scholarly journals Changes in northeast African hydrology and vegetation associated with Pliocene–Pleistocene sapropel cycles

2016 ◽  
Vol 371 (1698) ◽  
pp. 20150243 ◽  
Author(s):  
Cassaundra Rose ◽  
Pratigya J. Polissar ◽  
Jessica E. Tierney ◽  
Timothy Filley ◽  
Peter B. deMenocal
Keyword(s):  
Climate Change ◽  
Eastern Mediterranean ◽  
East African ◽  
Major Transitions ◽  
Tropical Oceans ◽  
Lignin Phenols ◽  
Run Off ◽  
Isotopic Analyses ◽  
Phenol Composition

East African climate change since the Late Miocene consisted of persistent shorter-term, orbital-scale wet–dry cycles superimposed upon a long-term trend towards more open, grassy landscapes. Either or both of these modes of palaeoclimate variability may have influenced East African mammalian evolution, yet the interrelationship between these secular and orbital palaeoclimate signals remains poorly understood. Here, we explore whether the long-term secular climate change was also accompanied by significant changes at the orbital-scale. We develop northeast African hydroclimate and vegetation proxy data for two 100 kyr-duration windows near 3.05 and 1.75 Ma at ODP Site 967 in the eastern Mediterranean basin, where sedimentation is dominated by eastern Sahara dust input and Nile River run-off. These two windows were selected because they have comparable orbital configurations and bracket an important increase in East African C 4 grasslands. We conducted high-resolution (2.5 kyr sampling) multiproxy biomarker, H- and C-isotopic analyses of plant waxes and lignin phenols to document orbital-scale changes in hydrology, vegetation and woody cover for these two intervals. Both intervals are dominated by large-amplitude, precession-scale (approx. 20 kyr) changes in northeast African vegetation and rainfall/run-off. The δ 13 C wax values and lignin phenol composition record a variable but consistently C 4 grass-dominated ecosystem for both intervals (50–80% C 4 ). Precessional δD wax cycles were approximately 20–30‰ in peak-to-peak amplitude, comparable with other δD wax records of the Early Holocene African Humid Period. There were no significant differences in the means or variances of the δD wax or δ 13 C wax data for the 3.05 and 1.75 Ma intervals studied, suggesting that the palaeohydrology and palaeovegetation responses to precessional forcing were similar for these two periods. Data for these two windows suggest that the eastern Sahara did not experience the significant increase in C 4 vegetation that has been observed in East Africa over this time period. This observation would be consistent with a proposed mechanism whereby East African precipitation is reduced, and drier conditions established, in response to the emergence of modern zonal sea surface temperature gradients in the tropical oceans between 3 and 2 Ma. This article is part of the themed issue ‘Major transitions in human evolution’.

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.

Abrupt change in North African hydroclimate and landscape evolution 3.2 million years ago

2021 ◽  
Author(s):  
Katharine Grant ◽  
Udara Amarathunga ◽  
Jessica Amies ◽  
Pengxiang Hu ◽  
Yao Qian ◽  
...  
Keyword(s):  
High Resolution ◽  
Eastern Mediterranean ◽  
North African ◽  
Hominin Evolution ◽  
Carbon Burial ◽  
Run Off ◽  
Landscape Response ◽  
Major Increase ◽  
And Migration

Abstract Dark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocene due to deep-sea dysoxia and enhanced carbon burial at times of intensified North African run-off during ‘Green’ Sahara Periods (GSPs). The existence of orbital precession-dominated Saharan aridity/humidity cycles is well known, but lack of long-term, high-resolution records hinders understanding of their precise relationships with environmental and hominin evolution. Here we present continuous, high-resolution geochemical and environmental magnetic records for the Eastern Mediterranean that span the past 5.2 million years, which reveal that organic burial in sapropels intensified 3.2 Myr ago. We deduce that fluvial terrigenous sediment inputs during GSPs doubled abruptly at this time, whereas monsoon run-off intensity remained relatively constant. We attribute the increase in sediment mobilisation to an abrupt non-linear North African landscape response associated with a major increase in arid:humid contrasts between GSPs and intervening dry periods. This likely limited hominin (and other animal) inhabitation of, and migration through, the Sahara region to GSPs only.

scholarly journals Modelling effects of acid deposition and climate change on soil and run-off chemistry at Risdalsheia, Norway

2001 ◽  
Vol 5 (3) ◽  
pp. 487-498 ◽  
Author(s):  
J. P. Mol-Dijkstra ◽  
H. Kros
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Temperature Effect ◽  
Elevated Carbon Dioxide ◽  
Nitrogen Leaching ◽  
Temporary Increase ◽  
Long Term Effects ◽  
Increased Temperature ◽  
Run Off

Abstract. Elevated carbon dioxide levels, caused by anthropogenic emissions of carbon dioxide to the atmosphere, and higher temperature may lead to increased plant growth and uptake of nitrogen, but increased temperature may lead to increased nitrogen mineralisation causing enhanced nitrogen leaching. The overall result of both counteracting effects is largely unknown. To gain insight into the long-term effects, the geochemical model SMART2 was applied using data from the catchment-scale experiments of the RAIN and CLIMEX projects, conducted on boreal forest ecosystems at Risdalsheia, southern Norway. These unique experiments at the ecosystem scale provide information on the short-term effects and interactions of nitrogen deposition and increased temperature and carbon dioxide on carbon and nitrogen cycling and especially the run-off chemistry. To predict changes in soil processes in response to climate change, the model was extended by including the temperature effect on mineralisation, nitrification, denitrification, aluminium dissolution and mineral weathering. The extended model was tested on the two manipulated catchments at Risdalsheia and long-term effects were evaluated by performing long-time runs. The effects of climate change treatment, which resulted in increased nitrogen fluxes at both catchments, were slightly overestimated by SMART2. The temperature dependency of mineralisation was simulated adequately but the temperature effect on nitrification was slightly overestimated. Monitored changes in base cation concentrations and pH were quite well simulated with SMART2. The long-term simulations indicate that the increase in nitrogen run-off is only a temporary effect; in the long-term, no effect on total nitrogen leaching is predicted. At higher deposition levels the temporary increase in nitrogen leaching lasts longer than at low deposition. Contrary to nitrogen leaching, temperature increase leads to a permanent decrease in aluminium concentrations and pH. Keywords: elevated carbon dioxide, temperature, forest ecosystem, modelling, nitrogen run-off.

scholarly journals Palaeoenvironmental perspectives for sustainable development in East Africa

2010 ◽  
Vol 6 (3) ◽  
pp. 963-1007 ◽  
Author(s):  
R. Marchant ◽  
J. Finch ◽  
R. Kinyanjui ◽  
V. Muiruri ◽  
C. Mumbi ◽  
...  
Keyword(s):  
Climate Change ◽  
Sustainable Development ◽  
East Africa ◽  
Land Tenure ◽  
Environmental Changes ◽  
Management Strategies ◽  
Co2 Concentration ◽  
Human Populations ◽  
East African

Abstract. East African ecosystems are shaped by long-term interaction with changing climate, human population, fire and wildlife. There remains today a strong connection between people and ecosystems, a relationship that is being strained by the rapidly developing and growing East African population, and their associated resource needs. Predicted climatic and atmospheric change will further impact on ecosystems culminating in a host of challenges for their management and sustainable development, further compounded by a backdrop of political, land tenure and economic constraints. Given the many direct and indirect benefits that ecosystems provide to surrounding human populations, understanding how they have changed over time and space deserves a special place on the ecosystem management agenda. Such a perspective can only be derived from a palaeoecology, particularly where there is high resolution, both through time and across space. The East African palaeoecological archive is reviewed, in particular to assess how it can meet this need. Although there remain crucial gaps, the number of palaeoecological archives from East Africa growing rapidly, some employing new and novel techniques to trace past ecosystem response to climate change. When compared to the archaeological record it is possible to disentangle human from climate change impacts, and how the former interacts with major environmental changes such as increased use of fire, changing herbivore densities and increased atmospheric CO2 concentration. With this multi-dimensional perspective of environmental change impacts it is imperative that our understanding of past human-ecosystem interactions are considered to impart effective long term management strategies; such an approach will enhance possibilities for a sustainable future for East African ecosystems and maximise the livelihoods of the populations that rely on them.

7. Regional scale pressures on reefs

2021 ◽  
pp. 85-101
Author(s):  
Charles Sheppard
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Regional Scale ◽  
Coral Diseases ◽  
Factors Associated ◽  
Run Off ◽  
Reef Degradation ◽  
Enormous Number ◽  
Harmful Effects

One consequence of the extremely high biodiversity found on reefs is the enormous number of interlocking connections between components. But connections can be destroyed by many kinds of stressors such as pollutants, as can the species themselves. Some species or processes have high redundancy—if destroyed others can fill their role on a reef—while other species or processes may be more or less irreplaceable, in which case when they are destroyed key processes maintaining a healthy reef can be destroyed too. Because so many countries and human communities are dependent on reefs, reef degradation, which is now occurring on a very worrying scale, is of increasing concern. Impacts fall into two main categories: those caused by numerous, usually localized, impacts, such as different forms of pollution and shoreline developments that create large quantities of sediment; and those caused by the more recently recognized, and probably more serious, long-term factors associated with climate change. All of these are ultimately interlinked and all are caused by human activities. Many occur concurrently, each exacerbating the harmful effects of others, and many are synergistic in their impacts. Sewage, nutrient run-off, landfill, dredging, and sedimentation are most important, as are chemicals, pesticides, and metals. Coral diseases are increasing also, commonly as a result. In many areas now too overfishing has become critical and may be the most ecosystem-distorting factor of all.

scholarly journals Organic carbon burial in Mediterranean sapropels intensified during Green Sahara Periods since 3.2 Myr ago

2022 ◽  
Vol 3 (1) ◽  
Author(s):  
Katharine M. Grant ◽  
Udara Amarathunga ◽  
Jessica D. Amies ◽  
Pengxiang Hu ◽  
Yao Qian ◽  
...  
Keyword(s):  
High Resolution ◽  
Eastern Mediterranean ◽  
North African ◽  
Carbon Burial ◽  
Run Off ◽  
Organic Carbon Burial ◽  
Landscape Response ◽  
Major Increase ◽  
Orbital Precession

AbstractDark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocene due to deep-sea dysoxia and enhanced carbon burial at times of intensified North African run-off during Green Sahara Periods (GSPs). The existence of orbital precession-dominated Saharan aridity/humidity cycles is well known, but lack of long-term, high-resolution records hinders understanding of their relationship with environmental evolution. Here we present continuous, high-resolution geochemical and environmental magnetic records for the Eastern Mediterranean spanning the past 5.2 million years, which reveal that organic burial intensified 3.2 Myr ago. We deduce that fluvial terrigenous sediment inputs during GSPs doubled abruptly at this time, whereas monsoon run-off intensity remained relatively constant. We hypothesize that increased sediment mobilization resulted from an abrupt non-linear North African landscape response associated with a major increase in arid:humid contrasts between GSPs and intervening dry periods. The timing strongly suggests a link to the onset of intensified northern hemisphere glaciation.

2018 Nobel Economics Prize: Integrating Climate Change Measures into Sustainable Economic Growth

2018 ◽  
Vol 34 (4) ◽  
Author(s):  
Nguyen Thi Thuc An ◽  
Dau Kieu Ngoc Anh
Keyword(s):  
Climate Change ◽  
Economic Growth ◽  
Endogenous Growth ◽  
Environmental Issues ◽  
Growth Theory ◽  
Endogenous Growth Theory ◽  
Technological Advances ◽  
Academy Of Sciences ◽  
Sustainable Economic Growth

The 2018 Nobel Economics Prize was awarded to two American economists - William D. Nordhaus and Paul M. Romer - who designed methods for better assessing environmental issues and technological advances on growth. This year’s Laureates, Nordhaus was the first person to create an intergrated model to assess interactions between society and nature and Romer laid the foundation for what is now called endogenous growth theory. According to the Swedish Royal Academy of Sciences, these two macroeconomists’ research have helped “significantly broaden the scope of economic analysis by constructing models that explain how the market economy interacts with nature and knowledge” which integrates climate change measures into long-term sustainable economic growth. Keywords Nobel in economics, William D. Nordhaus, Paul M. Romer, climate change, endogenous growth theory, economic growth References [1] Y Vân (2018), “Lý lịch 'khủng' của hai nhà khoa học vừa giành giải Nobel Kinh tế 2018”, Vietnambiz, đăng tải ngày 08/10/2018, https://vietnambiz.vn/ly-lich-khung-cua-hai-nha-khoa-hoc-vua-gianh-giai-nobel-kinh-te-2018-95776.html[2] Jonas O. Bergman, Rich Miller (2018), “Nordhaus, Romer Win Nobel for Thinking on Climate, Innovation”, đăng tải ngày 8/10/2018, https://www.bloomberg.com/news/articles/2018-10-08/nordhaus-romer-win-2018-nobel-prize-in-economic-sciences [3] Antonin Pottier (2018), “Giải Nobel” William Nordhaus có thật sự nghiêm túc?”, Nguyễn Đôn Phước dịch, đăng tải ngày 11/10/2018, http://www.phantichkinhte123.com/2018/10/giai-nobel-william-nordhaus-co-that-su.html[4] Thăng Điệp (2018), “Giải Nobel kinh tế 2018 về tay hai người Mỹ”, đăng tải ngày 8/10/2018, http://vneconomy.vn/giai-nobel-kinh-te-2018-ve-tay-hai-nguoi-my-20181008185809239.htm[5] Lars P. Syll (2018), “Cuối cùng - Paul Romer cũng có được giải thưởng Nobel”, Huỳnh Thiện Quốc Việt dịch, đăng tải ngày 14/10/2018, http://www.phantichkinhte123.com/2018/10/cuoi-cung-paul-romer-cung-co-uoc-giai.html[6] Phương Võ (2018), “Nobel Kinh tế 2018: Chạm tới bài toán khó của thời đại”, đăng tải ngày 9/10/2018, https://nld.com.vn/thoi-su-quoc-te/nobel-kinh-te-2018-cham-toi-bai-toan-kho-cua-thoi-dai-20181008221734228.htm[7] Đông Phong (2018), “Nobel Kinh tế cho giải pháp phát triển bền vững và phúc lợi người dân”, đăng tải ngày 8/10/2018, https://news.zing.vn/nobel-kinh-te-cho-giai-phap-phat-trien-ben-vung-va-phuc-loi-nguoi-dan-post882860.html[8] Thanh Trúc (2018), “Giải Nobel kinh tế 2018: Thay đổi tư duy về biến đổi khí hậu”, https://tusach.thuvienkhoahoc.com/wiki/Gi%E1%BA%A3i_Nobel_kinh_t%E1%BA%BF_2018:_Thay_%C4%91%E1%BB%95i_t%C6%B0_duy_v%E1%BB%81_bi%E1%BA%BFn_%C4%91%E1%BB%95i_kh%C3%AD_h%E1%BA%ADu[9] Cẩm Anh (2018), “Nobel kinh tế 2018: Lời giải cho tăng trưởng kinh tế bền vững”, đăng tải ngày 11/10/2018, http://enternews.vn/nobel-kinh-te-2018-loi-giai-cho-tang-truong-kinh-te-ben-vung-137600.html.

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.

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