scholarly journals Historical Climate off the Atlantic Iberian Peninsula

2017 ◽  
Author(s):  
Fátima Abrantes ◽  
Teresa Rodrigues ◽  
Marta Rufino ◽  
Emília Salgueiro ◽  
Dulce Oliveira ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Sediment Cores ◽  
Ice Age ◽  
Regional Variability ◽  
Higher Plant ◽  
European Continent ◽  
Sst Variability ◽  
Shelf Sediment ◽  
South Portugal

Abstract. The Iberian Peninsula, at North Atlantic mid-latitude and the western extreme of the European continent, is a key point for climate reconstructions. This work provides multi-proxy records measured in 8 inner-shelf sediment cores from 5 sites located between South Portugal (Algarve) and Northwest Spain (Galiza) (36 to 41º N) and target a regional reconstruction of climate variability during the Historic period (last 2 ky). The SST records reveal a long-term scale cooling (±1 ºC/2 ky) that ends at the beginning of the 20th century at all latitudes. This cooling is a follow up of the cooling process that started in the early Holocene driven by a decrease in summer insolation in the Northern Hemisphere. Within this long term SST variability multi-decadal/centennial scale variability is detected along Iberia. The different latitudinal SST reconstructions jointly with a determined regional SST stack were compared to on-land precipitation from higher plant n-alkanes and pollen data, to assess the relationship between hydroclimate (drought and/or precipitation) and SST. Regional variability is overall in consonance with NE Spain, and other European and north Hemisphere reconstructions. Warm conditions prevailed throughout 1300 yr, encompassing the Roman Period (RP), the Dark Ages (DA) and the Medieval Warm Period (MWP). The initial cooling at 1300 CE leads to 4 centuries of ±1 ºC colder mean SSTs contemporaneous with the Little Ice Age (LIA). The transition towards the Industrial Era starts by 1800 CE with a rise to pre-LIA SSTs. Climate specificities have been detected in western Iberian margin records and reveal the existence of two distinct phases within the MWP and a two-step SST increase towards the Industrial Era. The intense precipitation/flooding and warm winters but cooler intermediate seasons observed for the early MWP imply the interplay of internal oceanic variability with the three known atmospheric circulation modes, AMO, EA and SCAND in a positive phase. The late MWP, typified by drier and cooler winters and warmer intermediate seasons calls for a change in sign of the SCAND. A stronger mark of oceanic influences on western Iberian Peninsula (IP) starts with the transition to the Industrial Era.

scholarly journals The Climate of the Common Era off the Iberian Peninsula

2017 ◽  
Author(s):  
Fátima Abrantes ◽  
Teresa Rodrigues ◽  
Marta Rufino ◽  
Emília Salgueiro ◽  
Dulce Oliveira ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
Ice Age ◽  
Higher Plant ◽  
European Continent ◽  
Climate Conditions ◽  
Shelf Sediment ◽  
South Portugal

Abstract. The Iberian Peninsula, at North Atlantic mid-latitude and the western extreme of the European continent, is a relevant area for climate reconstructions. This work provides multi-proxy records measured in 7 inner-shelf sediment sequences from 5 sites located between South Portugal (Algarve) and Northwest Spain (Galiza) (36 to 42º N) and targets a regional reconstruction of climate variability during the last 2000 yr. Alkenone derived Sea Surface Temperature (SST) reconstructions were compared to on-land precipitation given by higher plant n-alkanes and pollen data, to assess the relationship between hydroclimate (drought and/or precipitation) and oceanic SST. The SST records reveal a long-term scale cooling (±1 ºC/2000 yr) that ends at the beginning of the 20th century at all sites. This cooling is a follow up of the cooling process started after the Holocene optimum and driven by a decrease in summer insolation in the Northern Hemisphere. A multi-decadal/ centennial variability is detected within this long-term cooling in convergence with other records from Spain, Europe and the Northern Hemisphere. Warm SST conditions prevailed throughout the first 1300 yr, encompassing the Roman Period (RP), the Dark Ages (DA) and the Medieval Warm Period (MWP). A cooling initiated at 1300 CE, led to 4 centuries of ±1 ºC colder mean SSTs contemporary with the Little Ice Age (LIA). The transition towards the Industrial Era starts by 1800 CE with a SST rise to pre-LIA levels. Particular climate conditions have been detected in Western Iberian margin records and reveal two distinct phases within the MWP and a two-step SST increase towards the Industrial Era. The intense precipitation/flooding and warm winters but cooler intermediate seasons (spring and fall) observed for the early MWP imply the interplay of internal oceanic variability with the three atmospheric circulation modes, North Atlantic Oscillation (NAO), East Atlantic (EA) and Sandinavia (SCAND) in a positive phase. The late MWP, marked by drier and cooler winters and warmer intermediate seasons calls for a change in sign of the SCAND. A stronger mark of oceanic influences on Western Iberian Peninsula starts with the transition to the Industrial Era.

scholarly journals Late-Quaternary Vegetational and Climatic History of the Yellowstone/Grand Teton Region

1988 ◽  
Vol 12 ◽  
pp. 189-192
Author(s):  
Cathy Barnosky
Keyword(s):  
Environmental History ◽  
Late Quaternary ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Fire Frequency ◽  
Ice Age ◽  
Sediment Chemistry ◽  
History Of ◽  
Climatic History

The research underway has focused on two different aspects of the environmental history of the Yellowstone/Grand Teton region. One objective has been to examine the long-term vegetational and climatic history of Jackson Hole, the Pinyon Peak Highlands, and Yellowstone Park since the end of late Pinedale glaciation, about 14,000 years ago. Fossil pollen in sediment cores from lakes in the region is being analyzed to clarify the nature and composition of ice-age refugia, the rate and direction of plant migrations in the initial stages of reforestation, and the long-term stability of postglacial communities. Sedimentary charcoal also is being examined to reconstruct fire frequency during different climatic regions and different vegetation types in the past. This information is necessary to assess the sensitivity of plant communities to environmental change and to understand postglacial landscapes of the northern rocky Mountains. The second objective has been a multidisciplinary investigation of the relationship of climate to sedimentation rates in lakes and ponds in Yellowstone, undertaken with Drs. Wright, D.R. Engstrom and S.C. Fritz of the University of Minnesota. This facet of the research examines the relative importance of climate, fire, hillslope erosion induced by overgrazing, and nutrient enrichment in the last 150 years, as recorded in selected lakes in the northern range of Yellowstone. Populations of elk and bison are known to have fluctuated greatly during this interval, and slight climatic changes are suggested from other lines of research. In this study pollen, diatoms, charcoal, sediment chemistry, and sediment accumulation rates are analyzed in short cores from small lakes.

scholarly journals Evidence that modern fires may be unprecedented during the last 3400 years in permafrost zone of central Siberia, Russia

2022 ◽  
Author(s):  
Elena Yu Novenko ◽  
Dmitry A. Kupryanov ◽  
Natalia G. Mazei ◽  
Anatoly Prokushkin ◽  
Leanne N. Phelps ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Forest Fires ◽  
Fire History ◽  
Sediment Cores ◽  
Fire Regimes ◽  
Ice Age ◽  
Fire Dynamics ◽  
Central Siberia ◽  
Recent Climate

Abstract Recent climate change in Siberia is increasing the probability of dangerous forest fires. The development of effective measures to mitigate and prevent fires is impossible without an understanding of long-term fire dynamics. This paper presents the first multi-site palaeo-fire reconstruction based on macroscopic charcoal data from peat and lake sediment cores located in different landscapes across the permafrost area of Central Siberia. The obtained results show similar temporal patterns of charcoal accumulation rates in the cores under study, and near synchronous changes in fire regimes. The paleo-fire record revealed moderate biomass burning between 3.4 and 2.6 ka BP, followed by the period of lower burning occurring from 2.6 to 1.7 ka BP that coincided with regional climate cooling and moistening. Minimal fire activity was also observed during the Little Ice Age (0.7 – 0.25 ka BP). Fire frequencies increased during the interval from 1.7 to 0.7 ka BP and appears to be partly synchronous with climate warming during the Medieval Climate Anomaly. Regional reconstructions of long-term fire history show that recent fires are unprecedented during the late Holocene, with modern high biomass burning lying outside millennial and centennial variability of the last 3400 years.

A 500-year record of paleoclimate and paleoenvironment from the Lacandon Forest, southern Mexico

2020 ◽  
Author(s):  
Karla Zurisadai Rubio Sandoval ◽  
Alexander Correa-Metrio ◽  
Juan Felipe Franco-Gaviria ◽  
Antje Schwalb ◽  
Philipp Hoelzmann ◽  
...  
Keyword(s):  
High Resolution ◽  
Surface Area ◽  
Sediment Cores ◽  
Ice Age ◽  
Water Conductivity ◽  
Southern Mexico ◽  
Ecological Changes ◽  
Terrestrial Biodiversity ◽  
Moisture Conditions

<p>Tropical karst Lakes Metzabok (550 masl, surface area = ~77 ha, z<sub>max</sub> = 25 m) and Nahá (832 masl, surface area = ~57 ha, z<sub>max</sub> = 36 m) are located in the Lacandon Forest, in the state of Chiapas, southern Mexico. The region is characterized by high aquatic and terrestrial biodiversity. We generated high-resolution paleoclimate and paleoenvironmental records that span the last ~500 years, using invertebrate remains (ostracodes and gastropods) and geochemical variables (elemental and mineralogical contents) in sediment cores from the two water bodies. We collected a short sediment core from each lake (Metzabok = 46 cm, Nahá = 60 cm) and analyses were carried out at 1-cm intervals. Uppermost sediments in the cores were dated using <sup>210</sup>Pb and <sup>137</sup>Cs, and deeper deposits were dated by <sup>14</sup>C. Ostracodes and snails were identified to species level and their abundances were quantified. Concentrations of Ti and Fe were determined by portable XRF. The geochemical record reveals information about past climate variability, human-mediated erosion and transport of terrigenous elements. Changes in ostracode and gastropod assemblages mainly reflect past lake level fluctuations and changes in water conductivity. The dominant ostracode species was Cytheridella ilosvayi and the most common gastropod is Aroapyrgus sp., indicative of water depths ≤40 m and low water conductivity, respectively. Analysis of the ecological distances between samples suggests that Lake Metzabok is unstable, with frequent ecological changes equal to or greater than 50% of the community. These changes may have resulted from dramatic environmental differences associated with hydrological dynamics during dry and rainy seasons. The Nahá record presents two environmental conditions, i.e. periods of high stability and periods of change, when the system was in transition from a dry period to a wetter one, or vice versa. Despite differences between the two lakes with respect to elevation, size, depth, and seasonal dynamics, both records contain evidence of droughts ca. 300 and 200 yr BP, during the Little Ice Age. Whereas both records show a long-term tendency towards higher moisture conditions, the high-resolution of our study enabled us to detect fluctuations between dry and wet periods over the last 500 years that previous studies failed to recognize.</p>

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.

scholarly journals Long-term changes in offshore wind power density and wind turbine capacity factor in the Iberian Peninsula (1900–2010)

Energy ◽  
2021 ◽  
Vol 226 ◽  
pp. 120364
Author(s):  
Sheila Carreno-Madinabeitia ◽  
Gabriel Ibarra-Berastegi ◽  
Jon Sáenz ◽  
Alain Ulazia
Keyword(s):  
Wind Turbine ◽  
Iberian Peninsula ◽  
Wind Power ◽  
Power Density ◽  
Capacity Factor ◽  
Offshore Wind ◽  
Offshore Wind Power ◽  
Long Term Changes ◽  
Turbine Capacity

Analysis of high yielding maize production - a study based on a commercial crop

2008 ◽  
Vol 48 (3) ◽  
pp. 296 ◽  
Author(s):  
C. J. Birch ◽  
G. McLean ◽  
A. Sawers
Keyword(s):  
Retrospective Analysis ◽  
Environmental Conditions ◽  
Sowing Date ◽  
Plant Population ◽  
Higher Plant ◽  
Maize Crop ◽  
Wide Range ◽  
Commercial Crop ◽  
Reduced Temperature

This paper reports on the use of APSIM – Maize for retrospective analysis of performance of a high input, high yielding maize crop and analysis of predicted performance of maize grown with high inputs over the long-term (>100 years) for specified scenarios of environmental conditions (temperature and radiation) and agronomic inputs (sowing date, plant population, nitrogen fertiliser and irrigation) at Boort, Victoria, Australia. It uses a high yielding (17 400 kg/ha dry grain, 20 500 kg/ha at 15% water) commercial crop grown in 2004–05 as the basis of the study. Yield for the agronomic and environmental conditions of 2004–05 was predicted accurately, giving confidence that the model could be used for the detailed analyses undertaken. The analysis showed that the yield achieved was close to that possible with the conditions and agronomic inputs of 2004–05. Sowing dates during 21 September to 26 October had little effect on predicted yield, except when combined with reduced temperature. Single year and long-term analyses concluded that a higher plant population (11 plants/m2) is needed to optimise yield, but that slightly lower N and irrigation inputs are appropriate for the plant population used commercially (8.4 plants/m2). Also, compared with changes in agronomic inputs increases in temperature and/or radiation had relatively minor effects, except that reduced temperature reduces predicted yield substantially. This study provides an approach for the use of models for both retrospective analysis of crop performance and assessment of long-term variability of crop yield under a wide range of agronomic and environmental conditions.

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