Nice talk. Fig.1 from the article mentioned above is shown below. Unfortunately its chronology appears to be flawed.
Permafrost thawing as a possible source of abrupt carbon release at the onset of the Bølling/Allerød
Peter Köhler, Gregor Knorr & Edouard Bard
Nature Comm 2014
https://www.nature.com/articles/ncomms6520 open source 27 follow-up cites
https://images.nature.com/m685/nature-assets/ncomms/2014/141120/ncomms6520/images_hires/ncomms6520-f1.jpgOne of the most abrupt and yet unexplained past rises in atmospheric CO2 (>10 p.p.m.v. in two centuries) occurred in quasi-synchrony with abrupt northern hemispheric warming into the Bølling/Allerød, ~14,600 years ago.
We suggest, in line with observations of atmospheric CH4 and terrigenous biomarkers, that thawing permafrost in high northern latitudes could have been the source of carbon, possibly with contribution from flooding of the Siberian continental shelf during meltwater pulse 1A. Our findings highlight the potential of the permafrost carbon reservoir to modulate abrupt climate changes via greenhouse-gas feedbacks.
Changes in the global carbon cycle during the last deglaciation are so far not completely understood. However, based on the data and model-based interpretation, the emerging picture indicates that the rise in atmospheric CO2 of ~45 p.p.m.v. during the first half of the deglaciation (~1 p.p.m.v. per century) was probably fuelled by the release of old, 13C- and 14C-depleted deep ocean carbon.
Atmospheric CH4 rose by 150 p.p.b.v. between 18.5 and 14.6 kyr BP and then by the same amount again, but within centuries, around the onset of the B/A. The changes in both greenhouse gases (GHG) imply that a ratio of both changes ΔCH4/ΔCO2 is a factor of five larger around 14.6 kyr BP than during the previous four millennia.
Radiocarbon calibration uncertainties during the last deglaciation: Insights from new floating tree-ring chronologies
Florian Adolphi et al
http://www.sciencedirect.com/science/article/pii/S0277379117300641Radiocarbon dating is the most commonly used chronological tool in archaeological and environmental sciences dealing with the past 50,000 years, making the radiocarbon calibration curve one of the most important records in paleosciences.
For the past 12,560 years, the radiocarbon calibration curve is constrained by high quality tree-ring data. Prior to this, however, its uncertainties increase rapidly due to the absence of suitable tree-ring 14C data. Here, we present new high-resolution 14C measurements from 3 floating tree-ring chronologies from the last deglaciation.
By using combined information from the current radiocarbon calibration curve and ice core 10Be records, we are able to absolutely date these chronologies at high confidence. We show that our data imply large 14C-age variations during the Bølling chronozone (Greenland Interstadial 1e) – a period that is currently characterized by a long 14C-age plateau in the most recent IntCal13 calibration record. We demonstrate that this lack of structure in IntCal13 may currently lead to
erroneous calibrated ages by up to 500 years.The resulting 14C records are in broad agreement with IntCal13 and its underlying raw datasets, even though we find significant differences to the Tahiti corals by Durand 2013. Independent of their exact absolute age, the tree-ring 14C records indicate substantial 14C-age variations between 14,000 and 14,700 cal BP e a period that is currently characterized by a
long 14C age plateau in IntCal13.
We demonstrate that the lack of these variations in IntCal13 can lead to erroneous age calibration by up to 500 years during the onset of the Bølling chronozone around 14,700 cal BP. On the other hand, the 14C-age variations indicated by our floating tree-ring chronologies, can aid in obtaining a higher accuracy and precision of calibrated 14C ages during this period, which is currently also limited by the long age plateau in IntCal13.
Given that the Tahiti coral record also disagrees with most other
14C datasets at that time, we suggest that it is more likely that reservoir/archive specific effects in the coral data are the cause for the offset between both datasets. Consequently, this would
contradict the conclusions of Köhler 2014 who inferred a release of old carbon from permafrost thawing as the reason for the rapid decline in delta
14C seen in the coral record around 14,600 cal BP.