Solar irradiance and primary productivity controlled mercury accumulation in sediments of a remote lake in the Southern Hemisphere during the past 4000 years

2017 ◽  
Vol 63 (2) ◽  
pp. 540-549 ◽  
Author(s):  
Harald Biester ◽  
Marta Pérez-Rodríguez ◽  
Benjamin-Silas Gilfedder ◽  
Antonio Martínez Cortizas ◽  
Yvonne-Marie Hermanns
Keyword(s):  
Southern Hemisphere ◽  
Primary Productivity ◽  
Solar Irradiance ◽  
Mercury Accumulation ◽  
The Past ◽  
Remote Lake

scholarly journals Improved estimates of preindustrial biomass burning reduce the magnitude of aerosol climate forcing in the Southern Hemisphere

2021 ◽  
Vol 7 (22) ◽  
pp. eabc1379
Author(s):  
Pengfei Liu ◽  
Jed O. Kaplan ◽  
Loretta J. Mickley ◽  
Yang Li ◽  
Nathan J. Chellman ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Radiative Forcing ◽  
Ice Core ◽  
Ice Cores ◽  
Terrestrial Ecosystems ◽  
Rapid Expansion ◽  
Past Century ◽  
Fire Emissions ◽  
The Past ◽  
Fire Activity

Fire plays a pivotal role in shaping terrestrial ecosystems and the chemical composition of the atmosphere and thus influences Earth’s climate. The trend and magnitude of fire activity over the past few centuries are controversial, which hinders understanding of preindustrial to present-day aerosol radiative forcing. Here, we present evidence from records of 14 Antarctic ice cores and 1 central Andean ice core, suggesting that historical fire activity in the Southern Hemisphere (SH) exceeded present-day levels. To understand this observation, we use a global fire model to show that overall SH fire emissions could have declined by 30% over the 20th century, possibly because of the rapid expansion of land use for agriculture and animal production in middle to high latitudes. Radiative forcing calculations suggest that the decreasing trend in SH fire emissions over the past century largely compensates for the cooling effect of increasing aerosols from fossil fuel and biofuel sources.

scholarly journals Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia

2014 ◽  
Vol 10 (3) ◽  
pp. 1125-1144 ◽  
Author(s):  
B. G. Koffman ◽  
K. J. Kreutz ◽  
D. J. Breton ◽  
E. J. Kane ◽  
D. A. Winski ◽  
...  
Keyword(s):  
Particle Size ◽  
Wind Speed ◽  
Atmospheric Circulation ◽  
Southern Hemisphere ◽  
Zonal Wind ◽  
Ice Core ◽  
Eastern Pacific ◽  
The Past ◽  
West Antarctic ◽  
Lower Elevation

Abstract. We present the first high-resolution (sub-annual) dust particle data set from West Antarctica, developed from the West Antarctic Ice Sheet (WAIS) Divide deep ice core (79.468° S, 112.086° W), and use it to reconstruct changes in atmospheric circulation over the past 2400 years. We find a background dust flux of ~4 mg m−2 year−1 and a mode particle size of 5–8 μm diameter. Through comparing the WAIS Divide record with other Antarctic ice core particle records, we observe that coastal and lower-elevation sites have higher dust fluxes and coarser particle size distributions (PSDs) than sites on the East Antarctic plateau, suggesting input from local dust sources at these lower-elevation sites. In order to explore the use of the WAIS Divide dust PSD as a proxy for past atmospheric circulation, we make quantitative comparisons between both mid-latitude zonal wind speed and West Antarctic meridional wind speed and the dust size record, finding significant positive interannual relationships. We find that the dust PSD is related to mid-latitude zonal wind speed via cyclonic activity in the Amundsen Sea region. Using our PSD record, and through comparison with spatially distributed climate reconstructions from the Southern Hemisphere (SH) middle and high latitudes, we infer that the SH westerlies occupied a more southerly position from circa 1050 to 1400 CE (Common Era), coinciding with the Medieval Climate Anomaly (MCA). Subsequently, at ca. 1430 CE, the wind belt shifted equatorward, where it remained until the mid-to-late twentieth century. We find covariability between reconstructions of El Niño–Southern Oscillation (ENSO) and the mid-latitude westerly winds in the eastern Pacific, suggesting that centennial-scale circulation changes in this region are strongly influenced by the tropical Pacific. Further, we observe increased coarse particle deposition over the past 50 years, consistent with observations that the SH westerlies have been shifting southward and intensifying in recent decades.

Evidence for Lack of Change in Seasonality of Suicide from Timiş County, Romania

2002 ◽  
Vol 94 (3_suppl) ◽  
pp. 1071-1078 ◽  
Author(s):  
Martin Voracek ◽  
Mona Vintilã ◽  
Maryanne L. Fisher ◽  
Paul S. F. Yip
Keyword(s):  
Southern Hemisphere ◽  
Marked Decrease ◽  
Transitional Period ◽  
Communist Regime ◽  
Northern Europe ◽  
The Past ◽  
And Shifts

Evidence from politically and socially stable countries in Northern Europe and the Southern Hemisphere indicates a marked decrease in the seasonality of suicide over the past two decades. Generalizability of this trend to societies in transition has not yet been investigated. Data for suicide by hanging in Timiş County of Romania show both a nondecrease in seasonality of suicide for the current transitional period (1990–98), relative to the last decade of the Communist regime (1980–89) and shifts in location for suicide peak and trough months. Recent decreases in the seasonality of suicide might not generalize to societies in transition, and research would improve from focusing on the “natural laboratories” these societies represent.

Relationship between the Southern Oscillation Index and Australian sugarcane yields

1994 ◽  
Vol 45 (7) ◽  
pp. 1557 ◽  
Author(s):  
I Kuhnel
Keyword(s):  
Southern Hemisphere ◽  
Southern Oscillation Index ◽  
Southern Oscillation ◽  
Significance Testing ◽  
The Past ◽  
Northern Areas ◽  
Eastern Australia ◽  
North Eastern ◽  
Sugarcane Yield ◽  
The Relationship

This study examines the relationship between the Southern Oscillation Index and the sugarcane yield anomalies at 27 mills in north-eastern Australia (Queensland) for the period 1950-1989. The major results of this work indicate that the SO1 alone seems to have only a limited value as predictor of total sugarcane yields over large areas (i.e. the whole of Queensland). However, on a smaller scale, the SO1 appears to be a useful indicator of yields for the northern sugarcane districts. In these northern areas, the highest correlations with the SO1 are reached during the southern hemisphere spring and summer months 6 to 11 months prior to the harvest. They are negative and explain about 40% of the total variance. They also suggest that a positive SO1 during the spring and summer months tends to be followed by lower-than-normal yields at the following harvest and vice versa. This signal is rather robust and withstands rigorous significance testing. Moreover, it appears that the relationship between the SO1 and the sugarcane yields has been relatively strong and stable for the past 40 years, but weakened substantially during the 1930-1940 period.

Predicting the past

2006 ◽  
Vol 27 (3) ◽  
pp. 235-246 ◽  
Author(s):  
Peter Trudgill ◽  
Elizabeth Gordon
Keyword(s):  
19Th Century ◽  
Southern Hemisphere ◽  
English Language ◽  
18Th Century ◽  
American English ◽  
Canadian English ◽  
The Past ◽  
The 19Th Century ◽  
English Canadian

The division of the world’s Englishes into rhotic and non-rhotic types is clearly due to the fact that the former are conservative in not having undergone loss of non-prevocalic /r/, whereas the latter have. The beginnings of the loss of non-prevocalic /r/ in English have generally been dated by historians of the language to the 18th century. It is therefore obvious, and has been widely accepted, that Irish English, Canadian English, and American English are predominantly rhotic because the English language was exported to these colonial areas before the loss of rhoticity in England began; and that the Southern Hemisphere Englishes are non-rhotic because English was exported to these areas in the 19th century after the loss of rhoticity. Analysing newly-discovered data from Australia, we present some surprising evidence that shows that this obvious conclusion is incorrect.

2000 years of marine primary productivity in the Eastern Tropical North Pacific

2020 ◽  
Author(s):  
Christina Treinen-Crespo ◽  
Jose Carriquiry ◽  
Julio Villaescusa ◽  
Elisabet Repiso-Terrones
Keyword(s):  
High Resolution ◽  
Climate Variability ◽  
Primary Productivity ◽  
North Pacific ◽  
Biogenic Silica ◽  
Change Scenario ◽  
The Past ◽  
Past 2000 Years ◽  
Increasing Trend ◽  
Marine Primary Productivity

<p>Changes in marine primary productivity (MPP) over the 21st century are expected to occur under the prevailing climate change scenario. For better understanding of past climate variability, we reconstructed MPP at high resolution (~1-2 years) for the past 2000 years analyzing biogenic silica and total organic carbon (TOC %) on a sediment core collected from Soledad Basin (25°N, 112°W), Baja  California, Mexico. Located in the Eastern Tropical North Pacific, this suboxic basin is ideal for palaeoceanographic reconstructions due to its high sedimentation rate (2 mm/year), which allow us to reconstruct past changes in the ocean and climate at high resolution. Our results show an increasing trend in the variability of MPP for the past 2000 years: biogenic silica content does not show a well-defined trend, but rather it is dominated by strong multidecadal and prominent centennial-scale cycles while TOC (%) shows a slight increasing trend towards the present, starting at least 2000 years ago. Spectral analysis confirms the presence of multidecadal to centennial cycles. These results will be discussed in the context of the Anthropocene and natural climate variability.</p>

scholarly journals Effect of Urban Growth on Aerosol Optical Depth—Tucson, Arizona, 35 Years Later

2014 ◽  
Vol 53 (8) ◽  
pp. 1876-1885 ◽  
Author(s):  
Gouri Prabhakar ◽  
Eric A. Betterton ◽  
W. Conant ◽  
Benjamin M. Herman
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Urban Growth ◽  
Solar Irradiance ◽  
Monthly Variation ◽  
The Past ◽  
Ozone Column

AbstractMultiwavelength solar irradiance measurements between 400 and 900 nm were made on cloudless days in Tucson, Arizona, over a 30-month period between March 2010 and August 2012. They were analyzed to simultaneously retrieve aerosol optical depth (AOD) and ozone column abundance and to examine their monthly variation. These retrievals were compared with results from a similar study done at the same location between 1975 and 1977. The near tripling of population in Tucson over the past 35 years may have contributed to a 19% increase in the AOD, and the annual-mean ozone column abundance was found to be 11% lower than that inferred during the mid-1970s.

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