A millennium-length temperature reconstruction for the eastern Mediterranean

2020 ◽  
Author(s):  
Jan Esper ◽  
Lara Klippel ◽  
Paul J. Krusic ◽  
Oliver Konter ◽  
Christoph Raible ◽  
...  
Keyword(s):  
Central Europe ◽  
Climate Model ◽  
Eastern Mediterranean ◽  
Temperature Reconstruction ◽  
Ice Age ◽  
Temperature Trends ◽  
Latewood Density ◽  
Scale Temperature ◽  
The Mediterranean ◽  
Millennial Scale

<p>The Mediterranean has been identified as particularly vulnerable to climate change, yet a high-resolution temperature reconstruction extending back into the Medieval Warm Period is still lacking. Here we present such a record from a high-elevation site on Mt. Smolikas in northern Greece, where some of Europe’s oldest trees provide evidence of warm season temperature variability back to 730 CE. The reconstruction is derived from 192 annually resolved, latewood density series from ancient living and relict Pinus heldreichii trees calibrating at r<sub>1911-2015</sub> = 0.73 against regional July-September (JAS) temperatures. Although the recent 1985-2014 period was the warmest 30-year interval (JAS T<sub>wrt.1961-90</sub> = +0.71°C) since the 11<sup>th</sup> century, temperatures during the 9-10<sup>th</sup> centuries were even warmer, including the warmest reconstructed 30-year period from 876-905 (+0.78°C). These differences between warm periods are statistically insignificant though. Several distinct cold episodes punctuate the Little Ice Age, albeit the coldest 30-year period is centered during high medieval times from 997-1026 (-1.63°C). Comparison with reconstructions from the Alps and Scandinavia shows that a similar cold episode occurred in central Europe but was absent at northern latitudes. The reconstructions also reveal different millennial-scale temperature trends (NEur = -0.73°C/1000 years, CEur = -0.13 °C, SEur = +0.23°C) potentially triggered by latitudinal changes in summer insolation due to orbital forcing. These features, the opposing millennial-scale temperature trends and the medieval multi-decadal cooling recorded in Central Europe and the Mediterranean, are not well captured in state-of-the-art climate model simulations.</p>

scholarly journals Influence of solar variability, CO<sub>2</sub> and orbital forcing between 1000 and 1850 AD in the IPSLCM4 model

2010 ◽  
Vol 6 (4) ◽  
pp. 445-460 ◽  
Author(s):  
J. Servonnat ◽  
P. Yiou ◽  
M. Khodri ◽  
D. Swingedouw ◽  
S. Denvil
Keyword(s):  
Climate Model ◽  
Internal Variability ◽  
Temperature Reconstruction ◽  
Temperature Variability ◽  
Ice Age ◽  
Last Millennium ◽  
Orbital Forcing ◽  
Temperature Reconstructions ◽  
Temperature Signal ◽  
The Impact

Abstract. Studying the climate of the last millennium gives the possibility to deal with a relatively well-documented climate essentially driven by natural forcings. We have performed two simulations with the IPSLCM4 climate model to evaluate the impact of Total Solar Irradiance (TSI), CO2 and orbital forcing on secular temperature variability during the preindustrial part of the last millennium. The Northern Hemisphere (NH) temperature of the simulation reproduces the amplitude of the NH temperature reconstructions over the last millennium. Using a linear statistical decomposition we evaluated that TSI and CO2 have similar contributions to secular temperature variability between 1425 and 1850 AD. They generate a temperature minimum comparable to the Little Ice Age shown by the temperature reconstructions. Solar forcing explains ~80% of the NH temperature variability during the first part of the millennium (1000–1425 AD) including the Medieval Climate Anomaly (MCA). It is responsible for a warm period which occurs two centuries later than in the reconstructions. This mismatch implies that the secular variability during the MCA is not fully explained by the response of the model to the TSI reconstruction. With a signal-noise ratio (SNR) estimate we found that the temperature signal of the forced simulation is significantly different from internal variability over area wider than ~5.106 km2, i.e. approximately the extent of Europe. Orbital forcing plays a significant role in latitudes higher than 65° N in summer and supports the conclusions of a recent study on an Arctic temperature reconstruction over past two millennia. The forced variability represents at least half of the temperature signal on only ~30% of the surface of the globe. This study suggests that regional reconstructions of the temperature between 1000 and 1850 AD are likely to show weak signatures of solar, CO2 and orbital forcings compared to internal variability.

Water cycle changes over the Mediterranean: a comparison study of a super-high-resolution global model with CMIP3

2010 ◽  
Vol 368 (1931) ◽  
pp. 5137-5149 ◽  
Author(s):  
Fengjun Jin ◽  
Akio Kitoh ◽  
Pinhas Alpert
Keyword(s):  
Climate Model ◽  
Water Cycle ◽  
Eastern Mediterranean ◽  
Global Climate ◽  
Global Climate Model ◽  
Coupled Model ◽  
Western Mediterranean ◽  
Significant Difference ◽  
The Mediterranean ◽  
Projected Changes

Water cycle components over the Mediterranean for both a current run (1979–2007) and a future run (2075–2099) are studied with the Japan Meteorological Agency’s 20 km grid global climate model. Results are compared with another study using the Coupled Model Intercomparison Project Phase 3 ensemble model (hereafter, the Mariotti model). Our results are surprisingly close to Mariotti’s. The projected mean annual change rates of precipitation ( P ) between the future and the current run for sea and land are −11 per cent and −10 per cent, respectively, which are not as high as Mariotti’s. Projected changes for evaporation ( E ) are +9.3 per cent and −3.6 per cent, compared with +7.2 per cent and −8.1 per cent in Mariotti’s study, respectively. However, no significant difference in the change in P – E over the sea body was found between these two studies. The increased E over the eastern Mediterranean was found to be higher than that in the western Mediterranean, but the P decrease was lower. The net moisture budget, P – E , shows that the eastern Mediterranean will become even drier than the western Mediterranean. The river model suggests decreasing water inflow to the Mediterranean of approximately 36 per cent (excluding the Nile).

scholarly journals Reconstructing Millennial-Scale, Regional Paleoclimates of Boreal Canada during the Holocene

2009 ◽  
Vol 22 (2) ◽  
pp. 316-330 ◽  
Author(s):  
A. E. Viau ◽  
K. Gajewski
Keyword(s):  
Climate Variability ◽  
Early Holocene ◽  
Ice Age ◽  
Western Canada ◽  
Eastern Canada ◽  
The Holocene ◽  
Northern Canada ◽  
Scale Temperature ◽  
Central Canada ◽  
Millennial Scale

Abstract Regional paleoclimate reconstructions for northern Canada quantify Holocene climate variability on orbital and millennial time scales and provide a context to better understand the current global warming. The reconstructions are based on available pollen diagrams from the boreal and low Arctic zones of Canada and use the modern analog technique (MAT). Four regional reconstructions document the space–time evolution of the climate during the Holocene. Highest summer and winter temperatures anomalies are found in central Canada during the early Holocene. Eastern Canada was relatively cool in the early Holocene, whereas central Canada was warmest at that time. Labrador was relatively dry in the early to mid-Holocene during which time western Canada was relatively moist. Millennial-scale temperature variations, especially the Medieval Warm Period and Little Ice Age are seen across the continent, with some suggestion of time-transgressive changes from west to east. At the millennial scale, precipitation anomalies are of opposite signs in eastern and western Canada. The results herein indicate that modern increases in temperatures in northern Canada far exceed natural millennial-scale climate variability.

scholarly journals Influence of solar variability, CO<sub>2</sub> and orbital forcing during the last millennium in the IPSLCM4 model

2010 ◽  
Vol 6 (2) ◽  
pp. 421-460
Author(s):  
J. Servonnat ◽  
P. Yiou ◽  
M. Khodri ◽  
D. Swingedouw ◽  
S. Denvil
Keyword(s):  
Climate Model ◽  
Internal Variability ◽  
Temperature Reconstruction ◽  
Temperature Variability ◽  
Ice Age ◽  
Last Millennium ◽  
Orbital Forcing ◽  
Temperature Reconstructions ◽  
Temperature Signal ◽  
The Impact

Abstract. Studying the climate of the last millennium gives the possibility to deal with a relatively well-documented climate essentially driven by natural forcings. We have performed two simulations with the IPSLCM4 climate model to evaluate the impact of Total Solar Irradiance (TSI), CO2 and orbital forcing on secular temperature variability during the preindustrial part of the last millennium. The Northern Hemisphere (NH) temperature of the simulation reproduces the amplitude of the NH temperature reconstructions over the last millennium. Using a linear statistical decomposition we evaluated that TSI and CO2 have similar contributions to secular temperature variability between 1425 and 1850 AD. They generate a temperature minimum comparable to the Little Ice Age shown by the temperature reconstructions. Solar forcing explains ~80% of the NH temperature variability during the first part of the millennium (1000–1425 AD) including the Medieval Climate Anomaly (MCA). It is responsible for a warm period which occurs two centuries later than in the reconstructions. This mismatch implies that the secular variability during the MCA is not fully explained by the response of the model to the TSI reconstruction. With a signal-noise ratio (SNR) estimate we found that the temperature signal of the forced simulation is significantly different from internal variability over area wider than ~5.106 km2, i.e. approximately the extent of Europe. Orbital forcing plays a significant role in latitudes higher than 65° N in summer and supports the conclusions of a recent study on an Arctic temperature reconstruction over past two millennia. The forced variability represents at least half of the temperature signal on only ~30% of the surface of the globe. The study of the SNR and local impacts of the forcings suggests that individual temperature reconstructions taken from random location around the Globe are potentially weakly affected by a linear response to external forcings.

scholarly journals Precipitation changes in the Mediterranean basin during the Holocene from terrestrial and marine pollen records: a model–data comparison

2017 ◽  
Vol 13 (3) ◽  
pp. 249-265 ◽  
Author(s):  
Odile Peyron ◽  
Nathalie Combourieu-Nebout ◽  
David Brayshaw ◽  
Simon Goring ◽  
Valérie Andrieu-Ponel ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Late Holocene ◽  
Climate Model ◽  
Eastern Mediterranean ◽  
Regional Climate ◽  
Summer Precipitation ◽  
The Holocene ◽  
Precipitation Estimates ◽  
The Mediterranean ◽  
The Mediterranean Basin

Abstract. Climate evolution of the Mediterranean region during the Holocene exhibits strong spatial and temporal variability, which is notoriously difficult for models to reproduce. We propose here a new proxy-based climate synthesis synthesis and its comparison – at a regional (∼ 100 km) level – with a regional climate model to examine (i) opposing northern and southern precipitation regimes and (ii) an east-to-west precipitation dipole during the Holocene across the Mediterranean basin. Using precipitation estimates inferred from marine and terrestrial pollen archives, we focus on the early to mid-Holocene (8000 to 6000 cal yr BP) and the late Holocene (4000 to 2000 cal yr BP), to test these hypotheses on a Mediterranean-wide scale. Special attention was given to the reconstruction of season-specific climate information, notably summer and winter precipitation. The reconstructed climatic trends corroborate the north–south partition of precipitation regimes during the Holocene. During the early Holocene, relatively wet conditions occurred in the south–central and eastern Mediterranean regions, while drier conditions prevailed from 45° N northwards. These patterns then reverse during the late Holocene. With regard to the existence of a west–east precipitation dipole during the Holocene, our results show that the strength of this dipole is strongly linked to the reconstructed seasonal parameter; early-Holocene summers show a clear east–west division, with summer precipitation having been highest in Greece and the eastern Mediterranean and lowest over Italy and the western Mediterranean. Summer precipitation in the east remained above modern values, even during the late-Holocene interval. In contrast, winter precipitation signals are less spatially coherent during the early Holocene but low precipitation is evidenced during the late Holocene. A general drying trend occurred from the early to late Holocene, particularly in the central and eastern Mediterranean. For the same time intervals, pollen-inferred precipitation estimates were compared with model outputs, based on a regional-scale downscaling (HadRM3) of a set of global climate-model simulations (HadAM3). The high-resolution detail achieved through the downscaling is intended to enable a better comparison between site-based paleo-reconstructions and gridded model data in the complex terrain of the Mediterranean; the model outputs and pollen-inferred precipitation estimates show some overall correspondence, though modeled changes are small and at the absolute margins of statistical significance. There are suggestions that the eastern Mediterranean experienced wetter summer conditions than present during the early and late Holocene; the drying trend in winter from the early to the late Holocene also appears to be simulated. The use of this high-resolution regional climate model highlights how the inherently patchy nature of climate signals and paleo-records in the Mediterranean basin may lead to local signals that are much stronger than the large-scale pattern would suggest. Nevertheless, the east-to-west division in summer precipitation seems more marked in the pollen reconstruction than in the model outputs. The footprint of the anomalies (like today, or dry winters and wet summers) has some similarities to modern analogue atmospheric circulation patterns associated with a strong westerly circulation in winter (positive Arctic Oscillation–North Atlantic Oscillation (AO–NAO)) and a weak westerly circulation in summer associated with anticyclonic blocking; however, there also remain important differences between the paleo-simulations and these analogues. The regional climate model, consistent with other global models, does not suggest an extension of the African summer monsoon into the Mediterranean. Therefore, the extent to which summer monsoonal precipitation may have existed in the southern and eastern Mediterranean during the mid-Holocene remains an outstanding question.

scholarly journals 1200 years of regular outbreaks in alpine insects

2006 ◽  
Vol 274 (1610) ◽  
pp. 671-679 ◽  
Author(s):  
Jan Esper ◽  
Ulf Büntgen ◽  
David C Frank ◽  
Daniel Nievergelt ◽  
Andrew Liebhold
Keyword(s):  
Population Cycles ◽  
Temperature Reconstruction ◽  
Ice Age ◽  
European Alps ◽  
Ecological Disturbance ◽  
Maximum Latewood Density ◽  
Latewood Density ◽  
History Of ◽  
Zeiraphera Diniana ◽  
The Impact

The long-term history of Zeiraphera diniana Gn. (the larch budmoth, LBM) outbreaks was reconstructed from tree rings of host subalpine larch in the European Alps. This record was derived from 47 513 maximum latewood density measurements, and highlights the impact of contemporary climate change on ecological disturbance regimes. With over 1000 generations represented, this is the longest annually resolved record of herbivore population dynamics, and our analysis demonstrates that remarkably regular LBM fluctuations persisted over the past 1173 years with population peaks averaging every 9.3 years. These regular abundance oscillations recurred until 1981, with the absence of peak events during recent decades. Comparison with an annually resolved, millennium-long temperature reconstruction representative for the European Alps ( r =0.72, correlation with instrumental data) demonstrates that regular insect population cycles continued despite major climatic changes related to warming during medieval times and cooling during the Little Ice Age. The late twentieth century absence of LBM outbreaks, however, corresponds to a period of regional warmth that is exceptional with respect to the last 1000+ years, suggesting vulnerability of an otherwise stable ecological system in a warming environment.

scholarly journals Mitogenomics of the endangered Mediterranean monk seal (Monachus monachus) reveals dramatic loss of diversity and supports historical gene-flow between Atlantic and eastern Mediterranean populations

2020 ◽  
Author(s):  
Alba Rey-Iglesia ◽  
Philippe Gaubert ◽  
Gonçalo Espregueira Themudo ◽  
Rosa Pires ◽  
Constanza De La Fuente ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
North Atlantic ◽  
Marine Mammals ◽  
Eastern Mediterranean ◽  
The Black Sea ◽  
Mediterranean Populations ◽  
Geographic Ranges ◽  
Western Sahara ◽  
The Mediterranean

Abstract The Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals, with only 600–700 individuals restricted to three populations off the coast of Western Sahara and Madeira (North Atlantic) and between Greece and Turkey (eastern Mediterranean). Its original range was from the Black Sea (eastern Mediterranean) to Gambia (western African coast), but was drastically reduced by commercial hunting and human persecution since the early stages of marine exploitation. We here analyse 42 mitogenomes of Mediterranean monk seals, from across their present and historical geographic ranges to assess the species population dynamics over time. Our data show a decrease in genetic diversity in the last 200 years. Extant individuals presented an almost four-fold reduction in genetic diversity when compared to historical specimens. We also detect, for the first time, a clear segregation between the two North Atlantic populations, Madeira and Cabo Blanco, regardless of their geographical proximity. Moreover, we show the presence of historical gene-flow between the two water basins, the Atlantic Ocean and the Mediterranean Sea, and the presence of at least one extinct maternal lineage in the Mediterranean. Our work demonstrates the advantages of using full mitogenomes in phylogeographic and conservation genomic studies of threatened species.

Annual to decadal-scale variations in northwest Atlantic sector temperatures inferred from Labrador tree rings

1996 ◽  
Vol 26 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Rosanne D. D'arrigo ◽  
Edward R. Cook ◽  
Gordon C. Jacoby
Keyword(s):  
Warm Season ◽  
Temperature Sensitive ◽  
Northwest Atlantic ◽  
Atlantic Sector ◽  
Grand Banks ◽  
Maximum Latewood Density ◽  
Latewood Density ◽  
Scale Temperature ◽  
Decadal Scale ◽  
North Atlantic Climate

Temperature-sensitive maximum latewood density chronologies from sites near tree line in Labrador are used to infer past changes in warm-season surface air and sea surface temperatures for the northwest Atlantic. Temperatures are reconstructed for the Grand Banks region based on density records from southern Labrador, while a density series from near Okak Fiord, northern Labrador, is used to infer past temperature variations for north-coastal Labrador and the adjacent Labrador Sea. The Labrador chronologies show good agreement with annual and decadal-scale temperature fluctuations over the recent period of instrumental record, and extend this temperature information into the past by several centuries. The lowest density value at the Okak site occurs in 1816, known as the "year without a summer" in eastern North America. Spectral analyses reveal statistically significant variations with periods of around 8.7, 18–22, and 45–66 years. These fluctuations are in general agreement with those identified in several instrumental and modeling analyses of North Atlantic climate.

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