Solar Activity Changes at the End of the Last Ice Age - Influences on Climate and Applications for Dating
(2014) In Lundqua thesis- Abstract
- Throughout its history Earth experienced a variety of natural climate changes. By investigating their spatial and temporal evolution we can increase the understanding of the mechanisms and dynamics underlying natural climate change and improve our general comprehension of the climate system. Prerequisites of these investigations are reliable reconstructions of past forcing variations as well as sound and consistent chronologies of paleoclimate records. The Sun is by far Earth’s most important source of energy and variations in its irradiance have been shown to influence climate on different temporal and spatial scales. The exact mechanisms of these solar influences on climate are, however, not fully understood. Variations in solar activity... (More)
- Throughout its history Earth experienced a variety of natural climate changes. By investigating their spatial and temporal evolution we can increase the understanding of the mechanisms and dynamics underlying natural climate change and improve our general comprehension of the climate system. Prerequisites of these investigations are reliable reconstructions of past forcing variations as well as sound and consistent chronologies of paleoclimate records. The Sun is by far Earth’s most important source of energy and variations in its irradiance have been shown to influence climate on different temporal and spatial scales. The exact mechanisms of these solar influences on climate are, however, not fully understood. Variations in solar activity also cause changes in the atmospheric production rates of cosmogenic radionuclides, such as 10Be and 14C. These radionuclides get subsequently deposited in various environments which can, hence, provide information about past solar activity levels. Furthermore, these records can be synchronized to each other by identifying coherent production rate related patterns in their radionuclide records. This project aims to extend solar activity reconstructions back into the late glacial and investigate potential sun-climate relationships. Furthermore, the consistency of the time scales underlying different records is tested by comparing their cosmogenic radionuclide records. In addition, it aims to improve radiocarbon dating calibration by extending its tree-ring based section further back in time.
We present the first solar activity reconstruction for the late glacial based new and published 10Be data from the GRIP and GISP2 ice cores, supported by published 14C data. We infer that late glacial and Holocene solar activity variations have been comparable in both patterns and amplitudes. We find a persistent influence of solar activity changes on Greenland climate during the Last Glacial Maximum which appears coherent with modern day observations and climate model results. This suggests that a similar solar forcing mechanism may have been operating under otherwise very different climate regimes. We propose a time scale transfer function between Greenland ice core and radiocarbon dated records by synchronizing the temporal variations of ice core 10Be and tree-ring 14C records. We outline a statistical framework that allows time scale differences and uncertainties to be inferred. We find that there is a continuously growing difference between Greenland ice core and radiocarbon based chronologies throughout the Holocene. Furthermore, we identify a rapid shift in this time scale difference around 12,500 years ago, that cannot be explained with ice core layer counting uncertainties alone. Instead, we propose that this effect may arise from uncertainties in the absolute dating of tree-ring records. We present new 14C data on floating tree-ring chronologies that can improve radiocarbon dating calibration between 14,000 to 14,700 years ago. We introduce a method of how combined information from 14C and 10Be records can aid us to infer absolute ages for these chronologies. These new records add substantial structure to the calibration curve and we note that missing this structure can lead to erroneous calibration of 14C dates by up to 500 years. (Less) - Abstract (Swedish)
- Popular Abstract in Swedish
Under sin livstid har Jorden genomlevt upprepade naturliga klimatförändringar. Genom att undersöka dessa klimatförändringar över tid och rum så kan vi öka vår förståelse för underliggande dynamik och mekanismer och därmed bättre förstå klimatsystemet. Två grundläggande förutsättningar för sådana undersökningar är trovärdiga rekonstruktioner av tidigare variationer i styrka och funktion hos relevanta drivkrafter, samt tillförlitliga och förenliga kronologier av tillgängliga paleoklimatologiska arkiv.
Solen utgör Jordens enskilt viktigaste energikälla. Variationer i dess strålning har visats påverka klimatet på olika rumsliga och tidsmässiga skalor. Exakt genom vilka mekanismer solen... (More) - Popular Abstract in Swedish
Under sin livstid har Jorden genomlevt upprepade naturliga klimatförändringar. Genom att undersöka dessa klimatförändringar över tid och rum så kan vi öka vår förståelse för underliggande dynamik och mekanismer och därmed bättre förstå klimatsystemet. Två grundläggande förutsättningar för sådana undersökningar är trovärdiga rekonstruktioner av tidigare variationer i styrka och funktion hos relevanta drivkrafter, samt tillförlitliga och förenliga kronologier av tillgängliga paleoklimatologiska arkiv.
Solen utgör Jordens enskilt viktigaste energikälla. Variationer i dess strålning har visats påverka klimatet på olika rumsliga och tidsmässiga skalor. Exakt genom vilka mekanismer solen påverkar Jordens klimat är däremot inte helt klarlagt. Förändringar i solens aktivitet leder till förändrade halter av kosmogena radionuklider, såsom 10Be och 14C, i atmosfären. Dessa radionuklider avsätts och inlagras i olika miljöer på Jorden som ett slags arkiv över svunnen solaktivitet. Genom att identifiera samstämmiga produktionshastigheter mellan sådana arkiv kan dessa synkroniseras.
Det här projektet ämnar rekonstruera solaktivitet tillbaka in i senglacial tid och därigenom analysera samband mellan solens aktivitet och Jordens klimat. Vidare undersöks samstämmigheten mellan kronologier för olika klimatarkiv, via förändringar i innehåll av kosmogena radionuklider i desamma över tid. Slutligen syftar arbetet också till att förbättra 14C-baserad datering genom att förlänga den träringsbaserade delen av kalibreringskurvan bakåt i tiden.
Vi presenterar den första solaktivitetsrekonstruktionen för senglacial tid, baserat på ny och tidigare publicerad 10Be data från de grönländska isborrkärnorna GRIP och GRIP2, understödd av tidigare publicerad 14C data. Vi visar att senglaciala och Holocena variationer i solaktivitet är jämförbara både vad gäller frekvens och amplitud. Vi konstaterar vidare att solens aktivitet har haft en ihållande påverkan på Grönlands klimat över det senaste glaciala maximat, en påverkan som förefaller motsvara nutida observationer och klimatmodeller. Detta tyder på att de mekanismer genom vilka solen påverkar Jordens klimat, varit och är jämförbara även mellan totalt skilda klimatregimer.
Vi föreslår synkronisering av borrkärnor från den grönländska inlandsisen och 14C-daterade klimatarkiv genom matchning av 10Be- och 14C-innehåll över tid. Vi beskriver ett statistiskt ramverk som möjliggör identifiering av kronologiska skillnader och osäkerheter för specifika klimatarkiv. Vidare konstaterar vi en alltjämt växande diskrepans mellan kronologier från de grönländska borrkärnorna och 14C-daterade klimatarkiv genom Holocen, med en speciellt kraftig förändring kring 12,500 år sedan, vilken inte kan förklaras genom osäkerheter i varvräkning i GRIP och GRIP2. Istället föreslår vi att den är en effekt av osäkerheter relaterad till absolut datering av trädringsarkiv.
Slutligen presenterar vi ny 14C data från flytande trädringskronologier som kan förbättra 14C–datering för organiskt material från mellan 14,000 och 14,700 år sedan. Vi beskriver en metodik för hur kombinerad 14C och 10Be data kan underlätta och påvisa absoluta åldrar för associerade kronologier. Dessa nya data kan användas för att förbättra och bestyrka kalibreringskurvan som i sin nuvarande utformning, inom detta tidsintervall, kan leda till åldersbestämningar med felmarginal på uppemot 500 år. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/4730721
- author
- Adolphi, Florian LU
- supervisor
- opponent
-
- Olsen, Jesper, Department of Physics and Astronomy, Aarhus University, Denmark
- organization
- publishing date
- 2014
- type
- Thesis
- publication status
- published
- subject
- keywords
- Solar Activity, 10Be, 14C, radiocarbon calibration, time scale, geochronology, paleoclimate, ice cores, tree rings, IntCal, cosmogenic radionuclides
- in
- Lundqua thesis
- issue
- 76
- pages
- 125 pages
- publisher
- Department of Geology, Lund University
- defense location
- Vaerlden, Geocentrum I
- defense date
- 2014-11-14 13:15:00
- ISSN
- 0281-3033
- ISBN
- 978-91-87847-02-8
- language
- English
- LU publication?
- yes
- id
- 0043e809-b4c8-4a4d-9258-a32c4f423047 (old id 4730721)
- date added to LUP
- 2016-04-01 13:48:41
- date last changed
- 2020-09-23 11:51:31
@phdthesis{0043e809-b4c8-4a4d-9258-a32c4f423047,
abstract = {{Throughout its history Earth experienced a variety of natural climate changes. By investigating their spatial and temporal evolution we can increase the understanding of the mechanisms and dynamics underlying natural climate change and improve our general comprehension of the climate system. Prerequisites of these investigations are reliable reconstructions of past forcing variations as well as sound and consistent chronologies of paleoclimate records. The Sun is by far Earth’s most important source of energy and variations in its irradiance have been shown to influence climate on different temporal and spatial scales. The exact mechanisms of these solar influences on climate are, however, not fully understood. Variations in solar activity also cause changes in the atmospheric production rates of cosmogenic radionuclides, such as 10Be and 14C. These radionuclides get subsequently deposited in various environments which can, hence, provide information about past solar activity levels. Furthermore, these records can be synchronized to each other by identifying coherent production rate related patterns in their radionuclide records. This project aims to extend solar activity reconstructions back into the late glacial and investigate potential sun-climate relationships. Furthermore, the consistency of the time scales underlying different records is tested by comparing their cosmogenic radionuclide records. In addition, it aims to improve radiocarbon dating calibration by extending its tree-ring based section further back in time.<br/><br>
We present the first solar activity reconstruction for the late glacial based new and published 10Be data from the GRIP and GISP2 ice cores, supported by published 14C data. We infer that late glacial and Holocene solar activity variations have been comparable in both patterns and amplitudes. We find a persistent influence of solar activity changes on Greenland climate during the Last Glacial Maximum which appears coherent with modern day observations and climate model results. This suggests that a similar solar forcing mechanism may have been operating under otherwise very different climate regimes. We propose a time scale transfer function between Greenland ice core and radiocarbon dated records by synchronizing the temporal variations of ice core 10Be and tree-ring 14C records. We outline a statistical framework that allows time scale differences and uncertainties to be inferred. We find that there is a continuously growing difference between Greenland ice core and radiocarbon based chronologies throughout the Holocene. Furthermore, we identify a rapid shift in this time scale difference around 12,500 years ago, that cannot be explained with ice core layer counting uncertainties alone. Instead, we propose that this effect may arise from uncertainties in the absolute dating of tree-ring records. We present new 14C data on floating tree-ring chronologies that can improve radiocarbon dating calibration between 14,000 to 14,700 years ago. We introduce a method of how combined information from 14C and 10Be records can aid us to infer absolute ages for these chronologies. These new records add substantial structure to the calibration curve and we note that missing this structure can lead to erroneous calibration of 14C dates by up to 500 years.}},
author = {{Adolphi, Florian}},
isbn = {{978-91-87847-02-8}},
issn = {{0281-3033}},
keywords = {{Solar Activity; 10Be; 14C; radiocarbon calibration; time scale; geochronology; paleoclimate; ice cores; tree rings; IntCal; cosmogenic radionuclides}},
language = {{eng}},
number = {{76}},
publisher = {{Department of Geology, Lund University}},
school = {{Lund University}},
series = {{Lundqua thesis}},
title = {{Solar Activity Changes at the End of the Last Ice Age - Influences on Climate and Applications for Dating}},
year = {{2014}},
}