scholarly journals Climate-induced variability in South Atlantic wave direction over the past three millennia

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
A. P. Silva ◽  
A. H. F. Klein ◽  
A. F. H. Fetter-Filho ◽  
C. J. Hein ◽  
F. J. Méndez ◽  
...  
Keyword(s):  
Global Climate ◽  
Southern Annular Mode ◽  
Wave Climate ◽  
Wave Generation ◽  
South Atlantic ◽  
Wave Direction ◽  
Global Climate Changes ◽  
Ocean Wave Climate ◽  
Forcing Mechanisms

Abstract Through alteration of wave-generating atmospheric systems, global climate changes play a fundamental role in regional wave climate. However, long-term wave-climate cycles and their associated forcing mechanisms remain poorly constrained, in part due to a relative dearth of highly resolved archives. Here we use the morphology of former shorelines preserved in beach-foredune ridges (BFR) within a protected embayment to reconstruct changes in predominant wave directions in the Subtropical South Atlantic during the last ~ 3000 years. These analyses reveal multi-centennial cycles of oscillation in predominant wave direction in accordance with stronger (weaker) South Atlantic mid- to high-latitudes mean sea-level pressure gradient and zonal westerly winds, favouring wave generation zones in higher (lower) latitudes and consequent southerly (easterly) wave components. We identify the Southern Annular Mode as the primary climate driver responsible for these changes. Long-term variations in interhemispheric surface temperature anomalies coexist with oscillations in wave direction, which indicates the influence of temperature-driven atmospheric teleconnections on wave-generation cycles. These results provide a novel geomorphic proxy for paleoenvironmental reconstructions and present new insights into the role of global multi-decadal to multi-centennial climate variability in controlling coastal-ocean wave climate.

scholarly journals Beach-foredune ridges as proxies for climate-induced wave direction changes in South Atlantic during Late Holocene

2020 ◽  
Author(s):  
Ana Paula Da Silva ◽  
Antonio Henrique da Fontoura Klein ◽  
Antonio Fernando Harter Fetter Filho ◽  
Christopher Hein ◽  
Fernando Mendez ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Wave Climate ◽  
South Atlantic ◽  
Wave Direction ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Easterly Wave ◽  
Wave Energy Flux

<p>Variability in global wave climate has been observed to occur in response to climate changes influencing the wave-generating zones. This highlights the need for an improved understanding of long-term wave-climate cycles, considering the multi-decadal variability of the atmospheric patterns and large-scale climate drivers. In this study, a novel use of the morphology of former shorelines preserved in beach-foredune ridges was applied to reconstruct changes in predominant wave directions in the Subtropical South Atlantic during the Late Holocene. A 3km wide semi-continuous sequence of beach-foredune ridges preserved within the Pinheira Strandplain (Santa Catarina State, Brazil) was mapped in order to extract the orientation of the former shorelines and derive a 3000-year record of inferred mean wave direction. The mean wave direction series was compared to ~1000 years of decadal means of mid-latitude mean sea-level pressure gradients (∆MSLP) and zonal westerly wind velocities estimated from the CESM1-CAM5 “Last Millennium Ensemble (LME)”, and to 2000 years of air-surface temperature anomalies for Southern Hemisphere. Results showed that multi-centennial cycles of oscillation in predominant wave direction occurred in accordance with stronger (weaker) South Atlantic mid-latitude mean sea-level pressure and zonal westerlies winds, favouring wave generation zones in higher (lower) latitudes and consequent southerly (easterly) wave climate dominance. It was identified the Southern Annular Mode as the main climate driver responsible for these changes, responding for 43% of the variance in the Subtropical South Atlantic atmospheric patterns in the last 1000 years. Long-term variations in interhemispheric air-surface temperature offsets, coincident with oscillations in wave direction, may have influenced wave-generation patterns similarly to the seasonal behaviour observed over recent decades. Periods of relatively warmer Southern Hemisphere (SH) as compared with Northern Hemisphere (NH) (e.g., during 400–800 CE and the Little Ice Age) favours the predominance of easterly wave energy flux along the eastern South American coast, whereas periods with equivalent NH-SH temperature anomalies (e.g., Medieval Warm Period) or with colder relative SH (last ~150 years) support an increase in the influence of the southerly wave energy flux over the South Atlantic. These results provide a novel geomorphic proxy for paleoenvironmental reconstructions and present new insights into the role of multi-decadal to multi-centennial climate variability on controlling coastal ocean wave climate.</p>

scholarly journals Meridional changes in the South Atlantic Subtropical Gyre during Heinrich Stadials

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tainã M. L. Pinho ◽  
Cristiano M. Chiessi ◽  
Rodrigo C. Portilho-Ramos ◽  
Marília C. Campos ◽  
Stefano Crivellari ◽  
...  
Keyword(s):  
Global Climate ◽  
South Atlantic ◽  
Subtropical Gyre ◽  
Climate System ◽  
The South ◽  
Foraminiferal Species ◽  
Ocean Gyres ◽  
Long Term Monitoring ◽  
Term Monitoring

AbstractSubtropical ocean gyres play a key role in modulating the global climate system redistributing energy between low and high latitudes. A poleward displacement of the subtropical gyres has been observed over the last decades, but the lack of long-term monitoring data hinders an in-depth understanding of their dynamics. Paleoceanographic records offer the opportunity to identify meridional changes in the subtropical gyres and investigate their consequences to the climate system. Here we use the abundance of planktonic foraminiferal species Globorotalia truncatulinodes from a sediment core collected at the northernmost boundary of the South Atlantic Subtropical Gyre (SASG) together with a previously published record of the same species from the southernmost boundary of the SASG to reconstruct meridional fluctuations of the SASG over last ca. 70 kyr. Our findings indicate southward displacements of the SASG during Heinrich Stadials (HS) 6-4 and HS1, and a contraction of the SASG during HS3 and HS2. During HS6-4 and HS1, the SASG southward displacements likely boosted the transfer of heat to the Southern Ocean, ultimately strengthening deep-water upwelling and CO2 release to the atmosphere. We hypothesize that the ongoing SASG poleward displacement may further increase oceanic CO2 release.

scholarly journals Trend analysis of wave storminess: wave direction and its impact on harbour agitation

2010 ◽  
Vol 10 (11) ◽  
pp. 2327-2340 ◽  
Author(s):  
M. Casas-Prat ◽  
J. P. Sierra
Keyword(s):  
Energy Content ◽  
Temporal Trends ◽  
Wave Climate ◽  
Maximum Energy ◽  
Wave Direction ◽  
The South ◽  
Wave Hindcast ◽  
Catalan Coast ◽  
Northwestern Mediterranean Sea

Abstract. In the context of wave climate variability, long-term alterations in the wave storminess pattern of the Catalan coast (northwestern Mediterranean Sea) are analysed in terms of wave energy content and wave direction, on the basis of wave hindcast data (from 44-year time series). In general, no significant temporal trends are found for annual mean and maximum energy. However, the same analysis carried out separately for different wave directions reveals a remarkable increase in the storm energy of events from the south, which is partly due to a rise in the annual percentage of such storms. A case study of Tarragona Port (on the southern Catalan coast) highlights the importance of including changes in wave direction in the study of potential impacts of climate change. In particular, an increase in the frequency of storms from the south leads to greater agitation inside the Port.

scholarly journals Hominin responses to environmental changes during the Middle Pleistocene in central and southern Italy

2013 ◽  
Vol 9 (2) ◽  
pp. 687-697 ◽  
Author(s):  
R. Orain ◽  
V. Lebreton ◽  
E. Russo Ermolli ◽  
A.-M. Sémah ◽  
S. Nomade ◽  
...  
Keyword(s):  
Western Europe ◽  
Southern Italy ◽  
Environmental Changes ◽  
Global Climate ◽  
Middle Pleistocene ◽  
Faunal Remains ◽  
Vegetation Dynamic ◽  
Local Climate ◽  
Global Climate Changes

Abstract. The palaeobotanical record of early Palaeolithic sites from Western Europe indicates that hominins settled in different kinds of environments. During the "mid-Pleistocene transition (MPT)", from about 1 to 0.6 Ma, the transition from 41- to 100-ka dominant climatic oscillations, occurring within a long-term cooling trend, was associated with an aridity crisis which strongly modified the ecosystems. Starting from the MPT the more favourable climate of central and southern Italy provided propitious environmental conditions for long-term human occupations even during the glacial times. In fact, the human strategy of territory occupation was certainly driven by the availabilities of resources. Prehistoric sites such as Notarchirico (ca. 680–600 ka), La Pineta (ca. 600–620 ka), Guado San Nicola (ca. 380–350 ka) or Ceprano (ca. 345–355 ka) testify to a preferential occupation of the central and southern Apennines valleys during interglacial phases, while later interglacial occupations were oriented towards the coastal plains, as attested by the numerous settlements of the Roma Basin (ca. 300 ka). Faunal remains indicate that human subsistence behaviours benefited from a diversity of exploitable ecosystems, from semi-open to closed environments. In central and southern Italy, several palynological records have already illustrated the regional- and local-scale vegetation dynamic trends. During the Middle Pleistocene climate cycles, mixed mesophytic forests developed during the interglacial periods and withdrew in response to increasing aridity during the glacial episodes. New pollen data from the Boiano Basin (Molise, Italy) attest to the evolution of vegetation and climate between MIS 13 and 9 (ca. 500 to 300 ka). In this basin the persistence of high edaphic humidity, even during the glacial phases, could have favoured the establishment of a refuge area for the arboreal flora and provided subsistence resources for the animal and hominin communities during the Middle Pleistocene. This could have constrained human groups to migrate into such a propitious area. Regarding the local climate evolution during the glacial episodes, the supposed displacement from these sites could be linked to the environmental dynamics solely due to the aridity increase, rather than directly to the global climate changes.

scholarly journals Anomalously warm temperatures are associated with increased injury deaths

2020 ◽  
Vol 26 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Robbie M. Parks ◽  
James E. Bennett ◽  
Helen Tamura-Wicks ◽  
Vasilis Kontis ◽  
Ralf Toumi ◽  
...  
Keyword(s):  
Global Climate ◽  
Credible Interval ◽  
Targeted Interventions ◽  
Global Climate Changes ◽  
Monthly Temperature ◽  
Temporal Model ◽  
Spatio Temporal ◽  
Paris Climate Agreement ◽  
Local Average

AbstractTemperatures that deviate from the long-term local norm affect human health, and are projected to become more frequent as the global climate changes1. There are limited data on how such anomalies affect deaths from injuries. In the present study, we used data on mortality and temperature over 38 years (1980–2017) in the contiguous USA and formulated a Bayesian spatio-temporal model to quantify how anomalous temperatures, defined as deviations of monthly temperature from the local average monthly temperature over the entire analysis period, affect deaths from unintentional (transport, falls and drownings) and intentional (assault and suicide) injuries, by age group and sex. We found that a 1.5 °C anomalously warm year, as envisioned under the Paris Climate Agreement2, would be associated with an estimated 1,601 (95% credible interval 1,430–1,776) additional injury deaths. Of these additional deaths, 84% would occur in males, mostly in adolescence to middle age. These would comprise increases in deaths from drownings, transport, assault and suicide, offset partly by a decline in deaths from falls in older ages. The findings demonstrate the need for targeted interventions against injuries during periods of anomalously warm temperatures, especially as these episodes are likely to increase with global climate change.

scholarly journals Agriculture Adaptation to Consequences of Global Climate Changes

2021 ◽  
Vol 18 (2) ◽  
pp. 13-20
Author(s):  
D. G. Galkin
Keyword(s):  
Climate Change ◽  
Agricultural Production ◽  
Climate Changes ◽  
Greenhouse Gas Emission ◽  
Traditional Approach ◽  
Global Climate ◽  
Global Climate Changes ◽  
Change Impact ◽  
Agriculture Development

The goal of the article is to work out recommendations aimed at providing sustainability of agriculture development on the level of national economy in conditions of changing climate. The agriculture development within the frames of traditional approach can be studied in two aspects: as a sector subjected to the global climate change impact; as a sector promoting climate change due to greenhouse gas emission. The authors showed that in regard to present trends scientific recommendations aimed at agriculture adaptation to climate changes are the most significant for Russia. On the basis of provided concepts they identified key lines in the said adaptation: to develop innovation connected with adaptation to consequences of climate changes; to upgrade the system of agro-insurance; to use methods of organic food production; to monitor and appraise adaptation of agriculture to climate changes; to introduce strategic planning of sustainable development and location of agricultural production. These lines should be realized on the basis of integrity, strategic orientation and scientific support of agricultural production. These lines can stabilize the level of key parameters of the sector in the long-term perspective.

Asian paleoenvironments, paleogeography and paleobiodiversity interactions during the Greenhouse-Icehouse transition

2020 ◽  
Author(s):  
Guillaume Dupont-Nivet ◽  
Niels Meijer ◽  
Mustafa Kaya ◽  
Jan Westerweel ◽  
Delphine Tardif ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Climate Modeling ◽  
Global Climate ◽  
Sedimentary Records ◽  
Driving Mechanisms ◽  
Magmatic Rocks ◽  
History Of ◽  
Pollen Grain Size ◽  
Forcing Mechanisms

<p>The ongoing surge of international research on Asian Climate and Tectonics enables to better assess interactions between forcing mechanisms (global climate, India-Asia collision, Tibetan Plateau growth) and paleoenvironmental changes (monsoons, aridification), land-sea distribution, surface processes, paleobiogeographic evolution and the global carbon cycle. We review here the progress of the ERC MAGIC project (Monsoons in Asia caused Greenhouse to Icehouse Change?) integrating regional geodynamic constraints, well-dated environmental / biodiversity records and climate modeling. MAGIC focuses on the Paleogene period that includes the global Greenhouse to Icehouse cooling, the early collision and plateau growth and associated regional development of monsoons and westerlies over the Proto-Paratethys sea. Our work focuses on three areas constraining Asian paleoenvironments. (1) In Myanmar, paleomagnetic results, new dating of magmatic rocks and sediments along with additional detrital geochronology and basin analysis of the Burmese subduction margin and implications for the history of India-Asia convergence. (2) Along the Northeastern Tibetan Plateau margin, the combination of multiple proxies (leaf wax stable isotope, pollen, grain size, etc…)  applied to an extended lacustrine Paleogene record enables to identify precisely Asian climate changes and their consequences on ecosystems. (3) In westernmost China and Tajikistan, the proto-Paratethys sea fluctuations and the sedimentary records of Pamir tectonic evolution are now precisely dated enabling to constrain driving mechanisms and paleoenvironmental consequences. Together these results are used to constrain climate modeling experiments which permit validation of hypotheses on interactions between paleogeography, paleoenvironments and paleobiodiversity at Asian and global scales in response to long-term and short-term events.</p>

scholarly journals High-latitude obliquity forcing drives the agulhas leakage

2011 ◽  
Vol 7 (3) ◽  
pp. 2193-2215 ◽  
Author(s):  
T. Caley ◽  
J.-H. Kim ◽  
B. Malaizé ◽  
J. Giraudeau ◽  
T. Laepple ◽  
...  
Keyword(s):  
High Latitude ◽  
Decadal Variability ◽  
Global Climate ◽  
Decisive Role ◽  
Meridional Overturning Circulation ◽  
Climate Forcing ◽  
Meridional Overturning ◽  
The Indian Ocean ◽  
Forcing Mechanisms

Abstract. The Agulhas Current (AC) transport of heat and salt from the Indian Ocean into the South Atlantic around South Africa (Agulhas leakage), has a profound role in the decadal variability of the Atlantic meridional overturning circulation (AMOC), which influences global climate. On glacial-interglacial timescales, paleostudies postulate that Agulhas leakage plays a decisive role for AMOC resumption during terminations (glacial-interglacial transitions). However, efforts to elucidate forcing mechanisms connecting Agulhas leakage with glacial-interglacial AMOC variability have been hampered due to a lack of climate records extracted from the area where the AC originates. Here we present 800-kyr sea surface temperature (SST) and salinity (SSS) records from the "precursor" region of the AC. These records contain strong obliquity-driven 41-kyr cycles, nearly in phase with changes in annual mean insolation and air temperature at high southern latitudes. In contrast, precession-driven cycles were negligible in our SST records, which is surprising given the low-latitude location of the Agulhas leakage. Together, this suggests that long-term Agulhas leakage dynamics are associated with a high latitude rather than a tropical climate forcing mechanism, probably by varying the position of the Southern Hemisphere subtropical convergence (STC) and its associated westerlies. We argue that during terminations stronger Agulhas leakage was triggered by increased obliquity exerting a positive feedback on the global climate system through modulating long-term AMOC variations.

scholarly journals Hominin responses to environmental changes during the Middle Pleistocene in Central and Southern Italy

2012 ◽  
Vol 8 (5) ◽  
pp. 5181-5207 ◽  
Author(s):  
R. Orain ◽  
V. Lebreton ◽  
E. Russo Ermolli ◽  
A.-M. Sémah ◽  
S. Nomade ◽  
...  
Keyword(s):  
Western Europe ◽  
Southern Italy ◽  
Environmental Changes ◽  
Global Climate ◽  
Middle Pleistocene ◽  
Faunal Remains ◽  
Vegetation Dynamic ◽  
Local Climate ◽  
Global Climate Changes

Abstract. The palaeobotanical record of early Palaeolithic sites from Western Europe indicates that hominins settled in different kinds of environments. During the "Mid-Pleistocene Transition (MPT)", from about 1 to 0.6 Ma, the transition from 41-ka to 100-ka dominant climatic oscillations, occurring within a long-term cooling trend, was associated with an aridity crisis which strongly modified the ecosystems. Starting from the MPT the more favorable climate of central and southern Italy provided propitious environmental conditions for long-term human occupations even during the glacial times. In fact, the human strategy of territory occupation was certainly driven by the availabilities of resources. Prehistoric sites such as Notarchirico (ca. 680–600 ka), La Pineta (ca. 600–620 ka), Gaudo San Nicola (ca. 380–350 ka) or Ceprano (ca. 345–355 ka) testify to a preferential occupation of the central and southern Apennines valleys during interglacial phases, while later interglacial occupations were oriented towards the coastal plains, as attested by the numerous settlements of the Roma basin (ca. 300 ka). Faunal remains indicate that human subsistence behaviors benefited of a diversity of exploitable ecosystems, from semi-open to closed environments. In central and southern Italy, several palynological records have already illustrated the regional and local scale vegetation dynamic trends. During the Middle Pleistocene climate cycles, mixed mesophytic forests developed during the interglacial periods and withdrew in response to increasing aridity during the glacial episodes. New pollen data from the Boiano basin (Molise, Italy), attest to the evolution of vegetation and climate between OIS 13 and 9 (ca. 500 to 300 ka). In this basin, the persistence of high edaphic humidity, even during the glacial phases, could have favored the establishment of a refuge area for the arboreal flora and provided subsistence resources for the animal and hominin communities during the Middle Pleistocene. This could have constrained human groups to migrate into such a propitious area. Regarding to the local climate evolution during the glacial episodes, the supposed displacement from these sites could be linked to the environmental dynamics solely due to the aridity increase rather than directly to the global climate changes.

Sign in / Sign up

Export Citation Format

Share Document