Antarctic Temperatures Over the Past two Centuries from Ice Cores

Fire plays a pivotal role in shaping terrestrial ecosystems and the chemical composition of the atmosphere and thus influences Earth’s climate. The trend and magnitude of fire activity over the past few centuries are controversial, which hinders understanding of preindustrial to present-day aerosol radiative forcing. Here, we present evidence from records of 14 Antarctic ice cores and 1 central Andean ice core, suggesting that historical fire activity in the Southern Hemisphere (SH) exceeded present-day levels. To understand this observation, we use a global fire model to show that overall SH fire emissions could have declined by 30% over the 20th century, possibly because of the rapid expansion of land use for agriculture and animal production in middle to high latitudes. Radiative forcing calculations suggest that the decreasing trend in SH fire emissions over the past century largely compensates for the cooling effect of increasing aerosols from fossil fuel and biofuel sources.

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Long-term evolution of the heliospheric magnetic field inferred from cosmogenic 44Ti activity in meteorites

Astronomy and Astrophysics ◽

10.1051/0004-6361/201730392 ◽

2018 ◽

Vol 610 ◽

pp. A28 ◽

Cited By ~ 2

Author(s):

S. Mancuso ◽

C. Taricco ◽

P. Colombetti ◽

S. Rubinetti ◽

N. Sinha ◽

...

Keyword(s):

Magnetic Field ◽

Ice Cores ◽

Long Term Evolution ◽

Galactic Cosmic Rays ◽

Sunspot Activity ◽

Cosmogenic Isotopes ◽

Heliospheric Magnetic Field ◽

The Past ◽

Term Evolution

Typical reconstructions of historic heliospheric magnetic field (HMF) BHMF are based on the analysis of the sunspot activity, geomagnetic data or on measurement of cosmogenic isotopes stored in terrestrial reservoirs like trees (14C) and ice cores (10Be). The various reconstructions of BHMF are however discordant both in strength and trend. Cosmogenic isotopes, which are produced by galactic cosmic rays impacting on meteoroids and whose production rate is modulated by the varying HMF convected outward by the solar wind, may offer an alternative tool for the investigation of the HMF in the past centuries. In this work, we aim to evaluate the long-term evolution of BHMF over a period covering the past twenty-two solar cycles by using measurements of the cosmogenic 44Ti activity (τ1∕2 = 59.2 ± 0.6 yr) measured in 20 meteorites which fell between 1766 and 2001. Within the given uncertainties, our result is compatible with a HMF increase from 4.87-0.30+0.24 nT in 1766 to 6.83-0.11+0.13 nT in 2001, thus implying an overall average increment of 1.96-0.35+0.43 nT over 235 years since 1766 reflecting the modern Grand maximum. The BHMF trend thus obtained is then compared with the most recent reconstructions of the near-Earth HMF strength based on geomagnetic, sunspot number, and cosmogenic isotope data.

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Volcanic synchronization of Dome Fuji and Dome C Antarctic deep ice cores over the past 216 kyr

Climate of the Past ◽

10.5194/cp-11-1395-2015 ◽

2015 ◽

Vol 11 (10) ◽

pp. 1395-1416 ◽

Cited By ~ 13

Author(s):

S. Fujita ◽

F. Parrenin ◽

M. Severi ◽

H. Motoyama ◽

E. W. Wolff

Keyword(s):

Age Differences ◽

Flow Model ◽

Ice Cores ◽

Ice Flow ◽

Surface Mass ◽

The Past ◽

The One ◽

Mis 5E ◽

Age Constraints ◽

Mis 5

Abstract. Two deep ice cores, Dome Fuji (DF) and EPICA Dome C (EDC), drilled at remote dome summits in Antarctica, were volcanically synchronized to improve our understanding of their chronologies. Within the past 216 kyr, 1401 volcanic tie points have been identified. DFO2006 is the chronology for the DF core that strictly follows O2 / N2 age constraints with interpolation using an ice flow model. AICC2012 is the chronology for five cores, including the EDC core, and is characterized by glaciological approaches combining ice flow modelling with various age markers. A precise comparison between the two chronologies was performed. The age differences between them are within 2 kyr, except at Marine Isotope Stage (MIS) 5. DFO2006 gives ages older than AICC2012, with peak values of 4.5 and 3.1 kyr at MIS 5d and MIS 5b, respectively. Accordingly, the ratios of duration (AICC2012 / DFO2006) range between 1.4 at MIS 5e and 0.7 at MIS 5a. When making a comparison with accurately dated speleothem records, the age of DFO2006 agrees well at MIS 5d, while the age of AICC2012 agrees well at MIS 5b, supporting their accuracy at these stages. In addition, we found that glaciological approaches tend to give chronologies with younger ages and with longer durations than age markers suggest at MIS 5d–6. Therefore, we hypothesize that the causes of the DFO2006–AICC2012 age differences at MIS 5 are (i) overestimation in surface mass balance at around MIS 5d–6 in the glaciological approach and (ii) an error in one of the O2 / N2 age constraints by ~ 3 kyr at MIS 5b. Overall, we improved our knowledge of the timing and duration of climatic stages at MIS 5. This new understanding will be incorporated into the production of the next common age scale. Additionally, we found that the deuterium signals of ice, δDice, at DF tends to lead the one at EDC, with the DF lead being more pronounced during cold periods. The lead of DF is by +710 years (maximum) at MIS 5d, −230 years (minimum) at MIS 7a and +60 to +126 years on average.

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Climate dependent contrast in surface mass balance in East Antarctica over the past 216 ka

Journal of Glaciology ◽

10.1017/jog.2016.85 ◽

2016 ◽

Vol 62 (236) ◽

pp. 1037-1048 ◽

Cited By ~ 4

Author(s):

F. PARRENIN ◽

S. FUJITA ◽

A. ABE-OUCHI ◽

K. KAWAMURA ◽

V. MASSON-DELMOTTE ◽

...

Keyword(s):

Mass Balance ◽

Ice Core ◽

Ice Cores ◽

East Antarctica ◽

Surface Mass Balance ◽

Last Interglacial ◽

Surface Mass ◽

The Past ◽

Water Stable Isotope ◽

Global Mean Sea Level

ABSTRACTDocumenting past changes in the East Antarctic surface mass balance is important to improve ice core chronologies and to constrain the ice-sheet contribution to global mean sea-level change. Here we reconstruct past changes in the ratio of surface mass balance (SMB ratio) between the EPICA Dome C (EDC) and Dome Fuji (DF) East Antarctica ice core sites, based on a precise volcanic synchronization of the two ice cores and on corrections for the vertical thinning of layers. During the past 216 000 a, this SMB ratio, denoted SMBEDC/SMBDF, varied between 0.7 and 1.1, being small during cold periods and large during warm periods. Our results therefore reveal larger amplitudes of changes in SMB at EDC compared with DF, consistent with previous results showing larger amplitudes of changes in water stable isotopes and estimated surface temperature at EDC compared with DF. Within the last glacial inception (Marine Isotope Stages, MIS-5c and MIS-5d), the SMB ratio deviates by up to 0.2 from what is expected based on differences in water stable isotope records. Moreover, the SMB ratio is constant throughout the late parts of the current and last interglacial periods, despite contrasting isotopic trends.

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Fire in ice: two millennia of Northern Hemisphere fire history from the Greenland NEEM ice core

Climate of the Past Discussions ◽

10.5194/cpd-10-809-2014 ◽

2014 ◽

Vol 10 (1) ◽

pp. 809-857 ◽

Cited By ~ 4

Author(s):

P. Zennaro ◽

N. Kehrwald ◽

J. R. McConnell ◽

S. Schüpbach ◽

O. Maselli ◽

...

Keyword(s):

Black Carbon ◽

Biomass Burning ◽

Fire History ◽

Global Climate ◽

Ice Cores ◽

Dominant Factor ◽

The Past ◽

Past 2000 Years ◽

Isotopic Analyses ◽

Fire Activity

Abstract. Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales, but there remains a need for broad-scale fire proxies that span millennia in order to understand the role of fire in the carbon cycle and climate system. We use the specific biomarker levoglucosan, and multi-source black carbon and ammonium concentrations to reconstruct fire activity from the North Greenland Eemian (NEEM) ice cores (77.49° N; 51.2° W, 2480 m a.s.l.) over the past 2000 years. Increases in boreal fire activity (1000–1300 CE and 1500–1700 CE) over multi-decadal timescales coincide with the most extensive central and northern Asian droughts of the past two millennia. The NEEM biomass burning tracers coincide with temperature changes throughout much of the past 2000 years except for during the extreme droughts, when precipitation changes are the dominant factor. Many of these multi-annual droughts are caused by monsoon failures, thus suggesting a connection between low and high latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative proximity to the NEEM camp. During major fire events, however, isotopic analyses of dust, back-trajectories and links with levoglucosan peaks and regional drought reconstructions suggest that Siberia is also an important source of pyrogenic aerosols to Greenland.

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The Impacts of Climate Change on Societies: What Can We Learn from the Past?

10.5194/egusphere-egu21-99 ◽

2021 ◽

Author(s):

Dagomar Degroot

Keyword(s):

Climate Change ◽

Case Studies ◽

Public Discourse ◽

Climate Change Policy ◽

Ice Cores ◽

Keynote Presentation ◽

The Past ◽

Change Policy ◽

History Of ◽

Paleoclimatic Proxy

<p>This keynote presentation introduces the sources, methods, and major findings of the History of Climate and Society (HCS), a recently-coined field that uncovers the past influences of climate change on human history. It begins by offering a brief history of the field, from the eighteenth century through the present. It then describes how HCS scholars &#8220;reconstruct&#8221; past climate changes by combining what they call the &#8220;archives of nature&#8221; &#8211; paleoclimatic proxy sources such as tree rings, ice cores, or marine sediments &#8211; with the texts, stories, and ruins that constitute the &#8220;archives of society.&#8221; Next, it explains how HCS scholars in different disciplines have used distinct statistical and qualitative methods, and distinct causal frameworks, to identify the influence of climate change in the archives of society. It explores how HCS scholars conceptualize the vulnerability and resilience of past societies by introducing some telling case studies, and explaining how those case studies have grown more complex as HCS matured as a field. It then emphasizes the enduring challenges faced by HCS scholars and how, in recent months, they have been identified and are beginning to be addressed. Finally, it describes how HCS has informed climate change policy and public discourse, before offering some key lessons that policymakers can learn from the field.</p>

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The Cryospheric Archive of the Past Atmosphere: Aerosol and Soluble Gases in Ice Cores

10.1142/9789811230134_0014 ◽

2021 ◽

pp. 687-753

Author(s):

Michel Legrand ◽

Eric W. Wolff

Keyword(s):

Ice Cores ◽

The Past

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Holocene temperature variations inferred from Antarctic ice cores

Annals of Glaciology ◽

10.1017/s0260305500016803 ◽

1994 ◽

Vol 20 ◽

pp. 427-436 ◽

Cited By ~ 1

Author(s):

P. Ciais ◽

J. Jouzel ◽

J. R. Petit ◽

V. Lipenkov ◽

J. W. C. White

Keyword(s):

Late Holocene ◽

Ice Core ◽

Ice Cores ◽

Temperature Fluctuations ◽

Base Line ◽

Temperature Changes ◽

Average Temperature ◽

The Past ◽

Reconstructed Temperature ◽

Line Temperature

We have reconstructed temperature changes over the past 15 000 years from ice-core data in Antarctica. We used measurements of the D/H isotope ratio in ice as a proxy of temperature for central sites (Vostok, Dome C and Komsomolskaya; as well as coastal sites (D47, D15 and D10). First, we examined the dating of each core and built up a common temporal framework for the ensemble of the data. Secondly, we addressed the problem of inferring small-amplitude temperature fluctuations from the isotope data, in the light of noise-generating mechanisms involved in snow deposition. Temperature was reconstructed so as to minimize distortion created by the sampling of ice cores in the field. The seven ice cores studied yield an average temperature curve which can be put in perspective with nearby paleoclimatic records. The early Holocene experienced climates warmer than today by 1-2°C. The late Holocene period shows more discernible, shorter-duration, temperature fluctuations, superimposed on a fairly stable "base-line" temperature.

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Correction Of Air-content Measurements In Polar Ice For The Effect Of Cut Bubbles At The Surface Of The Sample

Journal of Glaciology ◽

10.1017/002214390793701282 ◽

1990 ◽

Vol 36 (124) ◽

pp. 299-303 ◽

Cited By ~ 6

Author(s):

P. Martinerie ◽

V.Ya. Lipenkov ◽

D. Raynaud

Keyword(s):

Finite Number ◽

Theoretical Calculation ◽

Ice Sheets ◽

Ice Cores ◽

Polar Ice ◽

Density Data ◽

Hydrostatic Method ◽

Air Content ◽

The Past ◽

Statistical Noise

AbstractAir content (V) of polar ice has been used as an indicator of the past elevation of the ice sheets. A calculation is presented to correctVmeasurements performed on ice samples for the effect of cut bubbles at their surface. The results indicate a correction ranging from 1 to 10% for cubic ice samples with about 3 cm length. The correction depends mainly on the size of the bubbles. The theoretical calculation is experimentally verified. The statistical noise linked with the presence of a finite number of bubbles in the ice samples is evaluated. The influence of such a correction on theVprofiles measured on polar ice cores is discussed. The method in this paper can also be used for correction of ice-density data obtained by the hydrostatic method.

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