scholarly journals A 17-My-old whale constrains onset of uplift and climate change in east Africa

2015 ◽  
Vol 112 (13) ◽  
pp. 3910-3915 ◽  
Author(s):  
Henry Wichura ◽  
Louis L. Jacobs ◽  
Andrew Lin ◽  
Michael J. Polcyn ◽  
Fredrick K. Manthi ◽  
...  
Keyword(s):  
Indian Ocean ◽  
East Africa ◽  
Sea Level ◽  
Drainage System ◽  
Beaked Whale ◽  
East African ◽  
Surface Uplift ◽  
The Indian Ocean ◽  
Mantle Processes ◽  
The Impact

Timing and magnitude of surface uplift are key to understanding the impact of crustal deformation and topographic growth on atmospheric circulation, environmental conditions, and surface processes. Uplift of the East African Plateau is linked to mantle processes, but paleoaltimetry data are too scarce to constrain plateau evolution and subsequent vertical motions associated with rifting. Here, we assess the paleotopographic implications of a beaked whale fossil (Ziphiidae) from the Turkana region of Kenya found 740 km inland from the present-day coastline of the Indian Ocean at an elevation of 620 m. The specimen is ∼17 My old and represents the oldest derived beaked whale known, consistent with molecular estimates of the emergence of modern strap-toothed whales (Mesoplodon). The whale traveled from the Indian Ocean inland along an eastward-directed drainage system controlled by the Cretaceous Anza Graben and was stranded slightly above sea level. Surface uplift from near sea level coincides with paleoclimatic change from a humid environment to highly variable and much drier conditions, which altered biotic communities and drove evolution in east Africa, including that of primates.

scholarly journals The Impact of Indian Ocean Mean-State Biases in Climate Models on the Representation of the East African Short Rains

2018 ◽  
Vol 31 (16) ◽  
pp. 6611-6631 ◽  
Author(s):  
Linda Hirons ◽  
Andrew Turner
Keyword(s):  
Indian Ocean ◽  
Wind Stress ◽  
Equatorial Indian Ocean ◽  
East African ◽  
Easterly Wind ◽  
Low Level ◽  
The Indian Ocean ◽  
Short Rains ◽  
The Impact ◽  
Mean State

The role of the Indian Ocean dipole (IOD) in controlling interannual variability in the East African short rains, from October to December, is examined in state-of-the-art models and in detail in one particular climate model. In observations, a wet short-rainy season is associated with the positive phase of the IOD and anomalous easterly low-level flow across the equatorial Indian Ocean. A model’s ability to capture the teleconnection to the positive IOD is closely related to its representation of the mean state. During the short-rains season, the observed low-level wind in the equatorial Indian Ocean is westerly. However, half of the models analyzed exhibit mean-state easterlies across the entire basin. Specifically, those models that exhibit mean-state low-level equatorial easterlies in the Indian Ocean, rather than the observed westerlies, are unable to capture the latitudinal structure of moisture advection into East Africa during a positive IOD. Furthermore, the associated anomalous easterly surface wind stress causes upwelling in the eastern Indian Ocean. This upwelling draws up cool subsurface waters, enhancing the zonal sea surface temperature gradient between west and east and strengthening the positive IOD pattern, further amplifying the easterly wind stress. This positive Bjerknes coupled feedback is stronger in easterly mean-state models, resulting in a wetter East African short-rain precipitation bias in those models.

scholarly journals The Moderate Impact of the 2015 El Niño over East Africa and Its Representation in Seasonal Reforecasts

2019 ◽  
Vol 32 (22) ◽  
pp. 7989-8001 ◽  
Author(s):  
David MacLeod ◽  
Cyril Caminade
Keyword(s):  
Indian Ocean ◽  
East Africa ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Lower Troposphere ◽  
Eastern Indian Ocean ◽  
East African ◽  
The Indian Ocean ◽  
Short Rains

Abstract El Niño–Southern Oscillation (ENSO) has large socioeconomic impacts worldwide. The positive phase of ENSO, El Niño, has been linked to intense rainfall over East Africa during the short rains season (October–December). However, we show here that during the extremely strong 2015 El Niño the precipitation anomaly over most of East Africa during the short rains season was less intense than experienced during previous El Niños, linked to less intense easterlies over the Indian Ocean. This moderate impact was not indicated by reforecasts from the ECMWF operational seasonal forecasting system, SEAS5, which instead forecast large probabilities of an extreme wet signal, with stronger easterly anomalies over the surface of the Indian Ocean and a colder eastern Indian Ocean/western Pacific than was observed. To confirm the relationship of the eastern Indian Ocean to East African rainfall in the forecast for 2015, atmospheric relaxation experiments are carried out that constrain the east Indian Ocean lower troposphere to reanalysis. By doing so the strong wet forecast signal is reduced. These results raise the possibility that link between ENSO and Indian Ocean dipole events is too strong in the ECMWF dynamical seasonal forecast system and that model predictions for the East African short rains rainfall during strong El Niño events may have a bias toward high probabilities of wet conditions.

The History of Islam in East Africa

2018 ◽  
Author(s):  
Felicitas Becker
Keyword(s):  
Indian Ocean ◽  
East Africa ◽  
Electoral Politics ◽  
Minority Status ◽  
Peaceful Coexistence ◽  
East African ◽  
Nation States ◽  
History Of ◽  
The Indian Ocean ◽  
The Government

The history of Islam in East Africa stretches back to around 1000 CE. Until the mid-20th century, it remained largely confined to the coast and closely bound up with the history of the Swahili towns situated on it. The Swahili language remains central to many East African Muslims, hence the occasionally heard phrase, “Swahili Islam.” East African Muslims are mostly Shafiites and some belong to Sufi orders, especially Qadiriyya and Shadhiliyya. Since c. 1850, Islam, with many variations in ritual, has become the religion of speakers of a multitude of languages across the region, second only to Christianity. The region’s independent nation-states initially promised equality for all religions within a secular order. Since c. 1990, though, the minority status of East African Muslims has fed into a multitude of grievances related to the region’s economic and political impasses. This situation has led to growing movements of Islamic preaching and activism, supported by increased contacts with congregations elsewhere in the Indian Ocean. At times, they have influenced electoral politics, especially in Zanzibar, where Islamic activism resonates with fear of marginalization by the mainland. In Kenya, Somali-influenced Islamist terrorists committed a series of atrocities in the 2010s. East African governments, in turn, have been proactive in tracking and disrupting such networks, and in Kenya, the government engaged in targeted assassination. Nevertheless, peaceful coexistence between Muslims and adherents of other religions remains the norm in East Africa, and its dynamics are often poorly understood.

scholarly journals Tracking epidemic Chikungunya virus into the Indian Ocean from East Africa

2008 ◽  
Vol 89 (11) ◽  
pp. 2754-2760 ◽  
Author(s):  
M. Kariuki Njenga ◽  
L. Nderitu ◽  
J. P. Ledermann ◽  
A. Ndirangu ◽  
C. H. Logue ◽  
...  
Keyword(s):  
Indian Ocean ◽  
East Africa ◽  
Chikungunya Virus ◽  
Mosquito Vectors ◽  
East African ◽  
Genetic Elements ◽  
Coastal Kenya ◽  
New Variant ◽  
The Indian Ocean ◽  
African Clade

The largest documented outbreak of Chikungunya virus (CHIKV) disease occurred in the Indian Ocean islands and India during 2004–2007. The magnitude of this outbreak led to speculation that a new variant of the virus had emerged that was either more virulent or more easily transmitted by mosquito vectors. To study this assertion, it is important to know the origin of the virus and how the particular strain circulating during the outbreak is related to other known strains. This study genetically characterized isolates of CHIKV obtained from Mombasa and Lamu Island, Kenya, during 2004, as well as strains from the 2005 outbreak recorded in Comoros. The results of these analyses demonstrated that the virus responsible for the epidemic that spread through the Indian Ocean originated in coastal Kenya during 2004 and that the closest known ancestors are members of the Central/East African clade. Genetic elements that may be responsible for the scope of the outbreak were also identified.

scholarly journals East African origins for Madagascan chickens as indicated by mitochondrial DNA

2017 ◽  
Vol 4 (3) ◽  
pp. 160787 ◽  
Author(s):  
Michael B. Herrera ◽  
Vicki A. Thomson ◽  
Jessica J. Wadley ◽  
Philip J. Piper ◽  
Sri Sulandari ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Indian Ocean ◽  
Southeast Asia ◽  
East Africa ◽  
South Asian ◽  
Common Ancestor ◽  
East African ◽  
Mitochondrial Dna Control Region ◽  
History Of ◽  
The Indian Ocean

The colonization of Madagascar by Austronesian-speaking people during AD 50–500 represents the most westerly point of the greatest diaspora in prehistory. A range of economically important plants and animals may have accompanied the Austronesians. Domestic chickens ( Gallus gallus ) are found in Madagascar, but it is unclear how they arrived there. Did they accompany the initial Austronesian-speaking populations that reached Madagascar via the Indian Ocean or were they late arrivals with Arabian and African sea-farers? To address this question, we investigated the mitochondrial DNA control region diversity of modern chickens sampled from around the Indian Ocean rim (Southeast Asia, South Asia, the Arabian Peninsula, East Africa and Madagascar). In contrast to the linguistic and human genetic evidence indicating dual African and Southeast Asian ancestry of the Malagasy people, we find that chickens in Madagascar only share a common ancestor with East Africa, which together are genetically closer to South Asian chickens than to those in Southeast Asia. This suggests that the earliest expansion of Austronesian-speaking people across the Indian Ocean did not successfully introduce chickens to Madagascar. Our results further demonstrate the complexity of the translocation history of introduced domesticates in Madagascar.

‘Indian’ metalwork in East Africa: the bronze lion statuette from Shanga

Antiquity ◽  
1988 ◽  
Vol 62 (234) ◽  
pp. 11-23 ◽  
Author(s):  
M.C. Horton ◽  
T.R. Blurton
Keyword(s):  
Indian Ocean ◽  
East Africa ◽  
East African ◽  
The West ◽  
East African Coast ◽  
Early Date ◽  
Islamic World ◽  
African Coast ◽  
The Indian Ocean

There are few frontiers from later periods whose archaeology is more beguiling than the east African coast. To the east are the sea-routes of the Indian Ocean, to the Islamic world, to India, to Indonesia, to China. To the west are the distinctive cultures of medieval Africa. And on the coast are the settlements where the east and the west touch. This paper works towards the wider issue of circum-maritime cultures from a single find from the new excavations at Shanga which have revealed mosques of a remarkably early date.

A Long-Distance Nexus in the Indian Ocean: Gujarati Banias, Brokers, and Middlemen in Eighteenth-Century Portuguese East Africa

2020 ◽  
Vol 8 (2) ◽  
pp. 234-254
Author(s):  
Luís Frederico Dias Antunes
Keyword(s):  
Seventeenth Century ◽  
Indian Ocean ◽  
East Africa ◽  
Small Island ◽  
East African ◽  
Commercial Activity ◽  
Long Distance ◽  
East African Coast ◽  
African Coast ◽  
The Indian Ocean

Abstract Historiography has long recognized the strategic importance of Diu as a commercial hub in the Indian Ocean, despite the decline it experienced in the last quarter of the seventeenth century. A great deal of Diuese commerce, along with the island’s privileged connections with East Africa (especially Mozambique), was sustained by the activity of the Banias—Hindus and Jain—who had long used this small island as a platform for trade. This article analyzes the forms of organization, commercial and financial techniques, and main roles of the Banias of Gujarat, one of the largest and most important urban merchant communities in India and in other Asian and African markets along the Indian Ocean. In the case of Diu, we seek to understand the extent to which the financial capacity and commercial experience of the local Banias allowed them to dominate most commercial activity in Mozambique from the late seventeenth century onwards. We examine the internal structure of the Banias’ merchant communities, the hierarchical dependencies and trade links between the Banias of Diu and of Mozambique, and, lastly, the adaptation of their experience and commercial techniques to the East African coast.

scholarly journals Spatiotemporal Evolution and Determinant Factors of the Intra-Regional Trade Community Structures of the Indian Ocean Region

2021 ◽  
Vol 10 (4) ◽  
pp. 214
Author(s):  
Lihua Yuan ◽  
Xiaoqiang Chen ◽  
Changqing Song ◽  
Danping Cao ◽  
Hong Yi
Keyword(s):  
Indian Ocean ◽  
Explanatory Power ◽  
Community Structures ◽  
Indian Ocean Region ◽  
Spatiotemporal Evolution ◽  
Regional Trade ◽  
Determinant Factors ◽  
Ocean Region ◽  
The Indian Ocean ◽  
The Impact

The Indian Ocean Region (IOR) has become one of the main economic forces globally, and countries within the IOR have attempted to promote their intra-regional trade. This study investigates the spatiotemporal evolution of the community structures of the intra-regional trade and the impact of determinant factors on the formation of trade community structures of the IOR from 1996 to 2017 using the methods of social network analysis. Trade communities are groups of countries with measurably denser intra-trade ties but with extra-trade ties that are measurably sparser among different communities. The results show that the extent of trade integration and the trade community structures of the IOR changed from strengthening between 1996 and 2014 to weakening between 2015 and 2017. The largest explanatory power of the formation of the IOR trade community structures was the IOR countries’ economic size, indicating that market remained the strongest driver. The second-largest explanatory power was geographical proximity, suggesting that countries within the IOR engaged in intra-regional trade still tended to select geographically proximate trading partners. The third- and the fourth-largest were common civilization and regional organizational memberships, respectively. This indicates that sharing a common civilization and constructing intra-regional institutional arrangements (especially open trade policies) helped the countries within the IOR strengthen their trade communities.

scholarly journals Epidemic malaria and warmer temperatures in recent decades in an East African highland

2010 ◽  
Vol 278 (1712) ◽  
pp. 1661-1669 ◽  
Author(s):  
David Alonso ◽  
Menno J. Bouma ◽  
Mercedes Pascual
Keyword(s):  
Climate Change ◽  
East Africa ◽  
Nonlinear Response ◽  
Climate Change Impacts ◽  
Human Model ◽  
Recent Past ◽  
East African ◽  
Highly Nonlinear ◽  
The Impact

Climate change impacts on malaria are typically assessed with scenarios for the long-term future. Here we focus instead on the recent past (1970–2003) to address whether warmer temperatures have already increased the incidence of malaria in a highland region of East Africa. Our analyses rely on a new coupled mosquito–human model of malaria, which we use to compare projected disease levels with and without the observed temperature trend. Predicted malaria cases exhibit a highly nonlinear response to warming, with a significant increase from the 1970s to the 1990s, although typical epidemic sizes are below those observed. These findings suggest that climate change has already played an important role in the exacerbation of malaria in this region. As the observed changes in malaria are even larger than those predicted by our model, other factors previously suggested to explain all of the increase in malaria may be enhancing the impact of climate change.

Shipping and Trade between Hamburg-Bremen and the Indian Ocean, 1870–1914

1982 ◽  
Vol 13 (2) ◽  
pp. 349-386
Author(s):  
Hermann Kellenbenz
Keyword(s):  
Indian Ocean ◽  
East Africa ◽  
First World War ◽  
The Philippines ◽  
Early Years ◽  
World War ◽  
Short Survey ◽  
The First World War ◽  
The Indian Ocean ◽  
First World

This study is intended to give a short survey on the development of shipping and trade between two main German ports and the Indian Ocean from the early years of the Bismarck period to the beginning of the First World War. The study deals with the area from East Africa to East India and from Indochina to Indonesia. China, the Philippines, and Australia will not be considered. It is based on an analysis of published material.

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