanM
Hey guys,
Great discussion of the various theories of how and when ice ages end. Certainly the literature such as the 1992 Devil’s Hole paper (Science), deep sea cores and the Vostoc cores suggest that the last interglacial ended before the rise in summer insolation, a “problem of causality”. I would like to throw into the pot another study outside the usual realm of climate science. The Book “Homo Britannicus” by Chris Stringer is a detailed compilation of multidisplinary scientific studies of the climate and life of the British Isles during the Ice Ages. The study found that the interglacial 400,000 years ago lasted 40,000 years in Britain with a significant cool spell midway. Since the Milankovich signal is now about what it was 400,000 years ago, how can we say that the next ice age is overdue by 2000 years in light of what was observed in Britain. Certainly researchers like Imbrie and Shackleton have shown correlation with the Ice Ages but as we all know, correlation is not causation and it appears that the driver of ice ages is much more complex than simple high latitude insolation and its CO2 and albedo feedbacks.
In the rich & interesting figures 3-6 of Rohling et al. (2010), the following are cited:
1) Laskar, J.; Robutel, P.; Joutel, F.; Gastineau, M.; Correia, A.C.M.; & Levrard, B. (2004). A long term numerical solution for the insolation quantities of the Earth. Astronomy & Astrophysics 428, 261-285.
http://hal-sfo.ccsd.cnrs.fr/docs/00/00/20/23/PDF/La_2004_prep.pdf
Alternates:
http://scholar.google.ca/scholar?hl=en&lr=&cluster=7026466579078675410&um=1&ie=UTF-8&ei=vDNvS8PUKIr8tQPTw62xDQ&sa=X&oi=science_links&resnum=1&ct=sl-allversions&ved=0CAoQ0AIwAA
2) Huybers, P. (2006). Early Pleistocene glacial cycles and the integrated summer insolation forcing. Science 313, 508-511.
http://www.people.fas.harvard.edu/~phuybers/Doc/HuybersScience2006.pdf
http://dash.harvard.edu/bitstream/handle/1/3382981/Huybers_EarlyPleistoceneSummer.pdf?sequence=1
Just sharing the links.
Also found these, which may be of interest to some:
Stine, A.R; Huybers, P.; & Fung, I.Y. (2009). Changes in the phase of the annual cycle of surface temperature. Nature 457, 435-441. doi:10.1038/nature07675.
http://www.people.fas.harvard.edu/~phuybers/Doc/seasons.pdf
Stine, A.R; Huybers, P.; & Fung, I.Y. (2009). Defnitions of the Timing of the Seasons. [Supplementary to ‘Changes in the phase of the annual cycle of surface temperature. Nature 457, 435-441’.]
http://www.people.fas.harvard.edu/~phuybers/Doc/seasons_supplementary_info.pdf
Thompson, D.J. (2009). Shifts in season. Nature 457, 391-392.
http://www.people.fas.harvard.edu/~phuybers/Doc/Thomson_comment.pdf
The last one is a bit inflammatory, hitting on points that are both resonant & dissonant with opinions regularly expressed around here. He conveys the impression that he has no awareness of EOP (Earth orientation parameter) variations on decadal timescales.
Leif Svalgaard (08:46:43) : There is the 1.3 W/m2 variation of TSI.
I wonder exactly when energy considerations became passé? Perhaps the skill to judge what is large and what is small is not a popular topic in school anymore? We all know that most journalists have no idea of scale when they write about millions of tons of CO2, but judging what is a proper comparison should be elementary wisdom for scientists and engineers.
Cheers.
Invariant (without any “tan” from starlight on a clear night)
🙂
Paul Vaughan (10:20:58) :
He conveys the impression that he has no awareness of EOP (Earth orientation parameter) variations on decadal timescales.
I’m reasonably sure that he knows that the atmosphere and the oceans and their movements [changes of moment of inertia are the [almost sole] causes of changes in EOP.
Invariant (10:43:29) :
Leif Svalgaard (08:46:43) : There is the 1.3 W/m2 variation of TSI.
I wonder exactly when energy considerations became passé?
People pushing agendas ignore energy considerations. Even the 1.3 W/m2 TSI variation is sort of meaningless compared to the 90 W/m2 variation through the year [largest in January].
Leif Svalgaard (11:32:39) : meaningless compared to the 90 W/m²
Right! So we have a variation 1361 W/m² between day and night and a variation of 90 W/m² between summer and winter. Surely it is no exaggeration to state that the external (oscillatory) force is constant or nearly constant.
Jeff (15:33:31) :
Its an interesting question. How much change in the underlying plates would invalidate his work?
0.1 mm/year either up or down would suffice to invalidate the results.
Suzanne (09:58:56)
If the Milankovich curve isn’t a principal driver of ice-ages it seems very unlikely that the two dominant cyclicities (41 kyr, 100 kyr) would just happen to coincide with the obliquity and eccentricity cycles.
In any case the Milankovich cycles are clearly visible in high-quality sedimentary records through much of the Earths history, even in extreme hothouse climate periods.
However I agree that other factors also have influence, for example nobody has yet found a completely satisfactory explanation why glaciations switched from 41 kyr to 100 kyr cycles about 800 kyr ago.
“Some renewables are easily competitve with Nuclear now and have 7 hours storage built in now with 16 hours in development later”
Such as….?
Leif Svalgaard (10:44:48) “I’m reasonably sure that he knows that the atmosphere and the oceans and their movements [changes of moment of inertia are the [almost sole] causes of changes in EOP.”
Including nutation obliquity?
What do you think of his other work?
Invariant (11:44:53) :
a variation of 90 W/m² between summer and winter.
No , it is a global variation between January and July [summer and winter in SH]
I recollect Somerville saying the following,
“4. The standard skeptical arguments have been refuted many times over. The refutations are on many web sites and in many books. For example, natural climate change like ice ages is irrelevant to the current warming. We know why ice ages come and go. That is due to changes in the Earth’s orbit around the sun, changes that take thousands of years. The warming that is occurring now, over just a few decades, cannot possibly be caused by such slow-acting processes. But it can be caused by man-made changes in the greenhouse effect.”
http://wattsupwiththat.com/2010/01/20/scripps-institution-of-oceanography-cheapens-itself-by-using-the-d-word/
Somehow, I don’t think that Somerville understands as much about how orbital mechanics triggers ice ages as he thinks he does.
Mike Ramsey
Leif Svalgaard (11:32:39) :
But why is 0.2 W/m2 for 200 years meaningless, if that’s the difference from the preceeding 200 years? What would that do to OHC and ice cover? You don’t know because you don’t know how much of that is stored in the ocean. Aren’t you pushing the power argument and ignoring the energy considerations.
Paul Vaughan (12:19:35) :
Including nutation obliquity?
All astronomical causes are strictly periodic [on time scale of centuries] and don’t matter because there are no strictly periodic terms in our climate of the sharpness and magnitude required to stand out above the noise. If not above the noise [so sophisticated statistics is needed to flush them out], then the effects are not important.
I have not looked at his other work. The day only has 36 hours.
Leif Svalgaard (12:28:04) :No , it is a global variation between January and July
OK. Even more convincing then.
lgl (12:39:38) :
But why is 0.2 W/m2 for 200 years meaningless, if that’s the difference from the preceding 200 years?
We worry about what we have evidence [or good theory] about. And I have not seen any that qualify as good. People even claim that the temperatures the past century are unreliable. Also, there is a balance between what goes in and what goes out. As long as we don’t know what the delay is [if any], then we cannot conclude anything. There are some reasons to believe that the delay is short. People talks about 7 years, or 3 months, or something of that order. Something tells me that it short, e.g. we get 90 W/m2 more during January [scaled by varies factors: 4 and albedo] than during July. Are you telling me that that the 45 W/m2 we get above average is stored, but the 45 W/m2 we get the rest of the time is not? What difference is there between an extra Watt we get from solar activity from an extra Watt we get due to the orbit not being circular?
Leif Svalgaard (12:56:27) :
lgl (12:39:38) :
But why is 0.2 W/m2 for 200 years meaningless, if that’s the difference from the preceding 200 years?
Let me elaborate a bit more on the storage issue. Some people claim that the Watts from solar activity cycles are stored [e.g. in the oceans] and a string of high cycles will cause more heat to be stored as they [so it is claimed] add on top of each other. Then, by the same argument, the extra 90 W/m2 we get every January is stored, and every new January adds another 90 W/m2 to the store. This goes on for millions of years….
So, if those January Watts are not really stored, then how the system know only to store a solar activity Watt.
Also, I’m always amazed at the people that claim long-term storage not objecting to the thousands of papers that claim that there is solar cycle correlation with nary any delay [and vice versa].