Revised Holocene temperature record affirms role of greenhouse gases in recent millennia
RUTGERS UNIVERSITY
Scientists have resolved a key climate change mystery, showing that the annual global temperature today is the warmest of the past 10,000 years – contrary to recent research, according to a Rutgers-led study in the journal Nature.
The long-standing mystery is called the “Holocene temperature conundrum,” with some skeptics contending that climate model predictions of future warming must be wrong. The scientists say their findings will challenge long-held views on the temperature history in the Holocene era, which began about 12,000 years ago.
“Our reconstruction shows that the first half of the Holocene was colder than in industrial times due to the cooling effects of remnant ice sheets from the previous glacial period – contrary to previous reconstructions of global temperatures,” said lead author Samantha Bova, a postdoctoral researcher associate in the lab of co-author Yair Rosenthal, a Distinguished Professor in the Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences at Rutgers University-New Brunswick. “The late Holocene warming was indeed caused by the increase in greenhouse gases, as predicted by climate models, and that eliminates any doubts about the key role of carbon dioxide in global warming.”
Scientists used marine calcareous (calcium carbonate-containing) fossils from foraminifers – single-celled organisms that live at the ocean surface – to reconstruct the temperature histories of the two most recent warm intervals on Earth. They are the Last Interglacial period from 128,000 to 115,000 years ago and the Holocene. To get the fossils, the scientists collected a core of bottom sediments near the mouth of the Sepik River off northern Papua New Guinea during the Rutgers-led Expedition 363 of the International Ocean Discovery Program. The core features rapidly accumulating sediments that allowed the scientists to recreate the temperature history of the western Pacific warm pool, which closely tracks changes in global temperatures.
How temperature evolved during the Last Interglacial and Holocene eras is controversial. Some data suggest that the average annual global temperature during modern times does not exceed the warmth in the Holocene’s early warm period, called the “Holocene thermal maximum,” which was followed by global cooling. Meanwhile, climate models strongly suggest that global temperatures have risen throughout the past 10,000 years.
“The apparent discrepancy between climate models and data has cast doubts among skeptics about the role of greenhouse gases in climate change during the Holocene and possibly in the future,” Rosenthal said. “We found that post-industrial warming has indeed accelerated the long and steady trend of warming throughout the past 10,000 years. Our study also underscores the importance of seasonal changes, specifically Northern Hemisphere summers, in driving many climate systems. Our method can, for the first time, use seasonal temperatures to come up with annual averages.”
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Rutgers-affiliated co-authors include Shital P. Godad, a former Rutgers researcher now at National Taiwan University. Scientists at The Ohio State University and Nanjing Normal University contributed to the study.
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Are all scientists obese? It once thought that people with higher education and scocio-economic status were healthier and had correct diet.
Hannibal’s crossing of the Alps with his elephants is mentioned below. I looked up what my German reference ‘Die Alpen in Der Antike’ (The Alps in Antiquity) says about it. There is a source reporting snowfall just as the army crossed the pass. There is uncertainty among the two chroniclers of the period (Polybios and Livius) about which of the 4 or 5 possible routes was taken, but the two contenders are the Little St Bernard pass (2200m) and the Col de la Traversette (2950m). The latter gives a view of the Po river valley, which is mentioned by Polybios; the former, although not as high, would have meant a detour of more than 120km which for an army in difficult terrain could easily have taken 2 weeks longer. The higher route is therefore mostly assumed to be the one used. Pollen research has indicated that at the time the tree-line was 300m-400m above what it was in the 18th century. That means a climate warmer by 2.0C-2.5C (6.0 C/km lapse rate), hence at least 1C warmer than today.
A post doc has come up with proof that a past warming period was not as warm as everyone assumed. Why does that sound familiar?
You can tell from the pic….trip of a lifetime….these desk jocks will publish whatever allows them a chance at their next trip of a lifetime. If their chances of returning were similar to early explorers, their published papers would have the theme “climate is not changing so there is no need to go again”.
1) How can there be any mystery remaining when I’ve been assured over the last decade that “the science (of climate change) is settled”?
2) Regarding the article’s statement “The scientists say their findings will challenge long-held views on the temperature history in the Holocene era, which began about 12,000 years ago.” Uhhh . . . beyond “views” there are many well-documented, paleoclimate proxies (i.e., science-based data) that indicate there was indeed a Holocene interval, 8,000 ± 1,000 years ago where global surface temperatures (averaged over hundreds of years) were warmer than those of the last 100-200 years.
3) I’d like the see a real scientific hypothesis at to why all that previously-established data should now be dismissed out-of-hand based on the above discussed “reconstitution” of Earth’s temperature history over the last 10,000 years . . . but I will not be waiting on such, obviously.
Right now this reconstruction is a total outlier. It really offers nothing to support their hypothesis. It does not analyze and eliminate all other possible confounding factors that could cause the data to be as it is.
Just like analyzing tree rings assuming CO2 is the only controlling factor and ignoring all other confounding variables (moisture, density, etc).
“contrary to previous reconstruction… ” Ever notice how scientists (whom we are to believe) continuously insist that we “stop believing the science”?
Just how do these Rutgers researchers think that calcium carbonate levels in foraminifera in sediments from the mouth of a river in Papua (in the tropics) can indicate anything about climate change in Northern Hemisphere summers?
Is there any way of establishing the age of the sediments, and could the sedimentation rate have been higher or lower in the past due to changes in rainfall over Papua? Could the course of the river delta have changed over the past 100,000 years, and what is now midstream could have been an eddy 100,000 years ago, or vice versa? This could be possible due to earthquakes in the distant past.
We also know that in recent times the El Nino Southern Oscillation causes short-term cyclic shifts of water temperature in the western Pacific, with higher temperatures during El Nino and lower temperatures during La Nina, and such cycles have periods of a few years to possibly a few decades, and cause large fluctuations in the monsoons and rainfall rates in those areas, which could also affect sedimentation rates. Did the researchers figure ENSO fluctuations into their interpretation of the data from 100,000 years, and many ENSO cycles, ago?
Also, during a period of early warming after an ice age, large amounts of water would still be frozen as glacier ice, meaning that sea levels then would have been lower than they are now, and the mouth of the river then would be under the sea now. The current mouth of the river would have been inland then, probably with a faster current which would inhibit sedimentation. Did the researchers take into account changes in sea level over the past 100,000 years? After all, if sea levels are currently rising at a rate of about 2 mm per year, over the past 100,000 years sea levels could have risen by 200 meters…
Just some food for thought before jumping to conclusions!
It’s not obvious that they took *any* confounding variables into consideration.
So, just keep doing “reconstructions” until it matches what you want it to say?
YEP!
Unlike some on here, “studies” like this worry me a lot. These supposed findings are so completely at odds with common sense (many points are listed below that show it was incontrovertably warmer over last 10,000years) and yet they have no compunctions to publishing this garbage.
No consequences so who cares?
Pat, they are at odds with what WE took in school. But they know what we know is wrong…for example, we learned that fire was one of the greatest contributors to mankind’s success….etc….
But this is so clearly wrong and it’s abundantly clear it was much warmer in this interglacial
It’s just so pathetically corrupt.
It’s like Trudeau claiming he released all the info on his WE charity money laundering scheme when he redacted 5000 pages of evidence.
It’s so obviously a lie, like this “paper”
those poor people in the past just keep getting colder and colder
Couldn’t possibly ever be the reduction in albedo from conversion of the primary climate driver from reflective inert to absorbative gaseous form, no no no. Has to be that evil CO2 stuff!
Is the science settled now?
Just one piece of the biggest climate change “mystery”: Why doesn’t nature behave the way our models tell it to?
NO! Modelling the past is not called “prediction”. The “pre” bit means BEFORE, not 10,000 years later.
If your “predictions” of the past are going the wrong way, you model is worth nothing. The solution is to develop a better model, not to attempt to rewrite past climate history to fit the model.
A warming of the Pacific Warm Pool because of the increase in El Nino conditions from 6000 years ago when there was less ice as the sea level was around 2 meters higher.
The basis question still is whether the rise in Carbon Dioxide was a result of rising temperatures or visa versa ? Metabolism rises with temperature ( thus CO2 ).
Not checking again alternative solar hypothesis undermines the study’s legitimacy.