An early Miocene extinction in pelagic sharks

Science ◽  
2021 ◽  
Vol 372 (6546) ◽  
pp. 1105-1107
Author(s):  
Elizabeth C. Sibert ◽  
Leah D. Rubin
Keyword(s):  
Global Climate ◽  
Morphological Diversity ◽  
Open Ocean ◽  
Early Miocene ◽  
Transformative Change ◽  
Marine Predator ◽  
Climate Event ◽  
Predator Abundance ◽  
Abundance And Diversity

Shark populations have been decimated in recent decades because of overfishing and other anthropogenic stressors; however, the long-term impacts of such changes in marine predator abundance and diversity are poorly constrained. We present evidence for a previously unknown major extinction event in sharks that occurred in the early Miocene, ~19 million years ago. During this interval, sharks virtually disappeared from open-ocean sediments, declining in abundance by >90% and morphological diversity by >70%, an event from which they never recovered. This abrupt extinction occurred independently from any known global climate event and ~2 million to 5 million years before diversifications in the highly migratory, large-bodied predators that dominate pelagic ecosystems today, indicating that the early Miocene was a period of rapid, transformative change for open-ocean ecosystems.

scholarly journals Antarctic ice sheet and oceanographic response to eccentricity forcing during the early Miocene

2011 ◽  
Vol 7 (3) ◽  
pp. 869-880 ◽  
Author(s):  
D. Liebrand ◽  
L. J. Lourens ◽  
D. A. Hodell ◽  
B. de Boer ◽  
R. S. W. van de Wal ◽  
...  
Keyword(s):  
Global Climate ◽  
Ice Sheet ◽  
Early Miocene ◽  
High Temporal Resolution ◽  
Short Term ◽  
Antarctic Ice Sheet ◽  
Oxygen Isotope Record ◽  
Isotope Record ◽  
The Antarctic

Abstract. Stable isotope records of benthic foraminifera from ODP Site 1264 in the southeastern Atlantic Ocean are presented which resolve the latest Oligocene to early Miocene (~24–19 Ma) climate changes at high temporal resolution (<3 kyr). Using an inverse modelling technique, we decomposed the oxygen isotope record into temperature and ice volume and found that the Antarctic ice sheet expanded episodically during the declining phase of the long-term (~400 kyr) eccentricity cycle and subsequent low short-term (~100 kyr) eccentricity cycle. The largest glaciations are separated by multiple long-term eccentricity cycles, indicating the involvement of a non-linear response mechanism. Our modelling results suggest that during the largest (Mi-1) event, Antarctic ice sheet volume expanded up to its present-day configuration. In addition, we found that distinct ~100 kyr variability occurs during the termination phases of the major Antarctic glaciations, suggesting that climate and ice-sheet response was more susceptible to short-term eccentricity forcing at these times. During two of these termination-phases, δ18O bottom water gradients in the Atlantic ceased to exist, indicating a direct link between global climate, enhanced ice-sheet instability and major oceanographic reorganisations.

On Climate Change Risks of Long-Term Socio-Economic Development in Russia

2019 ◽  
pp. 79-95
Author(s):  
N.E. Terentiev
Keyword(s):  
Climate Change ◽  
Economic Development ◽  
Technological Innovation ◽  
Global Climate Change ◽  
Global Climate ◽  
Climate Risk ◽  
Climate Change Risks ◽  
Socio Economic Development ◽  
Management Policies

Based on the latest data, paper investigates the dynamics of global climate change and its impact on economic growth in the long-term. The notion of climate risk is considered. The main directions of climate risk management policies are analyzed aimed, first, at reducing anthropogenic greenhouse gas emissions through technological innovation and structural economic shifts; secondly, at adaptation of population, territories and economic complexes to the irreparable effects of climate change. The problem of taking into account the phenomenon of climate change in the state economic policy is put in the context of the most urgent tasks of intensification of long-term socio-economic development and parrying strategic challenges to the development of Russia.

scholarly journals Global climatology and trends in convective environments from ERA5 and rawinsonde data

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mateusz Taszarek ◽  
John T. Allen ◽  
Mattia Marchio ◽  
Harold E. Brooks
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Global Climate Models ◽  
Convective Precipitation ◽  
The Past ◽  
The Tropics ◽  
Rawinsonde Data

AbstractGlobally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

scholarly journals Biodiversity of butterflies in endosulfan-affected areas of Kerala, India

2020 ◽  
Vol 81 (1) ◽  
Author(s):  
K. N. Raghavendra ◽  
Kumar Arvind ◽  
G. K. Anushree ◽  
Tony Grace
Keyword(s):  
Monsoon Season ◽  
Winter Season ◽  
Wiener Index ◽  
Long Term Effects ◽  
Affected Area ◽  
Butterfly Assemblages ◽  
Abundance And Diversity ◽  
The One ◽  
One Way Anova

Abstract Background Butterflies are considered as bio-indicators of a healthy and diversified ecosystem. Endosulfan was sprayed indiscriminately in large plantations of Kasaragod district, Kerala which had caused serious threats to the ecosystem. In this study, we surveyed the butterflies for their abundance and diversity in three differentially endosulfan-affected areas viz., Enmakaje—highly affected area, Periye—moderately affected area, Padanakkad—unaffected area, carried out between the end of the monsoon season and the start of the winter season, lasting approximately 100 days. Seven variables viz., butterfly abundance (N), species richness (S), Simpson’s reciprocal index (D), the Shannon–Wiener index (H′), the exponential of the Shannon–Wiener index (expH′), Pielou’s evenness (J) and species evenness (D/S), related to species diversity were estimated, followed by the one-way ANOVA (F = 25.01, p < 0.001) and the Kruskal-Wallis test (H = 22.59, p < 0.001). Results A population of three different butterfly assemblages comprised of 2300 butterflies which represented 61 species were encountered. Our results showed that Enmakaje displayed significantly lower butterfly diversity and abundance, compared to the other two communities. Conclusion So far, this is the first study concerning the effect of endosulfan on the biodiversity of butterfly in the affected areas of Kasaragod, Kerala, India. This study may present an indirect assessment of the persisting effects of endosulfan in the affected areas, suggesting its long-term effects on the ecosystem.

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 Techniques for analyses of trends in GRUAN data

2015 ◽  
Vol 8 (4) ◽  
pp. 1673-1684 ◽  
Author(s):  
G. E. Bodeker ◽  
S. Kremser
Keyword(s):  
Measurement Uncertainty ◽  
Trend Analysis ◽  
Global Climate ◽  
Regional Climate ◽  
Added Value ◽  
Least Squares Regression ◽  
Target Uncertainty ◽  
Reference Quality ◽  
Measurement Uncertainties

Abstract. The Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) provides reference quality RS92 radiosonde measurements of temperature, pressure and humidity. A key attribute of reference quality measurements, and hence GRUAN data, is that each datum has a well characterized and traceable estimate of the measurement uncertainty. The long-term homogeneity of the measurement records, and their well characterized uncertainties, make these data suitable for reliably detecting changes in global and regional climate on decadal time scales. Considerable effort is invested in GRUAN operations to (i) describe and analyse all sources of measurement uncertainty to the extent possible, (ii) quantify and synthesize the contribution of each source of uncertainty to the total measurement uncertainty, and (iii) verify that the evaluated net uncertainty is within the required target uncertainty. However, if the climate science community is not sufficiently well informed on how to capitalize on this added value, the significant investment in estimating meaningful measurement uncertainties is largely wasted. This paper presents and discusses the techniques that will need to be employed to reliably quantify long-term trends in GRUAN data records. A pedagogical approach is taken whereby numerical recipes for key parts of the trend analysis process are explored. The paper discusses the construction of linear least squares regression models for trend analysis, boot-strapping approaches to determine uncertainties in trends, dealing with the combined effects of autocorrelation in the data and measurement uncertainties in calculating the uncertainty on trends, best practice for determining seasonality in trends, how to deal with co-linear basis functions, and interpreting derived trends. Synthetic data sets are used to demonstrate these concepts which are then applied to a first analysis of temperature trends in RS92 radiosonde upper air soundings at the GRUAN site at Lindenberg, Germany (52.21° N, 14.12° E).

Calcareous nannoplankton ecology and community change across the Paleocene-Eocene Thermal Maximum

Paleobiology ◽  
10.1666/12050 ◽  
2013 ◽  
Vol 39 (4) ◽  
pp. 628-647 ◽  
Author(s):  
Leah J. Schneider ◽  
Timothy J. Bralower ◽  
Lee R. Kump ◽  
Mark E. Patzkowsky
Keyword(s):  
Nutrient Availability ◽  
Multivariate Analyses ◽  
Geochemical Modeling ◽  
Community Change ◽  
Open Ocean ◽  
Data Set ◽  
Long Term Effect ◽  
Term Change ◽  
Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM; ca. 55.8 Ma) is thought to coincide with a profound but entirely transient change among nannoplankton communities throughout the ocean. Here we explore the ecology of nannoplankton during the PETM by using multivariate analyses of a global data set that is based upon the distribution of taxa in time and space. We use these results, coupled with stable isotope data and geochemical modeling, to reinterpret the ecology of key genera. The results of the multivariate analyses suggest that the community was perturbed significantly in coastal and high-latitudes sites compared to the open ocean, and the relative influence of temperature and nutrient availability on the assemblage varies regionally. The open ocean became more stratified and less productive during the PETM and the oligotrophic assemblage responded primarily to changes in nutrient availability. Alternatively, assemblages at the equator and in the Southern Ocean responded to temperature more than to nutrient reduction. In addition, the assemblage change at the PETM was not merely transient—there is evidence of adaptation and a long-term change in the nannoplankton community that persists after the PETM and results in the disappearance of a high-latitude assemblage. The long-term effect on communities caused by transient warming during the PETM has implications for modern-day climate change, suggesting similar permanent changes to nannoplankton community structure as the oceans warm.

Potentials for increasing resident wellbeing in energy renovation of multi-family social housing

2021 ◽  
pp. 1420326X2110398
Author(s):  
S. R. Jensen ◽  
C. Gabel ◽  
S. Petersen ◽  
P. H. Kirkegaard
Keyword(s):  
Mixed Methods ◽  
Built Environment ◽  
Social Housing ◽  
Global Climate ◽  
Perceived Health ◽  
Added Value ◽  
Design Processes ◽  
Mixed Methods Approach ◽  
Social Wellbeing

The paper explores potentials for increasing residents' wellbeing in multi-family social housing (MSH) undergoing energy renovation. The renovation measures needed to reach national and global climate goals are often not financially feasible when viewed in isolation. Therefore, it is relevant to identify potentials for added value, which can justify more extensive measures. This paper is based on the hypothesis that every renovation project holds potentials for added value in terms of increased resident wellbeing. Further, that it is crucial to extend current understandings of wellbeing beyond single, quantitative wellbeing parameters in order to promote more holistic, long-term sustainable renovation solutions. The paper sheds light on potentials for increased resident wellbeing based on an analysis of residents’ experience and satisfaction with gestures in the existing built environment and comparing these findings to their perceived health. The analysis is based on data collected through a mixed-methods approach in three MSH areas facing extensive renovation. The findings demonstrate and exemplify that energy renovation measures may influence a number of interrelated physiological, mental and social wellbeing aspects across scales. As such, the paper contributes with new insights, which can help promote previously neglected aspects of resident wellbeing in future energy renovation design processes.

scholarly journals Testing Farmers’ Perception of Climate Variability: A Case Study from Kirtipur of Kathmandu Valley

2012 ◽  
pp. 30-34
Author(s):  
Jiban Mani Poudel
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
Global Climate ◽  
Climatic Variability ◽  
Global Perspective ◽  
Kathmandu Valley ◽  
Climatic Fluctuations ◽  
Climate Fluctuations ◽  
Global And Local

In the 21st century, global climate change has become a public and political discourse. However, there is still a wide gap between global and local perspectives. The global perspective focuses on climate fluctuations that affect the larger region; and their analysis is based on long-term records over centuries and millennium. By comparison, local peoples’ perspectives vary locally, and local analyses are limited to a few days, years, decades and generations only. This paper examines how farmers in Kirtipur of Kathmandu Valley, Nepal, understand climate variability in their surroundings. The researcher has used a cognized model to understand farmers’ perception on weather fluctuations and climate change. The researcher has documented several eyewitness accounts of farmers about weather fluctuations which they have been observing in a lifetime. The researcher has also used rainfall data from 1970-2009 to test the accuracy of perceptions. Unlike meteorological analyses, farmers recall and their understanding of climatic variability by weather-crop interaction, and events associating with climatic fluctuations and perceptions are shaped by both physical visibility and cultural frame or belief system.DOI: http://dx.doi.org/10.3126/hn.v11i1.7200 Hydro Nepal Special Issue: Conference Proceedings 2012 pp.30-34

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