Two millennia of climate variability in the Central Mediterranean

Abstract. This experimental work addresses the need for high-resolution, long and homogeneous climatic time series that facilitate the study of climate variability over time scales of decades to millennia. We present a high-resolution record of foraminiferal δ18O from a Central-Mediterranean sediment core that covers the last two millennia. The record was analyzed using advanced spectral methods and shows highly significant oscillatory components with periods of roughly 600, 350, 200, 125 and 11 years. Over the last millennium, our data show several features related to known climatic periods, such as the Medieval Optimum, the Little Ice Age and a recent steep variation since the beginning of the Industrial Era. During the preceding millennium, the δ18O series also reveals a surprising maximum at about 0 AD, suggesting low temperatures at that time. This feature contradicts widely held ideas about the Roman Classical Period; it is, therefore, discussed at some length, by reviewing the somewhat contradictory evidence about this period. We compare the δ18O record with an alkenone-derived sea surface temperature time series, obtained from cores extracted in the same Central-Mediterranean area (Gallipoli Terrace, Ionian Sea), as well as with Italian and other European temperature reconstructions over the last centuries. Based on this comparison, we show that the long-term trend and the 200-y oscillation in the records are temperature driven and have a dominant role in describing temperature variations over the last two millennia.

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Climate Variability in Central Europe during the Last 2500 Years Reconstructed from Four High-Resolution Multi-Proxy Speleothem Records

Geosciences ◽

10.3390/geosciences11040166 ◽

2021 ◽

Vol 11 (4) ◽

pp. 166

Author(s):

Sarah Waltgenbach ◽

Dana F. C. Riechelmann ◽

Christoph Spötl ◽

Klaus P. Jochum ◽

Jens Fohlmeister ◽

...

Keyword(s):

Trace Elements ◽

High Resolution ◽

Climate Variability ◽

Little Ice Age ◽

Medieval Warm Period ◽

Warm Period ◽

Ice Age ◽

Cold Period ◽

Cave System ◽

Dark Ages

The Late Holocene was characterized by several centennial-scale climate oscillations including the Roman Warm Period, the Dark Ages Cold Period, the Medieval Warm Period and the Little Ice Age. The detection and investigation of such climate anomalies requires paleoclimate archives with an accurate chronology as well as a high temporal resolution. Here, we present 230Th/U-dated high-resolution multi-proxy records (δ13C, δ18O and trace elements) for the last 2500 years of four speleothems from Bunker Cave and the Herbstlabyrinth cave system in Germany. The multi-proxy data of all four speleothems show evidence of two warm and two cold phases during the last 2500 years, which coincide with the Roman Warm Period and the Medieval Warm Period, as well as the Dark Ages Cold Period and the Little Ice Age, respectively. During these four cold and warm periods, the δ18O and δ13C records of all four speleothems and the Mg concentration of the speleothems Bu4 (Bunker Cave) and TV1 (Herbstlabyrinth cave system) show common features and are thus interpreted to be related to past climate variability. Comparison with other paleoclimate records suggests a strong influence of the North Atlantic Oscillation at the two caves sites, which is reflected by warm and humid conditions during the Roman Warm Period and the Medieval Warm Period, and cold and dry climate during the Dark Ages Cold period and the Little Ice Age. The Mg records of speleothems Bu1 (Bunker Cave) and NG01 (Herbstlabyrinth) as well as the inconsistent patterns of Sr, Ba and P suggests that the processes controlling the abundance of these trace elements are dominated by site-specific effects rather than being related to supra-regional climate variability.

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A high-resolution δ<sup>18</sup>O record and Mediterranean climate variability

Climate of the Past Discussions ◽

10.5194/cpd-10-4057-2014 ◽

2014 ◽

Vol 10 (5) ◽

pp. 4057-4084

Author(s):

C. Taricco ◽

G. Vivaldo ◽

S. Alessio ◽

S. Rubinetti ◽

S. Mancuso

Keyword(s):

High Resolution ◽

Spectrum Analysis ◽

Singular Spectrum Analysis ◽

Ionian Sea ◽

Data Set ◽

Singular Spectrum ◽

Proxy Records ◽

Long Term Trends ◽

Temperature Proxy

Abstract. A~high-resolution, well-dated foraminiferal δ18O record from a shallow-water core drilled from the Gallipoli Terrace in the Gulf of Taranto (Ionian Sea), previously measured over the last two millennia, has been extended to cover 707 BC–1979 AD. Spectral analysis of this series, performed by Singular Spectrum Analysis (SSA) and other classical and advanced methods, strengthens the results obtained analysing the shorter δ18O profile, detecting the same highly significant oscillations of about 600 yr, 380 yr, 170 yr, 130 yr, and 11 yr, respectively explaining about 12%, 7%, 5%, 2% and 2% of the time series total variance, plus a millennial trend (18% of the variance). The comparison with the results of Multi-channel Singular Spectrum Analysis (MSSA) applied to a data set of 26 Northern Hemisphere (NH) temperature-proxy records shows that NH temperature anomalies share with our local record a long-term trend and a bicentennial cycle. These two variability modes, previously identified as temperature-driven, are the most powerful modes in the NH temperature data set. Both the long-term trends and the bicentennial oscillations, when reconstructed locally and hemispherically, show coherent phases. Also the corresponding local and hemispheric amplitudes are comparable, if changes in the precipitation-evaporation balance of the Ionian sea, presumably associated with temperature changes, are taken into account.

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SCOPE Climate: a 142-year daily high-resolution ensemble meteorological reconstruction dataset over France

10.5194/essd-2018-79 ◽

2018 ◽

Author(s):

Laurie Caillouet ◽

Jean-Philippe Vidal ◽

Eric Sauquet ◽

Benjamin Graff ◽

Jean-Michel Soubeyroux

Keyword(s):

High Resolution ◽

Climate Variability ◽

Reference Evapotranspiration ◽

Multivariate Time Series ◽

First Century ◽

Independent Data ◽

Commercial Use ◽

The 19Th Century ◽

Hydrological Applications

Abstract. SCOPE Climate (Spatially COherent Probabilistic Extended Climate dataset) is a 25-member ensemble of 142-year daily high-resolution reconstructions of precipitation, temperature and Penman-Monteith reference evapotranspiration over France, from 1 January 1871 to 29 December 2012. SCOPE Climate provides an ensemble of 25 spatially coherent gridded multivariate time series. It is derived from the statistical downscaling of the Twentieth Century Reanalysis (20CR) by the SCOPE method (Spatially COherent Probabilistic Extended method) which is based on the analogue approach. SCOPE Climate performs well in comparison to both dependent and independent data for precipitation and temperature. The ensemble aspect corresponds to the uncertainty related to the SCOPE method. SCOPE Climate is the first century-long gridded high-resolution homogeneous dataset available over France and thus paves the way for improving the knowledge on specific past meteorological events or for improving the knowledge on climate variability since the end of the 19th century. This dataset has also been designed as a forcing dataset for long-term hydrological applications and studies of the hydrological consequences of climate variability over France. SCOPE Climate is freely available for any non-commercial use, and can be downloaded as NetCDF files from http://doi.org/10.5281/zenodo.1299760 for precipitation, http://doi.org/10.5281/zenodo.1299712 for temperature, and http://doi.org/10.5281/zenodo.1251843 for reference evapotranspiration.

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Combat climate change challenges in considering climatic vulnerabilities and risk factors for wheat production

SAARC Journal of Agriculture ◽

10.3329/sja.v14i2.31252 ◽

2017 ◽

Vol 14 (2) ◽

pp. 137-149

Author(s):

MM Rahman ◽

MG Miah ◽

SR Saha

Keyword(s):

Climate Change ◽

Climate Variability ◽

Water Levels ◽

Agricultural Drought ◽

Maximum Temperature ◽

Climatic Data ◽

Wheat Production ◽

Combat Climate Change ◽

Northwest Region

The present study was undertaken for assessing the impacts of climate variability on wheat production as well as the field based suggestions opined by the wheat growers to combat the future challenges particularly climate variability during November 2014 to March 2015. The study was conducted at northwest region at Dinajpur sadar and Kaharul upazilas in Dinajpur of Bangladesh. One hundred sixty wheat farmers were selected by using previously pre-tested interview schedules adopting multistage proportionate systematic random sampling technique. Climatic variability was assessed by analysis of long term data of local meteorological station. Assessment of long term climatic data particularly for wheat growing season revealed that minimum temperature has been increased, while maximum temperature and rainfall were decreased. Farmers opinions on these aspects were almost similar. Farmers opined that both surface and ground water levels have been decreased, resulting agricultural drought. Farmers also opined regarding suitable technology to combat climate change impact on wheat production revealed the use of newly recommended varieties. Finally, the outcome of the results could help researchers as well as government and NGOs to take appropriate climate change adaptation policy thus facilitating farmers in sustaining their livelihoods against changing climate in the near future of Northwest region in Bangladesh.SAARC J. Agri., 14(2): 137-149 (2016)

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Natural Climate Variability During the Holocene

Radiocarbon ◽

10.1017/s0033822200042715 ◽

2007 ◽

Vol 49 (2) ◽

pp. 837-854 ◽

Cited By ~ 8

Author(s):

V A Dergachev ◽

O M Raspopov ◽

F Damblon ◽

H Jungner ◽

G I Zaitseva

Keyword(s):

Time Series ◽

Climate Variability ◽

Ice Cores ◽

Cosmogenic Isotope ◽

Radiocarbon Age ◽

Earth’S Climate ◽

Climatic Time Series ◽

Natural Climate ◽

Isotope Content

High-precision radiocarbon age calibration for different terrestrial samples allows us to establish accurate boundaries for many climatic time series. At the same time, the fluctuations of 14C content reflect solar variability. A bispectrum analysis of long-term series of the 14C content deduced from decadal measurements in tree rings demonstrates the existence of amplitude modulation, with a period of main modulation of ∼2400 yr. In 14C time series for the last 11 kyr, major oscillations are distinguished at 8.5–7.8, 5.4–4.7, 2.6–2.2, and 1.1–0.4 cal kyr BP with ∼2400-yr periodicity. High amplitudes in cosmogenic isotope content with a periodicity of about 2400 yr appear synchronous to cooling events documented in Greenland ice cores, to the timing of worldwide Holocene glacier expansion, and to the periods of lake-level changes. This paper focuses on revealing solar forcing on the Earth's climate and about the nature, significance, and impact of sharp Holocene climate variability on human societies and civilizations.

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Humidity changes and possible forcing mechanisms over the last millennium in arid Central Asia

10.5194/cp-2021-137 ◽

2021 ◽

Author(s):

Shengnan Feng ◽

Xingqi Liu ◽

Feng Shi ◽

Xin Mao ◽

Yun Li ◽

...

Keyword(s):

High Resolution ◽

Central Asia ◽

Southern Oscillation ◽

Atlantic Multidecadal Oscillation ◽

Warm Period ◽

Ice Age ◽

Wavelet Coherence ◽

Last Millennium ◽

Arid Central Asia ◽

Forcing Mechanisms

Abstract. Hydroclimate changes have exerted a significant influence on the historical trajectory of ancient civilizations in arid Central Asia where the central routes of the Silk Road have been hosted. However, the climate changes at different time scales and their possible forcing mechanisms over the last millennium remain unclear due to low-resolution records. Here, we provide a continuous high-resolution humidity history in arid Central Asia over the past millennium based on the ~1.8-year high-resolution multiproxy records with good chronological control from Lake Dalongchi in the central Tianshan Mountains. Generally, the climate was dry during the Medieval Warm Period (MWP) and Current Warm Period (CWP), and wet during the Little Ice Age (LIA), which could be attributed to the influence of the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO). Furthermore, we find that the humidity oscillation was dramatic and unstable at multidecadal to century-scale, especially within the LIA. The continuous wavelet analysis and wavelet coherence show that the humidity oscillation is modulated by the Gleissberg cycle at the century-scale and by the quasi-regular period of El Niño-Southern Oscillation (ENSO) at the multidecadal scale. Our findings suggest that the effect of the solar cycle and the quasi-regular period of ENSO should be seriously evaluated for hydroclimate predictions and climate simulations in arid Central Asia in the future.

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Late Holocene high resolution palaeoclimatic reconstruction inferred from Sebkha Mhabeul, southeast Tunisia

Quaternary Research ◽

10.1016/j.yqres.2008.06.002 ◽

2008 ◽

Vol 70 (2) ◽

pp. 240-250 ◽

Cited By ~ 43

Author(s):

L. Marquer ◽

S. Pomel ◽

A. Abichou ◽

E. Schulz ◽

D. Kaniewski ◽

...

Keyword(s):

High Resolution ◽

Fire History ◽

Ice Age ◽

Modern Times ◽

Climate Anomalies ◽

History Of ◽

Age Model ◽

Southeast Tunisia ◽

High Resolution Reconstruction ◽

The Last Two Millennia

AbstractRelations between climate change and landscape evolution during the last two millennia in southeastern coastal Tunisia have been documented using high-resolution reconstruction of flood history and fire activity in the Sebkha Mhabeul core. The age model, based on tephrochronology, indicates that the core extends from Roman to modern times and encompasses the well-defined climatic periods of the last two millennia. This record provides a first palaeoecological/palaeoclimatic high resolution reconstruction in North Africa using a cross-disciplinary approach with both physical (grey-scale intensity, quartz particles) and biological (charcoal and pollen) indicators. The flood history shows four wet/dry cycles (ca. AD 550–950, 950–1300, 1300–1570 and 1570–1870) of different duration. Major hydrological instabilities are concentrated during the Medieval Climate Anomalies and the early Little Ice Age, between AD 1000 and 1550. Direct correlation between climate and fire cannot be established suggesting that the fire history of the Sebkha environment is mainly influenced by human activity. This study demonstrates the great value of sebkhas as palaeoenvironmental archives.

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Impact of Genetic Improvements of Rice on Its Water Use and Effects of Climate Variability in Egypt

Agriculture ◽

10.3390/agriculture11090865 ◽

2021 ◽

Vol 11 (9) ◽

pp. 865

Author(s):

Mohamed Mehana ◽

Mohamed Abdelrahman ◽

Yasmin Emadeldin ◽

Jai S. Rohila ◽

Raghupathy Karthikeyan

Keyword(s):

Relative Humidity ◽

Climate Variability ◽

Negative Impact ◽

Rice Production ◽

Maximum Temperature ◽

Rice Cultivars ◽

Rice Productivity ◽

Unit Productivity ◽

The Impact

Developing and disseminating resilient rice cultivars with increased productivity is a key solution to the problem of limited natural resources such as land and water. We investigated trends in rice cultivation areas and the overall production in Egypt between 2000 and 2018. This study identified rice cultivars that showed potential for high productivity when cultivated under limited irrigation. The results indicated that there were significant annual reductions in both the rice-cultivated area (−1.7% per year) and the production (−1.9% per year) during the study period. Among the commonly cultivated varieties, Sakha101 showed the highest land unit productivity, while Sakha102 showed the highest water unit productivity. The impact of deploying new cultivars was analyzed by substitution scenarios. The results showed that substituting cultivars Giza179 and Sakha107 has the potential to increase land productivity by 15.8% and 22.6%, respectively. This could result in 0.8 million m3 in water savings compared to 2018 water consumption. Long-term impacts of climate variability on the minimum and maximum temperature, relative humidity, and average precipitation during on- and off-season for rice productivity were also analyzed using an autoregressive distributed lag (ARDL) model. The results indicated that climate variability has an overall negative impact on rice productivity. Specifically, minimum temperature and on- and off-season precipitation had major long-term impacts, while higher relative humidity had a pronounced short-term impact on rice yields. The study revealed that short-duration cultivars with higher yields provided greater net savings in irrigation resources. These analyses are critical to guide the development of strategic management plans to mitigate short- and long-term climate effects on overall rice production and for developing and deploying improved rice varieties for sustainable rice production.

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A multi-model analysis of ‘Little Ice Age’ climate over China

The Holocene ◽

10.1177/0959683618824761 ◽

2019 ◽

Vol 29 (4) ◽

pp. 592-605 ◽

Cited By ~ 2

Author(s):

Xuecheng Zhou ◽

Dabang Jiang ◽

Xianmei Lang

Keyword(s):

Little Ice Age ◽

Climate Models ◽

Surface Air Temperature ◽

Volcanic Eruptions ◽

Ice Age ◽

Last Millennium ◽

Orbital Parameters ◽

Community Earth System Model ◽

Intercomparison Project

Using the numerical experiments undertaken by nine climate models within the framework of the Paleoclimate Modeling Intercomparison Project Phase 3 (PMIP3), the ensemble simulations with the Community Earth System Model for the last millennium (CESM-LME), and proxy data, we investigate the climate over China during the ‘Little Ice Age’ (LIA; from 1450 to 1850 CE) against the background of the last millennium (from 850 to 1850 CE). The surface air temperature averaged over China generally decreased over time during the last millennium, with several multi-decadal to centennial variations superimposed on the long-term cooling. Relative to the climatology of the last millennium, the annual surface temperature during the LIA decreased over the country, with an average cooling of −0.07°C for the median of the PMIP3 models. Different magnitudes of cooling occurred in all seasons except spring. The cooling over China during the LIA was largely attributed to changes in volcanic eruptions and land use, while the change in orbital parameters played a role on a seasonal scale. The precipitation over China during the LIA decreased for the annual mean and summer and autumn but slightly increased in winter and spring. Model–data comparisons indicate that the models reproduced the colder and drier climate of the LIA reasonably, although there are some differences in certain aspects.

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