Rapid Holocene climate changes in the North Atlantic: evidence from lake sediments from the Faroe Islands

Abstract. Holocene climate was characterised by variability on multi-centennial to multi-decadal time scales. In central Europe, these fluctuations were most pronounced during winter. Here we present a new record of past winter climate variability for the last 10.8 ka based on four speleothems from Bunker Cave, Western Germany. Due to its central European location, the cave site is particularly well suited to record changes in precipitation and temperature in response to changes in the North Atlantic realm. We present high resolution records of δ18O, δ13C values and Mg/Ca ratios. We attribute changes in the Mg/Ca ratio to variations in the meteoric precipitation. The stable C isotope composition of the speleothems most likely reflects changes in vegetation and precipitation and variations in the δ18O signal are interpreted as variations in meteoric precipitation and temperature. We found cold and dry periods between 9 and 7 ka, 6.5 and 5.5 ka, 4 and 3 ka as well as between 0.7 to 0.2 ka. The proxy signals in our stalagmites compare well with other isotope records and, thus, seem representative for central European Holocene climate variability. The prominent 8.2 ka event and the Little Ice Age cold events are both recorded in the Bunker cave record. However, these events show a contrasting relationship between climate and δ18O, which is explained by different causes underlying the two climate anomalies. Whereas the Little Ice Age is attributed to a pronounced negative phase of the North Atlantic Oscillation, the 8.2 ka event was triggered by cooler conditions in the North Atlantic due to a slowdown of the Thermohaline Circulation.

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Changes of weather conditions in Ukraine under climate changes

Ukrainian hydrometeorological journal ◽

10.31481/uhmj.17.2016.04 ◽

2017 ◽

pp. 31-37

Author(s):

V.M. Khokhlov ◽

H.O. Borovska ◽

O.V. Umanska ◽

M.S. Tenetko

Keyword(s):

Wavelet Analysis ◽

North Atlantic ◽

Climate Changes ◽

Global Climate ◽

Weather Conditions ◽

Global Climate Changes ◽

The North ◽

Regional Feature ◽

The North Atlantic ◽

The North Atlantic Oscillation

The paper analyzes spatiotemporal features the indices of hot, cold and precipitation that are related to weather conditions. The temperature in Ukraine tends to be higher, which is the main regional feature of global climate changes. The North Atlantic Oscillation had an influence on the precipitation in Ukraine – weather is rainier during its negative phases. Also, colder night and hotter days were more frequent during negative phases of the NAO. This fact can be explained by enhancing meridional flows in Ukraine. The wavelet analysis also revealed an impact of the NAO on temperature anomalies – positive phases determined increasing monthly minimum temperatures before the 1980s and decreasing ones after 1980s. Also, the wavelet analysis showed that the Nor-th Atlantic Oscillation influenced the precipitation in northern and southern parts of Ukraine in different ways.

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Centennial to millennial-scale variability of Holocene climate and environmental dynamics in the western Mediterranean (Lake Sidi Ali, Middle Atlas, Morocco)

10.5194/egusphere-egu21-8650 ◽

2021 ◽

Author(s):

Johannes Schmidt ◽

Cathleen Kertscher ◽

Markus Reichert ◽

Helen Ballasus ◽

Birgit Schneider ◽

...

Keyword(s):

North Atlantic ◽

Climate Changes ◽

Western Mediterranean ◽

Future Climate ◽

Holocene Climate ◽

The Holocene ◽

The North ◽

Middle Atlas ◽

Environmental Responses

<p>The Western Mediterranean region including the North African desert margin is considered one of the most sensitive areas to future climate changes. In order to refine long-term scenarios for hydrological and environmental responses to future climate changes in this region, it is important to improve our knowledge about past environmental responses to climatic variability at centennial to millennial timescales. During the last two decades, the recovery and compilation of Holocene records from the subtropical North Atlantic and the Mediterranean Sea have improved our knowledge about millennial-scale variability of the Western Mediterranean palaeoclimate. The variabilities appear to affect regional precipitation patterns and environmental systems in the Western Mediterranean, but the timescales, magnitudes and forcing mechanisms remain poorly known. To compare the changes in Holocene climate variability and geomorphological processes across temporal scales, we analysed a 19.63-m long sediment record from Lake Sidi Ali (33&#176;03&#8217; N, 5&#176;00&#8217; W, 2080 m a.s.l.) in the sub-humid Middle Atlas that spans the last 12,000 years (23 pollen-based radiocarbon dates accompanied with <sup>210</sup>Pb results). We use calibrated XRF core scanning records with an annual to sub-decadal resolution to disentangle the complex interplay between climate changes and environmental dynamics during the Holocene. Data exploration techniques and time series analysis (Redfit, Wavelet) revealed long-term changes in lake behaviour. Three main proxy groups were identified (temperature proxies: 2ky, 1ky and 0.7ky cycles; sediment dynamic proxies: 3.5ky, 1.5ky cycles; hydrological proxies: 1.5ky, 1.2ky, 0.17ky cycles). For example, redox sensitive elements Fe and Mn show 1ky cycles and higher values in the Early Holocene and 1.5ky cycles and lower values in the Mid- to Late Holocene. All groups show specific periodicities throughout the Holocene, demonstrating their particular climatic and geomorphological dependencies. Furthermore, we discuss these periodicities relating to global and hemispheric drivers, such as the North Atlantic Oscillation (NAO), El-Ni&#241;o Southern Oscillation (ENSO), Innertropical Convergence Zone variability (ITCZ) and North Atlantic cold relapses (Bond events).</p>

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Holocene climate dynamics in Fennoscandia and the North Atlantic

Past Climate Variability through Europe and Africa - Developments in Paleoenvironmental Research ◽

10.1007/978-1-4020-2121-3_22 ◽

2007 ◽

pp. 465-494 ◽

Cited By ~ 40

Author(s):

Ian Snowball ◽

Atte Korhola ◽

Keith R. Briffa ◽

Nalan Koç

Keyword(s):

North Atlantic ◽

Climate Dynamics ◽

Holocene Climate ◽

The North ◽

The North Atlantic

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Oceanic Impact on European Climate Changes during the Quaternary

Geosciences ◽

10.3390/geosciences9030119 ◽

2019 ◽

Vol 9 (3) ◽

pp. 119

Author(s):

Gloria Martin-Garcia

Keyword(s):

Atmospheric Circulation ◽

North Atlantic ◽

Deep Water ◽

Climate Changes ◽

Formation Rate ◽

Ice Sheet ◽

Southern Europe ◽

The North ◽

European Climate ◽

The North Atlantic

Integrative studies on paleoclimate variations over oceanic and continental regions are scarce. Though it is known that Earth’s climate is strongly affected by sea-air exchanges of heat and moisture, the role of oceans in climate variations over land remains relatively unexplored. With the aim to unveil this influence, the present work studies major climate oscillations in the North Atlantic region and Europe during the Quaternary, focusing on the oceanic mechanisms that were related to them. During this period, the European climate experienced long-term and wide-amplitude glacial-interglacial oscillations. A covariance between the North Atlantic sea surface temperature and climate signals over the continent is especially observed in Southern Europe. The most severe and drastic climate changes occurred in association to deglaciations, as a consequence of major oceanographic reorganizations that affected atmospheric circulation and ocean-atmosphere heat-flow, which led to variation of temperature and precipitation inland. Most deglaciations began when Northern Hemisphere summer insolation was maximal. Increased heating facilitated the rapid ice-sheet collapse and the massive release of fresh water into the Northern Atlantic, which triggered the weakening or even the shutdown of the North Atlantic Deep Water (NADW) formation. Though the extension of ice-sheets determined the high-latitude European climate, the climate was more influenced by rapid variations of ice volume, deep-water formation rate, and oceanic and atmospheric circulation in middle and subtropical latitudes. In consequence, the coldest stadials in the mid-latitude North Atlantic and Europe since the early Pleistocene coincided with Terminations (glacial/interglacial transitions) and lesser ice-sheet depletions. They were related with decreases in the NADW formation rate that occurred at these times and the subsequent advection of subpolar waters along the western European margin. In Southern Europe, steppe communities substituted temperate forests. Once the freshwater perturbation stopped and the overturning circulation resumed, very rapid and wide-amplitude warming episodes occurred (interstadials). On the continent, raised temperature and precipitations allowed the rapid expansion of moisture-requiring vegetation.

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Centennial to millennial scale Holocene climate-deep water linkage in the North Atlantic

Quaternary Science Reviews ◽

10.1016/j.quascirev.2004.04.004 ◽

2004 ◽

Vol 23 (14-15) ◽

pp. 1529-1536 ◽

Cited By ~ 110

Author(s):

Ian R. Hall ◽

Giancarlo G. Bianchi ◽

John R. Evans

Keyword(s):

North Atlantic ◽

Deep Water ◽

Holocene Climate ◽

The North ◽

The North Atlantic ◽

Millennial Scale

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Evidence for Two Distinct Modes of Large-Scale Ocean Circulation Changes over the Last Century

Journal of Climate ◽

10.1175/2009jcli2867.1 ◽

2010 ◽

Vol 23 (1) ◽

pp. 5-16 ◽

Cited By ~ 44

Author(s):

Mihai Dima ◽

Gerrit Lohmann

Keyword(s):

Ocean Circulation ◽

North Atlantic ◽

Large Scale ◽

Climate Changes ◽

Thermohaline Circulation ◽

Conveyor Belt ◽

The North ◽

Symmetric Pattern ◽

The North Atlantic ◽

Circulation Changes

Abstract Through its nonlinear dynamics and involvement in past abrupt climate shifts the thermohaline circulation (THC) represents a key element for the understanding of rapid climate changes. The expected THC weakening under global warming is characterized by large uncertainties, and it is therefore of significant importance to identify ocean circulation changes over the last century. By applying various statistical techniques on two global sea surface temperature datasets two THC-related modes are separated. The first one involves relatively slow adjustment of the whole conveyor belt circulation and has an interhemispherically symmetric pattern. The second mode is associated with the relatively fast adjustment of the North Atlantic overturning cell and has the seesaw structure. Based on the separation of these two patterns the authors show that the global conveyor has been weakening since the late 1930s and that the North Atlantic overturning cell suffered an abrupt shift around 1970. The distinction between the two modes provides also a new frame for interpreting past abrupt climate changes.

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