scholarly journals Both climate trends and short‐term fluctuations affected algae–zooplankton interactions in a boreal lake during the late Holocene

2021 ◽  
Author(s):  
Simon Belle ◽  
Ilmar Tõnno ◽  
Tobias Vrede ◽  
Rene Freiberg ◽  
Jenny Nilsson ◽  
...  
Keyword(s):  
Late Holocene ◽  
Climate Trends ◽  
Short Term ◽  
Boreal Lake

scholarly journals Observing the climate impact of large wildfires on stratospheric temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthias Stocker ◽  
Florian Ladstädter ◽  
Andrea K. Steiner
Keyword(s):  
Lower Stratosphere ◽  
Volcanic Eruptions ◽  
Satellite Observation ◽  
Atmospheric Temperature ◽  
Climate Impact ◽  
Atmospheric Composition ◽  
Temperature Structure ◽  
Climate Trends ◽  
Short Term ◽  
Climate Signal

AbstractWildfires are expected to become more frequent and intense in the future. They not only pose a serious threat to humans and ecosystems, but also affect Earth’s atmosphere. Wildfire plumes can reach into the stratosphere, but little is known about their climate impact. Here, we reveal observational evidence that major wildfires can have a severe impact on the atmospheric temperature structure and short-term climate in the stratosphere. Using advanced satellite observation, we find substantial warming of up to 10 K of the lower stratosphere within the wildfire plumes during their early development. The short-term climate signal in the lower stratosphere lasts several months and amounts to 1 K for the Northern American wildfires in 2017, and up to striking 3.5 K for the Australian wildfires in 2020. This is stronger than any signal from recent volcanic eruptions. Such extreme events affect atmospheric composition and climate trends, underpinning their importance for future climate.

Long- and short-term carbon fluctuations in the Eastern Mediterranean during the late Holocene

Geology ◽  
2001 ◽  
Vol 29 (12) ◽  
pp. 1099 ◽  
Author(s):  
Bettina Schilman ◽  
Ahuva Almogi-Labin ◽  
Miryam Bar-Matthews ◽  
Laurent Labeyrie ◽  
Martine Paterne ◽  
...  
Keyword(s):  
Late Holocene ◽  
Eastern Mediterranean ◽  
Short Term

Coastal climatology of the North-Western Mediterranean area for long-term and short-term risk assessment.

2020 ◽  
Author(s):  
Carlo Brandini ◽  
Stefano Taddei ◽  
Valentina Vannucchi ◽  
Michele Bendoni ◽  
Bartolomeo Doronzo ◽  
...  
Keyword(s):  
Risk Assessment ◽  
High Resolution ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Climate Trends ◽  
Short Term ◽  
The North ◽  
The Mediterranean ◽  
North Western

<p>In this work we present the results obtained through a dynamic downscaling of the ERA5 reanalysis dataset (hindcast) of ECMWF, using high-resolution meteorological and wave models defined on unstructured computation grids along the Mediterranean coasts, with a particular focus on the North-Western Mediterranean area. Downscaling of the ERA5 meteorological data is obtained through the BOLAM and MOLOCH models (up to a resolution of 2.5 km) which force an unstructured WW3 model with a resolution of up to 500 m along the coast. Models were validated through available meteorological stations, wave buoy data and X-band wave radars, the latter for the purposes of wave spectra validation.</p><p>On the one hand, this allowed, by extracting the time series of some attack parameters of the waves along the coast, and according to the type of coast (rocky coasts, sandy coasts, coastal structures etc.), to compute the return periods and to characterize the impact of any individual storm. On the other hand, it is possible to highlight some trends observed in the last 30 years, during which recent research is showing an increasing evidence  of some changes in global circulation at regional to local scales. These changes also include effects of wind rotation, wave regimes, storm surges, wave-induced coastal currents and coastal morphodynamics. For example, in the North-Western Mediterranean extreme events belonging to cyclonic weather-types circulation with stronger S-SE components (like the storm of October 28-30th 2018 and many others), rather than events associated with perturbations of Atlantic origin and zonal circulation, are becoming more frequent. These long-term wind/wave climate trends can have consequences not only in the assessment of long-term risk due to main morphodynamic variations (ie. coastal erosion), but also in the short-term risk assessment.</p><p>This work was funded by the EU MAREGOT project (2017-2020) and ECMWF Special Project spitbran  “Evaluation of coastal climate trends in the Mediterranean area by means of high-resolution and multi-model downscaling of ERA5 reanalysis” (2018-2020).</p>

Late Holocene glacial history of Scimitar Glacier, Mt. Waddington area, British Columbia Coast Mountains, Canada

2013 ◽  
Vol 50 (12) ◽  
pp. 1195-1208 ◽  
Author(s):  
Jessica A. Craig ◽  
Dan J. Smith
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Regional Climate ◽  
Ice Age ◽  
Climate Trends ◽  
Glacier Surface ◽  
Coast Mountains ◽  
Standing Trees ◽  
History Of ◽  
Glacial Expansion

Scimitar Glacier originates below the northeast face of Mt. Waddington in the southern British Columbia Coast Mountains and flows 18 km down valley to calve into a proglacial lake. At several locations, downwasting of the glacier surface has exposed stacked till units separated by wood-bearing horizons in the proximal slopes of lateral moraines flanking the glacier. Historical moraine collapse and erosional breaching has also revealed the remains of standing trees buried in moraine-dammed lake sediments. Radiocarbon and tree-ring dating show that Scimitar Glacier expanded down valley at least three times in the late Holocene. The earliest evidence found for ice expansion indicates Scimitar Glacier was advancing in 3167–2737 cal years BP in association with the regional Tiedemann Advance. Following this advance, the glacier downwasted prior to expanding in 1568–1412 cal years BP during the First Millennial Advance. A final period phase of moraine construction was initiated during late Little Ice Age glacial expansion before A.D. 1742 and extended until at least A.D. 1851, after which Scimitar Glacier began to recede and downwaste. This record is comparable to that recorded at other glaciers in the southern British Columbia Coast Mountains and confirms the long-term relationship between regional climate trends and glacier behaviour in this setting.

Paleoclimatic changes during the Late Pleistocene - Holocene in Laguna Babícora, near the Chihuahuan Desert, México

1998 ◽  
Vol 35 (10) ◽  
pp. 1168-1179 ◽  
Author(s):  
Jose R Ortega-Ramírez ◽  
Alfonso Valiente-Banuet ◽  
Jaime Urrutia-Fucugauchi ◽  
Carlos A Mortera-Gutiérrez ◽  
Guillermo Alvarado-Valdez
Keyword(s):  
Late Holocene ◽  
Chihuahuan Desert ◽  
Early Holocene ◽  
Short Term ◽  
Radiocarbon Dates ◽  
Northern Mexico ◽  
Paleoclimatic Changes ◽  
Stream Migration ◽  
Late Wisconsinan ◽  
Humid Period

The paleoclimatic variability of northern Mexico since the Late Wisconsinan is determined from sedimentological, geochemical, and stratigraphic studies of the lacustrine sequence of Laguna Babícora (29.4°N, 107.7°W; elevation 2100 m asl). Chronological control is based on 13 radiocarbon dates (6 from this study and 7 previously reported) from four stratigraphic profiles that cover a range from 16 342 to 2800 BP. Two major periods of increased humidity are recognized by lake-level variation during the Late Wisconsinan and early Holocene. The Late Wisconsinan humid period may be related to jet stream migration to southerly latitudes and the influence of the mobile polar high. This period has been identified in the sedimentary record of El Diablo profile with a radiocarbon date of 16 342 ± 201 BP. The early Holocene humid period is recorded in El Diablo (10 976 ± 115 BP) and Cano profiles (9614 ± 130 BP). It is interpreted as a result of the Younger Dryas climatic anomaly characterized by a temperature decrease and cold paleoclimatic conditions similar to those for the Late Wisconsinan. The early Holocene was followed by an overall gradual drying that reached a maximum around 6000 BP, during the middle Holocene. For the late Holocene evidence of widespread erosion, sedimentation changes, flooded surfaces, and paleosoils indicates that Laguna Babícora was subjected to short-term climatic changes.

Mongolian dryland paleoenvironment and paleoclimate issues : calibrations and applicability of GDGT and pollen reconstructions over the Late Holocene.

2021 ◽  
Author(s):  
Lucas Dugerdil ◽  
Sébastien Joannin ◽  
Odile Peyron ◽  
Isabelle Jouffroy-Bapicot ◽  
Boris Vannière ◽  
...  
Keyword(s):  
Late Holocene ◽  
Qaidam Basin ◽  
Calibration Method ◽  
Altai Mountains ◽  
Climate Trends ◽  
Holocene Climate ◽  
Independent Dataset ◽  
The Holocene ◽  
Surface Samples

<p>Our understanding of climate changes throughout the Holocene is hampered by representativeness in sedimentary archives. Potential production and preservation biases of the markers are identified by comparing these proxies with modern environments. It is important to conduct robust calibrations on each biome. These calibrations use large database dominated by forest samples. The Mongolian plateau is especially characterized by low annual precipitation and continental annual air temperature. The characterization of the climate system of this area is crucial for the understanding of Holocene Monsoon Oscillations. This study focuses on the calibration of proxy-climate relationships for pollen and glycerol dialkyl glycerol tetraethers (GDGTs) by comparing large published Eurasian calibrations with a set of 49 new surface samples (moss polster, soil and mud from temporary dry pond). These calibrations are then cross-validated by an independent dataset of top-core samples and applied to two Late Holocene paleosequences in the Altai mountains and the Qaidam basin. We show that: (1) preserved pollen assemblages are clearly imprinted on the extremities of the ecosystem range but mitigated and unclear on the ecotones; (2) for both proxies, inferred relationships depend on the geographical range covered by the calibration database as well as on the nature of samples; (3) even if local calibrations suffer from reduced amplitude of climatic parameter due to local homogeneity, they better reflect actual climate than the global ones by reducing the limits for saturation impact, (4) a bias in climatic reconstructions is induced by the over-parameterization of the models and (5) paleoclimate values reconstructed here are consistent with Mongolia-China Late Holocene climate trends, and validate the application of local calibrations for both pollen and GDGTs. We encourage the application of this surface calibration method to reconstruct paleoclimate and especially consolidate our understanding of the Holocene climate and environment variations in Arid Central Asia.</p>

First Trial Geophysical Surveys at Kintampo Open-Air Sites: Results, Recommendations, Research Prospects

2018 ◽  
Vol 16 (1) ◽  
pp. 105-115
Author(s):  
Carlos Magnavita ◽  
Friedrich Lüth ◽  
Siaw Appiah-Adu
Keyword(s):  
Pilot Study ◽  
Research Program ◽  
Late Holocene ◽  
Settlement Pattern ◽  
Northern Ghana ◽  
Geophysical Prospecting ◽  
Short Term ◽  
Research Issues ◽  
Geophysical Surveys

AbstractWithin the scope of a short-term pilot study, the authors conducted trial geophysical surveys at two sites of the late Holocene food-producing Kintampo Complex (ca. 2100-1400BC) in northern Ghana. Overall goal of research was an evaluation of the potential of employing geophysical prospecting to map the subsurface extent of Kintampo open-air settlements. From an archaeological viewpoint, the results of the surveys were satisfactory but not outstanding in view of post-depositional disturbances at the locations. Based on that knowledge, we argue for the need of developing a systematic archaeological reconnaissance and research program for locating new and virtually undisturbed open-air Kintampo sites. We maintain that such a preliminary measure will be crucial both for investigating hitherto neglected research issues such as Kintampo settlement pattern and landscape exploitation as well as allowing geophysical technologies to fully evolve as central explorative tools in regard to settlement-related spatial questions.

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