Transient simulations, empirical reconstructions and forcing mechanisms for the Mid-holocene hydrological climate in southern Patagonia

Wagner, Sebastian; Jones, Julie Miller; Haberzettl, Torsten; Lücke, Andreas; Mayr, Christoph; Ohlendorf, Christian; Schäbitz, Frank; Zolitschka, Bernd

doi:10.1007/s00382-007-0229-x

Cited by 60 publications

(59 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Baltic Sea is one of the largest inland brackish seas with an estuarinelike circulation and sensitive to changes in the environmental conditions. For instance, it is known from sediment studies that the deep bottom layers were hypoxic during the MCA in contrast to the LIA (Zillén and Conley, 2010;Kabel et al, 2012). The period of hypoxia during the MCA correlate to population growth and large-scale changes in land use and with it the input of nutrients (Zillén and Conley, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…For instance, it is known from sediment studies that the deep bottom layers were hypoxic during the MCA in contrast to the LIA (Zillén and Conley, 2010;Kabel et al, 2012). The period of hypoxia during the MCA correlate to population growth and large-scale changes in land use and with it the input of nutrients (Zillén and Conley, 2010). Following their argumentation, salinity and temperature anomalies cannot explain hypoxia during the MCA.…”

Section: Introductionmentioning

confidence: 99%

“…Following their argumentation, salinity and temperature anomalies cannot explain hypoxia during the MCA. Therefore, it resulted from anthropogenic impacts (Zillén et al, 2008;Zillén and Conley, 2010) similarly to the 20th century (Conley et al, 2009;Hansson and Gustafsson, 2011;Gustafsson et al, 2012). However, historical nutrient loads are not estimated yet and the effect of pure natural climate change during the MCA has not been investigated so far.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The climate in the Baltic Sea region during the last millennium simulated with a regional climate model

et al. 2012

View full text Add to dashboard Cite

Abstract. Variability and long-term climate change in the Baltic Sea region is investigated for the pre-industrial period of the last millennium. For the first time dynamical downscaling covering the complete millennium is conducted with a regional climate model in this area. As a result of changing external forcing conditions, the model simulation shows warm conditions in the first centuries followed by a gradual cooling until ca. 1700 before temperature increases in the last centuries. This long-term evolution, with a Medieval Climate Anomaly (MCA) and a Little Ice Age (LIA), is in broad agreement with proxy-based reconstructions. However, the timing of warm and cold events is not captured at all times. We show that the regional response to the global climate anomalies is to a strong degree modified by the large-scale circulation in the model. In particular, we find that a positive phase of the North Atlantic Oscillation (NAO) simulated during MCA contributes to enhancing winter temperatures and precipitation in the region while a negative NAO index in the LIA reduces them. In a second step, the regional ocean model (RCO-SCOBI) is used to investigate the impact of atmospheric changes onto the Baltic Sea for two 100 yr time slices representing the MCA and the LIA. Besides the warming of the Baltic Sea, the water becomes fresher at all levels during the MCA. This is induced by increased runoff and stronger westerly winds. Moreover, the oxygen concentrations in the deep layers are slightly reduced during the MCA. Additional sensitivity studies are conducted to investigate the impact of even higher temperatures and increased nutrient loads. The presented experiments suggest that changing nutrient loads may be more important determining oxygen depletion than changes in temperature or dynamic feedbacks.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The climate in the Baltic Sea region during the last millennium simulated with a regional climate model

et al. 2012

View full text Add to dashboard Cite

show abstract

“…1d) and are partly inconsistent with our results. However, all previous reconstructions in this latitudinal band were based on records from the lee side of the Andes where other than westerly related rainfall sources become more important 8 . Moreover, plant communities at the dry lee side respond rather indirectly to SWW changes, as wind-induced dry stress is a major ecological factor in this region 9 .…”

mentioning

confidence: 99%

Holocene changes in the position and intensity of the southern westerly wind belt

Lamy¹,

Kilian²,

Arz³

et al. 2010

Nature Geosci

366

356

View full text Add to dashboard Cite

The position and intensity of the southern westerly wind belt varies seasonally as a consequence of changes in sea surface temperature. During the austral winter, the belt expands northward and the wind intensity in the core decreases. Conversely, during the summer, the belt contracts, and the intensity within the core is strengthened. Reconstructions of the westerly winds since the last glacial maximum, however, have suggested that changes at a single site reflected shifts throughout the entire southern wind belt 1-4 . Here we use sedimentological and pollen records to reconstruct precipitation patterns over the past 12,500 yr from sites along the windward side of the Andes. Precipitation at the sites, located in the present core and northern margin of the westerlies, is driven almost entirely by the wind belt 5 , and can be used to reconstruct its intensity. Rather than varying coherently throughout the Holocene epoch, we find a distinct anti-phasing of wind strength between the core and northern margin over multi-millennial timescales. During the early Holocene, the core westerlies were strong whereas the northern margin westerlies were weak. We observe the opposite pattern in the late Holocene. As this variation resembles modern seasonal variability, we suggest that our observed changes in westerly wind strength can best be explained by variations in sea surface temperature in the eastern South Pacific Ocean.Chile is ideally located to reconstruct past variability of the southern westerly wind belt (SWW) as the SWW almost entirely controls precipitation on the western side of the Andes in southern South America with an extreme north-south rainfall gradient from the semiarid, winter-rain climate in central Chile to yearround hyper-humid conditions in the fjord region of southern Chile 5 (Supplementary Fig. S1). Therefore, any paleoclimatic proxy record primarily controlled by rainfall changes is suitable for reconstructing past changes in the SWW in this region. In present-day austral winters, the SWW extends northward, providing rainfall to central Chile (33 • -40 • S), but zonal winds are reduced in its core zone in southernmost Chile (50 • -55 • S; Fig. 1a). During austral summer, the zonal wind pattern shows a latitudinally more confined and intensified SWW with maxima over southernmost Chile (Fig. 1b). Previous reconstructions of the SWW were primarily based on single sites and generally suggested a northward migration and intensification of the SWW during colder periods 1,2,4 . Intensity variations across the wind belt have only recently been addressed and interpreted in terms of co-varying

show abstract

“…As revealed by Garreaud et al (2013), the humid western side of the Andes exhibits a significantly positive correlation between precipitation and westerly wind strength, while the semi-arid eastern side of the Andes shows a distinct negative correlation. The significance of the relationship between precipitation and westerly wind intensity on the semi-arid leeward side of the southern Andes is in fact not as strong as it is on the windward side (Wagner et al, 2007;Garreaud et al, 2013), likely as a consequence of overall low and variable annual precipitation.…”

Section: Introductionmentioning

confidence: 90%

Climate history of the Southern Hemisphere Westerlies belt during the last glacial–interglacial transition revealed from lake water oxygen isotope reconstruction of Laguna Potrok Aike (52° S, Argentina)

Zhu¹,

Lücke²,

Wissel³

et al. 2014

Clim. Past

View full text Add to dashboard Cite

Abstract. The Southern Hemisphere Westerlies (SHW) play a crucial role in large-scale ocean circulation and global carbon cycling. Accordingly, the reconstruction of how the latitudinal position and intensity of the SHW belt changed during the last glacial termination is essential for understanding global climatic fluctuations. The southernmost part of the South American continent is the only continental mass intersecting a large part of the SHW belt. However, due to the scarcity of suitable palaeoclimate archives continuous proxy records back to the last glacial are rare in southern Patagonia. Here, we show an oxygen isotope record from cellulose and purified bulk organic matter of submerged aquatic moss shoots from Laguna Potrok Aike (52 • S, 70 • W), a deep maar lake located in semi-arid, extra-Andean Patagonia, covering the last glacial-interglacial transition (26 000 to 8500 cal BP). Based on the highly significant correlation between oxygen isotope values of modern aquatic mosses and their host waters and abundant well-preserved moss remains in the sediment record a high-resolution reconstruction of the lake water oxygen isotope (δ 18 O lw−corr ) composition is presented. The reconstructed δ 18 O lw−corr values for the last glacial are ca. 3 ‰ lower than modern values, which can best be explained by generally cooler air temperatures and changes in the moisture source area, together with the occurrence of permafrost leading to a prolonged lake water residence time. Thus, the overall glacial δ 18 O lw−corr level until 21 000 cal BP is consistent with a scenario of weakened or absent SHW at 52 • S compared to the present. During the last deglaciation, reconstructed δ 18 O lw−corr values reveal a significant two-step rise describing the detailed response of the lake's hydrological balance to this fundamental climatic shift. Rapid warming is seen as the cause of the first rise of ca. 2 ‰ in δ 18 O lw−corr during the first two millennia of deglaciation (17 600 to 15 600 cal BP) owing to more 18 O enriched precipitation and increasing temperature-induced evaporation. Following this interpretation, an early strengthening of the SHW would not be necessary. The subsequent decrease in δ 18 O lw−corr by up to 0.7 ‰ marks a millennial-scale transition period between 15 600 and 14 600 cal BP interpreted as the transition from a system driven by temperature-induced evaporation to a system more dominated by wind-induced evaporation. The δ 18 O lw−corr record resumes its pronounced increase around 14 600 cal BP. This further cumulative enrichment in 18 O of lake water could be interpreted as response to strengthened wind-driven evaporation as induced by the intensification and establishment of the SHW at the latitude of Laguna Potrok Aike (52 • S) since 14 600 cal BP.

show abstract

Transient simulations, empirical reconstructions and forcing mechanisms for the Mid-holocene hydrological climate in southern Patagonia

Cited by 60 publications

References 63 publications

The climate in the Baltic Sea region during the last millennium simulated with a regional climate model

The climate in the Baltic Sea region during the last millennium simulated with a regional climate model

Holocene changes in the position and intensity of the southern westerly wind belt

Climate history of the Southern Hemisphere Westerlies belt during the last glacial–interglacial transition revealed from lake water oxygen isotope reconstruction of Laguna Potrok Aike (52° S, Argentina)

Contact Info

Product

Resources

About