scholarly journals Radiowave propagation on microwave links in tropical regions: A key element in the future of satellite communications?

1990 ◽  
Vol 8 (3) ◽  
pp. 117-118
Author(s):  
Roger J. Colby
Keyword(s):  
Satellite Communications ◽  
Radiowave Propagation ◽  
Tropical Regions ◽  
The Future

The Future of Domestic Satellite Communications

1967 ◽  
Vol 19 (5) ◽  
pp. 1058
Author(s):  
Loren H. Mitchell
Keyword(s):  
Satellite Communications ◽  
The Future

scholarly journals The future of seagrass meadows

2002 ◽  
Vol 29 (2) ◽  
pp. 192-206 ◽  
Author(s):  
Carlos M. Duarte
Keyword(s):  
Human Impacts ◽  
Marine Ecosystem ◽  
Monitoring Network ◽  
Global Ocean ◽  
Major Barrier ◽  
Tropical Regions ◽  
Conservation Policies ◽  
Positive Effects ◽  
Seagrass Meadows ◽  
The Future

Seagrasses cover about 0.1–0.2% of the global ocean, and develop highly productive ecosystems which fulfil a key role in the coastal ecosystem. Widespread seagrass loss results from direct human impacts, including mechanical damage (by dredging, fishing, and anchoring), eutrophication, aquaculture, siltation, effects of coastal constructions, and food web alterations; and indirect human impacts, including negative effects of climate change (erosion by rising sea level, increased storms, increased ultraviolet irradiance), as well as from natural causes, such as cyclones and floods. The present review summarizes such threats and trends and considers likely changes to the 2025 time horizon. Present losses are expected to accelerate, particularly in South-east Asia and the Caribbean, as human pressure on the coastal zone grows. Positive human effects include increased legislation to protect seagrass, increased protection of coastal ecosystems, and enhanced efforts to monitor and restore the marine ecosystem. However, these positive effects are unlikely to balance the negative impacts, which are expected to be particularly prominent in developing tropical regions, where the capacity to implement conservation policies is limited. Uncertainties as to the present loss rate, derived from the paucity of coherent monitoring programmes, and the present inability to formulate reliable predictions as to the future rate of loss, represent a major barrier to the formulation of global conservation policies. Three key actions are needed to ensure the effective conservation of seagrass ecosystems: (1) the development of a coherent worldwide monitoring network, (2) the development of quantitative models predicting the responses of seagrasses to disturbance, and (3) the education of the public on the functions of seagrass meadows and the impacts of human activity.

scholarly journals More perceived but not faster evolution of heat stress than temperature extremes in the future

2020 ◽  
Author(s):  
Audrey Brouillet ◽  
Sylvie Joussaume
Keyword(s):  
Heat Stress ◽  
Human Body ◽  
Stress Index ◽  
Human Populations ◽  
World Population ◽  
Tropical Regions ◽  
Annual Variability ◽  
The Future ◽  
Perceived Change ◽  
Heat Stress Index

<p>Global warming is projected to intensify during the 21st century. This warming will be more readily perceived by human populations if it occurs rapidly and if it induces a thermal heat stress on the human body. Yet, only few studies investigate how climate change could be felt by future populations. Here we assess this possible perceived evolution between 1959 and 2100 only combining thermodynamic and statistical indicators. We analyse extremes of temperature (T<sub>99</sub>) and simplified Wet-Bulb Globe Temperature (WBGT<sub>99</sub>), a common heat stress index assessing the combined effect of elevated temperature and humidity on the human body. For each year of the period, we define the speed of change as a difference between two successive 20-year periods (i.e. with a moving baseline), and assess how these running changes emerge from each last 20-y inter-annual variability.</p><p>According to a subset of 12 CMIP5 Earth System Models and the RCP8.5 scenario, the change of T<sub>99</sub> and WBGT<sub>99</sub> will be twice as fast in the future compared to the current speed of change in the mid-latitudes, and by up to four times faster tropical regions such as Amazonia. Warming accelerations are thus similar for both T<sub>99</sub> and WBGT<sub>99</sub>. However, in tropical regions by 2080, the speed is projected to be 2.3 times larger than the recent inter-annual variability for WBGT<sub>99</sub>, and only 1.5 to 1.8 times larger for T<sub>99</sub>. Currently, speeds of change are only 0.2 to 0.8 times as large as the recent year-to-year variability for both metrics. We also show that 36% of the total world population will experience an emergent WBGT<sub>99</sub> intensification in 2080, but only 15% of the population for T<sub>99</sub>. According to future projections, the accelerated warming of future heat extremes will be more felt by populations than current changes, and this perceived change will be more severe for WBGT<sub>99</sub> than for T<sub>99</sub>, particularly in the tropics.</p>

International communications satellites: global and European

1984 ◽  
Vol 312 (1519) ◽  
pp. 27-32
Keyword(s):  
Growth Rates ◽  
Developing World ◽  
High Growth ◽  
Satellite Communications ◽  
Satellite System ◽  
Advanced Technology ◽  
World Markets ◽  
The Future ◽  
Terrestrial Network ◽  
Communications Satellites

The development of the Intelsat network has caused a revolution in international communications for most countries and particularly those in the developing world. The high growth rates in international communications have resulted in a new satellite generation every few years, which use progressively more advanced technology in both the space and Earth segment. However, Intelsat VI may be the end of the trend to ever larger, more complex satellites. Satellites were unable to compete effectively with Europe’s highly developed terrestrial network. However, European Governments took a view not only on the need for cheap communications but also the need to develop a capability in the field of satellite communications that would equip industry for the massive world markets foreseen for the future. The result was ECS, a regional communications Satellite system for Europe that will go into service within a few months and will be used well into the 1990s.

5. The geography of biological diversity

2020 ◽  
pp. 91-116
Author(s):  
Mark V. Lomolino
Keyword(s):  
Biological Diversity ◽  
Cellular Level ◽  
Tropical Regions ◽  
Levels Of Organization ◽  
The Future ◽  
Isolated Systems

How are we to comprehend all of nature’s diversity from the cellular level up through all taxonomic, biological, and ecological levels of organization? “The geography of biological diversity” focuses on the measures and meaning of biological diversity, and the general patterns across the principal geographic dimensions (e.g. latitude, area and isolation) which allow us to visualize it. Hotspots of diversity are concentrated in tropical regions, especially in large, topographically complex and isolated systems. Our exploration of these hotspots, and the patterns governing how rich and which types of species inhabit them, may provide key insights for attempts to conserve biological diversity long into the future.

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