From AGU weekly highlights:
After the fairly warm Miocene climate optimum about 17-15 million years ago, Earth’s climate began to cool. Holbourn et al. present a new high-resolution record of climate evolution over the middle to late Miocene from 12.9 to 8.4 million years ago based on stable isotopes in sedimentary benthic foraminifera in the western Pacific Ocean.
They also combine their data with previously published data going back to 16 million years ago from the same location to study the transition from a warmer climate to a cooler one. They focus on the relationship between climate and changes in the eccentricity and obliquity of Earth’s orbit around the Sun.
They find that changes in carbon isotope ratios track long-period (400,000 year) variations in the eccentricity cycle, and changes in oxygen isotope ratios track shorter-term (100,000 year) variations in eccentricity and 41,000 year variations in obliquity. From the oxygen isotope record, the authors observe that Earth’s climate cooled in a series of incremental steps at about 14.6, 13.9, 13.1, 10.6, 9.9, and 9.0 million years ago. In general, climate variability decreases after about 13 million years ago, except for a warming episode about 10.8–10.7 million years ago, which the authors associate with a maximum in the eccentricity of Earth’s orbit.
Source: Paleoceanography, doi: 10.1002/2013PA002538, 2013 http://onlinelibrary.wiley.com/doi/10.1002/2013PA002538/abstract
Title: Middle to late Miocene stepwise climate cooling: Evidence from a high-resolution deep-water isotope curve spanning 8 million years
Authors: Ann Holbourn and Wolfgang Kuhnt: Institute of Geosciences, Christian-Albrechts-University, Kiel, Germany;
Steven Clemens and Warren Prell: Department of Geological Sciences, Brown University, Providence, Rhode Island, USA;
Nils Andersen: Leibniz Laboratory for Radiometric Dating and Stable Isotope Research, Christian-Albrechts-University, Kiel, Germany.
I sometimes wonder how temperatures/climate was affected when the Lagarita Caldera was being formed 27 million years ago ( http://www.livescience.com/11113-biggest-volcanic-eruption.html )
It wil be interesting to compare it to the sea level curve of Haq et al. There was a major drop in sea level at 10.5 my, perhaps from the 10.6 my cooling episode.
http://curry.eas.gatech.edu/Courses/6140/ency/Chapter10/Ency_Oceans/Sea_Level_Variations.pdf
But, did they have coal power stations in the warming episode about 10.8–10.7 million years ago?
I thought that Miocene time was before Hero of Alexandria.
Perhaps the science isn’t settled?
Auto
Well I looked at that link, and just found an ad for a book or something; no graph of this high resolution climate.
I don’t put much weight on this study because they didn’t splice a 150 year “modern” instrumental record onto the end of their time series. (sarc/smiley)
I don’t think there is anything special about this. The temperature numbers are more-or-less the same as Zachos 2001 which had higher resolution than this paper and covered 60 million years.
Furthermore, we can’t really estimate the Earth’s orbital characteristics this far back. The data is showing 100,00 year cycles and then 41,000 year cycles and then back to 100,000 years again, which I guess is kind of interesting but there is not this periodicity in Zachos higher resolution data.
One of the main charts from the paper, Link probably won’t work but one can copy and paste it.
http://onlinelibrary.wiley.com/store/10.1002/2013PA002538/asset/image_n/palo20064-fig-0007.png?v=1&s=8cf5c6609c7c6ab22932248cbfabcbb34b90f38c
It was the beginning of the end. The Biosphere is barely alive. We need to get off this rock ASAP.
“They focus on the relationship between climate and changes in the eccentricity and obliquity of Earth’s orbit around the Sun.”
Amazing! They think that the big ball of fire in the sky has something to do with the planet’s climate. Or, at least, it used to a few million years ago. I wonder how this got past Mann and the rest of the peer review gatekeepers.
Wolfgang’s last name is pronounced “Koont.”
markstoval says:
February 4, 2014 at 3:08 pm
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The highlighted statement doesn’t say what you imply that it says.
Carbon and Oxygen isotope variations have been very closely correlated for a very long time. So now with “high resolution” we get Carbon following the 400kyr Milankovitch (this would be the only known signal for this theoretically strongest cycle), and Oxygen following the shorter 100kyr eccentricity plus the 41kyr obliquity, and neither of them following the 21kyr precession cycle? Seriously?
3107 cubic miles of lava is not 5000 cubic kilometers of same.
The above comment refers to the link provided by John at 12:10. That still is plenty of lava.
george e. smith says:
February 4, 2014 at 1:32 pm
Well I looked at that link, and just found an ad for a book or something; no graph of this high resolution climate.
Wiley is a pay walled site for technical and scientific publications. It is not an “ad” for a book. It is a link to the article in the journal, but you have to pay first. If you have family at a university, odds are they can acquire the article for you through the library. Just don’t abuse their privileges.
“They focus on the relationship between climate and changes in the eccentricity and obliquity of Earth’s orbit around the Sun.”
So you think that statement means the sun has no role in climate. Amazing how people can no longer read with comprehension. Common Core State Standards will fix that they say.
Bill Illis says:
February 4, 2014 at 2:05 pm
I don’t think there is anything special about this. The temperature numbers are more-or-less the same as Zachos 2001 which had higher resolution than this paper and covered 60 million years.
Furthermore, we can’t really estimate the Earth’s orbital characteristics this far back. The data is showing 100,00 year cycles and then 41,000 year cycles and then back to 100,000 years again, which I guess is kind of interesting but there is not this periodicity in Zachos higher resolution data.
It is interesting to see flipping between 100,000 and 41,000 year periodicity in earlier time periods similar to that occurring at the mid-Pleistocene revolution a million years ago during our current glacial epoch. If it is real, of course.
Looks like a good bit of science going on there. I want the complete paper.
In long-term geophysical context, Total Solar Irradiance (TSI) unquestionably drives cyclical climatic shifts on kiloyear scales. But geological eras on the order of 10 – 20 million years derive primarily from plate tectonics: Roughly from Miocene times, North and South American continental landmasses have separated Earth’s eastern from western hemispheres, disrupting atmospheric/oceanic circulation patterns.
Though complex global results were unpredictable, over some 2.6-million years our current Pleistocene Era has seen cyclically recurrent Ice Ages lasting an average 102,000 years, separated by interstadial remissions of median 12,250 years. Given the dissolution of continental ice sheets c. 14,400 years-before-present (YBP), absent the 1,500-year Younger Dryas exo-terrestrial “cold shock” our current Holocene Interglacial Epoch would likely have ended c. AD 450, coincident with Earth’s classic Roman Warm.
Now on the threshold of a 70-year “dead sun” Grand Solar Minimum similar to that of 1645 – 1715, Luddite sociopaths’ willful, purposeful sabotage of global coal, oil, nuclear energy-economies is a crime against humanity worthy of communo-fascist regimes at their vicious worst.
markstoval says:
February 5, 2014 at 1:24 am
Alan Robertson says:
_____________________
The highlighted statement doesn’t say what you imply that it says.
“They focus on the relationship between climate and changes in the eccentricity and obliquity of Earth’s orbit around the Sun.”
So you think that statement means the sun has no role in climate. Amazing how people can no longer read with comprehension. Common Core State Standards will fix that they say.
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Which is it? Did the author’s sentence indicate that variance in the Sun’s output, or the motion of the Earth around the Sun had more influence on the climate?
The speed with which you deployed the ad hominem speaks volumes. Unfortunately, your attack was only one of the logical fallacies which you used in your response to me. That’s ok, we’re all here to learn and increase our understanding. Here are some links which might help you:
http://www.theskepticsguide.org/resources/logical-fallacies
http://web.cn.edu/kwheeler/fallacies_list.html
http://www.logicalfallacies.info/
https://yourlogicalfallacyis.com/
“After the fairly warm Miocene climate optimum about 17-15 million years ago, Earth’s climate began to cool. Holbourn et al. present a new high-resolution record of climate evolution over the middle to late Miocene from 12.9 to 8.4 million years ago based on stable isotopes in sedimentary benthic foraminifera in the western Pacific Ocean.”
Looking at a span of 4.5 MILLION years, over 8.4 MILLION years ago? Can someone explain to me how that relates to our current situation? I have asked several times what our future time-frame should be for concern about our environment supporting humans. Are we looking at a 100 hundred years, a thousand, or a million?
I grew up with a grandfather who was a geology professor, and a mother who taught earth science in middle school. Human existence on this planet is less than a “pimple on a gnat’s butt”. We have no control over terrorist’s blowing nuke’s(maybe a little?), plate tectonics, asteroids, aliens, or the sun suddenly going nova (or going cold). Any day our planet could be wiped out.
I am not advocating self-destruction due to a lack of care about Earth. Resource conservation has always been a good thing, as long as it does more good than harm.
What is the current “consensus” on a time-frame?