53 research outputs found
Twentieth Century Black Carbon and Dust Deposition on South Cascade Glacier, Washington State, USA, as Reconstructed From a 158‐m‐Long Ice Core
Light absorbing particles (LAPs) include black carbon (BC) and mineral dust and are of interest due to their positive radiative forcing and contribution to albedo reductions and snow and glacier melt. This study documents historic BC and dust deposition as well as their effect on albedo on South Cascade Glacier (SCG) in Washington State (USA) through the analysis of a 158‐m (139.5‐m water equivalent [w.e.]) ice core extracted in 1994 and spanning the period 1840–1991. Peak BC deposition occurred between 1940 and 1960, when median BC concentrations were 16 times higher than background, likely dominated by domestic coal and forest fire emissions. Post 1960 BC concentrations decrease, followed by an increase from 1977 to 1991 due to melt consolidation and higher emissions. Differences between the SCG record and BC emission inventories, as well as ice core records from other regions, highlight regional differences in the timing of anthropogenic and biomass BC emissions. Dust deposition on SCG is dominated by local sources and is variable throughout the record. Albedo reductions from LAP are dominated by dust deposition, except during high BC deposition events from forest fires and during 1940–1960 when BC and dust similarly contribute to albedo reductions. This study furthers understanding of the factors contributing to historical snowmelt and glacier retreat in the Cascades and demonstrates that ice cores retrieved from temperate glaciers have the potential to provide valuable records of LAP deposition
Age ranges of the Tibetan ice cores with emphasis on the Chongce ice cores, western Kunlun Mountains
An accurate chronology is the essential first step for a sound understanding
of ice core records. However, dating ice cores drilled from the
high-elevation glaciers is challenging and often problematic, leading to
great uncertainties. The Guliya ice core, drilled
to the bedrock (308.6 m
in length) along the western Kunlun Mountains on the
north-western Tibetan Plateau (TP) and widely used as a benchmark for
palaeoclimate research, is believed to reach > 500 ka (thousand years) at
its bottom. Meanwhile other Tibetan ice cores (i.e. Dasuopu and East Rongbuk
in the Himalayas, Puruogangri in the central TP and Dunde in the
north-eastern TP) are mostly of Holocene origin. In this study, we drilled
four ice cores into bedrock (216.6, 208.6, 135.8 and 133.8 m in
length, respectively) from the Chongce ice cap ∼ 30 km
to the
Guliya ice core drilling site. We took measurements of 14C,
210Pb, tritium and β activity for the ice cores, and used
these values in a two-parameter flow model to establish the ice core
depth–age relationship. We suggested that the Chongce ice cores might be of
Holocene origin, consistent with the other Tibetan ice cores except Guliya.
The remarkable discrepancy between the Guliya and all the other Tibetan ice
core chronology implies that more effort is necessary to explore multiple
dating techniques to confirm the age ranges of the TP glaciers, including
those from Chongce and Guliya.</p
High-altitude glacier archives lost due to climate change-related melting.
Global warming has caused widespread surface lowering of mountain glaciers. By comparing two firn cores collected in 2018 and 2020 from Corbassière glacier in Switzerland, we demonstrate how vulnerable these precious archives of past environmental conditions have become. Within two years, the soluble impurity records were destroyed by melting. The glacier is now irrevocably lost as an archive for reconstructing major atmospheric aerosol components
A Holocene black carbon ice-core record of biomass burning in the Amazon Basin from Illimani, Bolivia
The Amazon Basin is one of the major contributors to global
biomass burning emissions. However, regional paleofire trends remain
particularly unknown. Due to their proximity to the Amazon Basin, Andean ice
cores are suitable to reconstruct paleofire trends in South America and
improve our understanding of the complex linkages between fires, climate and
humans. Here we present the first refractory black carbon (rBC) ice-core
record from the Andes as a proxy for biomass burning emissions in the Amazon
Basin, derived from an ice core drilled at 6300 m a.s.l. from the Illimani
glacier in the Bolivian Andes and spanning the entire Holocene back to the
last deglaciation 13 000 years ago. The Illimani rBC record displays a
strong seasonality with low values during the wet season and high values
during the dry season due to the combination of enhanced biomass burning
emissions in the Amazon Basin and less precipitation at the Illimani site.
Significant positive (negative) correlations were found with reanalyzed
temperature (precipitation) data for regions in eastern
Bolivia and western Brazil characterized by substantial fire activity. rBC
long-term trends indirectly reflect regional climatic variations through
changing biomass burning emissions as they show higher (lower) concentrations
during warm–dry (cold–wet) periods, in line with climate
variations such as the Younger Dryas, the 8.2 ka event, the Holocene
Climatic Optimum, the Medieval Warm Period and the Little Ice Age. The highest
rBC concentrations of the entire record occurred during the Holocene Climatic
Optimum between 7000 and 3000 BCE, suggesting that this exceptionally warm and
dry period caused high levels of biomass burning activity, unprecedented in the
context of the past 13 000 years. Recent rBC levels, rising since 1730 CE
in the context of increasing temperatures and deforestation, are similar to
those of the Medieval Warm Period. No decrease in fire activity was observed
in the 20th century, in contradiction to global biomass burning
reconstructions based on charcoal data.</p
19th century glacier retreat in the Alps preceded the emergence of industrial black carbon deposition on high-alpine glaciers
Light absorbing aerosols in the atmosphere and cryosphere play
an important role in the climate system. Their presence in ambient air and
snow changes the radiative properties of these systems, thus contributing to
increased atmospheric warming and snowmelt. High spatio-temporal variability
of aerosol concentrations and a shortage of long-term observations contribute
to large uncertainties in properly assigning the climate effects of aerosols
through time.Starting around AD 1860, many glaciers in the European Alps began to retreat
from their maximum mid-19th century terminus positions, thereby visualizing
the end of the Little Ice Age in Europe. Radiative forcing by increasing
deposition of industrial black carbon to snow has been suggested as the main
driver of the abrupt glacier retreats in the Alps. The basis for this
hypothesis was model simulations using elemental carbon concentrations at low
temporal resolution from two ice cores in the Alps.Here we present sub-annually resolved concentration records of refractory
black carbon (rBC; using soot photometry) as well as distinctive tracers for
mineral dust, biomass burning and industrial pollution from the Colle
Gnifetti ice core in the Alps from AD 1741 to 2015. These records allow
precise assessment of a potential relation between the timing of observed
acceleration of glacier melt in the mid-19th century with an increase of rBC
deposition on the glacier caused by the industrialization of Western Europe.
Our study reveals that in AD 1875, the time when rBC ice-core concentrations
started to significantly increase, the majority of Alpine glaciers had
already experienced more than 80 % of their total 19th century length
reduction, casting doubt on a leading role for soot in terminating of the
Little Ice Age. Attribution of glacial retreat requires expansion of the
spatial network and sampling density of high alpine ice cores to balance
potential biasing effects arising from transport, deposition, and snow
conservation in individual ice-core records.</p
Consistent histories of anthropogenic western European air pollution preserved in different Alpine ice cores
Individual high-Alpine ice cores have been proven to contain a well-preserved history of past anthropogenic air pollution in western Europe. The
question of how representative one ice core is with respect to the reconstruction of atmospheric composition in the source region has not been
addressed so far. Here, we present the first study systematically comparing longer-term ice-core records (1750–2015 CE) of various anthropogenic
compounds, such as major inorganic aerosol constituents (NH4+, NO3-, SO42-), black carbon (BC), and trace
species (Cd, F−, Pb). Depending on the data availability for the different air pollutants, up to five ice cores from four
high-Alpine sites located in the European Alps analysed by different laboratories were considered. Whereas absolute concentration levels can partly
differ depending on the prevailing seasonal distribution of accumulated precipitation, all seven investigated anthropogenic compounds are in
excellent agreement between the various sites for their respective, species-dependent longer-term concentration trends. This is related to common
source regions of air pollution impacting the four sites less than 100 km away including western European countries surrounding the
Alps. For individual compounds, the Alpine ice-core composites developed in this study allowed us to precisely time the onset of pollution caused by
industrialization in western Europe. Extensive emissions from coal combustion and agriculture lead to an exceeding of pre-industrial
(1750–1850) concentration levels already at the end of the 19th century for BC, Pb, exSO42- (non-dust, non-sea salt
SO42-), and NH4+, respectively. However, Cd, F−, and NO3- concentrations started surpassing
pre-industrial values only in the 20th century, predominantly due to pollution from zinc and aluminium smelters and traffic. The observed maxima of
BC, Cd, F−, Pb, and exSO42- concentrations in the 20th century and a significant decline afterwards clearly
reveal the efficiency of air pollution control measures such as the desulfurization of coal, the introduction of filters and scrubbers in power plants
and metal smelters, and the ban of leaded gasoline improving the air quality in western Europe. In contrast, NO3- and NH4+
concentration records show levels in the beginning of the 21th century which are unprecedented in the context of the past 250 years, indicating
that the introduced abatement measures to reduce these pollutants were insufficient to have a major effect at high altitudes in western Europe. Only
four ice-core composite records (BC, F−, Pb, exSO42-) of the seven investigated pollutants correspond well with
modelled trends, suggesting inaccuracies of the emission estimates or an incomplete representation of chemical reaction mechanisms in the models for
the other pollutants. Our results demonstrate that individual ice-core records from different sites in the European Alps generally provide a spatially
representative signal of anthropogenic air pollution trends in western European countries.</p
(210)Po poisoning as possible cause of death: forensic investigations and toxicological analysis of the remains of Yasser Arafat.
The late president of the Palestinian Authority, Yasser Arafat, died in November 2004 in Percy Hospital, one month after having experienced a sudden onset of symptoms that included severe nausea, vomiting, diarrhoea and abdominal pain and which were followed by multiple organ failure. In spite of numerous investigations performed in France, the pathophysiological mechanisms at the origin of the symptoms could not be identified. In 2011, we found abnormal levels of polonium-210 ((210)Po) in some of Arafat's belongings that were worn during his final hospital stay and which were stained with biological fluids. This finding led to the exhumation of Arafat's remains in 2012. Significantly higher (up to 20 times) activities of (210)Po and lead-210 ((210)Pb) were found in the ribs, iliac crest and sternum specimens compared to reference samples from the literature (p-value <1%). In all specimens from the tomb, (210)Po activity was supported by a similar activity of (210)Pb. Biokinetic calculations demonstrated that a (210)Pb impurity, as identified in a commercial source of 3MBq of (210)Po, may be responsible for the activities measured in Arafat's belongings and remains 8 years after his death. The absence of myelosuppression and hair loss in Mr Arafat's case compared to Mr Litvinenko's, the only known case of malicious poisoning with (210)Po, could be explained by differences in the time delivery-scheme of intake. In conclusion, statistical Bayesian analysis combining all the evidence gathered in our forensic expert report moderately supports the proposition that Mr Arafat was poisoned by (210)Po
A revised 1000 year atmospheric δ\u3csup\u3e13\u3c/sup\u3e C-CO2 record from Law Dome and South Pole, Antarctica
We present new measurements of δ13C of CO2 extracted from a high-resolution ice core from Law Dome (East Antarctica), together with firn measurements performed at Law Dome and South Pole, covering the last 150 years. Our analysis is motivated by the need to better understand the role and feedback of the carbon (C) cycle in climate change, by advances in measurement methods, and by apparent anomalies when comparing ice core and firn air δ13C records from Law Dome and South Pole. We demonstrate improved consistency between Law Dome ice, South Pole firn, and the Cape Grim (Tasmania) atmospheric δ13C data, providing evidence that our new record reliably extends direct atmospheric measurements back in time. We also show a revised version of early δ13C measurements covering the last 1000 years, with a mean preindustrial level of -6.50‰. Finally, we use a Kalman Filter Double Deconvolution to infer net natural CO2 fluxes between atmosphere, ocean, and land, which cause small δ13C deviations from the predominant anthropogenically induced δ13C decrease. The main features found from the previous δ13C record are confirmed, including the ocean as the dominant cause for the 1940 A.D. CO2 leveling. Our new record provides a solid basis for future investigation of the causes of decadal to centennial variations of the preindustrial atmospheric CO2 concentration. Those causes are of potential significance for predicting future CO2 levels and when attempting atmospheric verification of recent and future global carbon emission mitigation measures through Coupled Climate Carbon Cycle Models. Key Points New and revised, firn and ice δ13C-CO2 measurements from Antarctica Improve consistency between ice and firn δ13C-CO2 measurements Net natural CO2 fluxes between atmosphere, ocean and land inferred ©2013. American Geophysical Union. All Rights Reserved
Corrigendum to ``Gas transport in firn: multiple-tracer characterisation and model intercomparison for NEEM, Northern Greenland'' published in Atmos. Chem. Phys., 12, 4259–-4277, 2012
No abstract available
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