5. Early hominins

2019 ◽  
pp. 60-72
Author(s):  
Bernard Wood
Keyword(s):  
Climatic Changes ◽  
Hominin Evolution ◽  
The Earth ◽  
Candidate Species ◽  
Cooling Trend ◽  
Open Woodland

During the period from 8–5 million years ago, the Earth experienced the beginning of a long-term drying and cooling trend. Due to the increasing dryness, forests were replaced with open woodland, and areas of grassland began to appear. Hominin evolution began in Africa at the time of these climatic changes. ‘Early hominins: possible and probable’ reviews four collections of fossils that represent each of the ‘candidate’ species that have been put forward for being at the base of the hominin clade: Sahelanthropus tchadensis dated to 7.2–6.8 mya; Orrorin tugenensis dated to round 6 mya; Ardipithecus kadabba dated to 5.7–5.2 mya; and Ardipithecus ramidus from round 4.5 mya.

scholarly journals Climatic changes of seasonal and inter-annual variability of the ice cover of the Greenland and Barents Seas

2019 ◽  
Vol 65 (2) ◽  
pp. 148-168
Author(s):  
L. A. Timokhov ◽  
N. A. Vyazigina ◽  
E. U. Mironov ◽  
A. V. Yulin
Keyword(s):  
Sea Ice ◽  
Activity Index ◽  
Correlation Coefficients ◽  
Ice Cover ◽  
Climatic Changes ◽  
Winter Period ◽  
The Earth ◽  
Cross Correlation Analysis ◽  
Annual Changes

The structure of the long-period variability of the ice cover of the Barents and Greenland Seas over a long series of observations from 1930 to 2017 is analyzed. In both seas, there is a significant negative linear trend of ice cover for both the winter and summer seasons. Average for the period of 1950–2016 intra-annual changes in ice coverings demonstrate the conjugacy of the seasonal cycles of the Greenland and Barents Seas, but with certain differences. Three homogeneous groups with a similar character of intra-annual changes in the ice area are identified for each sea. Identified succession in a state of ice cover for 2 years.The conjugacy of changes in the average decadal values of sea ice cover in April and August with the average decadal indices of atmospheric circulation AO, AD, PNA, NAO and the index of the thermal state of the North Atlantic AMO is shown. Spectral analysis of the winter and summer ice cover of the Greenland and Barents Seas for the period 1930–2016 confirmed earlier received cyclical fluctuations of 22, 9–11 and 6–7 years.Cross-correlation analysis established a close relationship between the longitudinal changes in the ice cover and the average annual values of the following astrogeophysical parameters, the longitude coordinate of the Earth pole position Y, the Earth axis nutation indices dEps and dPsi, the Earth rotation speed index lod (length of day), Sun solar activity index (annual Wolf number) , the average for six months, the distance from the Sun to Earth in the summer SX-III and the winter SX-III periods. Significant correlation coefficients are quite large (R = |0,30| – |0,56|) for both seas, comparable to the correlation coefficients between the ice cover and average annual air temperature T, show the reality of the ice cover mediated reaction to changes in astrophysical factors. Statistical equations relating the sea ice cover to hydrometeorological and astrogeophysical factors were obtained by multiple correlation. The overall correlation coefficient varies from R = 0,80 to R = 0,87 AT. The Greenland Sea, the share of astrogeophysical factors in the long-term changes in the ice cover of both the winter and summer seasons exceeded the contribution of hydrometeorological factors by 3–4 times. In the Barents Sea, the contribution to the total dispersion of astrogeophysical factors in the winter period is somewhat less than that of hydrometeorological factors, and in the summer period they exceed only 1.4 times. The authors’ approach opens up the possibility of using it to obtain statistical equations for the diagnosis and forecast of long-term and climatic changes in sea-ice cover.

A quantitative synthesis of Holocene vegetation change in Nigeria (Western Africa)

The Holocene ◽  
2021 ◽  
pp. 095968362110331
Author(s):  
Matthew Adesanya Adeleye ◽  
Simon Edward Connor ◽  
Simon Graeme Haberle
Keyword(s):  
Vegetation Change ◽  
Climatic Changes ◽  
The Holocene ◽  
Continental Scale ◽  
Western Africa ◽  
Chord Distance ◽  
Quantitative Synthesis ◽  
Climatic Regime ◽  
Pollen Records

Understanding long-term (centennial–millennial scale) ecosystem stability and dynamics are key to sustainable management and conservation of ecosystem processes under the currently changing climate. Fossil pollen records offer the possibility to investigate long-term changes in vegetation composition and diversity on regional and continental scales. Such studies have been conducted in temperate systems, but are underrepresented in the tropics, especially in Africa. This study attempts to synthesize pollen records from Nigeria (tropical western Africa) and nearby regions to quantitatively assess Holocene regional vegetation changes (turnover) and stability under different climatic regimes for the first time. We use the squared chord distance metric (SCD) to assess centennial-scale vegetation turnover in pollen records. Results suggest vegetation in most parts of Nigeria experienced low turnover under a wetter climatic regime (African Humid Period), especially between ~8000 and 5000 cal year BP. In contrast, vegetation turnover increased significantly under the drier climatic regime of the late-Holocene (between ~5000 cal year BP and present), reflecting the imp role of moisture changes in tropical west African vegetation dynamics during the Holocene. Our results are consistent with records of vegetation and climatic changes in other parts of Africa, suggesting the Holocene pattern of vegetation change in Nigeria is a reflection of continental-scale climatic changes.

Cities Created by Modernity: A Fengshui Perspective

2015 ◽  
Vol 42 (5) ◽  
pp. 477-499
Author(s):  
Michael John Paton
Keyword(s):  
Hong Kong ◽  
Traditional Knowledge ◽  
East Coast ◽  
Chinese Art ◽  
Empirical Knowledge ◽  
Term Survival ◽  
Long Term Survival ◽  
The Earth ◽  
Human Habitation

The 2011 tsunami had a devastating effect on the east coast of Japan. Particularly poignant were the century-old markers on hillsides warning against building anywhere below. Nevertheless, such wisdom from traditional knowledge was disregarded because of the perceived invulnerability of the modern. This paper attempts to garner such traditional empirical knowledge regarding the siting of towns and cities by considering the Chinese art/science of fengshui (wind and water) or dili (principles of the earth), the original purpose of which was to site human habitation in the most favourable places for long term survival. This knowledge is then used to consider the placement of cities created by modernity, those founded on and flourishing through the advent of globalisation, such as Hong Kong, Shanghai, St Petersburg, and Sydney.

Late Accretion and the Origin of Water on Terrestrial Planets in the Solar System

2021 ◽  
Author(s):  
Cédric Gillmann ◽  
Gregor Golabek ◽  
Sean Raymond ◽  
Paul Tackley ◽  
Maria Schonbachler ◽  
...  
Keyword(s):  
Solar System ◽  
Long Term Evolution ◽  
Terrestrial Planets ◽  
Evolutionary Pathway ◽  
Giant Impact ◽  
The Earth ◽  
Term Evolution ◽  
Surface Liquid ◽  
Venus Atmosphere

<p>Terrestrial planets in the Solar system generally lack surface liquid water. Earth is at odd with this observation and with the idea of the giant Moon-forming impact that should have vaporized any pre-existing water, leaving behind a dry Earth. Given the evidence available, this means that either water was brought back later or the giant impact could not vaporize all the water.</p><p>We have looked at Venus for answers. Indeed, it is an example of an active planet that may have followed a radically different evolutionary pathway despite the similar mechanisms at work and probably comparable initial conditions. However, due to the lack of present-day plate tectonics, volatile recycling, and any surface liquid oceans, the evolution of Venus has likely been more straightforward than that of the Earth, making it easier to understand and model over its long term evolution.</p><p>Here, we investigate the long-term evolution of Venus using self-consistent numerical models of global thermochemical mantle convection coupled with both an atmospheric evolution model and a late accretion N-body delivery model. We test implications of wet and dry late accretion compositions, using present-day Venus atmosphere measurements. Atmospheric losses are only able to remove a limited amount of water over the history of the planet. We show that late accretion of wet material exceeds this sink. CO<sub>2</sub> and N<sub>2</sub> contributions serve as additional constraints.</p><p>Water-rich asteroids colliding with Venus and releasing their water as vapor cannot explain the composition of Venus atmosphere as we measure it today. It means that the asteroidal material that came to Venus, and thus to Earth, after the giant impact must have been dry (enstatite chondrites), therefore preventing the replenishment of the Earth in water. Because water can obviously be found on our planet today, it means that the water we are now enjoying on Earth has been there since its formation, likely buried deep in the Earth so it could survive the giant impact. This in turn suggests that suggests that planets likely formed with their near-full budget in water, and slowly lost it with time.</p>

scholarly journals Long term trends in the sea surface temperature of the Black Sea

Ocean Science ◽  
2010 ◽  
Vol 6 (2) ◽  
pp. 491-501 ◽  
Author(s):  
G. I. Shapiro ◽  
D. L. Aleynik ◽  
L. D. Mee
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Black Sea ◽  
Sea Surface ◽  
The Black Sea ◽  
The North ◽  
Sst Variability ◽  
Long Term Trends ◽  
Cooling Trend

Abstract. There is growing understanding that recent deterioration of the Black Sea ecosystem was partly due to changes in the marine physical environment. This study uses high resolution 0.25° climatology to analyze sea surface temperature variability over the 20th century in two contrasting regions of the sea. Results show that the deep Black Sea was cooling during the first three quarters of the century and was warming in the last 15–20 years; on aggregate there was a statistically significant cooling trend. The SST variability over the Western shelf was more volatile and it does not show statistically significant trends. The cooling of the deep Black Sea is at variance with the general trend in the North Atlantic and may be related to the decrease of westerly winds over the Black Sea, and a greater influence of the Siberian anticyclone. The timing of the changeover from cooling to warming coincides with the regime shift in the Black Sea ecosystem.

scholarly journals Geosystemics and Earthquakes

2018 ◽  
Author(s):  
Angelo De Santis ◽  
Gianfranco Cianchini ◽  
Rita Di Giovambattista ◽  
Cristoforo Abbattista ◽  
Lucilla Alfonsi ◽  
...  
Keyword(s):  
Dynamical System ◽  
Solid Earth ◽  
Case Studies ◽  
Central Italy ◽  
Point Of View ◽  
Earth System ◽  
Complex Dynamical System ◽  
The Earth ◽  
Earth’S Interior

Abstract. Geosystemics (De Santis 2009, 2014) studies the Earth system as a whole focusing on the possible coupling among the Earth layers (the so called geo-layers), and using universal tools to integrate different methods that can be applied to multi-parameter data, often taken on different platforms. Its main objective is to understand the particular phenomenon of interest from a holistic point of view. In this paper we will deal with earthquakes, considered as a long term chain of processes involving, not only the interaction between different components of the Earth’s interior, but also the coupling of the solid earth with the above neutral and ionized atmosphere, and finally culminating with the main rupture along the fault of concern (De Santis et al., 2015a). Some case studies (particular emphasis is given to recent central Italy earthquakes) will be discussed in the frame of the geosystemic approach for better understanding the physics of the underlying complex dynamical system.

scholarly journals Thermal structure and response to long-term climatic changes in Lake Qiandaohu, a deep subtropical reservoir in China

2014 ◽  
Vol 59 (4) ◽  
pp. 1193-1202 ◽  
Author(s):  
Yunlin Zhang ◽  
Zhixu Wu ◽  
Mingliang Liu ◽  
Jianbo He ◽  
Kun Shi ◽  
...  
Keyword(s):  
Thermal Structure ◽  
Climatic Changes

scholarly journals Water vapor total column measurements using the Elodie Archive at Observatoire de Haute Provence from 1994 to 2004

2009 ◽  
Vol 2 (2) ◽  
pp. 1075-1097
Author(s):  
A. Sarkissian ◽  
J. Slusser
Keyword(s):  
Water Vapor ◽  
Water Vapor Absorption ◽  
The Earth ◽  
Vapor Absorption ◽  
On Line ◽  
High Resolution Spectrometer ◽  
Long Term Trend ◽  
Resolution Spectrometer ◽  
Total Column

Abstract. Water vapor total column measurements at Observatoire de Haute Provence (5°42' E, +43°55' N), south of France, were obtained using observations of astronomical objects made between July 1994 and December 2004 on the 193-cm telescope with the high-resolution spectrometer Elodie. Spectra of stars, nebulae, and other astronomical objects were taken regularly during 10 years. More than 18 000 spectra from 400 nm to 680 nm are available on-line in the Elodie Archive. This archive, usually explored by astronomers, contains information to study the atmosphere of the Earth. Water vapor absorption lines appear in the visible in delimited bands that astronomers often avoid for their spectral analysis. We used the Elodie Archive with two objectives: firstly, to retrieve seasonal variability and long-term trend of atmospheric water vapor, and secondly, to remove signatures in spectra for further astronomical or geophysical use. The tools presented here are developed following, when possible, formats and standards recommended by the International Virtual Observatory Alliance.

scholarly journals Long-period changes of the air temperature in Tatarstan and their forecast till the end of the 21st century

2019 ◽  
pp. 94-107
Author(s):  
Yuri P. Perevedentsev ◽  
Konstantin M. Shantalinskii ◽  
Boris G. Sherstukov ◽  
Alexander A. Nikolaev
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
21St Century ◽  
Ocean Surface ◽  
The Arctic ◽  
Long Distance ◽  
Climate Fluctuations ◽  
Long Period ◽  
The Earth

Long-term changes in air temperature on the territory of the Republic of Tatarstan in the 20th–21st centuries are considered. The periods of unambiguous changes in the surface air temperature are determined. It is established that the average winter temperature from the 1970s to 2017, increased in the Kazan region by more than 3 °C and the average summer temperature increased by about 2 °C over the same period. The contribution of global scale processes to the variability of the temperature of the Kazan region is shown: it was 37 % in winter, 23 % in summer. The correlation analysis of the anomalies of average annual air temperature in Kazan and the series of air temperature anomalies in each node over the continents, as well as the ocean surface temperature in each coordinate node on Earth for 1880 –2017, was performed. Long-distance communications were detected in the temperature field between Kazan and remote regions of the Earth. It is noted that long-period climate fluctuations in Kazan occur synchronously with fluctuations in the high latitudes of Asia and North America, with fluctuations in ocean surface temperature in the Arctic ocean, with fluctuations in air temperature in the Far East, and with fluctuations in ocean surface temperature in the Southern hemisphere in the Indian and Pacific oceans, as well as air temperature in southern Australia. It is suggested that there is a global mechanism that regulates long-term climate fluctuations throughout the Earth in the considered interval of 200 years of observations. According to the CMIP5 project, climatic scenarios were built for Kazan until the end of the 21st century.

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