Suchergebnisse

Context Long-term changes in the breeding phenology of bird communities have been widely studied. For many species, breeding appears to be starting earlier as temperatures increase. For south-eastern Australia, such a trend has not so far been demonstrated. Aims The aim was to determine how the date of laying of the first egg (FE; for sedentary species) or arrival times (for migratory species) responded to climatic factors such as rainfall, air temperature and the Southern Oscillation Index (SOI), and whether FE or arrival time showed a trend through time. Methods The date of laying of the first egg (FE) for 13 sedentary species of birds was recorded over 18 (1975–1984 and 2007–2014) breeding seasons (August to January) at a single site in a coastal forest in south-eastern Australia. The arrival times for seven migratory species were also recorded for these seasons. Key results Linear mixed models showed that FE was negatively correlated with the mean monthly SOI for April to July (A-J SOI), the period directly before the breeding season. Eggs were laid earlier when A-J SOI was positive and later when it was negative. SOIs calculated over different combinations of months showed that those for the January to March period had no influence on FE. FE was not related to minimum or maximum temperatures during April to July, despite increases in temperature between 1975 and 2014, nor was it related to rainfall between April and July. Mixed linear models showed that arrival date for migratory species became earlier between 1975 and 2014, but was uninfluenced by A-J SOI or rainfall. Conclusions Migratory species arrived earlier by 0.27 days per year. However, this was at least an order of magnitude smaller than annual temporal changes in FE for sedentary species (6–7 days) associated with cyclical SOI fluctuations. Changes in SOI dominated the annual breeding phenology of the community. Implications The mechanisms by which A-J SOI influences the timing of nesting may be related to the primary productivity of forests and the influence of this on insect abundance. There are few data on these factors.

Abstract. This study investigates precipitation variability in five regions of Southern Italy (Campania, Apulia, Basilicata, Calabria and Sicily) using a homogeneous database of about 70 rain gauges with more than 50 years of observation. First, a statistical analysis was performed through the Mann-Kendall non-parametric test in order to determine rainfall the trend on both yearly and seasonal scales. Then, the relationship between the rainfall and some teleconnection pattern indexes was investigated using Spearman's test. The results show remarkable statistically significant negative trends for annual and winter aggregations in most part of the series. Moreover, a strong correlation has emerged between the teleconnection patterns and precipitation in Southern Italy, particularly in winter and on the Tyrrhenian side of the study area.

"Comprehensive and up-to-date information on Earth's most dominant year-to-year climate variation The El Niño Southern Oscillation (ENSO) in the Pacific Ocean has major worldwide social and economic consequences through its global scale effects on atmospheric and oceanic circulation, marine and terrestrial ecosystems, and other natural systems. Ongoing climate change is projected to significantly alter ENSO's dynamics and impacts. El Niño Southern Oscillation in a Changing Climate presents the latest theories, models, and observations, and explores the challenges of forecasting ENSO as the climate continues to change. Volume highlights include: Historical background on ENSO and its societal consequences - Review of key El Niño (ENSO warm phase) and La Niña (ENSO cold phase) characteristics - Mathematical description of the underlying physical processes that generate ENSO variations - Conceptual framework for understanding ENSO changes on decadal and longer time scales, including the response to greenhouse gas forcing ENSO impacts on extreme ocean, weather, and climate events, including tropical cyclones, and how ENSO affects fisheries and the global carbon cycle - Advances in modeling, paleo-reconstructions, and operational climate forecasting - Future projections of ENSO and its impacts - Factors influencing ENSO events, such as inter-basin climate interactions and volcanic eruptions"--

The presence of ENSO Events in South America is felt in two ways: a) through its effects on both the atmosphere and ocean systems, and b) through its impacts on natural ecosystems (both marine and terrestrial) and on societal and economical sectors (like fisheries, health, and agriculture). The main effects of El Niño/La Niña are: Increment/Decrement of sea surface temperature and salinity, Increment/Decrement of sea level and wave activity, Increment/Decrement of air temperature and amount of ultra violet radiation reaching the surface of the earth, and Changes in the rainfall and evaporation patterns. It is not easy to make an "average" pattern of ENSO impacts for a variety of reasons: the impacts depend greatly of factors like geographical extent and position of the oceanic anomalies, and intensity and timing of the anomalies; also the influence of social, economic and political structures determines whether climate anomalies caused by ENSO in a particular region will lead to severe societal and economical impacts. The scientific community also plays a potential role in the extent of the impacts that ENSO can produce, if scientists can provide information on the impact of the presence of ENSO by identifying and focusing on its precursors, intervention could be taken early enough. There is however, something to be said against that: information can be misleading, target inappropriate at-risk groups, or generate a false sense of security.

International audience ; The presence of ENSO Events in South America is felt in two ways: a) through its effects on both the atmosphere and ocean systems, and b) through its impacts on natural ecosystems (both marine and terrestrial) and on societal and economical sectors (like fisheries, health, and agriculture). The main effects of El Niño/La Niña are: Increment/Decrement of sea surface temperature and salinity, Increment/Decrement of sea level and wave activity, Increment/Decrement of air temperature and amount of ultra violet radiation reaching the surface of the earth, and Changes in the rainfall and evaporation patterns. It is not easy to make an "average" pattern of ENSO impacts for a variety of reasons: the impacts depend greatly of factors like geographical extent and position of the oceanic anomalies, and intensity and timing of the anomalies; also the influence of social, economic and political structures determines whether climate anomalies caused by ENSO in a particular region will lead to severe societal and economical impacts. The scientific community also plays a potential role in the extent of the impacts that ENSO can produce, if scientists can provide information on the impact of the presence of ENSO by identifying and focusing on its precursors, intervention could be taken early enough. There is however, something to be said against that: information can be misleading, target inappropriate at-risk groups, or generate a false sense of security.

The presence of ENSO Events in South America is felt in two ways: a) through its effects on both the atmosphere and ocean systems, and b) through its impacts on natural ecosystems (both marine and terrestrial) and on societal and economical sectors (like fisheries, health, and agriculture). The main effects of El Niño/La Niña are: Increment/Decrement of sea surface temperature and salinity, Increment/Decrement of sea level and wave activity, Increment/Decrement of air temperature and amount of ultra violet radiation reaching the surface of the earth, and Changes in the rainfall and evaporation patterns. It is not easy to make an "average" pattern of ENSO impacts for a variety of reasons: the impacts depend greatly of factors like geographical extent and position of the oceanic anomalies, and intensity and timing of the anomalies; also the influence of social, economic and political structures determines whether climate anomalies caused by ENSO in a particular region will lead to severe societal and economical impacts. The scientific community also plays a potential role in the extent of the impacts that ENSO can produce, if scientists can provide information on the impact of the presence of ENSO by identifying and focusing on its precursors, intervention could be taken early enough. There is however, something to be said against that: information can be misleading, target inappropriate at-risk groups, or generate a false sense of security.

Abstract
The relationship between El Niño–Southern Oscillation (ENSO) and the transatlantic slave trade (TAST) is examined using the Slave Voyages dataset and several reconstructed ENSO indices. The ENSO indices are used as a proxy for West African rainfall and temperature. In the Sahel, the El Niño (warm) phase of ENSO is associated with less rainfall and warmer temperatures, whereas the La Niña (cold) phase of ENSO is associated with more rainfall and cooler temperatures. The association between ENSO and the TAST is weak but statistically significant at a 2-yr lag. In this case, El Niño (drier and warmer) years are associated with a decrease in the export of enslaved Africans. The response of the TAST to El Niño is explained in terms of the societal response to agricultural stresses brought on by less rainfall and warmer temperatures. ENSO-induced changes to the TAST are briefly discussed in light of climate-induced movements of peoples in centuries past and the drought-induced movement of peoples in the Middle East today.
Significance Statement
The transatlantic slave trade was driven by economic and political forces, subject to the vagaries of the weather; it spanned two hemispheres and four continents and lasted more than 400 years. In this study we show that El Niño–Southern Oscillation, and its proxy association with West African rainfall and temperature, are significantly associated with the number of enslaved Africans that were transported from West Africa to the Americas. Lessons learned from the effects of weather and climate on the transatlantic slave trade reverberate today: extreme weather and climate change will continue to catalyze and amplify human conflict and migrations.

It is well established that El Niño–Southern Oscillation (ENSO) impacts the North Atlantic–European (NAE) climate, with the strongest influence in winter. In late winter, the ENSO signal travels via both tropospheric and stratospheric pathways to the NAE sector and often projects onto the North Atlantic Oscillation. However, this signal does not strengthen gradually during winter, and some studies have suggested that the ENSO signal is different between early and late winter and that the teleconnections involved in the early winter subperiod are not well understood. In this study, we investigate the ENSO teleconnection to NAE in early winter (November–December) and characterize the possible mechanisms involved in that teleconnection. To do so, observations, reanalysis data and the output of different types of model simulations have been used. We show that the intraseasonal winter shift of the NAE response to ENSO is detected for both El Niño and La Niña and is significant in both observations and initialized predictions, but it is not reproduced by free-running Coupled Model Intercomparison Project phase 5 (CMIP5) models. The teleconnection is established through the troposphere in early winter and is related to ENSO effects over the Gulf of Mexico and Caribbean Sea that appear in rainfall and reach the NAE region. CMIP5 model biases in equatorial Pacific ENSO sea surface temperature patterns and strength appear to explain the lack of signal in the Gulf of Mexico and Caribbean Sea and, hence, their inability to reproduce the intraseasonal shift of the ENSO signal over Europe. ; B.A. and M.P.B. were supported by the Natural Environment Research Council Grant NE/M006123/1, the European Project 398 603557- STRATOCLIM. B.A. was also funded by ''Ayudas para la contratación de personal posdoctoral de formación en docencia e investigación en los departamentos de la Universidad Complutense de Madrid.'' S.I. was supported by the PRIMAVERA project, funded by the European Union's Horizon 2020 Programme, Grant Agreement 641727. A.S. and N.D. were supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). ; Peer reviewed