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NOTICE: Noble gas global mean ocean thermometry on ice cores

English title NOTICE: Noble gas global mean ocean thermometry on ice cores
Applicant Fischer Hubertus
Number 155906
Funding scheme Project funding (Div. I-III)
Research institution Klima- und Umweltphysik Physikalisches Institut Universität Bern
Institution of higher education University of Berne - BE
Main discipline Other disciplines of Physics
Start/End 01.01.2015 - 31.03.2017
Approved amount 439'111.00
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All Disciplines (2)

Discipline
Other disciplines of Physics
Other disciplines of Environmental Sciences

Keywords (5)

ocean temperature; ice cores; noble gases; paleoclimate; dating

Lay Summary (German)

Lead
Klimaveränderungen in der Vergangenheit werden in physikalischen, chemischen oder biologischen Eigenschaften natürlicher Klimaarchive gespeichert und liefern so lokale (Proxy-) Temperaturinformationen. In NOTICE gehen wir über diesen Ansatz hinaus, in dem wir mithilfe einer präzisen massenspektrometrischen Methode die Edelgasverhältnisse in Luftblasen in polaren Eiskernen messen. Basierend auf der wohldefinierten Temperaturabhängigkeit der Löslichkeit dieser Gase im Ozean, liefert dies eine Temperaturinformation, die über den gesamte Ozean mittelt, und somit ein integrales Masse des Wärmeinhalts des Ozeans zu jedem Zeitpunkt der letzten bis zu 800,000 Jahre.
Lay summary

Um die vom Menschen verursachte Klimaerwärmung zu verstehen und deren Entwicklung vorauszusagen, ist die detaillierte Kenntnis der Veränderungen im Erdsystem und der Kopplung zwischen Klima und Strahlungsantrieb notwendig. Aufgrund der zeitlichen Beschränkung direkter Beobachtungen spielt die Rekonstruktion des Klimas mithilfe natürlicher Klimaarchive eine herausragende Rolle, um diese Variationen über lange Zeiträume zu untersuchen und wichtige Validierungsdaten für Klimamodelle zur Verfügung zu stellen. Eine globale Rekonstruktion des Klimas, bzw. eine Validierung von Klimamodellen, ist jedoch extrem schwierig, da die Daten aus Klimaarchiven räumlich limitiert sind und die Altersskalen der Klimaarchive häufig nicht konsistent. 

Es wird somit ein neues Paleothermometer benötigt, das globale Temperaturen liefert. Da bei Klimaänderungen der Grossteil der Wärme vom Ozean aufgenommen bzw. abgegeben wird, benötigen wir ein globales Ozeanthermometer. Interessanterweise liefern nicht marine Sedimente diese Information, sondern polare Eisbohrkerne. Diese archivieren die vergangenen Atmosphäre in kleinen Luftblasen, und somit auch die Konzentrationen des molekularen Stickstoffs und der Edelgase Argon, Krypton and Xenon. Obwohl sich der Grossteil dieser Gase in der Atmosphäre befindet, ist ein kleiner Prozentsatz im Ozean gelöst. Dieser Prozentsatz ist durch die bekannte Abhängigkeit der Löslichkeit von der Temperatur kontrolliert. Dementsprechend können wir die mittlere Ozeantemperatur im Vergleich zum heutigen Wert rekonstruieren, wenn wir die Verhältnisse dieser Gase präzise messen können.

In den letzten Jahren haben wir eine massenspektrometrische Methode entwickelt, die diese Verhältnisse mit der entsprechenden Genauigkeit an kleinen Luftproben aus Eisbohrkernen messen kann. In NOTICE wenden wir diese neue Technik auf Eiskerne aus Grönland und der Antarktis an, um die mittlere globale Ozeantemperatur über die letzten bis zu 800’000 Jahre zu rekonstruieren.

Direct link to Lay Summary Last update: 13.10.2014

Lay Summary (English)

Lead
Past climate changes are imprinted in natural archives in physical, chemical or biological properties providing local (proxy) temperature information. In NOTICE we will go beyond previous approaches by measuring the noble gas ratios in air bubbles in polar ice cores using a novel sensitive mass spectrometric technique. Based on the straightforward temperature dependence of the solubility of noble gases in the global ocean, this provides temperature information averaged over the entire ocean and thus an integrative measure of its heat content at any point back in time for up to the last 800,000 years.
Lay summary

To understand and predict anthropogenically induced global warming requires detailed knowledge of the variations in the Earth’s climate system and of the coupling processes between climate and radiative forcing. Due to the strong temporal limitations of direct observations, reconstructions of past climate from natural climate archives are key to studying these variations over an extended time scale and to providing crucial validation data for climate models. However, climate reconstructions with global coverage and data-model comparison on a global scale are virtually impossible for long-term climate changes, due to limited data availability and inconsistencies in the chronologies of individual climate records.

Accordingly, a new paleo-thermometer is required that provides global temperature. As most of the heat during climate changes is taken up or released from the ocean, this implies that we are essentially seeking for a global mean ocean thermometer. Interestingly, it is not marine sediments that provide such information but polar ice cores. These cores archive the past atmosphere in little air bubbles, which contain the natural concentration of molecular nitrogen (N2) and of noble gases such as Argon, Krypton and Xenon. Although the large majority of these gases is residing in the atmosphere, a small percentage is dissolved in the ocean. This percentage is controlled by the well-known dependence of their solubility on ocean temperature. Accordingly, we are able to quantify the global mean ocean temperature in the past compared to its present value by very precisely measuring the ratios of molecular nitrogen and noble gases .

We have developed a mass spectrometric technique in recent years, which is able to measure these ratios with the required precision on small air samples extracted from ice cores. In NOTICE we will employ this technique on ice cores from Greenland and Antarctica to reconstruct global mean ocean temperature over up to the last 800,000 years.

Direct link to Lay Summary Last update: 13.10.2014

Responsible applicant and co-applicants

Employees

Collaboration

Group / person Country
Types of collaboration
Dr. Kenji Kawamura, Dr. Kumiko Goto Azuma, National Institute for Polar Research, Tokyo Japan (Asia)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Amaelle Landais, Dr. Valerie Masson-Delmotte, LSCE, Paris France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Jeff Severinghaus, University of California San Diego, La Jolla United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Exchange of personnel
Prof. Ingeborg Levin, Institute for Environmental Physics, University of Heidelberg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Swiss Global Change Day 2017 Poster Mean ocean temperature evolution in the past 40,000 years from ice core noble gas thermometry 11.04.2017 Bern, Switzerland Fischer Hubertus; Baggenstos Daniel; Häberli Marcel; Kellerhals Thomas;
Swiss Global Change Day 2016 Poster Global mean ocean temperature in the late pleistocene based on ice core noble gas thermometry 12.04.2016 Bern, Switzerland Fischer Hubertus; Häberli Marcel; Baggenstos Daniel; Kellerhals Thomas;
Swiss Global Change Day 2016 Talk given at a conference What can we learn about the 1.5°C global warming target from the past? 12.04.2016 Bern, Switzerland Fischer Hubertus; Baggenstos Daniel; Schwander Jakob; Häberli Marcel; Kellerhals Thomas;
INTERNATIONAL PARTNERSHIPS IN ICE CORE SCIENCES SECOND OPEN SCIENCE CONFERENCE Poster Global mean ocean temperature in the late pleistocene based on ice core noble gas thermometry 07.03.2016 Hobart, Australia Kellerhals Thomas; Fischer Hubertus; Häberli Marcel; Baggenstos Daniel;
PAGES-PMIP Working Group on Quaternary Interglacials: Warm extremes workshop Talk given at a conference Global Mean Ocean Temperature 2°C warmer during the last interglacial – an Eemian analogue of a warmer future!? 09.11.2015 Cambridge, Great Britain and Northern Ireland Häberli Marcel; Fischer Hubertus; Kellerhals Thomas; Baggenstos Daniel; Schwander Jakob;
Symposium “40 year anniversary of the Institute for Environmental Physics“ Talk given at a conference Taking the Earth's temperature using new physical ice core thermometers 23.10.2015 Heidelberg, Germany Fischer Hubertus;


Communication with the public

Communication Title Media Place Year
Talks/events/exhibitions Eine 1.5°C wärmere Welt in 2100: Lehren aus der Klimavergangenheit German-speaking Switzerland 2016

Associated projects

Number Title Start Funding scheme
172506 iCEP - Climate and Environmental Physics: Innovation in ice core science 01.04.2017 Project funding (Div. I-III)
147174 Climate and Environmental Physics 01.04.2013 Project funding (Div. I-III)

Abstract

To understand, predict and mitigate anthropogenically induced global warming requires detailed knowledge of the variations in the Earth’s climate system and of the coupling processes between climate and radiative forcing. Due to the strong temporal limitations of direct observations, reconstructions of past climate from natural climate archives are key to studying these variations and the related feedback processes over an extended time scale and to providing crucial validation data for climate models. However, climate reconstructions with global coverage and data-model comparison on a global scale are virtually impossible for transient glacial/interglacial climate changes, due to limited data availability and inconsistencies in the chronologies of individual climate records. NOTICE will use a newly developed physical global mean ocean thermometer based on high-precision ice core measurements of the ratio of molecular nitrogen and noble gases (d?r/N2, dKr/N2, dXe/N2, dXe/Kr) that largely overcomes this problem. Precise ice core measurements of the ratios of these gases will allow us to determine global mean ocean temperature on glacial/interglacial time scales, based on the temperature dependence of the solubility of these gases in ocean water. Measurement of the entire suite of these gas ratios and their isotopic signatures (d15N2, d36Ar/40Ar, d84Kr/86Kr and d129Xe/132Xe) is required to allow the correction of systematic physical effects occurring during the gas transport in polar firn. The derived global mean ocean temperature has a one-point precision of 0.5°C. Using this novel technique, we will be able to reconstruct the changes in the integrated global ocean heat content over the last glacial/interglacial transition and quantify the global mean ocean temperature for glacials and interglacials 800,000 years back in time. As the ocean heat uptake carries the lion’s share of glacial/interglacial changes in the planetary heat content, this is the most integrative and representative parameter for quantifying the long-term changes in the energy budget of the Earth and can be directly compared to the ocean heat content in coupled climate models. We will contrast this mean ocean temperature record with other climate records from the same ice cores (such as greenhouse gas concentrations) avoiding critical dating inconsistencies to study the coupling and phasing between changes in temperature and radiative forcing.In a second application of our noble gas analyses, we will establish a new dating tool for ice as old as 1 million years, based on the long-term increase of atmospheric 40Ar due to 40K decay. To this end, we will expand our measurement capability to the simultaneous measurement of 38Ar. Precise measurements of both 36Ar and 38Ar are required to reliable correct 40Ar for systematic effects occurring in the firn column. This novel method provides absolute ages with an age uncertainty on the order of 10% and represents an important prerequisite for the dating of the deepest layers in a future “Oldest Ice” project, with an ice core reaching back as far as 1.5 million years. The work described in this proposal represents a continuation and expansion of the European Research Council (ERC) Advanced Grant project “MATRICs” (held by the PI of NOTICE) and will allow us to harvest the fruit of its extensive development work on noble gas thermometry after the end of MATRICs in 2014. Note that the noble gas thermometry represents a new, independent research line, which has not previously been funded by SNF. NOTICE is entirely focused on novel noble gas applications in ice cores to rule out any potential overlap with the ongoing SNF project “Climate and Environmental Physics”. Accordingly, none of the research described here nor any of the funding for personnel requested overlap with this or any other SNF project.
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