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2. 2 Quisiera antes que nada aclarar que no es el objetivo de esta plática comparar directamente los riesgos del calentamiento global contra los riesgos de la energía nuclear, porque de hecho no se trata de decidir entre la energía nuclear y el calentamiento global, ya que este último problema tiene muchas aristas; el objetivo es poner en perspectiva los riesgos del cambio climático y mostrar como la energía nuclear puede ayudar a reducir los gases de invernadero, sin incrementar de otras formas el riesgo público.
Quisiera antes que nada aclarar que no es el objetivo de esta plática comparar directamente los riesgos del calentamiento global contra los riesgos de la energía nuclear, porque de hecho no se trata de decidir entre la energía nuclear y el calentamiento global, ya que este último problema tiene muchas aristas; el objetivo es poner en perspectiva los riesgos del cambio climático y mostrar como la energía nuclear puede ayudar a reducir los gases de invernadero, sin incrementar de otras formas el riesgo público.
3. 3
4. 4 Referencias: http://www.ngdc.noaa.gov/paleo/globalwarming/what.html
http://www.cambioclimaticoglobal.com/causas.html
Presentación Power Point: Globalwarming bueno para consecuencias
Greenhouse gases are gaseous components of the atmosphere that contribute to the greenhouse effect. The major natural greenhouse gases are water vapor, which causes about 60% of the greenhouse effect on Earth, carbon dioxide (about 26%), and ozone.
Minor greenhouse gases include methane, nitrous oxide, sulfurhexafluoride (SF6) and halocarbons such as perfluoromethane, freon and other CFCs.
The major atmospheric constituents (N2 and O2) are not greenhouse gases, because (being diatomic) they do not absorb in the infrared.
CFCs (chlorofluorocarbons) are a family of artificial chemical compounds containing chlorine, fluorine and carbon. They were formerly used widely in industry, for example as refrigerants, propellants and cleaning solvents. Their use has been generally prohibited by the Montreal Protocol, because of fears of their possible destructive effects on the ozone layer (see ozone depletion). Hydrochlorofluorocarbons are now used as CFC substitutes.
CFCs were developed by the American engineer Thomas Midgley in 1928 as a replacement for ammonia (then a common refrigerant). The new compound developed had to have a low boiling point, a lack of toxicity and be generally non-reactive. In a demonstration for the American Chemical Association, Midgley flamboyantly demonstrated all these properties by inhaling a breath of the gas and using it to blow out a candle.
Midgley specifically developed CCl2F2 (CFC-12). However one of the attractive features of CFCs is that there exists a whole family of the compounds, each having a unique boiling point which can suit different applications. As well as refrigerants, CFCs have been used as propellants in aerosol cans, cleaning solvents for circuit boards, and as blowing agents for making expanded plastics (such as those once used to store fast-foods.)
There has been a movement since the late 1970s to ban CFCs because of their destructive effect on the ozone layer. This damage was discovered due mainly to the work of scientists Sherry Rowland and Mario Molina, first published in 1974. It turns out that one of CFCs most attractive features - its unreactivity - has been instrumental in making it one of our worst pollutants. CFC's lack of reactivity gives it a lifespan which can exceed 100 years in some cases. This gives it time to diffuse up in to the upper stratosphere. Here the sun's UV radiation is strong enough to break off the chlorine atom, which on its own is a highly reactive free radical. This catalyses the break up of ozone in to oxygen:
Cl + O3 ? ClO + O2
ClO + O ? Cl + O2
CFCs are a problem because the chlorine is regenerated at the end of these reactions, making it able to keep on reacting with millions of other ozone molecules. The ozone hole produced is able to let through UV light, which causes cancer in humans.
HALOCARBONOS
Clorofluorocarbonos: Compuestos mayormente de origen antrópico, que contienen carbono y halógenos como cloro, bromo, flúor y a veces hidrógeno. Los clorofluorocarbonos (CFCs) comenzaron a producirse en los años 30 para refrigeración. Posteriormente se usaron como propulsores para aerosoles, en la fabricación de espuma, etc. Existen fuentes naturales en las que se producen compuestos relacionados, como los metilhaluros. No existen sinks para los CFCs en la troposfera y por motivo de su casi inexistente reactividad son transportadas a la estratosfera donde se degradan por acción de los UV, momento en el cual liberan átomos libres de cloro que destruyen efectivamente el ozono. Hidroclorofluorocarbonos (HCFCs) e Hidrofluorocarbonos (HFCs): compuestos de origen antrópico que están usándose como sustitutos de los CFCs, sólo considerados como transicionales, pues también tienen efectos de gas invernadero. Estos se degradan en la troposfera por acción de fotodisociación. Por la larga vida que poseen son gases invernadero miles de veces más potentes que el CO2.
Referencias: http://www.ngdc.noaa.gov/paleo/globalwarming/what.html
http://www.cambioclimaticoglobal.com/causas.html
Presentación Power Point: Globalwarming bueno para consecuencias
Greenhouse gases are gaseous components of the atmosphere that contribute to the greenhouse effect. The major natural greenhouse gases are water vapor, which causes about 60% of the greenhouse effect on Earth, carbon dioxide (about 26%), and ozone.
Minor greenhouse gases include methane, nitrous oxide, sulfurhexafluoride (SF6) and halocarbons such as perfluoromethane, freon and other CFCs.
The major atmospheric constituents (N2 and O2) are not greenhouse gases, because (being diatomic) they do not absorb in the infrared.
CFCs (chlorofluorocarbons) are a family of artificial chemical compounds containing chlorine, fluorine and carbon. They were formerly used widely in industry, for example as refrigerants, propellants and cleaning solvents. Their use has been generally prohibited by the Montreal Protocol, because of fears of their possible destructive effects on the ozone layer (see ozone depletion). Hydrochlorofluorocarbons are now used as CFC substitutes.
CFCs were developed by the American engineer Thomas Midgley in 1928 as a replacement for ammonia (then a common refrigerant). The new compound developed had to have a low boiling point, a lack of toxicity and be generally non-reactive. In a demonstration for the American Chemical Association, Midgley flamboyantly demonstrated all these properties by inhaling a breath of the gas and using it to blow out a candle.
Midgley specifically developed CCl2F2 (CFC-12). However one of the attractive features of CFCs is that there exists a whole family of the compounds, each having a unique boiling point which can suit different applications. As well as refrigerants, CFCs have been used as propellants in aerosol cans, cleaning solvents for circuit boards, and as blowing agents for making expanded plastics (such as those once used to store fast-foods.)
There has been a movement since the late 1970s to ban CFCs because of their destructive effect on the ozone layer. This damage was discovered due mainly to the work of scientists Sherry Rowland and Mario Molina, first published in 1974. It turns out that one of CFCs most attractive features - its unreactivity - has been instrumental in making it one of our worst pollutants. CFC's lack of reactivity gives it a lifespan which can exceed 100 years in some cases. This gives it time to diffuse up in to the upper stratosphere. Here the sun's UV radiation is strong enough to break off the chlorine atom, which on its own is a highly reactive free radical. This catalyses the break up of ozone in to oxygen:
Cl + O3 ? ClO + O2
ClO + O ? Cl + O2
CFCs are a problem because the chlorine is regenerated at the end of these reactions, making it able to keep on reacting with millions of other ozone molecules. The ozone hole produced is able to let through UV light, which causes cancer in humans.
HALOCARBONOS
Clorofluorocarbonos: Compuestos mayormente de origen antrópico, que contienen carbono y halógenos como cloro, bromo, flúor y a veces hidrógeno. Los clorofluorocarbonos (CFCs) comenzaron a producirse en los años 30 para refrigeración. Posteriormente se usaron como propulsores para aerosoles, en la fabricación de espuma, etc. Existen fuentes naturales en las que se producen compuestos relacionados, como los metilhaluros. No existen sinks para los CFCs en la troposfera y por motivo de su casi inexistente reactividad son transportadas a la estratosfera donde se degradan por acción de los UV, momento en el cual liberan átomos libres de cloro que destruyen efectivamente el ozono. Hidroclorofluorocarbonos (HCFCs) e Hidrofluorocarbonos (HFCs): compuestos de origen antrópico que están usándose como sustitutos de los CFCs, sólo considerados como transicionales, pues también tienen efectos de gas invernadero. Estos se degradan en la troposfera por acción de fotodisociación. Por la larga vida que poseen son gases invernadero miles de veces más potentes que el CO2.
5. 5 Once, all climate changes occurred naturally. However, during the Industrial Revolution, we began altering our climate and environment through changing agricultural and industrial practices. Before the Industrial Revolution, human activity released very few gases into the atmosphere, but now through population growth, fossil fuel burning, and deforestation, we are affecting the mixture of gases in the atmosphere.
It is reasonable to expect that the Earth should warm as concentrations of greenhouse gases in the atmosphere increase above natural levels, much like what happens when the windows of a greenhouse are closed on a warm, sunny day. This additional warming is commonly referred to as Greenhouse Warming.
Greenhouse Warming is global warming due to increases in atmospheric greenhouse gases (e.g., carbon dioxide, methane, chlorofluorocarbons, etc.), whereas Global Warming refers only to the observation that the Earth is warming, without any indication of what might be causing the warming.
Once, all climate changes occurred naturally. However, during the Industrial Revolution, we began altering our climate and environment through changing agricultural and industrial practices. Before the Industrial Revolution, human activity released very few gases into the atmosphere, but now through population growth, fossil fuel burning, and deforestation, we are affecting the mixture of gases in the atmosphere.
It is reasonable to expect that the Earth should warm as concentrations of greenhouse gases in the atmosphere increase above natural levels, much like what happens when the windows of a greenhouse are closed on a warm, sunny day. This additional warming is commonly referred to as Greenhouse Warming.
Greenhouse Warming is global warming due to increases in atmospheric greenhouse gases (e.g., carbon dioxide, methane, chlorofluorocarbons, etc.), whereas Global Warming refers only to the observation that the Earth is warming, without any indication of what might be causing the warming.
6. 6 Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occuring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases:
Carbon dioxide is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned. Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills, and the raising of livestock. More information on methane. Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of solid waste and fossil fuels. Very powerful greenhouse gases that are not naturally occurring include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6), which are generated in a variety of industrial processes. Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occuring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases:
Carbon dioxide is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned.
7. 7 http://home.pacbell.net/sabsay/nuclear/chapter3.html
Carbon dioxide is responsible for only about half of the Earth's greenhouse effect warming. Methane, which is increased by escaping natural gas, contributes 18%, and nitrogen oxides, which are products of fossil fuel burning, account for 6%. Another major contributor is chlorinated fluorocarbons (CFCs), which are responsible for 14%. These are familiar as the working material in air conditioners, refrigerators, and freezers, and as the propellant in spray cans. (Other important sources of methane include flooded rice paddies and cows burping up gas from their stomachs.)
Another cause of the greenhouse effect is cutting down forests, since plants take carbon dioxide out of the air. Clearing of the Amazon rainforest is believed to be especially serious. Worldwide, an area of forests equal to the area of the state of Virginia is cleared every year. This is estimated to cause 20% of the greenhouse effect.
Burning wood (or biomass) releases carbon dioxide, but it does not contribute to the greenhouse effect because the wood was created from carbon dioxide, which the tree leaves absorb from the atmosphere.
In 1950, the United States was responsible for 45% of the 1.6 billion tons of carbon dioxide emitted throughout the world, but by 1980 world emissions increased to 5.1 billion tons with only 27% from the United States; Western Europe's share was 23% in 1950 and 16.5% in 1980. Increased use of fossil fuels in underdeveloped countries has played an important role in increasing emissions.
ENCARTA
The principal constituents of the atmosphere of Earth are nitrogen (78 percent) and oxygen (21 percent). The atmospheric gases in the remaining 1 percent are argon (0.9 percent), carbon dioxide (0.03 percent), varying amounts of water vapor, and trace amounts of hydrogen, ozone, methane, carbon monoxide, helium, neon, krypton, and xenon. http://home.pacbell.net/sabsay/nuclear/chapter3.html
Carbon dioxide is responsible for only about half of the Earth's greenhouse effect warming. Methane, which is increased by escaping natural gas, contributes 18%, and nitrogen oxides, which are products of fossil fuel burning, account for 6%. Another major contributor is chlorinated fluorocarbons (CFCs), which are responsible for 14%. These are familiar as the working material in air conditioners, refrigerators, and freezers, and as the propellant in spray cans. (Other important sources of methane include flooded rice paddies and cows burping up gas from their stomachs.)
Another cause of the greenhouse effect is cutting down forests, since plants take carbon dioxide out of the air. Clearing of the Amazon rainforest is believed to be especially serious. Worldwide, an area of forests equal to the area of the state of Virginia is cleared every year. This is estimated to cause 20% of the greenhouse effect.
Burning wood (or biomass) releases carbon dioxide, but it does not contribute to the greenhouse effect because the wood was created from carbon dioxide, which the tree leaves absorb from the atmosphere.
In 1950, the United States was responsible for 45% of the 1.6 billion tons of carbon dioxide emitted throughout the world, but by 1980 world emissions increased to 5.1 billion tons with only 27% from the United States; Western Europe's share was 23% in 1950 and 16.5% in 1980. Increased use of fossil fuels in underdeveloped countries has played an important role in increasing emissions.
ENCARTA
The principal constituents of the atmosphere of Earth are nitrogen (78 percent) and oxygen (21 percent). The atmospheric gases in the remaining 1 percent are argon (0.9 percent), carbon dioxide (0.03 percent), varying amounts of water vapor, and trace amounts of hydrogen, ozone, methane, carbon monoxide, helium, neon, krypton, and xenon.
8. 8 By overlying the reconstructed temperature record of the past 2000 years with atmospheric CO2 records obtained from ice cores the relationship between the two is apparent. Shown in this figure is the most recent temperature reconstruction (Moberg et al, 2005). This is not necessarily the best reconstruction (see this review), and other reconstructions (notably Mann & Jones, 2003) show less variability in the pre-industrial period. However, the reconstruction of Moberg et al provides a better match with the results of climate models (see "What caused temperature changes over the past 1000 years").By overlying the reconstructed temperature record of the past 2000 years with atmospheric CO2 records obtained from ice cores the relationship between the two is apparent. Shown in this figure is the most recent temperature reconstruction (Moberg et al, 2005). This is not necessarily the best reconstruction (see this review), and other reconstructions (notably Mann & Jones, 2003) show less variability in the pre-industrial period. However, the reconstruction of Moberg et al provides a better match with the results of climate models (see "What caused temperature changes over the past 1000 years").
9. 9 In the most recent Third Assessment Report (2001), IPCC wrote "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."
http://data.giss.nasa.gov/gistemp/2005/
Global warming is now 0.6°C in the past three decades and 0.8°C in the past century. It is no longer correct to say that "most global warming occurred before 1940". More specifically, there was slow global warming, with large fluctuations, over the century up to 1975 and subsequent rapid warming of almost 0.2°C per decade.
Figure 1: (Left) Global annual surface temperature relative to 1951-1980 mean based on surface air measurements at meteorological stations and ship and satellite measurements for sea surface temperature. Error bars are estimated 2s (95% confidence) uncertainty. (Right) Temperature anomaly for 2005 calendar year. Gray areas indicate a lack of station data within 1200km. In the most recent Third Assessment Report (2001), IPCC wrote "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."
http://data.giss.nasa.gov/gistemp/2005/
Global warming is now 0.6°C in the past three decades and 0.8°C in the past century. It is no longer correct to say that "most global warming occurred before 1940". More specifically, there was slow global warming, with large fluctuations, over the century up to 1975 and subsequent rapid warming of almost 0.2°C per decade.
Figure 1: (Left) Global annual surface temperature relative to 1951-1980 mean based on surface air measurements at meteorological stations and ship and satellite measurements for sea surface temperature. Error bars are estimated 2s (95% confidence) uncertainty. (Right) Temperature anomaly for 2005 calendar year. Gray areas indicate a lack of station data within 1200km.
10. 10 Figure 2: Long records of past changes in atmospheric composition provide the context for the influence of anthropogenic emissions.
(a) shows changes in the atmospheric concentrations of carbon dioxide (CO2), methane(CH4), and nitrous oxide (N2O) over the past 1000 years. The ice core and firn data for several sites in Antarctica and Greenland (shown by different symbols) are supplemented with the data from direct atmospheric samples over the past few decades (shown by the line for CO2 and incorporated in the curve representing the global average of CH4). The estimated positive radiative forcing of the climate
system from these gases is indicated on the righthand scale. Since these gases have atmospheric lifetimes of a decade or more, they are well mixed,
and their concentrations reflect emissions from sources throughout the globe. All three records show effects of the large and increasing growth in
anthropogenic emissions during the Industrial Era.
Concentrations of atmospheric greenhouse gases and their radiative forcing have continued to increase as a result of human
activities.
The atmospheric concentration of carbon dioxide (CO2) has increased by 31% since 1750. The present CO2 concentration has not been exceeded during the past 420,000 years and likely not during the past 20 million years. The current rate of increase is unprecedented during at least the past 20,000 years.
About three-quarters of the anthropogenic emissions of CO2 to the atmosphere during the past 20 years is due to fossil fuel burning. The rest is predominantly due to land-use change, especially deforestation. Currently the ocean and the land together are taking up about half of the anthropogenic CO2 emissions. On land,
the uptake of anthropogenic CO2 very likely7 exceeded the release of CO2 by deforestation during the 1990s. The rate of increase of atmospheric CO2 concentration has been about 1.5 ppm9 (0.4%) per year over the past two decades. During the 1990s the year to year increase varied from 0.9 ppm (0.2%) to 2.8 ppm (0.8%). A large part of this variability is due to the effect of climate variability (e.g., El Niño events) on CO2 uptake and release by land and oceans.Figure 2: Long records of past changes in atmospheric composition provide the context for the influence of anthropogenic emissions.
(a) shows changes in the atmospheric concentrations of carbon dioxide (CO2), methane(CH4), and nitrous oxide (N2O) over the past 1000 years. The ice core and firn data for several sites in Antarctica and Greenland (shown by different symbols) are supplemented with the data from direct atmospheric samples over the past few decades (shown by the line for CO2 and incorporated in the curve representing the global average of CH4). The estimated positive radiative forcing of the climate
system from these gases is indicated on the righthand scale. Since these gases have atmospheric lifetimes of a decade or more, they are well mixed,
and their concentrations reflect emissions from sources throughout the globe. All three records show effects of the large and increasing growth in
anthropogenic emissions during the Industrial Era.
Concentrations of atmospheric greenhouse gases and their radiative forcing have continued to increase as a result of human
activities.
The atmospheric concentration of carbon dioxide (CO2) has increased by 31% since 1750. The present CO2 concentration has not been exceeded during the past 420,000 years and likely not during the past 20 million years. The current rate of increase is unprecedented during at least the past 20,000 years.
About three-quarters of the anthropogenic emissions of CO2 to the atmosphere during the past 20 years is due to fossil fuel burning. The rest is predominantly due to land-use change, especially deforestation. Currently the ocean and the land together are taking up about half of the anthropogenic CO2 emissions. On land,
the uptake of anthropogenic CO2 very likely7 exceeded the release of CO2 by deforestation during the 1990s. The rate of increase of atmospheric CO2 concentration has been about 1.5 ppm9 (0.4%) per year over the past two decades. During the 1990s the year to year increase varied from 0.9 ppm (0.2%) to 2.8 ppm (0.8%). A large part of this variability is due to the effect of climate variability (e.g., El Niño events) on CO2 uptake and release by land and oceans.
11. 11 The atmospheric concentration of methane (CH4) has increased by 1060 ppb9 (151%) since 1750 and continues to increase. The present CH4 concentration has not been exceeded during the past 420,000 years. The annual growth in CH4 concentration slowed and became more variable in the 1990s, compared with the 1980s. Slightly more than half of current CH4 emissions are anthropogenic (e.g., use of fossil fuels, cattle, rice agriculture and landfills). In addition, carbon monoxide (CO) emissions have recently been identified as a cause of increasing CH4 concentration.
The atmospheric concentration of nitrous oxide (N2O) has increased by 46 ppb (17%) since 1750 and continues to increase. The present N2O concentration has not been exceeded during at least the past thousand years. About a third of current N2O emissions are anthropogenic (e.g., agricultural soils, cattle feed lots and chemical industry).
The atmospheric concentration of methane (CH4) has increased by 1060 ppb9 (151%) since 1750 and continues to increase. The present CH4 concentration has not been exceeded during the past 420,000 years. The annual growth in CH4 concentration slowed and became more variable in the 1990s, compared with the 1980s. Slightly more than half of current CH4 emissions are anthropogenic (e.g., use of fossil fuels, cattle, rice agriculture and landfills). In addition, carbon monoxide (CO) emissions have recently been identified as a cause of increasing CH4 concentration.
The atmospheric concentration of nitrous oxide (N2O) has increased by 46 ppb (17%) since 1750 and continues to increase. The present N2O concentration has not been exceeded during at least the past thousand years. About a third of current N2O emissions are anthropogenic (e.g., agricultural soils, cattle feed lots and chemical industry).
12. 12 Models have been used to make projections of atmospheric concentrations of greenhouse gases and aerosols, and hence of future climate, based upon emissions scenarios from the IPCC Special Report on Emission Scenarios (SRES) (Figure 5). These scenarios were developed to update the IS92 series,
which were used in the SAR and are shown for comparison here in some cases.
Greenhouse gases
-Emissions of CO2 due to fossil fuel burning are virtually certain7 to be the dominant influence on the trends in atmospheric CO2 concentration during the 21st century.
-As the CO2 concentration of the atmosphere increases, ocean and land will take up a decreasing fraction of anthropogenic CO2 emissions. The net effect of land and ocean climate feedbacks as indicated by models is to further increase projected atmospheric CO2 concentrations, by reducing both the ocean and land uptake of CO2.
- By 2100, carbon cycle models project atmospheric CO2concentrations of 540 to 970 ppm for the illustrative SRES scenarios (90 to 250% above the concentration of 280 ppm in the year 1750), Figure 5b. These projections include the land and ocean climate feedbacks. Uncertainties, especially
about the magnitude of the climate feedback from the terrestrial biosphere, cause a variation of about -10 to +30% around each scenario. The total range is 490 to 1260 ppm (75 to 350% above the 1750 concentration).
Changing land use could influence atmospheric CO2 concentration. Hypothetically, if all of the carbon released by historical land-use changes could be restored to the terrestrial biosphere over the course of the century (e.g., by reforestation), CO2 concentration would be reduced by 40 to 70 ppm.
- Model calculations of the concentrations of the non-CO2 greenhouse gases by 2100 vary considerably across the
SRES illustrative scenarios, with CH4 changing by –190 to +1,970 ppb (present concentration 1,760 ppb), N2O changing by +38 to +144 ppb (present concentration 316 ppb), total tropospheric O3 changing by -12 to +62%, and a wide range of changes in concentrations of HFCs, PFCs and SF6, all relative to the year 2000. In some scenarios, total tropospheric O3 would become as important a radiative forcing agent as CH4 and, over much of the Northern Hemisphere,
would threaten the attainment of current air quality targets.
- Reductions in greenhouse gas emissions and the gases that control their concentration would be necessary to stabilise radiative forcing. For example, for the most important anthropogenic greenhouse gas, carbon cycle models indicate
that stabilisation of atmospheric CO2 concentrations at 450, 650 or 1,000 ppm would require global anthropogenic CO2 emissions to drop below 1990 levels, within a few decades, about a century, or about two centuries, respectively, and continue to decrease steadily thereafter. Eventually CO2 emissions would need to decline to a very small fraction of current emissions.
Global average temperature and sea level are projected to rise under all IPCC SRES scenarios.
In order to make projections of future climate, models incorporate past, as well as future emissions of greenhouse gases and aerosols. Hence, they include estimates of warming to date and the commitment to future warming from past emissions.
Temperature
-The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C (Figure 5d) over the period 1990 to 2100. These results are for the full range of 35 SRES scenarios, based on a number of climate models10,11.
- Temperature increases are projected to be greater than those in the SAR, which were about 1.0 to 3.5°C based on the six IS92 scenarios. The higher projected temperatures and the wider range are due primarily to the lower projected sulphur dioxide emissions in the SRES scenarios relative to
the IS92 scenarios.
-The projected rate of warming is much larger than the observed changes during the 20th century and is very likely7 to be without precedent during at least the last 10,000 years, based on palaeoclimate data.
-By 2100, the range in the surface temperature response across the group of climate models run with a given scenario is comparable to the range obtained from a single model run with the different SRES scenarios.
-On timescales of a few decades, the current observed rate of warming can be used to constrain the projected response to a given emissions scenario despite uncertainty in climate sensitivity. This approach suggests that anthropogenic warming is likely7 to lie in the range of 0.1 to 0.2°C per
decade over the next few decades under the IS92a scenario, similar to the corresponding range of projections of the simple model used in Figure 5d.
-Based on recent global model simulations, it is very likely7 that nearly all land areas will warm more rapidly than the global average, particularly those at northern high latitudes in the cold season. Most notable of these is the warming in the northern regions of North America, and northern and central Asia, which exceeds global mean warming in each model by more than 40%. In contrast, the warming is less than the global mean change in south and southeast Asia in summer and in southern South America in winter.
- Recent trends for surface temperature to become more El Niño-like in the tropical Pacific, with the eastern tropical Pacific warming more than the western tropical Pacific, with a corresponding eastward shift of precipitation, are projected to continue in many models.
Precipitation
Based on global model simulations and for a wide range of scenarios, global average water vapour concentration and precipitation are projected to increase during the 21st century. By the second half of the 21st century, it is likely7 that precipitation will have increased over northern mid- to high latitudes and Antarctica in winter. At low latitudes there are both regional increases and decreases over land areas. Larger year to year variations in precipitation are very likely7 over most areas where an increase in mean precipitation is projected.
Models have been used to make projections of atmospheric concentrations of greenhouse gases and aerosols, and hence of future climate, based upon emissions scenarios from the IPCC Special Report on Emission Scenarios (SRES) (Figure 5). These scenarios were developed to update the IS92 series,
which were used in the SAR and are shown for comparison here in some cases.
Greenhouse gases
-Emissions of CO2 due to fossil fuel burning are virtually certain7 to be the dominant influence on the trends in atmospheric CO2 concentration during the 21st century.
-As the CO2 concentration of the atmosphere increases, ocean and land will take up a decreasing fraction of anthropogenic CO2 emissions. The net effect of land and ocean climate feedbacks as indicated by models is to further increase projected atmospheric CO2 concentrations, by reducing both the ocean and land uptake of CO2.
- By 2100, carbon cycle models project atmospheric CO2concentrations of 540 to 970 ppm for the illustrative SRES scenarios (90 to 250% above the concentration of 280 ppm in the year 1750), Figure 5b. These projections include the land and ocean climate feedbacks. Uncertainties, especially
about the magnitude of the climate feedback from the terrestrial biosphere, cause a variation of about -10 to +30% around each scenario. The total range is 490 to 1260 ppm (75 to 350% above the 1750 concentration).
Changing land use could influence atmospheric CO2 concentration. Hypothetically, if all of the carbon released by historical land-use changes could be restored to the terrestrial biosphere over the course of the century (e.g., by reforestation), CO2 concentration would be reduced by 40 to 70 ppm.
- Model calculations of the concentrations of the non-CO2 greenhouse gases by 2100 vary considerably across the
SRES illustrative scenarios, with CH4 changing by –190 to +1,970 ppb (present concentration 1,760 ppb), N2O changing by +38 to +144 ppb (present concentration 316 ppb), total tropospheric O3 changing by -12 to +62%, and a wide range of changes in concentrations of HFCs, PFCs and SF6, all relative to the year 2000. In some scenarios, total tropospheric O3 would become as important a radiative forcing agent as CH4 and, over much of the Northern Hemisphere,
would threaten the attainment of current air quality targets.
- Reductions in greenhouse gas emissions and the gases that control their concentration would be necessary to stabilise radiative forcing. For example, for the most important anthropogenic greenhouse gas, carbon cycle models indicate
that stabilisation of atmospheric CO2 concentrations at 450, 650 or 1,000 ppm would require global anthropogenic CO2 emissions to drop below 1990 levels, within a few decades, about a century, or about two centuries, respectively, and continue to decrease steadily thereafter. Eventually CO2 emissions would need to decline to a very small fraction of current emissions.
Global average temperature and sea level are projected to rise under all IPCC SRES scenarios.
In order to make projections of future climate, models incorporate past, as well as future emissions of greenhouse gases and aerosols. Hence, they include estimates of warming to date and the commitment to future warming from past emissions.
Temperature
-The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C (Figure 5d) over the period 1990 to 2100. These results are for the full range of 35 SRES scenarios, based on a number of climate models10,11.
- Temperature increases are projected to be greater than those in the SAR, which were about 1.0 to 3.5°C based on the six IS92 scenarios. The higher projected temperatures and the wider range are due primarily to the lower projected sulphur dioxide emissions in the SRES scenarios relative to
the IS92 scenarios.
-The projected rate of warming is much larger than the observed changes during the 20th century and is very likely7 to be without precedent during at least the last 10,000 years, based on palaeoclimate data.
-By 2100, the range in the surface temperature response across the group of climate models run with a given scenario is comparable to the range obtained from a single model run with the different SRES scenarios.
-On timescales of a few decades, the current observed rate of warming can be used to constrain the projected response to a given emissions scenario despite uncertainty in climate sensitivity. This approach suggests that anthropogenic warming is likely7 to lie in the range of 0.1 to 0.2°C per
decade over the next few decades under the IS92a scenario, similar to the corresponding range of projections of the simple model used in Figure 5d.
-Based on recent global model simulations, it is very likely7 that nearly all land areas will warm more rapidly than the global average, particularly those at northern high latitudes in the cold season. Most notable of these is the warming in the northern regions of North America, and northern and central Asia, which exceeds global mean warming in each model by more than 40%. In contrast, the warming is less than the global mean change in south and southeast Asia in summer and in southern South America in winter.
- Recent trends for surface temperature to become more El Niño-like in the tropical Pacific, with the eastern tropical Pacific warming more than the western tropical Pacific, with a corresponding eastward shift of precipitation, are projected to continue in many models.
Precipitation
Based on global model simulations and for a wide range of scenarios, global average water vapour concentration and precipitation are projected to increase during the 21st century. By the second half of the 21st century, it is likely7 that precipitation will have increased over northern mid- to high latitudes and Antarctica in winter. At low latitudes there are both regional increases and decreases over land areas. Larger year to year variations in precipitation are very likely7 over most areas where an increase in mean precipitation is projected.
13. 13
14. 14 Hacer ver el incremento de las emisiones de Asia y OceaniaHacer ver el incremento de las emisiones de Asia y Oceania
15. 15 In the IEO2005 reference case, world carbon dioxide emissions from the consumption of fossil fuels are expected to grow at an average rate of 2.0 percent per year from 2002 to 2025. Emissions in 2025 are projected to total 38,790 million metric tons, exceeding 1990 levels by 81 percent. Combustion of petroleum products contributes 5,454 million metric tons to the projected increase from 2002, coal 5,353 million metric tons, and natural gas 3,540 million metric tons (Figure 68). Although coal use is projected to grow at a slower rate than natural gas use over the projection period, coal is a more carbon-intensive fuel than natural gas. As a result, the increment in carbon dioxide emissions from coal combustion is larger than the increment in emissions from natural gas. In the IEO2005 reference case, world carbon dioxide emissions from the consumption of fossil fuels are expected to grow at an average rate of 2.0 percent per year from 2002 to 2025. Emissions in 2025 are projected to total 38,790 million metric tons, exceeding 1990 levels by 81 percent. Combustion of petroleum products contributes 5,454 million metric tons to the projected increase from 2002, coal 5,353 million metric tons, and natural gas 3,540 million metric tons (Figure 68). Although coal use is projected to grow at a slower rate than natural gas use over the projection period, coal is a more carbon-intensive fuel than natural gas. As a result, the increment in carbon dioxide emissions from coal combustion is larger than the increment in emissions from natural gas.
16. 16 http://home.pacbell.net/sabsay/nuclear/chapter3.html
Carbon dioxide is responsible for only about half of the Earth's greenhouse effect warming. Methane, which is increased by escaping natural gas, contributes 18%, and nitrogen oxides, which are products of fossil fuel burning, account for 6%. Another major contributor is chlorinated fluorocarbons (CFCs), which are responsible for 14%. These are familiar as the working material in air conditioners, refrigerators, and freezers, and as the propellant in spray cans. (Other important sources of methane include flooded rice paddies and cows burping up gas from their stomachs.)
Another cause of the greenhouse effect is cutting down forests, since plants take carbon dioxide out of the air. Clearing of the Amazon rainforest is believed to be especially serious. Worldwide, an area of forests equal to the area of the state of Virginia is cleared every year. This is estimated to cause 20% of the greenhouse effect.
Burning wood (or biomass) releases carbon dioxide, but it does not contribute to the greenhouse effect because the wood was created from carbon dioxide, which the tree leaves absorb from the atmosphere.
In 1950, the United States was responsible for 45% of the 1.6 billion tons of carbon dioxide emitted throughout the world, but by 1980 world emissions increased to 5.1 billion tons with only 27% from the United States; Western Europe's share was 23% in 1950 and 16.5% in 1980. Increased use of fossil fuels in underdeveloped countries has played an important role in increasing emissions.
ENCARTA
The principal constituents of the atmosphere of Earth are nitrogen (78 percent) and oxygen (21 percent). The atmospheric gases in the remaining 1 percent are argon (0.9 percent), carbon dioxide (0.03 percent), varying amounts of water vapor, and trace amounts of hydrogen, ozone, methane, carbon monoxide, helium, neon, krypton, and xenon. http://home.pacbell.net/sabsay/nuclear/chapter3.html
Carbon dioxide is responsible for only about half of the Earth's greenhouse effect warming. Methane, which is increased by escaping natural gas, contributes 18%, and nitrogen oxides, which are products of fossil fuel burning, account for 6%. Another major contributor is chlorinated fluorocarbons (CFCs), which are responsible for 14%. These are familiar as the working material in air conditioners, refrigerators, and freezers, and as the propellant in spray cans. (Other important sources of methane include flooded rice paddies and cows burping up gas from their stomachs.)
Another cause of the greenhouse effect is cutting down forests, since plants take carbon dioxide out of the air. Clearing of the Amazon rainforest is believed to be especially serious. Worldwide, an area of forests equal to the area of the state of Virginia is cleared every year. This is estimated to cause 20% of the greenhouse effect.
Burning wood (or biomass) releases carbon dioxide, but it does not contribute to the greenhouse effect because the wood was created from carbon dioxide, which the tree leaves absorb from the atmosphere.
In 1950, the United States was responsible for 45% of the 1.6 billion tons of carbon dioxide emitted throughout the world, but by 1980 world emissions increased to 5.1 billion tons with only 27% from the United States; Western Europe's share was 23% in 1950 and 16.5% in 1980. Increased use of fossil fuels in underdeveloped countries has played an important role in increasing emissions.
ENCARTA
The principal constituents of the atmosphere of Earth are nitrogen (78 percent) and oxygen (21 percent). The atmospheric gases in the remaining 1 percent are argon (0.9 percent), carbon dioxide (0.03 percent), varying amounts of water vapor, and trace amounts of hydrogen, ozone, methane, carbon monoxide, helium, neon, krypton, and xenon.
17. 17 Referencia de este texto: Hans-Holger Rogner, NUCLEAR POWER AND CLIMATE CHANGE (IAEA)
Figure 1 shows the IAEA’s estimates of total greenhouse gas (GHG) emissions from the complete electricity generation chains for lignite, coal, oil, natural gas, solar
photovoltaics, hydroelectricity, biomass, wind and nuclear power.2 The results include all six Kyoto GHG’s and are converted to “grams carbon equivalent per kilowatt-hour” (gCeq/kWh) using the global warming potentials of the Intergovernmental Panel on Climate Change (IPCC).
For nuclear power, it is important that we look at complete electricity chains and all GHGs. Some anti-nuclear lobbyists, while agreeing that nuclear electricity generation produces virtually no GHG emissions at the point of generation, have contended that the balance of the nuclear electricity chain produces emissions comparable to those from fossil fuels. Figure 1 refutes that claim. GHG emissions at the point of electricity generation are shown in the dark bar segments. Shown in the light bar segments are emissions from all other stages of the electricity chain, i.e., fuel mining, preparation, and transport; plant construction and decommissioning; the manufacture of equipment; and (in the case of some renewables like hydroelectricity) the decay of organic matter. Nuclear power, wind, biomass, and hydroelectricity have the lowest full-chain emissions.
Figure 1’s estimates were developed in a series of IAEA advisory group meetings over several years. The process produced a range of emissions for each electricity generating option, reflecting differences in assessment methods, conversion efficiencies, practices in fuel preparation and subsequent transport to the location of the power plant, and local issues, such as the fuel mix assumed for electricity requirements related to plant construction and the manufacture of equipment. The several bars for each option in the figure show the range of estimates, including future projections incorporating improvements in the fuel-to-energy service conversion process, reductions during fuel extraction and transport, and lower emissions during plant and equipment construction.
LO QUE SIGUE FUEN OBTENIDO EN: WWF (organización ecologista) ver reporte Climate change and nuclear power:
Since carbon emissions per kilowatt-hour of electricity are much higher in the US than they are on
average in the EU, and because several EU states operate the less energy-intensive centrifuge
enrichment process rather than gaseous diffusion plants, the greenhouse gas emissions associated with
nuclear electricity in the US are also much higher than in European nuclear countries. The greenhouse
gas emissions of French nuclear electricity have not been calculated, though they should be
comparable to other European nuclear countries since the industry uses the more energy-intensive
gaseous diffusion process, but has a higher percentage of nuclear and hydro power in their electricity
mix.
Referencia de este texto: Hans-Holger Rogner, NUCLEAR POWER AND CLIMATE CHANGE (IAEA)
Figure 1 shows the IAEA’s estimates of total greenhouse gas (GHG) emissions from the complete electricity generation chains for lignite, coal, oil, natural gas, solar
photovoltaics, hydroelectricity, biomass, wind and nuclear power.2 The results include all six Kyoto GHG’s and are converted to “grams carbon equivalent per kilowatt-hour” (gCeq/kWh) using the global warming potentials of the Intergovernmental Panel on Climate Change (IPCC).
For nuclear power, it is important that we look at complete electricity chains and all GHGs. Some anti-nuclear lobbyists, while agreeing that nuclear electricity generation produces virtually no GHG emissions at the point of generation, have contended that the balance of the nuclear electricity chain produces emissions comparable to those from fossil fuels. Figure 1 refutes that claim. GHG emissions at the point of electricity generation are shown in the dark bar segments. Shown in the light bar segments are emissions from all other stages of the electricity chain, i.e., fuel mining, preparation, and transport; plant construction and decommissioning; the manufacture of equipment; and (in the case of some renewables like hydroelectricity) the decay of organic matter. Nuclear power, wind, biomass, and hydroelectricity have the lowest full-chain emissions.
Figure 1’s estimates were developed in a series of IAEA advisory group meetings over several years. The process produced a range of emissions for each electricity generating option, reflecting differences in assessment methods, conversion efficiencies, practices in fuel preparation and subsequent transport to the location of the power plant, and local issues, such as the fuel mix assumed for electricity requirements related to plant construction and the manufacture of equipment. The several bars for each option in the figure show the range of estimates, including future projections incorporating improvements in the fuel-to-energy service conversion process, reductions during fuel extraction and transport, and lower emissions during plant and equipment construction.
LO QUE SIGUE FUEN OBTENIDO EN: WWF (organización ecologista) ver reporte Climate change and nuclear power:
Since carbon emissions per kilowatt-hour of electricity are much higher in the US than they are on
average in the EU, and because several EU states operate the less energy-intensive centrifuge
enrichment process rather than gaseous diffusion plants, the greenhouse gas emissions associated with
nuclear electricity in the US are also much higher than in European nuclear countries. The greenhouse
gas emissions of French nuclear electricity have not been calculated, though they should be
comparable to other European nuclear countries since the industry uses the more energy-intensive
gaseous diffusion process, but has a higher percentage of nuclear and hydro power in their electricity
mix.
18. 18 A more objective answer assumes that the mix of energy sources in the 84% of global electricity supplied today from non-nuclear
sources is the best indicator of what might replace nuclear power in a hypothetical nonnuclear 2003. The calculations in Table 1 therefore assume that non-nuclear electricity sources would expand their contributions proportionately, with the one exception of hydropower. It is more constrained than other sources of electricity, especially in the developed countries that are major users of nuclear power, so Table 1’s calculations postulate that hydropower would be largely unable to expand. The table is based on data for 2000 from the World Energy Outlook 2002 published by the OECD International Energy Agency (IEA).4
The first row in the table (not counting the header row) shows the global electricity generation mix in 2000. The second row shows carbon emissions from electricity generation, also from the World Energy Outlook 2002. The third row calculates the carbon intensity of electricity production by dividing the second row by the first. The fourth row shows the hypothetical energy mix when nuclear power is eliminated and its electricity generation is spread proportionately over the other electricity sources except hydropower. The fifth row calculates the resulting carbon emissions using the carbon intensities in the third row. The sixth row shows the differences in emissions between the hypothetical mix without nuclear and the actual 2000 energy mix, i.e. the carbon emissions avoided by nuclear power in 2000.
The total in the bottom right corner is 622 MtC avoided due to nuclear power. Since some hydropower expansion is possible in developing countries with small nuclear shares, such as Brazil or China, the IAEA rounds this number down to “approximately 600 MtC” in its publications.
A more objective answer assumes that the mix of energy sources in the 84% of global electricity supplied today from non-nuclear
sources is the best indicator of what might replace nuclear power in a hypothetical nonnuclear 2003. The calculations in Table 1 therefore assume that non-nuclear electricity sources would expand their contributions proportionately, with the one exception of hydropower. It is more constrained than other sources of electricity, especially in the developed countries that are major users of nuclear power, so Table 1’s calculations postulate that hydropower would be largely unable to expand. The table is based on data for 2000 from the World Energy Outlook 2002 published by the OECD International Energy Agency (IEA).4
The first row in the table (not counting the header row) shows the global electricity generation mix in 2000. The second row shows carbon emissions from electricity generation, also from the World Energy Outlook 2002. The third row calculates the carbon intensity of electricity production by dividing the second row by the first. The fourth row shows the hypothetical energy mix when nuclear power is eliminated and its electricity generation is spread proportionately over the other electricity sources except hydropower. The fifth row calculates the resulting carbon emissions using the carbon intensities in the third row. The sixth row shows the differences in emissions between the hypothetical mix without nuclear and the actual 2000 energy mix, i.e. the carbon emissions avoided by nuclear power in 2000.
The total in the bottom right corner is 622 MtC avoided due to nuclear power. Since some hydropower expansion is possible in developing countries with small nuclear shares, such as Brazil or China, the IAEA rounds this number down to “approximately 600 MtC” in its publications.
19. 19 Emissions avoided by nuclear power are calculated using regional fossil fuel emissions rates (from the Environmental Protection Agency’s Continuous Emission Monitoring System) and individual plant generation data from NRC. Total emissions are calculated from EPA CEMS data.
Emissions avoided by nuclear power are calculated using regional fossil fuel emissions rates (from the Environmental Protection Agency’s Continuous Emission Monitoring System) and individual plant generation data from NRC. Total emissions are calculated from EPA CEMS data.
20. 20
21. 21 To estimate how much carbon avoidance nuclear power will or might provide in the future, scenarios are needed for the future evolution of the electricity generating mix and for improvements (reductions) in the carbon intensity of different generation options. The “reference scenario” of the IEA’s World Energy Outlook 2002 provides one such scenario. It assumes no new nuclear plants beyond what is already being built or seriously planned today, plus the retirement of older reactors as originally scheduled. The result is a small rise in nuclear electricity generation to 2010, but then a gradual decline through the end of the
scenario in 2030, as retirements in Europe and North America start to outpace new nuclear additions in Asia.
Repeating the calculations in Table 1 for this scenario yields the projections in Figure 3 for avoided carbon emissions that could be attributed to nuclear power if the world develops along the path of the IEA’s reference scenario. Annually avoided emissions attributable to nuclear power (the left panel in Figure 3) follow the same trajectory that the IEA scenario projects for nuclear generation, a slight increase to 2010 and then a gradual decline through 2030. The right panel shows cumulative avoided emissions from 2000 onwards – a steep and steady increase.
To estimate how much carbon avoidance nuclear power will or might provide in the future, scenarios are needed for the future evolution of the electricity generating mix and for improvements (reductions) in the carbon intensity of different generation options. The “reference scenario” of the IEA’s World Energy Outlook 2002 provides one such scenario. It assumes no new nuclear plants beyond what is already being built or seriously planned today, plus the retirement of older reactors as originally scheduled. The result is a small rise in nuclear electricity generation to 2010, but then a gradual decline through the end of the
scenario in 2030, as retirements in Europe and North America start to outpace new nuclear additions in Asia.
Repeating the calculations in Table 1 for this scenario yields the projections in Figure 3 for avoided carbon emissions that could be attributed to nuclear power if the world develops along the path of the IEA’s reference scenario. Annually avoided emissions attributable to nuclear power (the left panel in Figure 3) follow the same trajectory that the IEA scenario projects for nuclear generation, a slight increase to 2010 and then a gradual decline through 2030. The right panel shows cumulative avoided emissions from 2000 onwards – a steep and steady increase.
22. 22 To estimate nuclear power’s full potential for reducing future carbon emissions,
however, the calculations have to be done for scenarios in which nuclear power truly expands
its contribution to world energy supplies, rather than contracts as in the IEA scenario. Our
starting point is the long-term scenarios of the IPCC’s Special Report on Emission Scenarios
(SRES).5 Although these were not designed to explore specifically nuclear power or any
other particular energy option, their objective of minimizing total long-term system costs
leads to future expansions of nuclear energy very different from the IEA’s projected
intermediate-term contractions.
The SRES scenarios are global scenarios based on a global process – an open
invitation that resulted in 28 authors from around the world and six modelling teams from
three continents (Asia, Europe, and North America) doing the analysis. They have been
subjected to the most thorough and documented expert and governmental reviews of any
scenario set we know of. And they are relatively transparent, with extensive qualitative and
quantitative results available at http://www.grida.no/climate/ipcc/emission/. Given their
international authorship and comprehensive review by governments and scientific experts,
the SRES scenarios are the state of the art in long-term energy scenarios.
SRES developed four narrative storylines, each representing a different coherent set
of demographic, social, economic, technological, and environmental developments. For each
storyline, several different quantifications, or scenarios, were then developed by the six
modeling teams. The result is 40 scenarios grouped in four “families” (A1, A2, B1, and B2)
corresponding to the four narrative storylines. Economic objectives dominate in the “A”
storylines, while environmental objectives dominate in the “B” storylines. The “1” storylines
emphasize globalization, while the “2” storylines are better characterized by regionalism.
The following summaries are almost verbatim from the SRES report.
For each of the A2, B1, and B2 storylines we use a single “marker” scenario
representative of central tendencies within the scenario family. For the A1 storyline, SRES
projections showed that greenhouse gas emissions (the principal focus of SRES) vary greatly
depending on the technologies assumed to progress most quickly. We use the A1T Scenario,
which assumes that advances in non-fossil technologies – renewables, nuclear, and high efficiency
conservation technologies – make them most cost-competitive.
The left panel of Figure 4 projects the carbon emissions avoided by nuclear power in
each of the four selected SRES scenarios as adjusted to match actual 2000 electricity
generation data in the World Energy Outlook 2002. All four project increased carbon
avoidance attributable to nuclear power corresponding to their projections of increasing
nuclear electricity generation. One reason that the SRES scenarios differ from the IEA is that
they minimize total energy system costs looking ahead 100 years. They thus take greater
account of the projected depletion of low-cost fossil fuels and give greater weight to longterm
returns than do current deregulating energy markets – which form the basis for the IEA
reference scenario. From the longer-term perspective of SRES, nuclear power is a more
attractive investment than from the near-term perspective of the IEA.
But although the SRES scenarios generally project nuclear expansion, they don’t push
the envelope. They don’t explore the full potential for large reductions in GHG emissions
through aggressive expansions of nuclear energy. The IAEA has developed for each of the
four SRES scenarios in the left panel of Figure 4 an aggressive-nuclear variant that assumes
improvements in nuclear technologies, relative to alternatives, at faster rates than those
assumed by the original SRES modeling teams.6 Faster technological improvements mean
greater economic competitiveness, which in term means greater market shares and faster
expansion. The resulting projections for carbon avoidance from nuclear power are given in
the right panel of Figure 4.
To estimate nuclear power’s full potential for reducing future carbon emissions,
however, the calculations have to be done for scenarios in which nuclear power truly expands
its contribution to world energy supplies, rather than contracts as in the IEA scenario. Our
starting point is the long-term scenarios of the IPCC’s Special Report on Emission Scenarios
(SRES).5 Although these were not designed to explore specifically nuclear power or any
other particular energy option, their objective of minimizing total long-term system costs
leads to future expansions of nuclear energy very different from the IEA’s projected
intermediate-term contractions.
The SRES scenarios are global scenarios based on a global process – an open
invitation that resulted in 28 authors from around the world and six modelling teams from
three continents (Asia, Europe, and North America) doing the analysis. They have been
subjected to the most thorough and documented expert and governmental reviews of any
scenario set we know of. And they are relatively transparent, with extensive qualitative and
quantitative results available at http://www.grida.no/climate/ipcc/emission/. Given their
international authorship and comprehensive review by governments and scientific experts,
the SRES scenarios are the state of the art in long-term energy scenarios.
SRES developed four narrative storylines, each representing a different coherent set
of demographic, social, economic, technological, and environmental developments. For each
storyline, several different quantifications, or scenarios, were then developed by the six
modeling teams. The result is 40 scenarios grouped in four “families” (A1, A2, B1, and B2)
corresponding to the four narrative storylines. Economic objectives dominate in the “A”
storylines, while environmental objectives dominate in the “B” storylines. The “1” storylines
emphasize globalization, while the “2” storylines are better characterized by regionalism.
The following summaries are almost verbatim from the SRES report.
For each of the A2, B1, and B2 storylines we use a single “marker” scenario
representative of central tendencies within the scenario family. For the A1 storyline, SRES
projections showed that greenhouse gas emissions (the principal focus of SRES) vary greatly
depending on the technologies assumed to progress most quickly. We use the A1T Scenario,
which assumes that advances in non-fossil technologies – renewables, nuclear, and high efficiency
conservation technologies – make them most cost-competitive.
The left panel of Figure 4 projects the carbon emissions avoided by nuclear power in
each of the four selected SRES scenarios as adjusted to match actual 2000 electricity
generation data in the World Energy Outlook 2002. All four project increased carbon
avoidance attributable to nuclear power corresponding to their projections of increasing
nuclear electricity generation. One reason that the SRES scenarios differ from the IEA is that
they minimize total energy system costs looking ahead 100 years. They thus take greater
account of the projected depletion of low-cost fossil fuels and give greater weight to longterm
returns than do current deregulating energy markets – which form the basis for the IEA
reference scenario. From the longer-term perspective of SRES, nuclear power is a more
attractive investment than from the near-term perspective of the IEA.
But although the SRES scenarios generally project nuclear expansion, they don’t push
the envelope. They don’t explore the full potential for large reductions in GHG emissions
through aggressive expansions of nuclear energy. The IAEA has developed for each of the
four SRES scenarios in the left panel of Figure 4 an aggressive-nuclear variant that assumes
improvements in nuclear technologies, relative to alternatives, at faster rates than those
assumed by the original SRES modeling teams.6 Faster technological improvements mean
greater economic competitiveness, which in term means greater market shares and faster
expansion. The resulting projections for carbon avoidance from nuclear power are given in
the right panel of Figure 4.
23. 23 Because it is not so much annual emissions but cumulative carbon emissions that
drive climate change, Figure 5 shows the cumulative carbon emissions avoided by nuclear
power (from 2000 forward) both for the selected SRES scenarios and the aggressive-nuclear
variants.
Because it is not so much annual emissions but cumulative carbon emissions that
drive climate change, Figure 5 shows the cumulative carbon emissions avoided by nuclear
power (from 2000 forward) both for the selected SRES scenarios and the aggressive-nuclear
variants.
24. 24 Plantas Surry 1 (PWR) y Peach Bootom 2 (BWR).
Los resultados indicaron que:
Plantas Surry 1 (PWR) y Peach Bootom 2 (BWR).
Los resultados indicaron que:
25. 25 Plantas Surry 1 (PWR) y Peach Bootom 2 (BWR).
Los resultados indicaron que:
Plantas Surry 1 (PWR) y Peach Bootom 2 (BWR).
Los resultados indicaron que:
26. 26
27. 27
28. 28
29. 29
30. 30 TASI = number of accidents resulting in lost work, restricted work, or job transfer per 200,000 worker hours
Sources: Nuclear (World Association of Nuclear Operators), others (US Bureau of Labor Statistics). Data updated April 2005
Fuente NEI – Presentación Power PointTASI = number of accidents resulting in lost work, restricted work, or job transfer per 200,000 worker hours
Sources: Nuclear (World Association of Nuclear Operators), others (US Bureau of Labor Statistics). Data updated April 2005
Fuente NEI – Presentación Power Point
31. 31
32. 32 FIG. 1. Probabilities per gigawatt-year of electricity production of immediate fatalities due
to severe accidents for nuclear power, hydropower and fossil fuel options. ((E) is the reference
curve determined on the basis of the mean values of the expected release category frequencies;
(M) is the curve determined on the basis of the median values of the expected release category
frequencies; LWR: light water reactor; DRS: German Risk Study [12]) (after Refs [9, 13]).
Figure 1 shows the immediate mortality risk due to severe accidents in the
nuclear power (LWR), fossil fuel afld hydropower energy cycles. It is seen that
severe accidents with a specific number of acute fatalities are expected to occur about
10 000 times more frequently in mines to produce coal for the coal electric cycle than
would occur at nuclear power plants producing the same amount of energy.
Refining of oil is only one of the major processes in the oil-electricity cycle.
Yet severe accidents at oil refineries are about a factor of 1000 times more frequent
than is expected for accidents of the same severity at nuclear plants.
According to the estimates in Ref.[ll], for equivalent severity, an accident to
a hydropower dam is more likely by a factor of about 1000 than an accident to a
nuclear plant.
Converting these data to a basis which allows for the quantities of electricity
generated leads to a risk of 0.0001 fatalities/GW-a for the nuclear option. The corresponding
figures for the fossil fuelled cycles are given in Table VI as:
Coal 0.34
Oil 0.10
Gas 0.17
In this connection, die renewable energy systems, solar, wind and biomass
(excluding wood), are exceptional. In contrast to all other energy options they have
practically no potential for severe accidents or for catastrophic failure in the actual
production of electricity. The corresponding risks in their support cycles have not
been evaluated.
FIG. 1. Probabilities per gigawatt-year of electricity production of immediate fatalities due
to severe accidents for nuclear power, hydropower and fossil fuel options. ((E) is the reference
curve determined on the basis of the mean values of the expected release category frequencies;
(M) is the curve determined on the basis of the median values of the expected release category
frequencies; LWR: light water reactor; DRS: German Risk Study [12]) (after Refs [9, 13]).
Figure 1 shows the immediate mortality risk due to severe accidents in the
nuclear power (LWR), fossil fuel afld hydropower energy cycles. It is seen that
severe accidents with a specific number of acute fatalities are expected to occur about
10 000 times more frequently in mines to produce coal for the coal electric cycle than
would occur at nuclear power plants producing the same amount of energy.
Refining of oil is only one of the major processes in the oil-electricity cycle.
Yet severe accidents at oil refineries are about a factor of 1000 times more frequent
than is expected for accidents of the same severity at nuclear plants.
According to the estimates in Ref.[ll], for equivalent severity, an accident to
a hydropower dam is more likely by a factor of about 1000 than an accident to a
nuclear plant.
Converting these data to a basis which allows for the quantities of electricity
generated leads to a risk of 0.0001 fatalities/GW-a for the nuclear option. The corresponding
figures for the fossil fuelled cycles are given in Table VI as:
Coal 0.34
Oil 0.10
Gas 0.17
In this connection, die renewable energy systems, solar, wind and biomass
(excluding wood), are exceptional. In contrast to all other energy options they have
practically no potential for severe accidents or for catastrophic failure in the actual
production of electricity. The corresponding risks in their support cycles have not
been evaluated.
33. 33 El almacenamiento no es un problema de ingeniería como lo demuestran los proyectos avanzados en Francia, Suecia y Japón.El almacenamiento no es un problema de ingeniería como lo demuestran los proyectos avanzados en Francia, Suecia y Japón.
34. 34 http://home.pacbell.net/sabsay/nuclear/chapter11.html
QUANTITATIVE RISK ASSESSMENT FOR HIGH-LEVEL WASTE
Our next task is to develop a quantitative estimate of the hazard from buried radioactive waste.8 Our treatment is based on an analogy between buried radioactive waste and average rock submerged in groundwater. We will justify this analogy later, but it is very useful because we know a great deal about the behavior of average rock and its interaction with groundwater. Using this information in a calculation outlined in the Chapter 11 Appendix demonstrates that an atom of average rock submerged in groundwater has one chance in a trillion each year of being dissolved out of the rock, eventually being carried into a river, and ending up in a human stomach.
In the spirit of our analogy between this average rock and buried radioactive waste, we assume that this probability also applies to the latter; that is, an atom of buried radioactive waste has one chance in a trillion of reaching a human stomach each year. The remainder of our calculation is easy, because we know from Fig. 1 the consequences of this waste reaching a human stomach. All we need do is multiply the curve in Fig. 1 by one-trillionth to obtain the number of fatal cancers expected each year. This is done by simply relabeling the vertical scale, as shown on the right side of Fig. 1. For example, if all of the waste were to reach human stomachs a thousand years after burial, there would be 300,000 deaths, according to the scale on the left side of Fig. 1, but since only one-trillionth of it reaches human stomachs each year, there would be (300,000 / 1 trillion =) 3 X 10-7 deaths per year, as indicated by reading the curve with the scale on the right side of Fig. 1. This result is equivalent to one chance in 3 million of a single death each year.
What we really want to know is the total number of people who will eventually die from the waste. Since we know how many will die each year, we simply must add these up. Totalling them over millions of years gives 0.014 eventual deaths. One might ask how far into the future we should carry this addition, and therein lies a complication that requires some explanation.
From the measured rate at which rivers carry dissolved and suspended material into the ocean each year, it is straightforward to calculate that the surfaces of the continents are eroding away at an average rate of 1 meter (3.3 feet) of depth every 22,000 years. (All the while the continents are being uplifted such that on an average the surface remains at about the same elevation.) Nearly all of this erosion comes from river beds and the minor streams and runoff that feed them. However, rivers change their courses frequently; changing climates develop new rivers and eliminate old ones (e.g., 10,000 years ago the Arizona desert was a rain forest); and land areas rise and fall under geological pressures to change drainage patterns. Therefore, averaged over very long time periods, it is reasonable to assume that most land areas erode away at roughly this average rate, 1 meter of depth every 22,000 years. This suggests that the ground surface will eventually erode down to the level of the buried radioactive waste. Since the waste will be buried at a depth of about 600 meters, this may be expected to occur after about (600 x 22,000 =) 13 million years. When it happens, the remaining radioactivity will be released into rivers, and according to estimates developed in the Chapter 11 Appendix, one part in 10,000 will get into human stomachs.
Therefore, the process of adding up the number of deaths each year should be discontinued after 13 million years; that was done in calculating the number of deaths given above as 0.014. To this we must add the number of deaths caused by release of the remaining radioactivity. A simple calculation given in the Chapter 11 Appendix shows that this leads to 0.004 deaths. Adding that number to the 0.014 deaths during the first l3 million years gives 0.018 as the total number of eventual deaths from the waste produced by one power plant in one year. This is the final result of this section, 0.018 eventual fatalities. Recall now that air pollution, one of the wastes from coal burning, kills 75 people in generating the same amount of electricity; perhaps new pollution control technology may reduce this number to 15 deaths per year. Even if this comes to pass, we see that this one waste from coal burning would still be a thousand times more injurious to human health than are the high-level nuclear wastes.
Another way of understanding the results of our analysis is to consider a situation in which all of the present electricity used in the United States has been provided by nuclear power plants — about 300 would be required — continuously for millions of years. We would then expect (300 x 0.018 =) 5.4 cancer deaths per year on an average from all of the accumulated waste. Compare this with the 30,000 deaths each year we now get from coal-burning power plants.http://home.pacbell.net/sabsay/nuclear/chapter11.html
QUANTITATIVE RISK ASSESSMENT FOR HIGH-LEVEL WASTE
Our next task is to develop a quantitative estimate of the hazard from buried radioactive waste.8 Our treatment is based on an analogy between buried radioactive waste and average rock submerged in groundwater. We will justify this analogy later, but it is very useful because we know a great deal about the behavior of average rock and its interaction with groundwater. Using this information in a calculation outlined in the Chapter 11 Appendix demonstrates that an atom of average rock submerged in groundwater has one chance in a trillion each year of being dissolved out of the rock, eventually being carried into a river, and ending up in a human stomach.
In the spirit of our analogy between this average rock and buried radioactive waste, we assume that this probability also applies to the latter; that is, an atom of buried radioactive waste has one chance in a trillion of reaching a human stomach each year. The remainder of our calculation is easy, because we know from Fig. 1 the consequences of this waste reaching a human stomach. All we need do is multiply the curve in Fig. 1 by one-trillionth to obtain the number of fatal cancers expected each year. This is done by simply relabeling the vertical scale, as shown on the right side of Fig. 1. For example, if all of the waste were to reach human stomachs a thousand years after burial, there would be 300,000 deaths, according to the scale on the left side of Fig. 1, but since only one-trillionth of it reaches human stomachs each year, there would be (300,000 / 1 trillion =) 3 X 10-7 deaths per year, as indicated by reading the curve with the scale on the right side of Fig. 1. This result is equivalent to one chance in 3 million of a single death each year.
What we really want to know is the total number of people who will eventually die from the waste. Since we know how many will die each year, we simply must add these up. Totalling them over millions of years gives 0.014 eventual deaths. One might ask how far into the future we should carry this addition, and therein lies a complication that requires some explanation.
From the measured rate at which rivers carry dissolved and suspended material into the ocean each year, it is straightforward to calculate that the surfaces of the continents are eroding away at an average rate of 1 meter (3.3 feet) of depth every 22,000 years. (All the while the continents are being uplifted such that on an average the surface remains at about the same elevation.) Nearly all of this erosion comes from river beds and the minor streams and runoff that feed them. However, rivers change their courses frequently; changing climates develop new rivers and eliminate old ones (e.g., 10,000 years ago the Arizona desert was a rain forest); and land areas rise and fall under geological pressures to change drainage patterns. Therefore, averaged over very long time periods, it is reasonable to assume that most land areas erode away at roughly this average rate, 1 meter of depth every 22,000 years. This suggests that the ground surface will eventually erode down to the level of the buried radioactive waste. Since the waste will be buried at a depth of about 600 meters, this may be expected to occur after about (600 x 22,000 =) 13 million years. When it happens, the remaining radioactivity will be released into rivers, and according to estimates developed in the Chapter 11 Appendix, one part in 10,000 will get into human stomachs.
Therefore, the process of adding up the number of deaths each year should be discontinued after 13 million years; that was done in calculating the number of deaths given above as 0.014. To this we must add the number of deaths caused by release of the remaining radioactivity. A simple calculation given in the Chapter 11 Appendix shows that this leads to 0.004 deaths. Adding that number to the 0.014 deaths during the first l3 million years gives 0.018 as the total number of eventual deaths from the waste produced by one power plant in one year. This is the final result of this section, 0.018 eventual fatalities. Recall now that air pollution, one of the wastes from coal burning, kills 75 people in generating the same amount of electricity; perhaps new pollution control technology may reduce this number to 15 deaths per year. Even if this comes to pass, we see that this one waste from coal burning would still be a thousand times more injurious to human health than are the high-level nuclear wastes.
Another way of understanding the results of our analysis is to consider a situation in which all of the present electricity used in the United States has been provided by nuclear power plants — about 300 would be required — continuously for millions of years. We would then expect (300 x 0.018 =) 5.4 cancer deaths per year on an average from all of the accumulated waste. Compare this with the 30,000 deaths each year we now get from coal-burning power plants.
35. 35 El almacenamiento no es un problema de ingeniería como lo demuestran los proyectos avanzados en Francia, Suecia y Japón.El almacenamiento no es un problema de ingeniería como lo demuestran los proyectos avanzados en Francia, Suecia y Japón.
36. 36 El almacenamiento no es un problema de ingeniería como lo demuestran los proyectos avanzados en Francia, Suecia y Japón.El almacenamiento no es un problema de ingeniería como lo demuestran los proyectos avanzados en Francia, Suecia y Japón.
37. 37
38. 38 . En 1910 el Glacier National Park tenía mas de 150 glaciares; hoy quedan menos de 30 y el área de los que aún quedan se ha disminuido en dos tercios. Se pronostica que en 30 años podría ya no quedar ninguno.. En 1910 el Glacier National Park tenía mas de 150 glaciares; hoy quedan menos de 30 y el área de los que aún quedan se ha disminuido en dos tercios. Se pronostica que en 30 años podría ya no quedar ninguno.
39. 39 El coral del planeta se encuentra en aguas cada vez más calientes, las que hacen que se cueza en periodos con clima estable y soleado. El calor provoca que el coral se desprenda de las algas que lo alimentan, lo que ocasiona que se decolore y se torne blanco. Algunos se recuperan pero otros no. En 1998 los corales del mundo sufrieron el peor año que se haya registrado, en el cual el 16% de ellos se decoloró o murió (Fuente National Geographic).
Dry Conditions produced the worst wildfires in Florida in 50 years.
El coral del planeta se encuentra en aguas cada vez más calientes, las que hacen que se cueza en periodos con clima estable y soleado. El calor provoca que el coral se desprenda de las algas que lo alimentan, lo que ocasiona que se decolore y se torne blanco. Algunos se recuperan pero otros no. En 1998 los corales del mundo sufrieron el peor año que se haya registrado, en el cual el 16% de ellos se decoloró o murió (Fuente National Geographic).
Dry Conditions produced the worst wildfires in Florida in 50 years.
40. 40 Parte de la plataforma de hielo Larsen B se rompió a principios de 2002. Si bien el hielo flotante no cambia el nivel del mar al derretirse (al igual que no lo hacen cubos de hielo en un vaso de agua al derretirse), los científicos se preocuparon porque este colapso podría presagiar el rompimiento de otras plataformas de hielo en la antártida y permitir el aumento en la descarga glacial al mar desde capas de hielo en el continente (fuente National Geographic).Parte de la plataforma de hielo Larsen B se rompió a principios de 2002. Si bien el hielo flotante no cambia el nivel del mar al derretirse (al igual que no lo hacen cubos de hielo en un vaso de agua al derretirse), los científicos se preocuparon porque este colapso podría presagiar el rompimiento de otras plataformas de hielo en la antártida y permitir el aumento en la descarga glacial al mar desde capas de hielo en el continente (fuente National Geographic).
41. 41
42. 42 Rising sea levels
Partly due to glacier melt
Mainly due to thermal expansion of seawater
Maximum density of water is at 4°C
As water temperature increases, density of water decreases. Therefore, volume of seawater increases.
Seawater is not as quick to warm as air or land. So consequences of global warming will be delayed.
Half the world’s population lives in coastal areas.
Rising sea levels
Partly due to glacier melt
Mainly due to thermal expansion of seawater
Maximum density of water is at 4°C
As water temperature increases, density of water decreases. Therefore, volume of seawater increases.
Seawater is not as quick to warm as air or land. So consequences of global warming will be delayed.
Half the world’s population lives in coastal areas.
43. 43
44. 44 A 2005 study published in the journal Nature suggests that storm intensity and duration is linked to the recent ocean warming trends associated with global warming. Scientists tracked measurements of the destructive power of storms, termed the Power Dissipation Index (PDI), since 1950. The study, which combined each storm’s maximum wind speeds and storm duration, found that during the last 30 years, the destructive power of storms has doubled in the Atlantic and Pacific.¹
Most of this has occurred during the past 10 years when global average surface ocean temperatures were at record levels. Thus far, scientific evidence does not link worldwide storm frequency with global warming. Individual ocean basins have multiyear cycles of storm activity. While the total number of storms in the tropics remained similar through time, the percentage of category 4 and 5 hurricanes have increased over the past 30 years, according to a 2005 paper in the journal Science.
Protecting Coastal Communities
Given the huge price tag from the cleanup of recent hurricanes such as Andrew ($43.7 billion)², Ivan ($14.2 billion), and Katrina ($125 billion projected), it is essential to do whatever we can to avoid dangerous warming and preserve healthy and prosperous coastal communities for ourselves and our children. Because CO2 can stay in the atmosphere for 100 years or more, even an aggressive plan to use energy more efficiently and reduce emissions from power plants and vehicles will not stop warming in it tracks. Therefore, it is essential that we combine aggressive emission reduction efforts with improved measures to protect coastal communities. These measures— including building codes, storm drainage plans, and preservation and restoration of wetlands, dunes, and barrier islands— must be designed to cope with increasing sea level rise and storm intensity due to global warming.
¹Tracking of ocean temperatures has been relatively accurate over the past 50 years while storm tracking data have improved significantly in the past 30 years. Both sea surface temperatures and hurricane intensity increased most rapidly over the past 15 years. A 2005 study published in the journal Nature suggests that storm intensity and duration is linked to the recent ocean warming trends associated with global warming. Scientists tracked measurements of the destructive power of storms, termed the Power Dissipation Index (PDI), since 1950. The study, which combined each storm’s maximum wind speeds and storm duration, found that during the last 30 years, the destructive power of storms has doubled in the Atlantic and Pacific.¹
Most of this has occurred during the past 10 years when global average surface ocean temperatures were at record levels. Thus far, scientific evidence does not link worldwide storm frequency with global warming. Individual ocean basins have multiyear cycles of storm activity. While the total number of storms in the tropics remained similar through time, the percentage of category 4 and 5 hurricanes have increased over the past 30 years, according to a 2005 paper in the journal Science.
Protecting Coastal Communities
Given the huge price tag from the cleanup of recent hurricanes such as Andrew ($43.7 billion)², Ivan ($14.2 billion), and Katrina ($125 billion projected), it is essential to do whatever we can to avoid dangerous warming and preserve healthy and prosperous coastal communities for ourselves and our children. Because CO2 can stay in the atmosphere for 100 years or more, even an aggressive plan to use energy more efficiently and reduce emissions from power plants and vehicles will not stop warming in it tracks. Therefore, it is essential that we combine aggressive emission reduction efforts with improved measures to protect coastal communities. These measures— including building codes, storm drainage plans, and preservation and restoration of wetlands, dunes, and barrier islands— must be designed to cope with increasing sea level rise and storm intensity due to global warming.
¹Tracking of ocean temperatures has been relatively accurate over the past 50 years while storm tracking data have improved significantly in the past 30 years. Both sea surface temperatures and hurricane intensity increased most rapidly over the past 15 years.
45. 45 Katrina:200 billones en pérdidas y 1383 muertos (4000 desaparecidos).
Fuentes Katrina:
http://www.cnsnews.com/Facts/2005/facts20051222.asp
http://www.usatoday.com/news/nation/2005-09-10-katrinacosts_x.htm
Katrina:200 billones en pérdidas y 1383 muertos (4000 desaparecidos).
Fuentes Katrina:
http://www.cnsnews.com/Facts/2005/facts20051222.asp
http://www.usatoday.com/news/nation/2005-09-10-katrinacosts_x.htm
46. 46 Katrina:200 billones en pérdidas y 1383 muertos (4000 desaparecidos).
Fuentes Katrina:
http://www.cnsnews.com/Facts/2005/facts20051222.asp
http://www.usatoday.com/news/nation/2005-09-10-katrinacosts_x.htm
Katrina:200 billones en pérdidas y 1383 muertos (4000 desaparecidos).
Fuentes Katrina:
http://www.cnsnews.com/Facts/2005/facts20051222.asp
http://www.usatoday.com/news/nation/2005-09-10-katrinacosts_x.htm
47. 47 NOAA: National Oceanic & Atmospheric Administration /US Department of CommerceNOAA: National Oceanic & Atmospheric Administration /US Department of Commerce
48. 48
49. 49
50. 50
51. 51
52. 52 WMO: World Meteorological Organization (United Nations)
UNEP: United Nations Environment ProgrammeWMO: World Meteorological Organization (United Nations)
UNEP: United Nations Environment Programme
53. 53 Sequías: En la mayoría de los interiores continentales de latitudes medias.
Índice de Calor: En la mayoría de las áreas.
Ciclones: En algunas áreas.
Muy probable: 90 a 99% de posibilidad.
Probable: 66 a 90% de posibilidad. Sequías: En la mayoría de los interiores continentales de latitudes medias.
Índice de Calor: En la mayoría de las áreas.
Ciclones: En algunas áreas.
Muy probable: 90 a 99% de posibilidad.
Probable: 66 a 90% de posibilidad.
54. 54
55. 55
56. 56
57. 57
58. 58
59. 59
