What is some of the most convincing evidence for climate change? Final Version

I believe that a brief understanding of the earth’s climate history and greenhouse gases is essential to interpreting the evidence of warming and climate change.  Throughout history our planet ahs undergone multiple phases of change.  However, this doesn’t mean we should ignore our current situation.  Just because the planet was warmer in the past, does not mean that we should ignore modern climate change.  Studies show that there are a few key factors that contribute to climate change. Factors such as, extremely small variations in Earth’s orbit, which change the amount of solar energy our planet receives, which in turn contributes to climate change.  The current trend of warming is particularly worrisome and noteworthy because it is it occurring at an unprecedented rate not seen in the last 1,300 years; as a result of human activities.

History of Earth’s Climate Change:

Throughout history the earth’s climate has undergone tremendous change.  There are two distinct stages that accurately characterize earth’s climate:  greenhouse and icehouse.  During a greenhouse stage, there is little to no, permanent ice on both the south and north poles.  Warm temperatures are also found at high latitudes.  An icehouse climate is characterized by cool temperatures, cold enough to sustain large ice sheets at both poles.  The planet has transitioned between these two phases only a few times over the past 540 million years.  The most recent of these changes took place during the Cenozoic Era, which was approximately 56 million years ago.  It its extremely important that we have a brief understand of the history of earths climate; in order to analyze current evidence supporting global warming and climate change as an issue. The sudden end of the last ice age about 7,000 years ago, marks the beginning of the modern climate period.  We currently inhabit an icehouse earth, which is comparatively colder to other periods in earth’s history.

Greenhouse Gasses:

The overall levels of greenhouse gases have increased over time. Source: WWF Global
The overall levels of greenhouse gases have increased over time.
Source: WWF Global

Many chemical compounds in Earth’s atmosphere behave like greenhouse gases.  Many gases are naturally occurring while others are synthetic and man made.  Carbon dioxide and other greenhouse gases have a heat trapping nature. They allow direct sunlight to reach the earth’s surface. Greenhouse gases absorb this energy, which allows less heat to escape back to space, and traps it in the lower atmosphere.  Their propensity to affect the transfer of infrared energy through the atmosphere is the scientific basis of many studies and arguments that, increased levels of greenhouse gases cause the Earth to warm in response. Atmospheric concentrations of both the natural and synthetic gases have been rising at an alarming rate over the last few centuries due to the industrial revolution. Also, as the global population has increased; our reliance and use of fossil fuels has increased.  Therefore, emissions of these gases has increased.  Even though carbon dioxide is naturally occurring in the atmosphere, our interference with the carbon cycle through burning forest lands, mining and fossil fuel consumption.  We are artificially manipulating carbon from solid storage to its gaseous state (sublimation).  This increases atmospheric concentrations, which contributes to global warming.

 

The chart shows different types of gases. Source: NOAA
The chart shows different types of gases.
Source: NOAA

Studies conducted by the World Resources Institute indicate that human beings are responsible for contributing 2.3 trillion tones of carbon dioxide to the atmosphere, in only the last 200 years!  Greenhouse gases are being emitted due to human activity at  a groundbreaking rate.  At this current trend, we have already increased the overall atmospheric carbon dioxide by 3.1%.  As a result, fossil fuel emissions and in particular CO2 emissions are 12 times larger when compared to emission levels 24 years ago.  It is now not even surprising that our climate has changed so drastically in an comparatively minuscule time period.

“Scientific evidence for warming of the climate system is unequivocal.”

– Intergovernmental Panel on Climate Change

There is currently a plethora of evidence that supports the notion that our earth is warming and the climate is charging. Evidence such as increased sea levels, global temperature rise, warming oceans, shrinking ice sheets, declining arctic sea ice, glacial retreat, extreme weather events, ocean acidification, and decreased snow cover.  Nonetheless, I want to focus on two specific areas and go in-depth and examine the cause and effect of these two factors on the planet.  Global temperature rise and shrinking ice mass are indisputable pieces of evidence that I will focus on and discuss further.

Global Temperature Rise:

The World is undeniably getting hotter; whether the cause is due to human activities or environmental variability and cyclical events.  Numerous studies have indicated the occurrence of this trend. According to the Intergovernmental Panel on climate change, “temperatures warmed roughly 1.53 °F between 1880 to 2012 across land and ocean surfaces.”  In a 30-year time period ranging from 1983 to 2012, the earth has experienced the warmest temperatures ever in the last 1,400 years.  So, why are temperatures rising globally?  These changes are largely a result of human activities such as burning fossil fuels and increasing levels of greenhouse gasses such as CO2.  Since the industrial revolution mankind has been using fossil fuels on an unprecedented scale.   Fossil fuels emit CO2 because they are carbon based; subsequently when burned and utilized as an energy source, the CO2 stored inside these elements are released.  CO2 and other greenhouse gases contribute to the greenhouse effect and the ‘blanket’ surrounding the earth.  The greenhouse effect refers to the process in which the sun emits short wavelengths of visible light that pass through transparent areas in the atmosphere and are absorbed.  This transparent medium exits because this medium is transparent to the visible light.  This transparency is due to the available electrons; the photons of visible light do not have enough quantum energy to get the electrons to the necessary available energy level.  So therefore the visible light is not transparent in the infrared.  The longer wavelengths of the re-radiated heat from earths heated surface are unable to pass through the transparent medium and are thus trapped in the atmosphere.  This phenomenon explains why sunlight will warm up the interior of your car and stay trapped inside. Visible light passes easily through the clear windshield; while the ultraviolet light is blocked by the glass because of their greater quantum energy. When the longer wavelengths are trapped, this leads to increased heating and results in higher temperatures.  Carbon dioxide in the atmosphere only exacerbates this issue.  Due to is inherent heat trapping properties, CO2 effectively absorbs infrared and prevents significant amounts from escaping back into space.

Global average temperature since 1880. The range of uncertainty is represented by the gray vertical bars. The blue line tracks the changes in the trend over time. source:NOAA National Climatic Data Center
Global average temperature since 1880. The range of uncertainty is represented by the gray vertical bars. The blue line tracks the changes in the trend over time.
source:NOAA National Climatic Data Center
The Graph illustrates earth's CO2 levels over a period of time. Source: NASA
The Graph illustrates earth’s CO2 levels over a period of time.
Source: NASA

Some may ask, “what are the potential consequences of such a drastic temperature rise, if any?”  There are many detrimental effects of global temperature increases that pose a tremendous threat to our planet.  Firstly, our agricultural system would be forever impacted.  Crops need certain and very specific conditions to grow and thrive.  If temperatures continue to rise, some plants will simply stop growing.  Our food resources are very much so in jeopardy if this trend continues.  Climate change will dwindle our current water supply by drying out bodies of water.  Precipitation patterns will be altered, causing  increased incidence of droughts and groundwater depletion.  Climate  change contributes to species extinction and loss of biodiversity through habitat destruction.  As the earth becomes water and water supplies continue to dwindle, wildfires will not only become more common, but also much more destructive.  This will also contribute a large amount of habitat and ecosystem destruction.

Disappearing Ice:

The Ross Ice Shelf Source: Google Images
The Ross Ice Shelf
Source: Google Images

Ice covers approximately 10% of the Earth’s total surface area.  Ice sheets are pieces of glacial mass that stretch for more than 20,000 square miles.  Today, there are two major ice sheets located in Greenland and Antarctica.  Unfortunately, these significant sheets are disappearing expeditiously!  The Antarctic ice sheet is composed of more than 7.2 cubic miles of ice and extends for more than 5.4 million square miles.  To put this into perspective, an ice sheet of this size is approximately the same area of Mexico and The United Sates!  However, the ice shelves lose about 134 billion metric tons of ice annually.  Greenland’s ice sheet is also substantially large; extending 656,000 square miles, covering about 82% of Greenland.  This is equivalent to three times the size of Texas!  During the summer melting period, in an observed period between 1979 to 2006, melting on the ice sheet increased as much as 30!  This rate of melting contributes to the annual ice loss of about 287 billion metric tons.  Due mostly to rising global temperatures the ice is melting.  Sunlight and temperature are generally the two main factors that control the amount of ice and general melting patterns.  Therefore, as temperatures continue to rise, it is no surprise that we continue to observe ice mass loses.   However, another factor is thermal expansion of oceans that contributes to the destruction of sea ice. As seawater warms it expands.  In other words, this leads to an increase of ocean volume, the water now takes up more space in the ocean basin and sea levels rise as a result.

A schematic illustrating the gradual decline of Antarctic ice mass over time. Source:Google Images
A schematic illustrating the gradual decline of Antarctic ice mass over time.
Source:Google Images

I will also mention sea ice because it plays an extremely vital and important role in regulating our climate.  Sea Ice is extremely effective at reflecting incoming solar radiation.  This ability is known as albedo, which indicates how effectively any given surface can reflect sunlight.  Sea ice is capable of reflecting 90% of the sun’ radiation, which really illustrates its effectiveness at reflecting solar radiation.    The Sea ice regulates temperatures by keeping them low through the albedo effect.  If there is less ice and more exposed ocean surface, the cold climates of the artic and Greenland will become warmer!

Arctic Sea Ice Depletion Source: Google Images
Arctic Sea Ice Depletion
Source: Google Images

Glaciers, are dynamic nature, responding to climate variation, revealing the effects and evidence of climate change. According to The World Glacier Monitoring service, Glacial retreat is occurring throughout the world. It is happening in areas such as the Alps, Himalayas, Rockies and Andes mountain ranges! But why are they melting? The retreat is due to serval factors, such as increasing summer temperatures and a sharp reduction in the winter snowpack. The snowpack is essential in forming and maintaining the glaciers. The mean average annual temperature has increased. Spring and summer temperatures have also increased. This causes an earlier snow melt during the summer. Additionally, rain has taken place as he dominant form of precipitation rather than snow. As a result glaciers have continued to shrink, indicating that the snowpack is not adequate to counteract the temperature changes and preserve the integrity of the glacier.

The image shows the retreat of the Gangotri Glacier in the Himalayas since 1780 Source: NSIDC
The image shows the retreat of the Gangotri Glacier in the Himalayas since 1780
Source: NSIDC

Conclusion:

After a large amount of research there are many different deductions and interpretations that can be derived.  Firstly, there is concrete and scientifically backed evidence that climate change and global warming is occurring.  One cannot argue against the vast plethora of evidence and quantitative figures that indicate our climate is in a dire situation.  I don’t believe one single factor is the most convincing evidence of global warming. I think all are equally important and when these different factors are combined together, they are the root cause of the issue at hand.  For example, rising temperatures contribute to melting ice mass which causes rising sea levels.  It is important to realize all these incidents of climate change are interconnected to each other.  Even in some cases dependent on one occurring for the other to happen.  If we as humans can develop a way to control and mitigate our negative impact and footprint on the environment, we may have a chance at bettering our current situation.

Sources:

  1. http://climate.nasa.gov/evidence/
  2. http://www.wunderground.com/climate/SeaIce.asp
  3. https://www2.ucar.edu
  4. https://nsidc.org
  5. http://wwf.panda.org/about_our_earth/aboutcc/problems/weather_chaos/temp_weather/
  6. https://nsidc.org/cryosphere/seaice/processes/albedo.html
  7. http://ete.cet.edu/gcc/?/icecaps_icesheets
  8. https://nsidc.org/glims/glaciermelt/
  9. http://www.climatecentral.org/gallery/graphics/co2-and-rising-global-temperatures

What is some of the most convincing evidence for climate change?

“Scientific evidence for warming of the climate system is unequivocal.”
– Intergovernmental Panel on Climate Change

 

History of  Earth’s Climate Change

Throughout history the earth’s climate has undergone tremendous change.  There are two distinct stages that accurately characterize earth’s climate:  greenhouse and icehouse.  During a greenhouse stage, there is little to no, permanent ice on both the south and north poles.  Warm temperatures are also found at high latitudes.  An icehouse climate is characterized by cool temperatures, cold enough to sustain large ice sheets at both poles.  The planet has transitioned between these two phases only a few times over the past 540 million years.  The most recent of these changes took place during the Cenozoic Era, which was approximately 56 million years ago.  It its extremely important that we have a brief understand of the history of earths climate; in order to analyze current evidence supporting global warming and climate change as an issue.

203_co2-graph-080315
This graph, based on the comparison of atmospheric samples contained in ice cores and direct measurements, shows that atmospheric CO2 has increased since the Industrial Revolution.

In the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago.  This marks the beginning of the modern climate era and of human civilization.  We currently inhabit an icehouse earth, comparatively colder to other periods in earth’s history.  However, just because the planet was warmer in the past, does not mean that we should ignore modern climate change.  Studies show that there are a few key factors that contribute to climate change.  The current trend of warming is particularly worrisome and significant because it is it occurring at an unprecedented rate not seen in the last 1,300 years.  It is also very likely occurring because of human activities, which is very concerning.  Very small variations in Earth’s orbit, change the amount of solar energy our planet receives, which in turn contributes to climate change.

Evidence of Climate Change:

Increased levels of Greenhouse Gases

Many chemical compounds in Earth’s atmosphere behave like greenhouse gases.  Many gases are naturally occurring while others are synthetic and man made.  Carbon dioxide and other greenhouse gases have a heat trapping nature. They allow direct sunlight to reach the earth’s surface.  As the shortwave energy (direct sunlight) heats the surface, longer-wave (infrared) heat energy is reradiated to the atmosphere. Greenhouse gases absorb this energy, which allows less heat to escape back to space, and traps it in the lower atmosphere.  Their propensity to affect the transfer of infrared energy through the atmosphere is the scientific basis of many studies and arguments that, increased levels of greenhouse gases cause the Earth to warm in response.

The chart shows different types of gases.
The chart shows different types of gases.

Atmospheric concentrations of both the natural and synthehtic gases have been rising at an alarming rate over the last few centuries due to the industrial revolution. Also, as the global population has increased; our reliance and use  of fossil fuels has increased.  Therefore emissions of these gases has increased.  Even though carbon dioxide is naturally  occurring in the atmosphere, our interference with the carbon cycle through burning forest lands,mining and fossil fuel consumption.  We are artificially manipulating carbon from solid storage to its gaseous state (sublimation).  This increases atmospheric concentrations, which contributes to  global warming.

Rising Sea Levels

“Global sea level rose about 17 centimeters (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century.” – CSIRO ( The Commonwealth Scientific and Industrial Research Organization)

The latest sea level measurement take in June 2015: 65.91 mm

Rate of change: 3.22 mm increase per year

As the graph demonstrates, sea level is steadily on the rise.
As the graph demonstrates, sea level is steadily on the rise.

Sea-level rise is a result of increasing quantities and concentrations of greenhouse gases in the atmosphere and the subsequent changes in the global climate.  The rise in sea level is caused by primary two main factors due to the earth’s warming.  Firstly, as seawater warms it expands.  In other words, this leads to an increase of ocean volume, through the process of thermal expansion.   The water now takes up more space in the ocean basin and sea levels rise as a result.  Secondly, due to the added water from melting ice sheets, glaciers, and land ice.  More water is now added to the ocean.  This rapid increase poses huge detrimental environmental effects.  Such as, costal erosion and flooding of low lying areas.   The rise in sea level also contributes to saltwater intrusion into aquifers, deltas and estuaries.  This change damages coastal ecosystems, water resources, and settlement areas.

Annual averages of global sea level. Red: sea-level since 1870; Blue: tide gauge data; Black: based on satellite observations. The inset shows global mean sea level rise since 1993 - a period over which sea level rise has accelerated.
Annual averages of global sea level. Red: sea-level since 1870; Blue: tide gauge data; Black: based on satellite observations. The inset shows global mean sea level rise since 1993 – a period over which sea level rise has accelerated.

Global Temperature Rise

Temperature averages are one of the most citied sources of evidence for global climate change. According to NASA’s Goddard Institute for Space Studies, in recent decades with most occurring the 1970s, the average temperatures have risen over 0.8 degree Celsius around the world since 1880.  Studies conducted by the  United Nations’ Intergovernmental Panel on Climate Change (IPCC) reports that 11 of the past 12 years are among the dozen warmest since 1850.  This indicates that rate of warming is occurring at an alarming rate.  The 20 warmest years having earth has ever experience occurred since 1981.  All 10 of the warmest years occurring in the past 12 years.  Despite, a solar output decline  in the 2000s, surface temperatures continue to increase.  This decline resulted in an unusually deep solar minimum in 2007-2009.  However temperatures seemed to keep rising.

This graph shows the world annual average temperature measured over land and sea. The red bars indicate temperatures above and blue bars denote temperatures below the 1901-2000 average temperature. The black line represents atmospheric carbon dioxide concentration in parts per million.
This graph shows the world annual average temperature measured over land and sea. The red bars indicate temperatures above and blue bars denote temperatures below the 1901-2000 average temperature. The black line represents atmospheric carbon dioxide concentration in parts per million.

The warming trend that is apparent and confirmed by events such as the melting of mountain glaciers on every continent. Reductions in the extent and total area of snow cover.  Plants now are blooming earlier in spring due to recent warming. A shorter ice season on lakes and rivers has been observed.  The ocean heat content has also increased. Reduced ice levels in the  arctic sea, and rising sea levels are indicative signs of climate change and warming.

Warming Oceans

“The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of 0.302 degrees Fahrenheit since 1969.8”- NASA Global Climate Change

The ocean covers 70% of Earth’s surface, a tremendously large surface area.  However, because the Ocean is so large, it plays a big role in absorbing heat energy and distributing it evenly around Earth.  The ocean also soaks up large quantities of CO2. As the planet warms, the ocean gets most of the extra heat energy.  The ocean is an excellent absorber of excess heat from the atmosphere.  Interestingly, the top few meters of the ocean store as much heat as Earth’s entire atmosphere! So,  therefore as the planet warms, it is inevitable that ocean will also heat up.  However, if the ocean becomes too hot, it will become inhospitable to the plethora of species of fauna that inhabit the seas.  The leads to a loss of biodiversity through habitat destruction and food chain disruption. The ocean is also  great at absorbing CO2 from the air . Studies indicate that the oceans absorb about one-quarter of the CO2 that we humans create when we burn fossil fuels such as oil, coal, and natural gas.  If we didn’t have the oceans to absorb excess CO2 we would be in an even more dire situation.

A new study by NASA and university researchers, has show that warmer ocean waters are melting the undersides of Antarctic ice shelves.  The increasing temperature of ocean waters are responsible for most of the continent’s ice shelf mass loss.

The graph shows, global upper ocean heat content steadily rising
The graph shows, global upper ocean heat content steadily rising

Shrinking Ice Sheets & Glacial Retreat

Meltwater flowing off an ice sheet in Greenland
Meltwater flowing off an ice sheet in Greenland

Data from NASA’s Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers of ice per year between 2002 and 2006.  Antarctica lost about 152 cubic kilometers of ice between 2002 and 2005.  These are extremely shocking figures that indicate our ice sheets are shrinking rapidly.  Both Antarctica and Greenland are losing ice sheet mass extremely quickly.  Data from NASA’s Grace Satellite show that Antartica has already lost134 billion metric tons of ice since 2002.  While, Greenland’s ice sheets have been losing approximately 287 billion metric tons per year.

arctic ice Figure 3

Glaciers, are dynamic nature, responding to climate variation, revealing the effects and evidence of climate change.  According to The World Glacier Monitoring service, Glacial retreat is occurring throughout the world.  It is happening in areas such as the Alps, Himalayas, Andes, Rockies, Alaska and Africa!  But why are they melting?   The retreat is due to serval factors, such as increasing summer temperatures and a sharp reduction in the winter snowpack.  The snowpack is essential in forming and maintaining the glaciers.  The mean average annual temperature has increased. Spring and summer temperatures have also increased.  This causes an earlier snow melt during the summer. Additionally, rain has taken place as he dominant form of precipitation rather than snow.   As a result glaciers have continued to shrink, indicating that the snowpack is not adequate to counteract the temperature changes and preserve the integrity of the glacier.

Declining Arctic Sea Ice

Studies conducted by the National Snow & Ice Data Center have indicated that not only the extent but also the thickness of Arctic sea ice has declined rapidly over the last several decades.  “In summer months, ice extent has declined by more than 30 percent since the start of satellite observations in 1979. ”

The increase of CO2 levels are huge driving factor in the reduction of Arctic Ice.  There is a  clear and plausible correlation between increasing CO2 levels and decreasing sea-ice.  Previous research showed a relationship between sea ice decline and global warming.  However, most of those studies focused on climate models, which explains the results of the study.  However a new study that was conducted provides independent confirmation that sea ice is declining because of human caused climate change.

A graphic showing arctic sea-ice melt: A comparison of March (left) and September (right) sea ice extent between 1979 (white plus blue) and 2014 (white)
A graphic showing arctic sea-ice melt: A comparison of March (left) and September (right) sea ice extent between 1979 (white plus blue) and 2014 (white)

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Increases of Extreme Weather Incidents

The number of record high temperature events in the United States has been steadily rising.  The number of record low temperature events has been decreasing, since the 1950s. The U.S. has also experienced increasing numbers of extreme weather incidents, such as extreme rainfall events.  You may be wondering,  how extreme weather and global warming are related?   One result of global warming and increased temperatures is an increase in both ocean evaporation into the atmosphere, and the water  vapor capacity of the atmosphere.  Increased levels of water vapor in the atmosphere; create conditions more that facilitate heavy precipitation in the form of intense rain and snow storms.

storm1

Acidification of The ocean

What is acidification? Chemical reactions occur when carbon dioxide comes into contact and is absorbed by seawater.  When CO2 is absorbed the result is reduced seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions and changes that occur are defining factors of the acidification process.   According to the PMEL Carbon Program, since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units.   This represents an 30% increase in acidity. This is the result of human activity. We are increasingly emitting more carbon dioxide into the atmosphere.  Therefore more is being absorbed into the oceans. Studies suggest that the amount of C02 absorbed by the uppermost layers of the oceans is increasing by about 2 billion tons per year! Quite an alarming figure that really puts into perspective the severity of the issue.

Bibliography

  1. “Global Climate Change Indicators.” NCDC. National Oceanic And Atmospheric Administration, n.d. Web. 1 Nov. 2015.
  2. “Clues for Understanding Modern Climate Change.” National Fossil Day. National Park Foundation, 22 Sept. 2010. Web. 01 Nov. 2015.
  3. “Climate Has Changed Throughout Earth’s History.” National Fossil Day. National Park Foundation, 22 Sept. 2010. Web. 1 Nov. 2015.
  4. “Greenhouse Gases.” Greenhouse Gases. National Climatic Data Center, n.d. Web. 01 Nov. 2015.
  5. “Sea-level Rise Observations, Projections and Causes.” CSIRO. Commonwealth Scientific and Industrial Research Organisation, n.d. Web. 01 Nov. 2015.
  6. “Global Warming Fast Facts.” National Geographic. National Geographic Society, 14 June 2007. Web. 01 Nov. 2015.
  7. Beitler, Jane. “Antarctic Sea Ice at Its 2015 Maximum.” Arctic Ice News. National Snow & Ice Data Center, n.d. Web. 1 Nov. 2015.
  8. “Global Climate Change: Vital Signs of the Planet.” The National Aeronautics and Space Administration. NASA, n.d. Web. 1 Nov. 2015.
  9. Leitzell, Katherine. “National Snow and Ice Data Center.” Icelights Your Burning Questions About Ice Climate. National Snow & Ice Data Center, 16 May 2012. Web. 01 Nov. 2015.
  10. What Is Ocean Acidification?” PMEL Carbon Program. National Oceanic And Atmospheric Administration, n.d. Web. 01 Nov. 2015.
  11. “Is Global Warming Linked to Severe Weather?” UCSUSA. Union of Concerned Scientists, 17 June 2011. Web. 1 Nov. 2015.

The Controversy Surrounding Nuclear Waste, What Should We Do with It?

The first step in effectively analyzing this problem is understanding how we generate energy through nuclear power and its fuel source. Uranium is the main source of energy used in reactors in power plants.  Uranium is a heavy metal which contains large amounts of concentrated energy when properly used/harvested.  It is present in earths crust as well as in seawater and the ocean.  Uranium occurs in different forms, such as the two types are used as fuel, U-238 and U-235.  This difference is manifested in the isotopes found in the nucleus (the number of uncharged particles, neutrons).  The isotope U-235 is interesting because under the correct conditions it can be easily split which unleashes large amounts of energy.  This process is known as nuclear fission, the process in which the nucleus of an atom is split into smaller parts.  The nucleus is made up of protons and neutrons is unstable.  The nuclei split up and release neutrons, the neutrons strike other atoms, which split again.  One fission reaction triggers and causes a chain reaction, this process becomes continuous and self sufficient.  U-238 is fissionable but needs an energetic neutron in order to start the fission process.  This isotope decays extremely slowly with a half life of 4500 million years!  However, most of the uranium present in nuclear fuel is U-238.  Now that we understand the fuel source of nuclear power, we can discuss what goes on in nuclear power plants and the reactor core. Fission Reaction

Nuclear Fission Reaction
Nuclear Fission Reaction

uran2

Reactor Construction   

There are a vast number of different types and constructions of nuclear reactors such as the boiling water, pressurized water, breeder, and fast neutron reactors.  The two types used in the United States are boiling water reactors or pressurized water reactors.  Water is needed for to create steam.  Steam is used to move turbine generators which create electricity.

In pressurized water reactors, water is kept under pressure to prevent it from boiling and to heat it.  The heated water is used moved through tubes into turbine generators, the water turns to steam, which moves the turbine and produces energy.  Water in the reactor and the water used to make steam are kept separately and never mix

.Pressurized Water Reactor Diagram

Boiling Water Reactors operate differently, water is heated through fission.  It is boiled and turned into steam, which turns the turbine generator. In both types of reactors steam is turned back to water and is used again.BWR-schematic

Refinement Process

After uranium is mined it undergoes an enrichment process so it can be used as fuel.   The process requires the uranium to be converted into a gaseous form.  Through sublimation it is transformed into uranium hexafluoride (UF6). This process raises the uranium content from 0.07% to approximately 5%.   The uranium hexafluoride (UF6) is brought to fuel fabrication plant where is is converted into uranium dioxide power.  The powder is compressed into small pellets, which heated until them become a hard ceramic texture.  The newly created pellets are inserted into small tubes to form fuel rods, the rods are placed together to form a fuel assembly.  The number rods in each assembly differs with the type of reactor.

images
Uranium Ore
Fuel Pellet
Fuel Pellet
Fuel Rod
Fuel Rod

The controversy arises from the spent fuel rods as the by product of generating nuclear energy.  As the fission reactions continues, the fuel rods become used, and eventually they become no longer useful.  The plant workers use control rods to cease the reaction and remove the spent fuel from the reactor core. When the are first removed they are highly radioactive.  The rods are moved to a cooling pool, where they are submerged in water.  The water provides a shield from radioactivity and allows them to cool.  The rods are allowed to cool in the pools for about 5 years before they are moved.  They are then transported to dry cask storage, caskets made of reinforced concrete with steel liners.  Here they continue the decay process, which has a half life of approximately 4.5 billion years.  The rods are stored here until they can be permanently stored elsewhere.  This is where the dilemma of where to store nuclear waste arises from.  We have been unable to decide where is the best place to dispose of the waste.  Many critics of nuclear power see this has a major flaw and drawback.  The consequences of the waste being released back into the environment could be catastrophic.

Spent Fuel Rod Pool
Spent Fuel Rod Pool
Dry Casket Storage Diagram
Dry Casket Storage Diagram

Yucca Mountain, Nevada

In 1982, the Nuclear Waste Policy Act was passed by congress.  This legislation required the Department of Energy to create a storage site for spent fuel rods and other radioactive waste.  Waste from nuclear power plants was supposed to be moved off site to the new waste repository. In 1897 a potential site was picked and underwent inspection and examination, the Yucca mountain located in a remote desert region of Nevada.  The waste was to be stored deep inside the mountain in an underground repository. This has the characteristics of a good storage location. The mountains are extremely secluded and therefore pose very little danger in case of a leakage. The mountain is also naturally hard and thick, so it would be hard for anyone to attempt to reach these materials.  However, a major risk and flaw of this design is radioactive waste leakage into the surrounding groundwater.  A leak proof containment area or buffer zone would have to be created before this idea is viable.  Geologists have been canvasing the area, testing the sorrowing rocks and testing the mineral composition to determine if the surfaces are permeable. Ultimately all the capital and work put into the potential site was in vain.  Many of Nevada’s citizens vehemently opposed the project since its inception.  They didn’t want to be the state where all of the US nuclear waste was stored. This is an example of the NIMBY syndrome, opposition of a new development because of its proximity to one’s community. A phenomenon that has plagued the development of nuclear power plants in certain areas. In 2010 president Obama revoked the Yucca Mountain license review, thus effectively ending the project.  The task of finding a new location was tasked to the Blue Ribbon Commission on America’s nuclear Future.  The committee’s stance is that deep geological disposal is the best option to proceed with.

Yucca Mountain, Nevada
Yucca Mountain, Nevada
How The Waste Would be Stored
How The Waste Would be Stored

 

In depth look at the storage system
In depth look at the storage system

Since the US government has decided to close down the Yucca Mountain Repository, which was our best option at time, we are left with a huge dilemma on our hands.  Where do we put the waste now?  We are in dire need of an alternate solution!  Nuclear waste is will become a huge part of our future problems; if do not find a viable option as soon as possible.  There have been a variety of solutions proposed, many that could be considered far fetched or even impossible.  But at this point, it would be wise to not dismiss these ideas and explore them fully to determine the best course of action.

Deep Geological Disposal/ Boreholes

As mentioned before, deep geological disposal is a popular idea at the moment.  Simply explained radioactive waste is buried deep underground.  However, going about how it is deposited and buried there is the source of debate.  Spent fuel rods would be encased in steel and then be buried miles below the surface of the earth.  This prevents the waste being accessed easily or being released unintentionally.  Another advantage is that the boreholes can be placed close to the power facility which reduces the risk of transporting radioactive waste to an off site location. A major downside is that Plutonium recovery would be extremely challenging and complicated. Also pulling waste 3 miles up to surface, safely is a daunting task. Nuclear energy that is spent can eventually be reused to recover fissionable materials.  The recovery of these materials is useful because it provides fuel to existing and future power installations.

Deep Borehole
Deep Borehole

Sites similar to the Yucca Mountain Project can be considered a form of geological burial.  However an concept originating in the Czech Republic has improved on the design and has a possible solution to prevent groundwater contamination. A hydraulic cage is a moat like structure which is built around the waste containers, this creates an alternate path of contaminated liquid, incase of a leakage.  A fully leakproof storage system has not been deviled yet, so the hydraulic cage is currently a viable option and soultion.

emplacement
Deep Underground Storage

Outer Space

Hubble Space Telescope Image
Hubble Space Telescope Image

NASA’s Jet Propulsion Laboratory has their own take on the matter, shooting spent fuel rods into space.  The idea behind this is that the universe has natural radioactive properties, therefore it should also be able to take it away.  The sun is undergoing a constant nuclear reaction that is enormous, approximately 330,000 times larger than earth.  At this rate, more than 10,000 tones of spent fuel rods could be absorbed very easily.  Radioactive material would pose little threat to humans if it was floating aimlessly through space and eventually being absorbed into the sun.  However, getting it there safely is major impediment to the progression of this idea.  There isn’t a hundred percent foolproof method to get it there. Rockets launches and lift-offs have failed in the past resulting in fires, crashes and explosions.  Any 3 of these results are dangerous and have the potential to spread into the atmosphere and over large areas quickly. Also if we ever want to recover these materials to re use, we cant, there are floating in the solar system

Ice and Glaciers

In the 1970s it was proposed that we could burrow waste into glaciers by placing a sphere of waste into an ice sheet and letting re solidify. This idea was dismissed quickly for obvious reasons.  Ice sheets move which would cause waste to float in the ocean as a radioactive iceberg.  The iceberg could also melt which would lead to a toxic leakage into the sea.

images-3

Deep Sea Storage

seafloor l

The bottom of the seafloor is composed of a heavy and thick clay substance. Coincidentally this material is a great at absorbing radioactive decay by products.  This process would require deep underwater drilling and boring.  This storage method becomes a touchy political subject because its being stored at sea not on land, this would require international cooperation to even be successful.

Synthetic Rock Material

This material was specially designed to absorb and retain waste products.  The material comes into different forms to cater to the variety of waste being disposed of.  This material is designed to imitate geologically stable materials; they wont leak the waste outside of the containment area.

Conclusion

When describing waste it is often difficult to visualize and comprehend the gravity of the issue.  I will provided some quantitative figures and qualitative measurements to help those understand the problem.

A typical nuclear power plant annually generates about 20 metric tons of used nuclear fuel. The entire nuclear industry in total creates of about 2,000 – 2,300 metric tons of used fuel per year.  According to the Nuclear Energy Institute, “Over the past four decades, the entire industry has produced 74,258 metric tons of used nuclear fuel. If used fuel assemblies were stacked end-to-end and side-by-side, this would cover a football field about eight yards deep.” Thats a lot of waste!

The World Nuclear Association provides some figures regarding LLW and HLW, “Low-level waste (LLW) and most intermediate-level waste (ILW), which make up most of the volume of waste produced (97%), are being disposed of securely in near-surface repositories in many countries so as to cause no harm or risk in the long-term….The amount of HLW produced (including used fuel when this is considered a waste) is in fact small in relation to other industry sectors. HLW is currently increasing by about 12,000 tonnes worldwide every year, which is the equivalent of a two-storey structure built on a basketball court or about 100 double-decker buses and is modest compared with other industrial wastes.”

After careful consideration of my research and all options, I have come to realize that there is a viable solution to this large problem.  My solution combines various methods together to create the most effective system of storage.  I would store the waste in a deep underground repository in a remote area that is heavily monitored.  People wouldn’t be allowed to live in close proximity to the facility, in order to minimize the potential harmful effects of accidental radiation exposure.  The underground storage area would be lined with synthetic rock material that would prevent groundwater contamination.  The waste containers would be surrounded by a hydraulic cage, so in the case of a leak, the waste would have an alternative rout and not contaminate ground water supplies.  The area is also accessible enough for efficient plutonium and material recovery.  I believe this idea takes from all options and uses the positive attributes to create an almost infallible storage facility.

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  12. All images courtesy of google