scholarly journals Effects of atmospheric CO<sub>2</sub> variability of the past 800 kyr on the biomes of southeast Africa

2019 ◽  
Vol 15 (3) ◽  
pp. 1083-1097 ◽  
Author(s):  
Lydie M. Dupont ◽  
Thibaut Caley ◽  
Isla S. Castañeda
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Coastal Region ◽  
River Mouth ◽  
Mountain Forest ◽  
Pollen Record ◽  
Carbon Dioxide Pressure ◽  
Brunhes Chron ◽  
Glacial Periods ◽  
The Impact ◽  
Atmospheric Pco2

Abstract. Very little is known about the impact of atmospheric carbon dioxide pressure (pCO2) on the shaping of biomes. The development of pCO2 throughout the Brunhes Chron may be considered a natural experiment to elucidate relationships between vegetation and pCO2. While the glacial periods show low to very low values (∼220 to ∼190 ppmv, respectively), the pCO2 levels of the interglacial periods vary from intermediate to relatively high (∼250 to more than 270 ppmv, respectively). To study the influence of pCO2 on the Pleistocene development of SE African vegetation, we used the pollen record of a marine core (MD96-2048) retrieved from Delagoa Bight south of the Limpopo River mouth in combination with stable isotopes and geochemical proxies. Applying endmember analysis, four pollen assemblages could be distinguished representing different biomes: heathland, mountain forest, shrubland and woodland. We find that the vegetation of the Limpopo River catchment and the coastal region of southern Mozambique is influenced not only by hydroclimate but also by temperature and atmospheric pCO2. Our results suggest that the extension of mountain forest occurred during those parts of the glacials when pCO2 and temperatures were moderate and that only during the colder periods when atmospheric pCO2 was low (less than 220 ppmv) open ericaceous vegetation including C4 sedges extended. The main development of woodlands in the area took place after the Mid-Brunhes Event (∼430 ka) when interglacial pCO2 levels regularly rose over 270 ppmv.

scholarly journals Effects of atmospheric CO<sub>2</sub> variability of the past 800 ka on the biomes of Southeast Africa

2019 ◽  
Author(s):  
Lydie M. Dupont ◽  
Thibaut Caley ◽  
Isla S. Castañeda
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Coastal Region ◽  
River Mouth ◽  
Mountain Forest ◽  
Pollen Record ◽  
Main Development ◽  
Carbon Dioxide Pressure ◽  
Brunhes Chron ◽  
Glacial Periods ◽  
The Impact

Abstract. Very little is known about the impact of atmospheric carbon dioxide pressure (pCO2) on the shaping of biomes. The development of pCO2 throughout the Brunhes Chron may be considered a natural experiment to elucidate relationships between vegetation and pCO2. While the glacial periods show low to very low values (~ 230 to ~ 190 ppmv, respectively), the pCO2 levels of the interglacial periods vary from intermediate to relatively high (~250 to ~ 270, respectively). To study the influence of pCO2 on the Pleistocene development of SE African vegetation, we used the pollen record of a marine core (MD96-2048) retrieved from Maputo Bay south of the Limpopo River mouth in combination with stable isotope and geochemical proxies. Applying endmember analysis, four pollen assemblages could be distinguished representing different biomes: heathland, mountain forest, shrubland and woodland. We find that the vegetation of the Limpopo River catchment and the coastal region of southern Mozambique is not only influenced by hydroclimate but by also temperature and atmospheric pCO2. Our results suggest that the extension of either open ericaceous vegetation including C4 sedges or mountain forest depended on glacial pCO2 levels, and that the main development of woodlands in the area took place after the Mid-Brunhes Event when interglacial pCO2 levels rose over 270 ppmv.

scholarly journals Different silicon forms sinalize an input of urbanized river and indicate the presence of phytoplankton with silicon structures in the tropical coastal area of Recife (PE-Brazil)

2018 ◽  
Vol 66 (1) ◽  
pp. 104-114
Author(s):  
Ana Teresa Cordeiro Cid Bastos ◽  
Elisabete de Santis Braga
Keyword(s):  
Primary Production ◽  
Chlorophyll A ◽  
Coastal Area ◽  
Biogenic Silica ◽  
Coastal Region ◽  
River Mouth ◽  
Low Concentrations ◽  
Hydrological System ◽  
Silicon Structures ◽  
The Impact

Abstract The urbanized areas mark its presence in the hydrological systems with some biogeochemical signs including silicon inputs. Natural influence of leaching and erosion is done by silicate contribution and sometimes, the agriculturally soil contains microphytoliths and contributes with biogenic silica. Once in the hydrological system, the silicon can integrate the biogeochemical cycles showing a balance or not between inorganic and biological forms that reveals a tendency of processes that occur in each sector of the estuarine-marine interface. This study aims to evaluate the impact of a heavily polluted/urbanized river, whose input can be evidenced by the contribution of different forms of silicon that can evidence the terrestrial contribution, erosion process, the presence of phytoplankton species with siliceous structures, mainly associated to diatoms and also, to study the river plume spreading on the coastal area by undertaking silicon profiles in the region adjacent to the river mouth. The coastal region of Recife is under influence of fluvial inputs from Capibaribe and Beberibe rivers verified by observed low salinity (min. 33.93). The distribution of silicon forms showed sectorial variation, and the maximum values were dissimilar. Dissolved silicate reached 14.40 µmol L-1, lithogenic silicon (LSi) maximum of 25.76 µmol L-1 and biogenic silica (BSi) reaching 7.39 µmol L-1 near the river mouth toward the sea, evidencing the river influence coming from the west, achieving the port barrier at the end and propagating in the sea toward northeast. Due to higher nutrient availability in the stations nearest to the coast, primary production was encouraged with evidencing by high values of chlorophyll-a associated to silicate (r=0.71) and to BSi (r=0.44). In the stations more distant to the coast, the forms of silicon showed very low concentrations and BSi/Chlorophyll-a showed negative correlation associated with chlorophyll-a concentrations evidencing the participation of non-silicon actors in the primary production in medium depth in oligotrophic tropical waters.

scholarly journals The Influence of Ocean Thermocline Temperatures on the Earth’s Surface Climate

2005 ◽  
Vol 18 (13) ◽  
pp. 2222-2246 ◽  
Author(s):  
Robert J. Oglesby ◽  
Monica Y. Stephens ◽  
Barry Saltzman
Keyword(s):  
Carbon Dioxide ◽  
Mixed Layer ◽  
General Circulation ◽  
Atmospheric Carbon Dioxide ◽  
Deep Ocean ◽  
High Latitudes ◽  
Surface Climate ◽  
Low Latitudes ◽  
Atmospheric Carbon ◽  
The Impact

Abstract A coupled mixed layer–atmospheric general circulation model has been used to evaluate the impact of ocean thermocline temperatures (and by proxy those of the deep ocean) on the surface climate of the earth. Particular attention has been devoted to temperature regimes both warmer and cooler than at present. The mixed layer ocean model (MLOM) simulates vertical dynamics and thermodynamics in the upper ocean, including wind mixing and buoyancy effects, and has been coupled to the NCAR Community Climate Model (CCM3). Simulations were made with globally uniform thermocline warmings of +2°, +5°, and +10°C, as well as a globally uniform cooling of −5°C. A simulation was made with latitudinally varying changes in thermocline temperature such that the warming at mid- and high latitudes is much larger than at low latitudes. In all simulations, the response of surface temperature over both land and ocean was larger than that expected just as a result of the imposed thermocline temperature change, largely because of water vapor feedbacks. In this respect, the simulations were similar to those in which only changes in atmospheric carbon dioxide were imposed. In fact, when carbon dioxide was explicitly changed along with thermocline temperatures, the results were not much different than if only the thermocline temperatures were altered. Land versus ocean differences are explained largely by latent heat flux differences: the ocean is an infinite evaporative source, while land can be quite dry. The latitudinally varying case has a much larger response at mid- to high latitudes than at low latitudes; the high latitudes actually appear to effectively warm the low latitudes. Simulations exploring scenarios of glacial inception suggest that the deep ocean alone is not likely to be a key trigger but must operate in conjunction with other forcings, such as reduced carbon dioxide. Moist upland regions at mid- and high latitudes, and land regions adjacent to perennial sea ice, are the preferred locations for glacial inception in these runs. Finally, the model combination equilibrates very rapidly, meaning that a large number of simulations can be made for a fairly modest computational cost. A drawback to this is greatly reduced sensitivity to parameters such as atmospheric carbon dioxide, which requires a full response of the ocean. Thus, this approach can be considered intermediate between fixing, or prescribing, sea surface temperatures and a fully coupled modeling approach.

scholarly journals The influence of hypercapnia and the infaunal brittlestar <i>Amphiura filiformis</i> on sediment nutrient flux – will ocean acidification affect nutrient exchange?

2009 ◽  
Vol 6 (10) ◽  
pp. 2015-2024 ◽  
Author(s):  
H. L. Wood ◽  
S. Widdicombe ◽  
J. I. Spicer
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Marine Invertebrates ◽  
Nutrient Flux ◽  
Additional Treatment ◽  
Direct Effects ◽  
Exposure Study ◽  
Physicochemical Changes ◽  
Amphiura Filiformis ◽  
The Impact

Abstract. Rising levels of atmospheric carbon dioxide and the concomitant increased uptake of this by the oceans is resulting in hypercapnia-related reduction of ocean pH. Research focussed on the direct effects of these physicochemical changes on marine invertebrates has begun to improve our understanding of impacts at the level of individual physiologies. However, CO2-related impairment of organisms' contribution to ecological or ecosystem processes has barely been addressed. The burrowing ophiuroid Amphiura filiformis, which has a physiology that makes it susceptible to reduced pH, plays a key role in sediment nutrient cycling by mixing and irrigating the sediment, a process known as bioturbation. Here we investigate the role of A. filiformis in modifying nutrient flux rates across the sediment-water boundary and the impact of CO2- related acidification on this process. A 40 day exposure study was conducted under predicted pH scenarios from the years 2100 (pH 7.7) and 2300 (pH 7.3), plus an additional treatment of pH 6.8. This study demonstrated strong relationships between A. filiformis density and cycling of some nutrients;

scholarly journals Modelling key market impacts and land allocation for biofuel production and forestry

2006 ◽  
Vol 2006 ◽  
pp. 1-12
Author(s):  
A. Korobeinikov ◽  
P. Read ◽  
A. Parshotam ◽  
J. Lermit
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Large Scale ◽  
Low Cost ◽  
Wood Products ◽  
Biofuel Production ◽  
Fuel Wood ◽  
Carbon Dioxide Levels ◽  
The Cost ◽  
The Impact

It has been suggested that the large scale use of biofuel, that is, fuel derived from biological materials, especially in combination with reforestation of large areas, can lead to a low-cost reduction of atmospheric carbon dioxide levels. In this paper, a model of three markets: fuel, wood products, and land are considered with the aim of evaluating the impact of large scale biofuel production and forestry on these markets, and to estimate the cost of a policy aimed at the reduction of carbon dioxide in the atmosphere. It is shown that the costs are lower than had been previously expected.

scholarly journals Exploring farmers’ perception on climate-induced events and adaptation practices to protect crop production and livestock farming in Haor area of northeastern Bangladesh

2021 ◽  
Author(s):  
Tasneem Chowdhury Fahim ◽  
Bivuti Bhushan Sikder
Keyword(s):  
Climate Change ◽  
Crop Production ◽  
Coastal Region ◽  
Climate Extremes ◽  
Livestock Farming ◽  
Chi Square ◽  
Study Results ◽  
Tools And Techniques ◽  
Adaptation Practices ◽  
The Impact

Abstract Bangladesh is confronting terrible impacts of climate change on agriculture across the country, especially in the low-lying area like- Haor, coastal region, and islands. This behavioral study (N = 320) examines the perception and knowledge of farmers on climate-induced events and experiences, and explores the adaptation practices they adopt to protect crop production and livestock farming from the impact of climate change in the Northeastern Haor area of the country. Using triangulation method, it is detected that farmers of the study area have erroneous idea on climate change and the causes of frequent climate extremes. Study results show that respondents’ perception and experiences on climate-induced event are verified positively with the historical trend and time-series analysis of climate indicators as well as with the findings of researchers using PRA tools and techniques. This study explores the traditional and systematic adaptation approaches of farmers which are practiced in individual or community level. The rationale of each of the approach from respondents’ side is also analyzed in the study. It is statistically tested using chi-square that some of the scientific and systematic adaptation options for crop production is predominantly influenced by the educational qualifications of the respondents. The study reveals that lack of proper information prevents subsistence farmers to find the most effective adaptation pathways.

scholarly journals Regional characteristics of spring Asian dust and its impact on aerosol chemistry over northern China

2006 ◽  
Vol 6 (6) ◽  
pp. 12825-12864 ◽  
Author(s):  
Y. L. Sun ◽  
G. S. Zhuang ◽  
Z. F. Wang ◽  
Y. Wang ◽  
W. J. Zhang ◽  
...  
Keyword(s):  
Dust Storm ◽  
Fine Particles ◽  
Coastal Region ◽  
Northern China ◽  
Asian Dust ◽  
Aerosol Chemistry ◽  
Transport Pathway ◽  
Regional Characteristics ◽  
Source Regions ◽  
The Impact

Abstract. TSP and PM2.5 aerosol samples were synchronously collected at six sites along the transport pathway of dust storm from desert regions to coastal areas in the spring of 2004. The aerosol concentration and composition were measured to investigate the regional characteristics of spring Asian dust and its impact on aerosol chemistry over northern China. Based on the daily PM10 concentrations in 13 cities, the northern China could be divided into five regions, i.e., Northern Dust Region, Northeastern Dust Region, Western Dust Region, Inland Passing Region, and Coastal Region. Northern Dust Region was characterized by high content of Ca and Northeastern Dust Region was characterized by low one instead. Northeastern Dust Region was a relatively clean area with the lowest concentrations of pollutants and secondary ions among all sites. Inland Passing Region and Coastal Region showed high concentrations of pollutants, of which As and Pb in Inland Passing Region, and Na+, SO42− and NO3− in Coastal Region were the highest, respectively. The impact of dust on air quality was the greatest in the cities near source regions, and this impact decreased in the order of Yulin/Duolun > Beijing > Qingdao/Shanghai as the increase of transport distance. The spring Asian dust was inclined to affect the chemical components in coarse particles near source regions and those in fine particles in the cities far from source regions. Dust storm could mix significant quantities of pollutants on the pathway and carry them to the downwind cities or dilute the pollutants in the cities over northern China. Each dust episode corresponded to a low ratio of NO3−/SO42− with the lowest value appearing after the peak of dust storm. Asian dust played an important role in buffering and neutralizing the acidity of atmosphere in the cities over northern China, which could lead to the pH in the aerosols increase ~1 in spring.

scholarly journals HYDRODYNAMIC MODELLING IN INSHORE REEF AREA WITHIN KUANTAN COASTAL REGION

2020 ◽  
Vol 4 (1) ◽  
pp. 01-07
Author(s):  
Muhammad Faiz Mohd Hanapiah ◽  
Shahbudin Saad ◽  
Zuhairi Ahmad
Keyword(s):  
Model Simulation ◽  
Coastal Region ◽  
Flow Speed ◽  
Current Speed ◽  
Benthic Organism ◽  
Reef Area ◽  
Inshore Reef ◽  
Highly Correlated ◽  
The Impact ◽  
Current Circulation

Current circulation provides major transport mechanism especially for benthic organism in the ocean. The present study described current circulation in inshore reef area within Kuantan coastal region by applying a numerical modelling of MIKE 21 Flow Model FM software. Model simulation produced good outcomes when compared with field data measurement with root mean square error (RMSE) for surface elevation, current speed and direction were below 20. Results also clearly indicated that current speed in inshore reef area was highly correlated with local tidal pattern in which higher flow speed were observed during high tides compared to low tide. Contrary to previous belief, our results clearly show the prevalence of tidal forcing in shaping current flow pattern in the study area since the impact of wind forcing was minimal during different monsoon seasons. This study gave new insight into how local tidal properties can regulate hydrodynamic pattern especially in fine-scale inshore reef area.

The impact of SST on the wind and air temperature simulations: a case study for the coastal region of the Rio de Janeiro state

2018 ◽  
Vol 131 (4) ◽  
pp. 1083-1097 ◽  
Author(s):  
Ian Cunha D`Amato Viana Dragaud ◽  
Mauricio Soares da Silva ◽  
Luiz Paulo de Freitas Assad ◽  
Márcio Cataldi ◽  
Luiz Landau ◽  
...  
Keyword(s):  
Air Temperature ◽  
Rio De Janeiro ◽  
Coastal Region ◽  
The Impact ◽  
Janeiro State

Issues, Concerns, and Local Stakes

2017 ◽  
pp. 50-69
Author(s):  
Navendu Chaudhary ◽  
Yogesh Pisolkar
Keyword(s):  
Climate Change ◽  
Coastal Zone Management ◽  
Coastal Region ◽  
Holistic Approach ◽  
Coastal Communities ◽  
Integrated Coastal Zone Management ◽  
Coastal Tourism ◽  
Developmental Issues ◽  
Zone Management ◽  
The Impact

Coastal Maharashtra is in transition. Growing coastal tourism and allied developmental activities along southern Maharashtra coast needs integration of various stakeholders to address the various issues and concerns. Integrated Coastal Zone Management (ICZM), which can cater to the needs of people while preserving the environment is thus need of the hour. The effects on natural resources, including water, will change the socioeconomic as well as the cultural fabric of coastal communities. This chapter explores a holistic approach to the developmental issues and the impact of climate change on the coastal region with specific cases of villages of Devbag and Tarkarli, coastal Maharashtra, India. It explores both physical and socioeconomic landscapes with special attention given to water resources in the context of changing dynamics of coastal communities and coastal tourism. The chapter discusses the issues and concerns of villages of Devbag and Tarkarli and proposes solutions for a sustainable development.

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