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1. INTRODUCTION
Global warming, fuel shortages, pollution, problems with XXXXXXX power, and the deregulation of electric power may dramatically change energy using technologies in North America as well as other parts of the world. Looming on the horizon for stationary power is the dream of hot and perhaps even cold fusion powerplants.
Our modern world consumes vast amounts of energy. Electricity is the favored form of energy because it can be used in so many different ways. One of the main reasons why electricity is so valuable is that it is a form of external energy [1]. This means that it can theoretically be converted into any other form of energy and can be done so at a high efficiency. It is a very clean power and can be easily controlled. Industrialized countries rely on their electric grid in which most of the country is interconnected to different power generating facilities.
Common methods of generating the electricity are by using hydro dams, steam power plants burning coal, gas turbines burning natural gas, and XXXXXXX fission power plants. Presently these generating facilities are generally very large. There is however a shift away from centralized powerplants to smaller distributed powerplants.
Solid Oxide fuel cells presently look the most promising for electricity production but also for larger transportation vehicles such as buses, trucks, trains, and ships. If solar cells become even more efficient and inexpensive they could really gain in popularity for grid connected systems.
It is not likely that we will have a hydrogen supply system any time soon. Hydrogen is too hard to store and transport. Liquid fuel is more convenient for mobile applications and so alcohol will be popular. Direct alcohol fuel cells may be widely used for powering portable equipment such as power tools, laptop computers, portable phones, and emergency generators, but may also be used for automobiles.
It is likely that natural gas will continue to be popular for stationary applications as it will be made synthetically in the future from biomass, coal, and solar energy.
The most common method for producing mechanical power for transportation applications presently is with internal combustion engines that burn fossil fuels. While renewable sources of energy such as wind power can be easily converted to electricity and connected to the electric grid, developing new ways of powering transportation devices will prove to be difficult in the future.
Much of the energy we use in society is for heating buildings and for industrial processes. Because much of this thermal energy is only required at low temperatures, burning fuels represents a waste of high grade energy. Theoretically much of this thermal energy could come from solar energy but this is considered too intermittent a source. Waste thermal energy from distributed fuel cells would be a more ideal source of this heat.
2. KNOWN PRESENT AND PROPOSED SOURCES OF ENERGY
There are many sources of energy on earth. The original source of all this energy is XXXXXXX energy in the universe. All other forms of energy are the result of XXXXXXX energy trickling down into lower forms. The following are common sources of energy on earth:
Geothermal ..taking thermal energy from the earth's core
Falling water ..rivers, ocean tides
Wave motion ..in ocean
Thermal cycles ..in water and air
Wind motion ..of air
Pressure changes ..in atmosphere
Solar radiation ..from the sun
Fossil fuels ..coal, oil, natural gas
Biomass ..trees, plants
Fission XXXXXXX energy ..splitting atoms
Fusion XXXXXXX energy ..combining atoms
3. MAJOR TECHNOLOGIES FOR PRODUCING POWER
Electricity and mechanical power are largely used for powering our modern industrialized society. These are not stored in some natural form on earth in any great quantity. Other forms of energy must be converted. Different conversion technologies must be used. With some methods the electricity or mechanical power is produced directly in a single process. In others there are multiple steps involved.
Hydro turbines ..convert moving water from river and ocean dams into electricity
Wave generators ..use floats that move up and down with waves and produce electricity
Solar cells ..solid state materials that produce electricity directly from solar radiation impact
Thermocouples ..also called thermoelectric devices that produce electricity by heating dissimilar XXXXls
Thermionic devices ..turn thermal energy into electricity by solid state means
Vapor turbines ..convert steam pressure into rotary motion then electricity
Piston vapor engines ..convert vapor pressure into rotary motion then electricity
Piston gas engines ..turn expanding gases to motion then electricity, Diesel, Otto, Brayton, Atkinson etc.
Gas turbines ..turn hot expanding gases to rotary motion then electricity
Stirling piston engines ..closed cycle engines turn thermal energy into motion then electricity
MHD ..turn moving charged fluids directly to electricity
Fuel cells ..turn chemical energy directly to electricity by the action of moving ions
Wind turbines ..turn moving air into rotary motion then electricity
XXXXXXX radiation cells ..solid state materials that produce electricity directly from XXXXXXX radiation impact
XXXXXXX "ion" cells ..solid state materials that produce electricity directly from XXXXXXX "ions"

http://www.benwiens.com/powerpl.gif
Fig 1 Chart showing projected efficiencies of different future electricity generating powerplants
4. ELECTRICITY DEREGULATION AND COGENERATION
There is a rapid trend in North America to deregulate the production of electric power. One of the benefits of deregulation is that it will promote smaller scale electric power production technologies. Many of these technologies are only viable on a deregulated basis. Large utilities do not like to maintain thousands of small sites.
There is a rapid trend in North America to deregulate the production of electric power. One of the benefits of deregulation is that it could promote CHP...combined heat and power, also known as cogeneration. North America will likely generate much of its electricity by burning fossil fuel for the next 10-40 years. CHP could conserve fuel by utilizing the thermal energy that is produced as a result of generating electricity. Unfortunately, in their quest to go totally green, many governments are outlawing many forms of cogeneration. This is a mistake in my opinion, because it will take many years to develop totally renewal forms of electric power.
Because thermal energy cannot be piped efficiently for long distances, CHP powerplants will generally need to be much smaller than the present ones which are often around 200,000 kw. Fuel cells will likely be the favored technology of the future for small electric powerplants. Not only do they produce reasonable efficiencies in 30 kw sizes, they will likely be able to run quietly, need infrequent maintenance, emit little pollution and have high efficiency even at part load conditions.
Some of the more common sources of energy and conversion technologies that will likely be used in the next 50 years will be investigated in the next chapters.
5. HYDRO ELECTRIC POWER
Ecologically acceptable places to put new hydro dams are rapidly diminishing around the world. While there are no emissions produced with hydro electric power, there is generally a deterioration of fish spawning in the areas when dams are used. One advantage with this type of hydro electric power is that there is little loss of efficiency by varying the amount of power produced between peak and low periods of electricity demand.
Dams can also be put in ocean inlets to generate electricity from the tidal action. These are also not so ecologically friendly. Also dams disrupt the passage of ships. The height of the tide is not generally enough to be profitable.
Hydroelectric power can also be generated without dams by using run of the river systems. In rivers, part of the flow can be diverted to pipes leading down to a water turbine. Water turbines can also be placed directly in the flow of the river or moving ocean tides. While these methods are often considered to be more environmentally friendly, they result in only a fraction of the power produced by a system using a dam.
6. COAL FIRED STEAM POWER PLANTS
A considerable amount of electricity in the world is produced by burning coal in steam powerplants. These powerplants must be large to be efficient. Presently the best steam powerplants have up to 50% fuel to electricity efficiency (50% A-X eff or chemical lower heating value to electricity). As these powerplants in their simplest form produce unwanted gases and particulates, different technologies must be used to clean up the exhaust gases.
7. GAS TURBINES
Presently many new large electric powerplants use gas turbines and burn natural gas. Contrary to popular opinion, these gas turbines (with addition of heat exchanging or steam turbines) can be highly efficient in the large sizes. The latest are 60% efficient in converting fuel to electricity . In the future, ceramic gas turbines may even reach 70% efficiency. Unfortunately very small gas turbines are not nearly as efficient. Present microturbines in the 30 kw range are only about 25% efficient even when heat exchanging is employed though future ceramic microturbines may achieve 35% efficiency. While fuel cells are largely in the process of being developed, reliable gas turbines are available now. Gas turbines are considered superior to diesel engines because of their lower maintenance, vibration and emissions. For more information on gas turbine efficiency read the online paper "Simple Second law Analysis of Gas Turbines"
8. DIESEL PISTON ENGINES
Diesel piston engines are presently seeing somewhat of a revival. This is because of deregulation. They are presently the most efficient small powerplant available for CHP. Small diesel powerplants are about 30% fuel to electricity efficient, medium diesel powerplants are 40% efficient, and large one's are up to 50% efficient. Their efficiency is good from about 30%-100% power and they can be running at peak efficiency in a short period of time after startup.
9. FUEL CELLS
Fuel cells, which can convert chemical energy directly into electricity, have been proposed as a replacement for other methods of generating power from fossil fuels for 100 years. Till recently there have been numerous difficulties in commercializing them however. Will these problems be overcome in the new century? If the problems can be overcome, fuel cells will likely be the favored technology of the future for all CHP as well as large centralized powerplants. Not only do fuel cells produce reasonable efficiencies at the smaller sizes, they will likely be able to run quietly, need infrequent maintenance and emit little pollution.
A fuel cell works similar to a battery. In a battery, electricity is generated as a result of a fixed amount of substance undergoing a chemical change inside the cell. In a fuel cell, a continuous flow of chemical substance flows through the cell and is made into electricity. While a battery has a limited amount of electricity it can produce per cycle, a fuel cell can produce electricity as long as more fuel is pumped through it.
Solid oxide fuel cells will likely be the favored fuel cell for CHP [2]. Small solid oxide fuel cells will be about 50% fuel to electricity efficient, medium powerplants 60% efficient, and large one's up to 70% efficient. Their efficiency is good from about 15%-100% power. Most solid oxide fuel cells utilize XXXX hydrogen and carbon monoxide fuel inside the cell. This means that they can readily operate on hydrocarbon fuels such as coal gas, gasoline, diesel fuel, jet fuel, alcohol, and natural gas. The efficiency of the solid oxide fuel cell used in CHP applications will be higher than the polymer electrolyte fuel cells for two major reasons. The first reason is that the hydrocarbon fuel is reformed into hydrogen and carbon monoxide fuel largely inside the solid oxide fuel cell. This results in some of the high temperature waste thermal energy being recycled back into the fuel. The second reason is that air compression is not required. Especially on smaller systems, this results in a higher amount of net electricity being produced and quieter operation.
Most polymer electrolyte fuel cells that are being developed for automobiles and CHP use hydrogen gas as a fuel. It is not likely that we will have hydrogen pipelines supplying homes and businesses in the near future. This means that hydrogen will often be extracted from hydrocarbon fuels in CHP systems. Because the polymer electrolyte fuel cell operates at a low temperature, there is no waste thermal energy recycling in the reformer. Air compression to about 3 atmospheres or higher must be used to have a reasonable power density [3]. On small systems this results in a substantial loss of efficiency. Small polymer electrolyte fuel cells will be about 35% fuel to electricity efficient, medium powerplants 40% efficient, and large one's up to 45% efficient.
Because of the high temperatures that the solid oxide fuel cell must run , they may not be XXXXXXXXX for sizes much below 1,000 watts or when portable applications are involved. Several companies in the world are presently working on direct alcohol fuel cells. In this type of fuel cell, the alcohol is not reformed but used directly in a very simple type of fuel cell. This fuel cell is ideal for portable equipment such as power tools, laptop computers, portable phones, and emergency generators. For more information on fuel cells read the web-booklet "The Future of Fuel Cells"
10. WIND POWER
There is enough energy in the blowing winds to generate a substantial proportion of the electrical energy requirements in the world. In windy areas, the cost to produce electricity is already less than using fossil fueled combined cycle powerplants. One of the major problems with wind turbines in the past has been durability. Often serious wind storms would damage many units. Newer units appear to be built stronger. Another large problem is the extremely variable speed of the wind. Wind turbines may provide peak power in times when the electricity is not required. Storage of the electricity is expensive. If wind turbines are linked into a large grid system, such fluctuations are not as much of a disadvantage. Of course if a major proportion of our electricity would be generated this way, that would create major problems. Wind turbines in the past resulted in bird kills however it appears that with newer one’s this may not be a problem. Wind turbines are also noisy and can be unsightly. Still there are major advantages in tapping into a source of inexpensive power that can be converted into electricity in such a simple device as a wind turbine.
11. SOLAR POWER
During the day, there is a constant supply of radiation coming from the sun. The amount of radiation is considerable, but presently low cost commercial solid state solar cells only convert about 11% of the solar radiation into electricity. There are already laboratory solar cells that are 40% efficient, and in the future even higher efficiencies may be possible. Solid state solar cells are very attractive because they have no moving parts and are very simple. Because sunlight is free, this makes the technology very attractive especially in countries that have difficulty buying fuel. The downside of solid state solar cells is that when the sun goes down, there is no electricity being produced. Batteries can be used, but present batteries are only about 60-80% efficient in storing the electricity. Just as with wind turbines, if solar panels are linked into a large grid system, such fluctuations are not as much of a disadvantage.
A second method of using the sun's radiation is to convert it into high temperature thermal energy and then use conventional steam turbines, gas turbines or Stirling engines to generate electricity. Such methods are already 30-50% efficient in converting the sun's radiation into electricity. There are also efficient solid state thermoelectric converters being researched. If a fluid is heated, a large amount can be stored for operation of the plant during the night or cloudy days. As well, a backup fuel fired heater can be used, but this is only economical when the power plant is highly efficient.
A third desirable method is to use the sun's rays produce a fuel. This fuel could then be used at a later date. Hydrogen could be produced but it is difficult to store. An ideal fuel to produce would be ethanol or natural gas which could be used in a fuel cell at a later date to generate electricity or be used in other applications that require fuel. The solar cell would recycle the carbon dioxide from the atmosphere back into the ethanol or natural gas fuel. Such a solar cell might use genetically engineered bacteria to do the job.
Theoretically much of the thermal energy required in society could come from solar energy. XXXXXXXXXly so far it has been considered too intermittent a source. Solar collectors for this purpose can be quite simple, but storage of the thermal energy during periods when the sun isn’t shining has so far been considered expensive compared to cheap fossil fuel. This situation is dramatically changing as fuel prices have recently gone up in price rapidly.
12. FISSION POWERPLANTS
In XXXXXXX fission, large atoms are split apart to form new smaller atoms. Because the new atoms have a slightly smaller amount of matter than the old atoms, a large amount of energy is emitted. After the 2nd World War some prominent people predicted that fission XXXXXXX powerplants would be able to create electricity so cheaply that the power companies would not XXXXer installing electric meters. This prediction did not come true. XXXXXXX powerplants are unpopular today not only because of the possible threat of radiation leaks, but because they are expensive to operate. The safety precautions are very costly and the life span of the equipment is rather short. Scientists also have not come up with satisfactory ways of storing the waste products.
Present XXXXXXX powerplants generally use the thermal energy produced by the XXXXXXX reaction to produce steam and turn a steam turbine. Some designs use a gas turbine instead. In outer space the thermal energy is turned to electricity with thermoelectric devices which are very reliable and have no moving parts but are presently inefficient. Theoretically other solid-state conversion methods could be used.
13. HOT FUSION POWERPLANTS
In XXXXXXX fusion, atoms are fused together to form new atoms. Because the new atoms have a slightly smaller amount of matter than the old atoms, a large amount of energy is emitted. In a hot fusion power plant the extra energy is released in the form of thermal energy. Presently scientists have not been able to maintain a fusion reaction for long enough to be XXXXXXXXX, but many hope that sustained reactions may be possible within the next 2 decades. The thermal energy produced could be used in the same way as in the fission powerplant. Though there is radiation during the fusion reaction, there would not be the problem of having to dispose of spent fuel. If a problem would occur, the reaction could be shut down immediately and the radiation stops almost instantly.
If hot fusion power becomes XXXXXXXXX, it could completely reverse the trend towards distributed power. Fusion powerplants would likely be even larger than the present centralized powerplants.
14. COLD FUSION POWERPLANTS
There is some controversy as to whether cold fusion is even possible as far as producing excess external energy. In a most basic theoretical sense, cold fusion is possible. If cold fusion ever proves to work, then XXXX large central powerplants as well as smaller distributed powerplants would likely be XXXXXXXXX.
15. GEOTHERMAL
There appears to be incredible amounts of thermal energy just below the crust of the earth. It is likely that the earth is gradually cooling down, but the center of the earth hasn't cooled off nearly as fast as the surface. Also slow XXXXXXX processes are continously producing more thermal energy. In places near volcanoes there is hot molten rock very close to the surface of the earth. In other places underground water streams run into the hot molten rock and produce steam or hot water. There are already geothermal steam powerplants operating. Surely more of this hot lava could be tapped to produce electric power. It appears that there is a fear among scientists that cooling off the lava too much would produce earthquakes.
16. CONCLUSIONS
It is very difficult to tell which form of energy and which technologies will be predominant for providing energy for society in the future. This means that more work should be done on many alternate systems.
17. REFERENCES
Kordesch, K., Simader, G. 1996 Fuel Cells and their Applications VCH Press NY USA
Buswell, Clause, Cohen, Louie, Watkins 1994 Ballard US Patent 5,360,679 ..Hydrocarbon Fueled Solid Polymer Fuel Cell Electric Power Generation System
18. NOTES
[1] Read online book "Energy Science Made Simple" for energy terms used.
[2] Global Thermoelectric in Calgary Alberta Canada is a working on planar solid oxide fuel cells of this type for small CHP and even for automobiles and buses. Westinghouse is working on tubular solid oxide fuel cells which have considerably less efficiency due to the high internal resistance.
[3] Ballard Power Systems in Burnaby BC Canada is working on polymer electrolyte fuel cells of this type for CHP.
19. REVISION HISTORY
1999Apr21 First printing, 4 pages, 1 picture
1999May03 Corrected chapter hyperlinks, added paragraph to Chapter 6
2001Mar22 Added wind power due to popular demand. Of course there are many other technologies which I have not mentioned due to the short nature of this booklet.
2002May03 Made minor terminology changes and rewrote parts of the whole XXXXXXXX.
2008Aug11 Made minor terminology changes and updated the whole XXXXXXXX. COPYRIGHT © 1999-2008 by Ben Wiens Consulting Inc.
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Global Warming
An increase in the near surface temperature of the Earth. Global warming has occurred in the distant past as the result of natural influences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases. Scientists generally agree that the Earth\'s surface has warmed by about 1 degree Fahrenheit in the past 140 years. The Intergovernmental Panel on Climate Change (IPCC) recently concluded that increased concentrations of greenhouse gases are causing an increase in the Earth\'s surface temperature and that increased concentrations of sulfate aerosols have led to relative cooling in some regions, generally over and downwind of heavily industrialized areas.

Global surface temperatures have increased about 0.74°C (plus or minus 0.18°C) since the late-19th century, and the linear trend for the past 50 years of 0.13°C (plus or minus 0.03°C) per decade is nearly twice that for the past 100 years. The warming has not been globally uniform. Some areas (including parts of the southeastern U.S. and parts of the North Atlantic) have, in fact, cooled slightly over the last century. The recent warmth has been greatest over North America and Eurasia between 40 and 70°N. Lastly, seven of the eight warmest years on record have occurred since 2001 and the 10 warmest years have all occurred since 1995.


Recent analyses of temperature trends in the lower and mid- troposphere (between about 2,500 and 26,000 ft.) using $$$$ satellite and radiosonde (weather balloon) data show warming rates that are similar to those observed for surface air temperatures. These warming rates are consistent with their uncertainties and these analyses reconcile a discrepancy between warming rates noted on the IPCC Third Assessment Report .
An enhanced greenhouse effect is expected to cause cooling in higher parts of the atmosphere because the increased "blanketing" effect in the lower atmosphere holds in more heat, allowing less to reach the upper atmosphere. Cooling of the lower stratosphere (about 49,000-79,500 ft.) since 1979 is shown by $$$$ satellite Microwave Sounding Unit and radiosonde data (see previous figure), but is larger in the radiosonde data likely due to uncorrected errors in the radiosonde data.
Relatively cool surface and tropospheric temperatures, and a relatively warmer lower stratosphere, were observed in 1992 and 1993, following the 1991 eruption of Mt. Pinatubo. The warming reappeared in 1994. A dramatic global warming, at least partly associated with the record El Niño, took place in 1998. This warming episode is reflected from the surface to the top of the troposphere.

There has been a general, but not global, tendency toward reduced diurnal temperature range (DTR: the difference between daily high or maximum and daily low or minimum temperatures) over about 70% of the global land mass since the middle of the 20th century. However, for the period 1979-2005 the DTR shows no trend since the trend in $$$$ maximum and minimum temperatures for the same period are virtually identical; $$$$ showing a strong warming signal. A variety of factors likely contribute to this change in DTR, particularly on a regional and local basis, including changes in cloud cover, atmospheric water vapor, land use and urban effects.

Indirect indicators of warming such as borehole temperatures, snow cover, and glacier recession data, are in substantial agreement with the more direct indicators of recent warmth. Evidence such as changes in glacial mass balance (the amount of snow and ice contained in a glacier) is useful since it not only provides qualitative support for existing meteorological data, but glaciers often exist in places too remote to support meteorological stations. The records of glacial advance and retreat often extend back further than weather station records, and glaciers are usually at much higher altitudes than weather stations, allowing scientists more insight into temperature changes higher in the atmosphere.

Large-scale measurements of sea-ice have only been possible since the satellite era, but through looking at a number of different satellite estimates, it has been determined that September Arctic sea ice has decreased between 1973 and 2007 at a rate of about -10% +/- 0.3% per decade. Sea ice extent for September for 2007 was by far the lowest on record at 4.28 million square kilometers, eclipsing the previous record low sea ice extent by 23%. Sea ice in the Antarctic has shown very little trend over the same period, or even a slight increase since 1979. Though extending the Antarctic sea-ice record back in time is more difficult due to the lack of direct observations in this part of the world.
El Niños are not caused by global warming. Clear evidence exists from a variety of sources (including archaeological studies) that El Niños have been present for thousands, and some indicators suggest maybe millions, of years. However, it has been hypothesized that warmer global sea surface temperatures can enhance the El Niño phenomenon, and it is also true that El Niños have been more frequent and intense in recent decades. Whether El Niño occurrence changes with climate change is a major research question.
Scientists have determined that a number of human activities are contributing to global warming by adding excessive amounts of greenhouse gases to the atmosphere. Greenhouse gases such as carbon dioxide accummulate in the atmosphere and trap heat that normally would exit into outer space.
Greenhouse Gases and Global Warming
While many greenhouse gases occur naturally and are needed to create the greenhouse effect that keeps the Earth warm enough to support life, human use of fossil fuels is the main source of excess greenhouse gases
By driving cars, using electricity from coal-fired power plants, or heating our homes with oil or natural gas, we release carbon dioxide and other heat-trapping gases into the atmosphere. Deforestation is another significant source of greenhouse gases, because fewer trees means less carbon dioxide conversion to oxygen.
During the 150 years of the industrial age, the atmospheric concentration of carbon dioxide has increased by 31 percent. Over the same period, the level of atmospheric methane has risen by 151 percent, mostly from agricultural activities such as raising cattle and growing rice.
The Consequences of Global Warming
As the concentration of greenhouse gases grows, more heat is trapped in the atmosphere and less escapes back into space. This increase in trapped heat changes the climate and alters weather patterns, which may hasten species extinction, influence the length of seasons, cause coastal flooding, and lead to more frequent and severe storms.the possibility that global warming might make life on Earth better, not just for humans, but all species. The article argues that 'worst-case scenarios' are often the result of inaccurate simulations made in the 1980s. While climate change is a reality, as far as the article is concerned, some planning and forethought may mean that more benefits than drawbacks will result from higher temperatures. From the article:'The medical benefits of higher average temperatures have also been ignored. According to Richard Tol, an environmental economist, "warming temperatures will mean that in 2$$$ there will be about 40,000 fewer deaths in Germany attributable to cold-related illnesses like the flu." Another widespread fear about global warming -- that it will cause super-storms that could devastate towns and villages with unprecedented fury -- also appears to be unfounded. Current long-term simulations, at any rate, do not suggest that such a trend will in fact materialize.'"
Smile when you say that. Most flus over the past few decades have been fairly mild. But there is always the possibility that a new flu (such as the much bruited avian influenza A (H5N1)) could create a new pandemic as deadly as the 1918 out-break, which killed more than 600,000 here in the US.
Of course, flus are not caused by cold weather, they are caused by viruses, many of which originate in south-east Asia which is tropical or semi-tropical. That in turn is not a result of climate, but of the poverty and which in turn leads to close contact between humans and farm animals that serve as the reservoirs of infectious viruses.
The reason that flus spread in the winter in the northern hemisphere is that winter leads to close human contact in schools, offices, and shopping malls that allow the viruses to be transmitted between infected and uninfected human hosts. Flu pandemics are not caused by weather.
Similarly, the tropical diseases you mention are not truly tropical. They are transmitted by insects (mostly mosquitoes) that thrive in water. The reason that they are largely found in the tropics now is that the tropics are largely poor and dominated by bad governments. In Europe and North America public works of sanitation, drainage and insect extermination have largely eliminated these diseases, and they could in the tropics, if they were used, These are not really climate issues.
Conclusion:
In conclusion, throughout human history known as the land of many climatic changes that scientists were able to justify most of natural causes, such as: some volcanic eruptions or solar fluctuations, but the dramatic increase in the Earth's surface temperature over the last two centuries (since the beginning of the Industrial Revolution) And especially the last twenty years scientists had been unable to subject themselves to natural causes; where human activity during this period a significant impact be taken into account to explain this steady rise in the temperature of the Earth's surface or what is called the greenhouse effect and global warming

Global warming

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For past climate change, see paleoclimatology and geologic temperature record.

Global mean surface temperature anomaly relative to 1961–1990
http://upload.wikimedia.org/wikipedi...arming_Map.jpg
Mean surface temperature anomalies during the period 1999 to 2008 with respect to the average temperatures from 1940 to 1980


Global warming is the increase in the average temperature of the Earth's near-surface air and the oceans since the mid-twentieth century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 100 years ending in 2005.[1][A] The Intergovernmental Panel on Climate Change (IPCC) concludes that anthropogenic greenhouse gases are very likely[B] responsible for most of the observed temperature increase since the middle of the twentieth century,[1] and natural phenomena such as solar variation and volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward.[2][3] These basic conclusions have been endorsed by 30 scientific societies and academies of science,[B] including all of the national academies of science of the major industrialized countries.[4][5]
Climate model projections summarized in the latest IPCC report indicate that global surface temperature will likely rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century.[1] The uncertainty in this estimate arises from the use of models with differing climate sensitivity, and the use of differing estimates of future greenhouse gas emissions. Some other uncertainties include how warming and related changes will vary from region to region around the globe. Although most studies focus on the period up to 2100, warming is expected to continue after 2100, even in the absence of new emissions, because of the large heat capacity of the oceans and the lifespan of CO2 in the atmosphere.[6][7][8]
Increasing global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, likely including an expanse of the subtropical desert regions.[9] Other likely effects include Arctic shrinkage and resulting Arctic methane release, shrinkage of the Amazon rainforest, increases in the intensity of extreme weather events, changes in agricultural yields, modifications of trade routes, glacier retreat, species extinctions and changes in the ranges of disease vectors.
Political and public debate continues regarding the appropriate response to global warming. The available options are mitigation to reduce further emissions; adaptation to reduce the damage caused by warming; and, more speculatively, geoengineering to reverse global warming. Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions.



لمزيد
Global warming - Wikipedia, the free encyclopedia

Global warming

Global warming is the increase in the average measured temperature of the Earth's near-surface air and oceans since the mid-20th century, and its projected continuation.
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Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 100 years ending in 2005.[1][2] The Intergovernmental Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations"[3][4] via an enhanced greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward.[5][6] These basic conclusions have been endorsed by at least 30 scientific societies and academies of science,[7] including all of the national academies of science of the major industrialized countries.[8][9][10] While individual scientists have voiced disagreement with these findings,[11] the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.[12][13]


Global warming is the increase in the average measured temperature of the Earth's near-surface air and oceans since the mid-20th century, and its projected continuation.



Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 100 years ending in 2005.[1][2] The Intergovernmental Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations"[3][4] via an enhanced greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward.[5][6] These basic conclusions have been endorsed by at least 30 scientific societies and academies of science,[7] including all of the national academies of science of the major industrialized countries.[8][9][10] While individual scientists have voiced disagreement with these findings,[11] the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.[12][13]
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Climate model projections summarized by the IPCC indicate that average global surface temperature will likely rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century.[3] This range of values results from the use of differing scenarios of future greenhouse gas emissions as well as models with differing climate sensitivity. Although most studies focus on the period up to 2100, warming and sea level rise are expected to continue for more than a thousand years even if greenhouse gas levels are stabilized. The delay in reaching equilibrium is a result of the large heat capacity of the oceans.[3]

Increasing global temperature is expected to cause sea levels to rise, an increase in the intensity of extreme weather events, and significant changes to the amount and pattern of precipitation, likely leading to an expanse of tropical areas and increased pace of desertification. Other expected effects of global warming include changes in agricultural yields, modifications of trade routes, glacier retreat, mass species extinctions and increases in the ranges of disease vectors.


Remaining scientific uncertainties include the amount of warming expected in the future, and how warming and related changes will vary from region to region around the globe. Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions, but there is ongoing political and public debate worldwide regarding what, if any, action should be taken to reduce or reverse future warming or to adapt to its expected consequences.

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حبيت أناقش معكم ظاهرة الإحتباس الحراري وأشوف آرائكم فيها ..

موضوعي هو :- ظــاهرة الإحتباس الحراري ..
GLOBAL WARMING

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[عزيزي الزائر يتوجب عليك التسجيل للمشاهدة الرابطللتسجيل اضغط هنا]

المقدمة
في وقتنا الحالي أصبح الشغل الشاغل لعلماء الطبيعة والمنــاخ وحتى أكبر المنظمات البيئية هي ظاهرة الإحتباس الحراري وظهرت العديد من التحيليلات والتوقعــات حول معرفة سببها ومن المسؤول عن حدوثها وما الأخطار الناتجية عنها لو تفاقمت أكثر .. تعالوا نتعرف على تعريف الظاهرة ..

الاحتباس الحراري
هو ظاهرة إرتفاع درجة الحرارة في بيئة ما نتيجة تغيير في سيلان الطاقة الحرارية من البيئة و إليها. و عادة ما يطلق هذا الإسم على ظاهرة إرتفاع درجات حرارة الأرض في معدلها.

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إختلاف رأي العلماء في سببها
أنقسم العلماء إلى ثلاثة أحزاب وكانت الأغلبية الكبرى ترجح أن سبب هذه الظاهرة هو إصدارات الغازات الملوثة كالآزوت و ثاني أوكسيد الكربون بينما يرى باقي العلماء أنه سببها هو مرور الأرض بفترات ساخنة و فترت باردة مستشهدين بذلك عن طريق فترة جليدية أو باردة نوعا ما بين القرن 17 و 18 في أوروبا أما القسم الثلاث يرى أن ظاهرة الإنحباس الحراري إلى التلوث وحده فقط .

سبب الظاهرة
الأنشطة بشرية مثل تكرير النفط ومحطات الطاقة وعادم السيارات أسباب مهمة لارتفاع حرارة الكون. بحيث أن الغازات المسببة للاحتباس الحراري تتراكم في غلاف الأرض نتيجة أنشطة بشرية مما يتسبب في ارتفاع المتوسط العالمي لحرارة الهواء على سطح الأرض وحرارة المحيطات تحت السطح.

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آثـــار الظاهرة في وقتنا الحالي
من آثار هذه الظاهرة إرتفاع درجة حرارة المناخ العالمي خلال القرن الماضي نصف درجة مئوية بحيث أخذ الجليد في القطبين وفوق قمم الجبال الأسترالية في الذوبان بشكل ملحوظ . ولاحظ علماء المناخ أن مواسم الشتاء إزدادت خلال الثلاثة عقود الأخيرة دفئا عما كانت عليه من قبل وقصرت فتراته والربيع يأتي مبكرا عن مواعيده . كما لوحظ أن الأشجار في المنطقة الشيه قطبية هناك قد إزداد إرتفاعها عما ذي قبل . فلقد زاد إرتفاعها 40 مترا علي غير عادتها منذ ربع قرن . وهذا مؤشر تحذيري مبكر لبقية العالم .لأن زيادة ظاهرة الإحتباس الحراري قد تحدث تلفا بيئيا في مناطق أخري به. وهذا الإتلاف البيئي فوق كوكبنا قد لاتحمد عقباه .فقد يزول الجليد من فوقه تماما خلال هذا القرن . وهذا الجليد له تأثيراته علي الحرارة والمناخ والرياح الموسم . وأيضا أدى الإرتفاع في درجة الحرارة إلى تغير في عدد حيـــوانات البلانكتون (هو عبارة عن مجموعة من الكائنات الحية الدقيقة التي تعيش في المسطحات المائية مثل المحيطات و البحار)

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آثـــار الظاهرة المتوقع حدوثها عن تزايد الظاهرة
قد يُحدث إزدياد هذه الظاهرة إلى ذوبـــان الجليد الموجود بالقطبين وغرق المناطق الســـاحلية بالعالم حيث انه يتوقع إرتفـــاع مستوى البحر 48 ســم وتصحر مساحات شــاسعة من الأرض . وإنتشار من 50 - 80 مليون بعوضة التى تحمل مرض الملاريا إلى مناطق متفرقة من أنحاء العالم .

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ثااانكس حبووبه بس شو معنااة الاكسااات فالموضوع ؟.؟

شكرا .. كتر الله من أمثالك يا مبرمجة ... شكرا

حبيت أسال ... شو قصدك بالبحث بال XXXX ، انا اعرف X ترمز للشيء المجهول باللغة الانجليزية متل X wife أي الزوجة السابقة ..
وتقال للأشعة السينية X التي اسمها الاشعة المجهولة ... اجو توضيح الأمر اذا مافي غلبة

ما عندي اي فكرة عن معنى اكس
سوري
أنا نسخته لكم بشكل مباشر
لكن اتمنى انكم تستفيدون من بقية المعلومات
اعتذر ..ربي يوفقكم