scholarly journals Quantitative reconstruction of precipitation changes in the Iberian Peninsula during the Late Pleistocene and the Holocene

2019 ◽  
Author(s):  
Liisa Ilvonen ◽  
José Antonio López-Sáez ◽  
Lasse Holmström ◽  
Francisca Alba-Sánchez ◽  
Sebastián Pérez-Díaz ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Late Pleistocene ◽  
Late Holocene ◽  
Calibration Model ◽  
Temperature Changes ◽  
The North ◽  
Temperature Trends ◽  
Precipitation Increase ◽  
Precipitation Changes ◽  
Reconstructed Precipitation

Abstract. Precipitation is a key climate driver of vegetation and ecosystems of the Iberian Peninsula. Here, we use a regional pollen-climate calibration model and fossil pollen data from seven sites from different parts of Spain to provide quantitative reconstructions of annual precipitation values for the last 15 000 years. Our records show that in the Late Pleistocene (~ 15 000 to 11 600 cal yr BP) precipitation changes took place markedly in tune with the temperature trends in northern Europe, with higher precipitation during the Greenland interstadial 1 (Bølling-Allerød) and lower precipitation during the Greenland stadial 1 (Younger Dryas). The early Holocene was characterized by a rapid precipitation increase after 11 600 cal yr BP, followed by a slowly declining trend until roughly 8000 cal yr BP. From 8000 to 4000 cal yr BP the reconstructed precipitation values are the highest in most records, with maximum values nearly 100 % higher that the modern reconstructed values. The results suggest a gradually declining precipitation over the last four millennia, although the late-Holocene reconstructions are biased by intensifying human impact on vegetation. In general, our results suggest that the main changes in precipitation in the Iberian Peninsula have occurred in pace with the main temperature changes in the North European-Atlantic region, with warm (cold) periods in the North corresponding with humid (dry) periods in the Iberian Peninsula.

scholarly journals A Weather-Type Approach to Analyzing Winter Precipitation in France: Twentieth-Century Trends and the Role of Anthropogenic Forcing

2008 ◽  
Vol 21 (13) ◽  
pp. 3118-3133 ◽  
Author(s):  
J. Boé ◽  
L. Terray
Keyword(s):  
Twentieth Century ◽  
Large Scale ◽  
Precipitation Amount ◽  
Winter Precipitation ◽  
Weather Type ◽  
Weather Types ◽  
Anthropogenic Forcing ◽  
Temperature Changes ◽  
The North ◽  
Precipitation Changes

Abstract The relationship between large-scale atmospheric circulation and November–March precipitation over France during the twentieth century is investigated. A long daily MSLP dataset is used to derive daily weather types that are discriminant for precipitation. A linear regression model is then used to relate the November–March-accumulated precipitation amount and the occurrence frequency of the weather types. This simple model shows that an important part of the interannual variability of precipitation is directly linked to large-scale circulation changes. Trends in observed precipitation and precipitation series reconstructed by regression are computed and compared. Spatially coherent trends in November–March precipitation during the second half of the twentieth century are observed, with an increase in the north and a decrease in the south. The spatial pattern of the trends in reconstructed precipitation is very similar to that observed, even if an underestimation of the positive trends in the north is seen, indicating that other mechanisms play a role. A detection study then leads to a better understanding of the respective roles of anthropogenic forcing (greenhouse gases and sulfate aerosol) and sea surface temperature in the evolution of the weather-type occurrence. Finally, it is shown that intratype dynamical variability has also played a role in precipitation changes in northern France, whereas no impact of temperature changes is seen.

scholarly journals Analysis of Average Temperatures And Trends In Brazil: Applying CUSUM Graphic from 2000 to 2014

2019 ◽  
Vol 8 (1) ◽  
pp. 169-184
Author(s):  
Leonardo Rodrigues de Oliveira Merelles ◽  
Viviane de Souza Dias ◽  
José Elmo de Menezes ◽  
Marta Pereira da Luz ◽  
Ricardo Luiz Machado ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Multiple Regression ◽  
Cumulative Sum ◽  
Temperature Changes ◽  
The North ◽  
Temperature Trends ◽  
Daily Data ◽  
In Series ◽  
Weather Stations ◽  
Annual Trends

In recent decades the temperature trends are being confirmed earlier. To determine the temperature changes in Brazil, analysis of annual trends and seasons was carried out based on daily data from 187 weather stations, covering the period from 2000 to 2014. Trends were confirmed using the Cumulative Sum Chart, a method that notices the changes in series faster than others. The modeling of temperature was obtained by Multiple Regression and using Cluster Analysis, and through this it was possible to group weather stations. The observed trends confirmed oscillations in cooling, heating and, in some cases, cooling followed by heating. These main trends presented during the study period were from -15 to 0 in latitude. The region with the highest confirmation of inversions in temperature was the North, then Northeast. Heights below 500 meters presented higher trends. Regarding the seasons, autumn contributed significantly to the trends.

scholarly journals A debris-covered glacier at Kerguelen (49°S, 69°E) over the past 15 000 years

2020 ◽  
pp. 1-13
Author(s):  
Joanna Charton ◽  
Vincent Jomelli ◽  
Irene Schimmelpfennig ◽  
Deborah Verfaillie ◽  
Vincent Favier ◽  
...  
Keyword(s):  
Climate Variability ◽  
Late Holocene ◽  
Ice Cores ◽  
Cosmic Ray ◽  
Late Glacial ◽  
Temperature Changes ◽  
Precipitation Changes ◽  
The Antarctic ◽  
Exposure Ages

Abstract Debris-covered glaciers constitute a large part of the world's cryosphere. However, little is known about their long-term response to multi-millennial climate variability, in particular in the Southern Hemisphere. Here, we provide first insights into the response of a debris-covered glacier to multi-millennial climate variability in the sub-Antarctic Kerguelen Archipelago, which can be compared to that of recently investigated debris-free glaciers. We focus on the Gentil Glacier and present 13 new 36Cl cosmic-ray exposure ages from moraine boulders. The Gentil Glacier experienced at least two glacial advances: the first one during the Late Glacial (19.0–11.6 ka) at ~14.3 ka and the second one during the Late Holocene at ~2.6 ka. Both debris-covered and debris-free glaciers advanced broadly synchronously during the Late Glacial, most probably during the Antarctic Cold Reversal event (14.5–12.9 ka). This suggests that both glacier types at Kerguelen were sensitive to abrupt temperature changes recorded in Antarctic ice cores, associated with increased moisture. However, during the Late Holocene, the advance at ~2.6 ka was not observed in other glaciers and seems to be an original feature of the debris-covered Gentil Glacier, related to either distinct dynamics or to distinct sensitivity to precipitation changes.

Imanolen Arrobia: A New Late Pleistocene Carnivore Den from the North of the Iberian Peninsula (Deba, Spain)

Ameghiniana ◽  
2017 ◽  
Vol 54 (4) ◽  
pp. 370-389 ◽  
Author(s):  
Jone Castaños ◽  
Pedro Castaños ◽  
Xabier Murelaga
Keyword(s):  
Iberian Peninsula ◽  
Late Pleistocene ◽  
The North

Supplementary material to "Quantitative reconstruction of precipitation changes in the Iberian Peninsula during the Late Pleistocene and the Holocene"

2019 ◽  
Author(s):  
Liisa Ilvonen ◽  
José Antonio López-Sáez ◽  
Lasse Holmström ◽  
Francisca Alba-Sánchez ◽  
Sebastián Pérez-Díaz ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Late Pleistocene ◽  
Quantitative Reconstruction ◽  
The Holocene ◽  
Supplementary Material ◽  
Precipitation Changes

scholarly journals Simulated range of mid-Holocene precipitation changes to extended lakes and wetlands over North Africa

2021 ◽  
Author(s):  
Nora Farina Specht ◽  
Martin Claussen ◽  
Thomas Kleinen
Keyword(s):  
North Africa ◽  
High Surface ◽  
Large Lakes ◽  
Small Lake ◽  
The North ◽  
Budget Analysis ◽  
Sediment Records ◽  
Precipitation Increase ◽  
Wetland Extent ◽  
Precipitation Changes

Abstract. Enhanced summer insolation over North Africa induced a monsoon precipitation increase during the mid-Holocene, about 6000 years ago, and led to a widespread expansion of lakes and wetlands in the present-day Sahara. This expansion of lakes and wetlands is documented in paleoenvironmental sediment records, but the spatially sparse and often discontinuous sediment records provide only a fragmentary picture. Former simulation studies prescribed either a small lake and wetland extent from reconstructions or focused on documented mega-lakes only to investigate their effect on the mid-Holocene climate. In contrast to these studies, we investigate the possible range of mid-Holocene precipitation changes in response to a small lake extent and a potential maximum lake and wetland extent.  Results show that the maximum lake and wetland extent shift the North African rain belt about 3 ° farther northward than the small lake extent. Vegetated wetlands cause a larger precipitation increase than the equally-large lakes due to their high surface roughness. A moisture budget analysis reveals that both, lakes and wetlands, cause an enhanced inland moisture transport and local moisture recycling to their southern side. In contrast, increased moisture advection by the Harmattan winds causes a drying response to the north of the lakes and wetlands. These results indicate that the latitudinal position of the lakes and wetlands influences the northward extension of the African summer monsoon. In the sensitivity experiments, the northern position of West Saharan lakes and wetlands substantially contributes to the strong monsoon northward shift seen in the maximum lake and wetland simulations.

scholarly journals Impact of air–sea coupling on the climate change signal over the Iberian Peninsula

2021 ◽  
Author(s):  
Alba de la Vara ◽  
William Cabos ◽  
Dmitry V. Sein ◽  
Claas Teichmann ◽  
Daniela Jacob
Keyword(s):  
Climate Change ◽  
Iberian Peninsula ◽  
Mediterranean Sea ◽  
Large Scale ◽  
Regional Distribution ◽  
Coupled Model ◽  
Climate Change Signal ◽  
The North ◽  
The Mediterranean ◽  
The Impact

AbstractIn this work we use a regional atmosphere–ocean coupled model (RAOCM) and its stand-alone atmospheric component to gain insight into the impact of atmosphere–ocean coupling on the climate change signal over the Iberian Peninsula (IP). The IP climate is influenced by both the Atlantic Ocean and the Mediterranean sea. Complex interactions with the orography take place there and high-resolution models are required to realistically reproduce its current and future climate. We find that under the RCP8.5 scenario, the generalized 2-m air temperature (T2M) increase by the end of the twenty-first century (2070–2099) in the atmospheric-only simulation is tempered by the coupling. The impact of coupling is specially seen in summer, when the warming is stronger. Precipitation shows regionally-dependent changes in winter, whilst a drier climate is found in summer. The coupling generally reduces the magnitude of the changes. Differences in T2M and precipitation between the coupled and uncoupled simulations are caused by changes in the Atlantic large-scale circulation and in the Mediterranean Sea. Additionally, the differences in projected changes of T2M and precipitation with the RAOCM under the RCP8.5 and RCP4.5 scenarios are tackled. Results show that in winter and summer T2M increases less and precipitation changes are of a smaller magnitude with the RCP4.5. Whilst in summer changes present a similar regional distribution in both runs, in winter there are some differences in the NW of the IP due to differences in the North Atlantic circulation. The differences in the climate change signal from the RAOCM and the driving Global Coupled Model show that regionalization has an effect in terms of higher resolution over the land and ocean.

A multi-proxy reconstruction of climate during the late-Pleistocene to early Holocene transition in the northeastern, USA

2021 ◽  
pp. 1-17
Author(s):  
Laurie D. Grigg ◽  
Kevin J. Engle ◽  
Alison J. Smith ◽  
Bryan N. Shuman ◽  
Maximilian B. Mandl
Keyword(s):  
Late Pleistocene ◽  
Climatic Variability ◽  
Warming Trend ◽  
Early Holocene ◽  
Individual Species ◽  
Environmental Preferences ◽  
The North ◽  
Show Evidence ◽  
Dry Conditions ◽  
Components Analysis

Abstract A multiproxy record from Twin Ponds, VT, is used to reconstruct climatic variability during the late Pleistocene to early Holocene transition. Pollen, ostracodes, δ18O, and lithologic records from 13.5 to 9.0 cal ka BP are presented. Pollen- and ostracode-inferred climatic reconstructions are based on individual species’ environmental preferences and the modern analog technique. Principal components analysis of all proxies highlights the overall warming trend and centennial-scale climatic variability. During the Younger Dryas cooling event (YD), multiple proxies show evidence for cold winter conditions and increasing seasonality after 12.5 cal ka BP. The early Holocene shows an initial phase of rapid warming with a brief cold interval at 11.5 cal ka BP, followed by a more gradual warming; a cool, wet period from 11.2 to 10.8 cal ka BP; and cool, dry conditions from 10.8 to 10.2 cal ka BP. The record ends with steady warming and increasing moisture. Post-YD climatic variability has been observed at other sites in the northeastern United States and points to continued instability in the North Atlantic during the final phases of deglaciation.

scholarly journals Vulnerability of the North Water ecosystem to climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sofia Ribeiro ◽  
Audrey Limoges ◽  
Guillaume Massé ◽  
Kasper L. Johansen ◽  
William Colgan ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Late Holocene ◽  
Sediment Cores ◽  
Arctic Ecosystems ◽  
Little Auk ◽  
The North ◽  
Water Ecosystem ◽  
North Water

AbstractHigh Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique seaice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-to-late Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, leading to periods of polynya instability and marine productivity decline, is strikingly coeval with the human abandonment of Greenland from c. 2200–1200 cal yrs b2k. Our long-term perspective highlights the future decline of the North Water ecosystem, due to climate warming and changing sea-ice conditions, as an important climate change risk.

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