scholarly journals Incomplete similarity of the ice-climate system

2021 ◽  
Author(s):  
Mikhail Verbitsky
Keyword(s):  
Climate System ◽  
Middle Pleistocene ◽  
Physical Processes ◽  
Physical Similarity ◽  
Future Scenario ◽  
The Past ◽  
Proxy Records ◽  
Climate Evolution ◽  
Incomplete Similarity ◽  
Middle Pleistocene Transition

Abstract. Reconstruction and explanation of past climate evolution using proxy records is the essence of paleoclimatology. In this study, we use dimensional analysis and concepts of similarity to recognize theoretical limits of such forensic inquiries. Specifically, we demonstrate that incomplete similarity in the dynamical ice-climate system implies the absence of physical similarity in conglomerate similarity parameters. It means that major events of the past such as, for example, the middle-Pleistocene transition could have been produced by different physical processes, and, therefore, the task of disambiguation of the historical paleo-records may be fundamentally difficult, if not impossible. It also means that any future scenario may not have a unique cause and, in this sense, the orbital time-scale future may be to some extent insensitive to specific physical circumstances.

Solar-type periodicities in the climate variability of Northern Fennoscandia during the last three centuries: Real influence of solar activity or natural instability in the climate system

The Holocene ◽  
2021 ◽  
pp. 095968362110604
Author(s):  
Maxim Ogurtsov ◽  
Samuli Helama ◽  
Risto Jalkanen ◽  
Högne Jungner ◽  
Markus Lindholm ◽  
...  
Keyword(s):  
Solar Activity ◽  
Climate Variability ◽  
Western Siberia ◽  
Climate System ◽  
Solar Cycles ◽  
Activity Data ◽  
The Past ◽  
Proxy Records ◽  
Northern Fennoscandia ◽  
Solar Type

Fifteen proxy records of summer temperature in Fennoscandia, Northern Europe and in Yamal and Taymir Peninsulas (Western Siberia) were analyzed for the AD 1700–2000 period. Century-long (70–100 year) and quasi bi-decadal periodicities were found from proxy records representing different parts of Fennoscandia. Decadal variation was revealed in a smaller number of records. Statistically significant correlations were revealed between the timescale-dependent components of temperature variability and solar cycles of Schwabe (~11 year), Hale (~22 year), and Gleissberg (сentury-long) as recorded in solar activity data. Combining the results from our correlation analysis with the evidence of solar-climatic linkages over the Northern Fennoscandia obtained over the past 20 years suggest that there are two possible explanations for the obtained solar-proxy relations: (a) the Sun’s activity actually influences the climate variability in Northern Fennoscandia and in some regions of the Northern Hemisphere albeit the mechanism of such solar-climatic linkages are yet to be detailed; (b) the revealed solar-type periodicities result from natural instability of climate system and, in such a case, the correlations may appear purely by chance. Multiple lines of evidence support the first assumption but we note that the second one cannot be yet rejected. Guidelines for further research to elucidate this question are proposed including the Fisher’s combined probability test in the presence of solar signal in multiple proxy records.

scholarly journals Persistent influence of obliquity on ice age terminations since the Middle Pleistocene transition

Science ◽  
2020 ◽  
Vol 367 (6483) ◽  
pp. 1235-1239 ◽  
Author(s):  
Petra Bajo ◽  
Russell N. Drysdale ◽  
Jon D. Woodhead ◽  
John C. Hellstrom ◽  
David Hodell ◽  
...  
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Radiometric Dating ◽  
Ice Age ◽  
Middle Pleistocene ◽  
Interglacial Period ◽  
The Past ◽  
Middle Pleistocene Transition ◽  
High Phase ◽  
Age Estimates

Radiometric dating of glacial terminations over the past 640,000 years suggests pacing by Earth’s climatic precession, with each glacial-interglacial period spanning four or five cycles of ~20,000 years. However, the lack of firm age estimates for older Pleistocene terminations confounds attempts to test the persistence of precession forcing. We combine an Italian speleothem record anchored by a uranium-lead chronology with North Atlantic ocean data to show that the first two deglaciations of the so-called 100,000-year world are separated by two obliquity cycles, with each termination starting at the same high phase of obliquity, but at opposing phases of precession. An assessment of 11 radiometrically dated terminations spanning the past million years suggests that obliquity exerted a persistent influence on not only their initiation but also their duration.

scholarly journals The (mis)conception of average Quaternary conditions

2021 ◽  
pp. 1-6
Author(s):  
Matteo Spagnolo ◽  
Brice R. Rea ◽  
Iestyn Barr
Keyword(s):  
Landscape Evolution ◽  
Middle Pleistocene ◽  
Extreme Caution ◽  
The Past ◽  
Isotope Record ◽  
Middle Pleistocene Transition ◽  
Clear Change

Abstract The concept of Quaternary average conditions has gained popularity over the past few decades, especially with studies of long-term landscape evolution. In this paper, we critically assess this concept by analyzing the marine isotope record (LR04 δ18O stack) relative to the Quaternary. This shows that the frequency and amplitude of climate glacial-interglacial cycles are not constant throughout the Quaternary, with a clear change during the Middle Pleistocene Transition (MPT), and that many minor oscillations exist within each cycle. For this reason, the identification of pre- and post-MPT most-frequent and, cumulatively, longest-lasting (rather than average) conditions is recommended. The most-frequent pre-MPT δ18O value of 3.725 ± 0.025‰ last occurred during 11.31–11.47 ka, while the most-frequent post-MPT δ18O value of 4.475 ± 0.025‰ last occurred during 14.81–15.04 ka. However, many other δ18O values were almost as frequent throughout the Quaternary and we present geomorphological reasons as to why it is unlikely that the present-day landscape reflects Quaternary average or, indeed, most-frequent conditions. Collectively, our results indicate that extreme caution should be taken when attempting to infer long-term landscape evolution processes (including the buzzsaw hypothesis) based on average Quaternary conditions.

scholarly journals Climate evolution across the Mid-Brunhes Transition

2018 ◽  
Vol 14 (12) ◽  
pp. 2071-2087 ◽  
Author(s):  
Aaron M. Barth ◽  
Peter U. Clark ◽  
Nicholas S. Bill ◽  
Feng He ◽  
Nicklas G. Pisias
Keyword(s):  
Ice Core ◽  
Ice Sheets ◽  
High Amplitude ◽  
Climate System ◽  
Atmospheric Co2 ◽  
Sea Levels ◽  
The Past ◽  
Climate Evolution ◽  
Monsoon Strength ◽  
Climate Variance

Abstract. The Mid-Brunhes Transition (MBT) began ∼ 430 ka with an increase in the amplitude of the 100 kyr climate cycles of the past 800 000 years. The MBT has been identified in ice-core records, which indicate interglaciations became warmer with higher atmospheric CO2 levels after the MBT, and benthic oxygen isotope (δ18O) records, which suggest that post-MBT interglaciations had higher sea levels and warmer temperatures than pre-MBT interglaciations. It remains unclear, however, whether the MBT was a globally synchronous phenomenon that included other components of the climate system. Here, we further characterize changes in the climate system across the MBT through statistical analyses of ice-core and δ18O records as well as sea-surface temperature, benthic carbon isotope, and dust accumulation records. Our results demonstrate that the MBT was a global event with a significant increase in climate variance in most components of the climate system assessed here. However, our results indicate that the onset of high-amplitude variability in temperature, atmospheric CO2, and sea level at ∼430 ka was preceded by changes in the carbon cycle, ice sheets, and monsoon strength during Marine Isotope Stage (MIS) 14 and MIS 13.

scholarly journals Climate evolution across the Mid-Brunhes Transition

2018 ◽  
Author(s):  
Aaron M. Barth ◽  
Peter U. Clark ◽  
Nicholas S. Bill ◽  
Feng He ◽  
Nicklas G. Pisias
Keyword(s):  
Ice Core ◽  
Ice Sheets ◽  
High Amplitude ◽  
Climate System ◽  
Atmospheric Co2 ◽  
Sea Levels ◽  
The Past ◽  
Climate Evolution ◽  
Monsoon Strength ◽  
Climate Variance

Abstract. The Mid-Brunhes Transition (MBT) began ∼ 430 ka with an increase in the amplitude of the 100-kyr climate cycles of the past 800,000 years. The MBT has been identified in ice-core records, which indicate interglaciations became warmer with higher atmospheric CO2 levels after the MBT, and benthic oxygen isotope (δ18O) records, which suggest that post-MBT interglaciations had higher sea levels than pre-MBT interglaciations. It remains unclear, however, whether the MBT was a globally synchronous phenomenon that included other components of the climate system. Here we further characterize changes in the climate system across the MBT through statistical analyses of ice-core and δ18O records as well as sea-surface temperature, benthic carbon isotope, and dust accumulation records. Our results demonstrate that the MBT was a global event with a significant increase in climate variance in most components of the climate system assessed here. However, our results indicate that the onset of high-amplitude variability in temperature, atmospheric CO2, and sea level at ∼ 430 ka was preceded by changes in the carbon cycle, ice sheets, and monsoon strength during MIS 14 and 13.

scholarly journals Radiocarbon Dating of Alkenones from Marine Sediments: III. Influence of Solvent Extraction Procedures on 14C Measurements of Foraminifera

Radiocarbon ◽  
2005 ◽  
Vol 47 (3) ◽  
pp. 425-432 ◽  
Author(s):  
Naohiko Ohkouchi ◽  
Timothy I Eglinton ◽  
Konrad A Hughen ◽  
Ellen Roosen ◽  
Lloyd D Keigwin
Keyword(s):  
Solvent Extraction ◽  
Climate Changes ◽  
Extraction Procedures ◽  
Surface Ocean ◽  
The Past ◽  
Proxy Records ◽  
Temporal Relationships ◽  
Ocean Properties ◽  
Bermuda Rise ◽  
Influence Of Solvent

As a result of the growing use of multiple geochemical proxies to reconstruct ocean and climate changes in the past, there is an increasing need to establish temporal relationships between proxies derived from the same marine sediment record and ideally from the same core sections. Coupled proxy records of surface ocean properties, such as those based on lipid biomarkers (e.g. alkenone-derived sea surface temperature) and planktonic foraminiferal carbonate (oxygen isotopes), are a key example. Here, we assess whether 2 different solvent extraction procedures used for isolation of molecular biomarkers influence the radiocarbon contents of planktonic foraminiferal carbonate recovered from the corresponding residues of Bermuda Rise and Cariaco Basin sediments. Although minor Δ14C differences were observed between solvent-extracted and unextracted samples, no substantial or systematic offsets were evident. Overall, these data suggest that, in a practical sense, foraminiferal shells from a solvent-extracted residue can be reliably used for 14C dating to determine the age of sediment deposition and to examine age relationships with other sedimentary constituents (e.g. alkenones).

scholarly journals A single-station prediction model as a contribution to instantaneous mapping

1994 ◽  
Vol 37 (2) ◽  
Author(s):  
I. Stanislawska
Keyword(s):  
Time Series ◽  
Prediction Model ◽  
Prediction Method ◽  
Physical Processes ◽  
The Past ◽  
Ionospheric Station ◽  
Single Station ◽  
Daily Forecast

The paper presents two opposite approaches for single-station prediction and forecast. Both methods are based on different assumptions of physical processes in the ionosphere and need the different set of incoming data. Different heliogeophysical data, mainly f0F2 parameters from the past were analyzed for f0F2 obtaining for the requested period ahead. In the first method - the autocovariance prediction method - the time series of f0F2 from one station are used for daily forecast at that point. The second method may be used for obtaining f0F2 not only at the particular ionospheric station, but also at any point within the considered area.

scholarly journals The exponential eigenmodes of the carbon-climate system, and their implications for ratios of responses to forcings

2013 ◽  
Vol 4 (1) ◽  
pp. 31-49 ◽  
Author(s):  
M. R. Raupach
Keyword(s):  
Linear Systems ◽  
Co2 Emissions ◽  
Radiative Forcing ◽  
Co2 Emission ◽  
Climate Model ◽  
Climate System ◽  
First Order ◽  
The Past ◽  
Emissions Scenarios ◽  
Co2 Sink

Abstract. Several basic ratios of responses to forcings in the carbon-climate system are observed to be relatively steady. Examples include the CO2 airborne fraction (the fraction of the total anthropogenic CO2 emission flux that accumulates in the atmosphere) and the ratio T/QE of warming (T) to cumulative total CO2 emissions (QE). This paper explores the reason for such near-constancy in the past, and its likely limitations in future. The contemporary carbon-climate system is often approximated as a set of first-order linear systems, for example in response-function descriptions. All such linear systems have exponential eigenfunctions in time (an eigenfunction being one that, if applied to the system as a forcing, produces a response of the same shape). This implies that, if the carbon-climate system is idealised as a linear system (Lin) forced by exponentially growing CO2 emissions (Exp), then all ratios of responses to forcings are constant. Important cases are the CO2 airborne fraction (AF), the cumulative airborne fraction (CAF), other CO2 partition fractions and cumulative partition fractions into land and ocean stores, the CO2 sink uptake rate (kS, the combined land and ocean CO2 sink flux per unit excess atmospheric CO2), and the ratio T/QE. Further, the AF and the CAF are equal. Since the Lin and Exp idealisations apply approximately to the carbon-climate system over the past two centuries, the theory explains the observed near-constancy of the AF, CAF and T/QE in this period. A nonlinear carbon-climate model is used to explore how future breakdown of both the Lin and Exp idealisations will cause the AF, CAF and kS to depart significantly from constancy, in ways that depend on CO2 emissions scenarios. However, T/QE remains approximately constant in typical scenarios, because of compensating interactions between CO2 emissions trajectories, carbon-climate nonlinearities (in land–air and ocean–air carbon exchanges and CO2 radiative forcing), and emissions trajectories for non-CO2 gases. This theory establishes a basis for the widely assumed proportionality between T and QE, and identifies the limits of this relationship.

Sign in / Sign up

Export Citation Format

Share Document