is a device that converts HYPERLINK “http://en.wikipedia.org/wiki/Mechanical_energy”mechanical energy to HYPERLINK “http://en.wikipedia.org/wiki/Electrical_energy”electrical energy
Turbines are large machines that rely on a spinning shaft which rotates coils of wires through magnetic field.
Faraday discovered in 1831 that if you move a coil of wire through a magnetic field, electrons would flow through the wire. All modern generators rely on this basic principleMain difference is the type of fuel used to boil water – coal, oil, gas, nuclear fissionWind, water, and geothermal power sources turn the turbine shaft directly
Most commercial electricity is generated by use of a turbine: Fuel is burned to heat water, which turns into steam, which turns the fan blades of a turbine.
water turbine (hydroelectricity)
is a rotaryengine that takes energy from moving water.Water turbines were developed in the nineteenth century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation. They harness a clean and renewable energy source.
A gas turbine, also called a combustion turbine, is a rotary engine that extracts energy from a flow of Combustion”combustion gas.
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion
Today we rely on the “big three” fossil fuels: Coal, Oil, Natural GasLet’s take a closer look at our use of coal, oil and natural gas…Coal is no longer king, but still accounts for ~ 30% of global energy useCoal has been used directly as fuel for thousands of years, now often used to generate electricity.
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Natural Gas less than 20%Fuel of choice for the last several decades has been oil and fuels derived from crude oil, including:Gasoline, Kerosene, Diesel oil, heating oil, Aviation fuelWhere do fossil fuels come from the “deep phase” of the carbon cycle? Fossil fuels are formed from the deposition and compression of plant matter over hundreds of millions of yearsUnfortunately, it takes far less time to extract it and vaporize it than it does to make it!Recent estimate of world oil reserves = about one trillion barrels before mining. We’ve already used up ~ 800 billion barrels….At our current rate of production, oil will peak around 2010, then start a precipitous decline. Oil production will hit rock bottom around 2100!!
At current rate of consumption, global coal reserves should last ~275 years. US (27%) and Russia (17%) together control ~ 1/4 global reserves. US reserves should last us about 400 years!Unfortunately, coal is extremely dirty. Strip mining devastates the landscape. Coal sludge from mining destroys local habitats
Black Lung disease
Black Lung disease, from inhaling coal dust, has claimed thousands of lives
efficiency with which one form of energy is transformed into another (coal has low efficiency)
fluidized bed combustion
Most efficient technique is fluidized bed combustion – efficiency of about 33% – 40% Thin stream of burning coal particles suspended in a stream of air – burns cleanly.
Takes ~ 8,000 tons of coal per day to fuel a single 1,000 megawatt power plant. Equals a train of coal cars one mile long!
synthetic fuels (synfuels)
Synfuels (synthetic fuels) – convert coal into a liquid fuel, more efficient burn. Tried synfuels in the 1970’s – too expensive.
Cheapest synfuels only competitive if oil reaches about $65 per barrel
liquified natural gas
Natural gas burns cleaner than coal or oil. Limited supply is a problem. Transportation is difficult – need natural gas pipelines (LA is covered with them). Can pressurize it into a liquid, LNG – liquified natural gas, highly volatile!
Most recent attempt at global oil monopoly is due to OPEC – Organization of Petroleum Exporting Countries.
OPEC turned off the tap in the 1970’s to force up the price of oil
Arab oil embargo
Arab Oil Embargo in 1973 – purpose was to pressure nations that supplied arms to Israel. Drove the global economy into a two-year recession. Unbridled greed of OPEC nations has so far prevented a successful repeat of the embargo
Increased exploration, conservation, created huge domestic surplus. Alaskan Oil Pipeline kicked in, carrying thousands of barrels per day to fuel our increasing demand. Attempts to conserve oil were quickly forgotten in the 1980’s, 1990’s.
Churchill decided in 1917 to switch the British navy from coal to oil, thus creating the first big international market.
Oil industry quickly became a monumental monopoly, thanks to John D. Rockefeller. Rockefeller’s Standard Oil company was the epitome of monopolistic ambition
Exxon-Valdez oil spill
March 24, 1989 – the oil tanker Exxon Valdez was in southeast of Anchorage, Alaska full of oil from the Trans-Alaskan Pipeline constructed in the aftermath of the Arab Oil Embargo. Captain Hazelwood was away from the bridge, having turned command of the tanker over to an inexperienced deck officer. The pilot ran the vessel aground on the treacherous Bligh Reef, just south of the town of Valdez. Over 260,000 barrels of crude oil, nearly 11 million gallons, poured out of the shattered hull before the tide was stemmed. Within a few days, winds had spread the slick far and wide, covering nearly 1,100 miles of Alaskan shoreline.
Only 14% of the spilled oil was recovered. The oil industry was completely unprepared for an oil spill of this magnitude. The oil contaminated one of the most pristine wilderness areas on Earth. An estimated 645,000 seabirds died from the spill, along with 13% of the local population of harbor seals and 28% of the sea otter population. Untold billions of fish and invertebrates died. Captain Hazelwood had a long history of substance abuse, and may have been drunk when the ship ran aground. He was fired, and later tried for criminal negligence.
Exxon paid a whopping fine 2.5 billion. The cleanup itself cost an estimated three billion. Fine reduced in 2008 to $500 million
Persian Gulf War
On Aug. 2, 1990, Iraqi military forces, on orders from President Saddam Hussein, invaded and occupied Kuwait. The Persian Gulf War of 1991 was brutal and short, only lasted from January 16 to February 28. $53 billion was pledged from many nations to restore Kuwait’s independenceWe currently budget about $50 billion per year to defend the oil supply in the Persian GulfAs many as 80,000 US veterans were afflicted with what became known as “Gulf War Syndrome”, a reaction to a toxic brew of burning oil and chemical warfare
In the wake of the Manhattan Project, nuclear power was everyman’s vision of the futureNuclear power remains the ideal energy technology, at least on paper. Nuclear fuel burns cleanly, with a moderate level of gaseous emissions and heat pollution.
Supplies of uranium are sufficient to last for at least 100 years. The actual process of generating electrical power is simple – nuclear power plants are just fancy turbines. Use the heat of the nuclear reaction to boil water into steam, steam turns the blades of the turbine. What makes nuclear power hard to comprehend is the fundamental physical process that generates the heat used to make steam to drive the turbine
Breeder reactors actually generate new fuel as they burn but are bad news, because the process also creates weapons-grade plutonium!
Nuclear fission is the basis of modern nuclear power plants. Sun is nuclear powered – relies not on fission but on fusion. Both fission and fusion involve riding herd on a barely controlled slow motion nuclear explosion.
Uranium exists in nature in the form of several isotopes. Uranium is extracted from a variety of ores, such as pitchblende and uraninite.
Isotopes are forms of the same element that differ from one another in mass number
Uranium exists mainly as 235U and 238U, the 238U isotope has three extra neutrons in its nucleus. Most natural Uranium (~99.3%) exists as U-238, which is a relatively stable form. Unfortunately, we can’t use it as fuel. U-235 is relatively unstable, and therefore much more rare than U-238.
Enrichment relies on the minute weight difference between U-235 and U-238. Engineering task is formidable – only the most technologically advanced nations have enrichment technology
unstable isotopes tend to degrade into stable isotopes, giving off radiation in the process
time required for one half of the isotope to decay into another form. We must concentrate rare U-235 to get enough for a power source = enrichment
U-235 naturally decays into lighter elements giving off radiation in the form of protons, neutrons, and EM radiation.
Radioactive decay releases large numbers of neutrons, which fly off at high speed. If neutrons strike another atom of U-235, they can cause it to break down in turnThink of throwing a ping pong ball into a room full of mousetraps. If the U-235 is sufficiently pure, the process of decay feeds on itself, producing a chain reaction.
Left to itself, the chain reaction will rapidly spiral out of control, resulting in a nuclear explosion. The real trick in nuclear power production is to slow the chain reaction down, but not stop it altogether…
To maintain a low-level chain reaction, you need to find some way to moderate the number of free neutrons whizzing about. A substance such as graphite or “heavy water” (deuterium-H2O with an extra neutron in the Hydrogen atom – an isotope of H)
A moderator. heavy water is water containing a higher-than-normal proportion of the isotope deuterium.
Nuclear reactors slow down or absorb free neutrons by using a moderator
Heat released by the process of nuclear fission turns water into steam, steam turns the turbine fan blades. Can’t use the heated water from the reactor vessel directly because it is radioactive
Nuclear reactors use fuel rods of enriched uranium pellets
Control rods of graphite moderator are inserted between the fuel rods.
Control rods can be inserted or withdrawn to speed up or slow down the chain reaction
Fuel rods and control rods are immersed in water in a thick sealed reactor vessel, housed in a “containment building”
Nuclear reactors have a “double loop” – two streams of water that interface with one another
loss of coolant water causes the reactor vessel to overheat, melting the fuel rods and control rodsPressure builds up inside the thick concrete containment building, can literally blow the roof off!
Radioactive wastes are a normal byproduct of nuclear fission. Uranium decays into lighter radioactive elements, stray neutrons also strike other elements and make them radioactive. Much of the worst radiation in radioactive wastes will dissipate in ~ 10-20 years. But it can take thousands or tens of thousands of years before these wastes lose their sting!
EPA sets a limit of 10,000 years for long-term storage of nuclear wastes. More conservative standard from the National Research Council is set at 100,000 years!! Storage of radioactive wastes from military or commercial reactors is a sad tribute to our inability to properly manage nuclear power. DOE estimates that it will cost up to $1.5 trillion to clean up the 20 sites where nuclear weapons were manufactured. Worldwide, we generate 10,000 tons of radioactive wastes every year!Current accumulation of ~ 170,000 tons of wastes currently stored onsite at nuclear power plantsNobody wants this stuff in their back yard…NIMBY (Not in my back yard)
Dumped wastes directly into the Techa River, poisoned an entire watershed, cause at least 1,000 cases of leukemia
Lake Karachy, into which the Techa River flows, is the deadliest spot on Earth.
Standing next to the Lake for one hour will kill you !!
Most recent accident occurred in Japan at Tokaimura, near Tokyo, in March 1999. Fuel reprocessing plant stored low-level radioactive wastes in barrels of asphalt. Poorly trained workers dumped too much waste into the mixture to save time and money.
Caused a chain reaction in the storage barrels!Material caught fire, exposed 37 workers to radioactive smoke. First attempt to control the disaster failed, mixture of wastes and asphalt binder later exploded. Plant officials tried to cover up the accident. Didn’t even tell the villagers until the next day!! Several officials were indicted, following a public apology.
Three Mile Island
Harrisburg, Pennsylvania, 1979 – Three Mile Island nuclear power plant was chugging along on schedule.
Malfunction in the pump system feeding water to the steam generator. Forced an emergency shutdown Unfortunately….Pressure from the steam generator forced open an emergency release valve (that’s good…). Emergency release valve stuck in the open position, drained coolant water from the reactor vessel (that’s bad…). To make matters worse, gauges incorrectly showed safe water levels in the reactor vessel. Reactor vessel was actually exposed to the air, rapidly overheatingPlant operators did all the wrong things, trusting their faulty dials and meters. Turned off the emergency backup coolant system (!) and shut down the water pumps in the reactorResult was a partial meltdown, some radioactive gas escaped.
Thirty years later, we’re still cleaning up the mess. No one was seriously injured, except for public confidence in the nuclear industry
The Russians remain the record holders for the worst nuclear accident in history In 1986 the badly-managed Soviet nuclear industry made a very big mistake in the sleepy little town of Chernobyl…Nuclear plant at Chernobyl lost coolant water to the reactor vessel. Core reached 5,400 degrees F!! Meltdown blew the roof off the containment building. Graphite moderator caught fire!! Plume of radioactive smoke spread out around the world. 31 people died of radiation sickness, many hospitalized. Crops and cattle all across Europe and Asia were poisonedAll milk, cheese and other dairy products were contaminated directly or by cattle feeding on radioactive hay.
Hundreds of cases of leukemia and other cancers. Chernobyl may eventually claim as many as 16,000 victims. All the vegetation within 7 km of the plant was destroyedUltimate irony, the area around the plant is like a wildlife sanctuary, still not safe for humans…May never know the effect of genetic damage on local wildlife
Modern research efforts are focused not on nuclear fission, but on nuclear fusionIn nuclear fusion, two atoms of Hydrogen fuse to form one atom of Helium, releasing an enormous amount of energy. Nuclear fusion is the same process that powers the sun.
Nuclear fusion could provide unlimited pollution free energy from liquid water! Unfortunately, starting the reaction requires tremendous temperatures and pressures (like those on the sun!). Years away from a commercial fusion reactor, if we ever get one to work at all
A renewable energy source though not 100% clean because Windmill farms harm wildlife, especially birds, with immense rotating blades, powerful draft
water power (hydroelectricity)
A renewable energy source though not 100% clean because Hydroelectric dams wipe out wild rivers, alter entire watershed
Geothermal energy is a great alternative energy source. Steam to power the generator comes right out of the ground. Unfortunately limited to very few areas worldwide?. Geothermal as of 2007 – 212 plants, generating 3,119 megawatts
Bioconversion – convert biomass into energy.
Directly burning wood, dung, peat moss. Burning garbage to generate electricity. Burning animal wastes to make methane gas. Fermenting vegetable crops to make alcohol. Tapping biogas from landfills
Most promising technology today is solar power. Tremendous resistance to solar power for many reasons. Economic – the old “peasants vs feudal lords” scenario – who shall control the sun?Technical – still clumsy technology, expensive. Solar power has been around for some time, but has never accounted for more than a fraction of US power production.
Slow to live up to its initial hypeAmericans aren’t famous for their long attention spans…. Price of photovoltaic (PV) cells has dropped 50-fold since their invention, only recently affordable, rapid increase in sales. Sun is the ultimate fusion reactor. Harness 1/10th of 1% of that energy, we could power the entire worldSolar power is the ultimate clean, renewable, non-polluting energy source. Solar power is used in many ways: Solar hot water heater, Solar space heaters, Direct production of electricity from PV cells
photovoltaic cell (PVC)
PV cells are made of silicon, cheap and essentially unlimited element (quartz, sand).
Few or no moving parts to wear out. Lifetime wear of materials exposed to the elements is around 20 yearsEach PV cell consists of two thin wafers. Top layer has atoms that lack electrons, will accept stray electrons from other atoms. Bottom layer has atoms that readily lose electrons when struck by sunlight. Each PV cell consists of two thin wafers. Sun hits PV cell, knocks electrons out of bottom layer, current passes to top layer. Flow of electrons (electricity) maintained by a tiny motor or similar device that recycles electrons back to the lower layer
Electrolysis requires energy. But…you can use solar power to provide the energy to split water molecules, then use the liberated hydrogen to power the fuel cell.
Cars of tomorrow may cruise along on solar hydrogen
hydrogen fuel cells
Best use of solar power may be to make hydrogen for use in fuel cells . Hydrogen fuel cells are a very promising source of energy, especially to replace oil-powered auto engines – electric carsFuel cells combine hydrogen and oxygen to form water, releases electrons. Problem – no free hydrogen on Earth since primordial days – all bound up in water, methane, and other compoundsHydrogen for fuel cells has to be made from splitting water into hydrogen and oxygen (electrolysis)
There is little doubt that the temperature of the planet is changing. But there is also evidence of past changes of similar magnitude, long before we arrived on the scene
Global warming is due to the greenhouse effect, something we’re all familiar with. Greenhouse glass lets the heat and light through, but some of the heat (infrared) is reflected back inside by the glass. Our atmosphere acts like a gigantic pane of greenhouse glass. Some atmospheric gases like carbon dioxide (CO2) and methane (CH4) absorb some of the infrared radiation released from the heated surface of the Earth
Gases like carbon dioxide and methane are called greenhouse gasesIncreasing the atmospheric content of these gases raises the average global temperatureGood news – if it weren’t for the greenhouse effect, we would be in a permanent Ice AgeAverage surface temperature of Earth would be 70 degrees Fahrenheit lower if it weren’t for them.
Climate change is a normal response to changes in planetary fluids – the atmosphere and oceans.
National Academy of Science defines climate as the “average state of the atmosphere and the underlying land and water, on time scales of seasons or less” So climate is not a single event or phenomenon…Climate is a statistical average of many interconnected variables: rainfall, temperature, relative humidity, cloudiness, wind speed, thickness of snow and ice packs, other factors?. Climate is caused by cosmic forces: changes in the Earth’s axis, Changes in the shape of the Earth’s orbit around the sun, Changes in the degree of wobbling of the planet as it spins on its axis These forces affect the amount and intensity of solar radiation that reaches the Earth’s surface. Changes in solar radiation create several short-term and long-term climate cycles
tilt of axis
Consider the beam of a flashlight striking a tabletop…The angle at which the suns rays strike part of the earth determines how much solar energy that part of the earth receives…As you change the angle of the flashlight, you don’t change the total amount of energy that hits the top of the table but you reduce the amount of energy that hits any one part of the table top – the beam becomes “smeared out” over a wider area. Now think about the tilt of our planet’s axisHow does this affect the amount or intensity of solar radiation that strikes the surface?The tilt of our axis is not constant…It changes over a range of 22.1 degrees to 24.5 degrees over a period of 41,000 year
eccentricity (of orbit)
Superimposed on these two long-term cycles (axial tilt and precession) is a third cycle – changes in the shape of the Earth’s orbit around the sun. Sometimes the orbit is nearly circular, sometimes elliptical – eccentricity of orbit. Orbital eccentricity has a long-term cycle of about 100,000 yearsChanges in orbital shape also affect the amplitude of the effects of precession (reduce or enhance)
the spin of the Earth’s axis is not perfectly circular.
Axis wobbles back and forth like a topPrecession has a long-term cycle of about 23,000 years
These cycles are called Milankovitch cycles, proposed in 1920’s-1930’s by Yugoslav astronomer Milutin Milankovitch. Predicted that these cycles could cause variation in sunlight in the Northern Hemisphere by up to 20% – couldn’t prove it, no precision data…These three long-term cycles interact with one another in many complex ways, still not well understood. Only recently have we realized that these cycles explain one of the greatest scientific mysteries – the Ice Ages. Milankovitch cycles explain the pattern of change, but not the amplitude of change. Based on cycles alone, climate should only change a few degrees during an ice age, but global climates are 4 to 10 times colder during an ice age. We still don’t know what factors act to amplify the effects of changes due to Milankovitch cycles. Some obvious candidates are: Dust in the atmosphere (reflects light/heat), Composition of gases in the atmosphere, Reflectivity of the Earth’s surface
The North Pole is the part of the sky where the Earth’s axis points.
The pole star, or North Star, is the closest star to that point
Our current pole star is Polaris, but that was not always the case…
When the pyramids were under construction, some 4,800 years ago, the pole star was Thuban, in the constellation of Draco the Dragon
Pleistocene cavemen also saw a different pole star. 12,000 years ago, Vega was the pole star, the brightest star in the constellation Lyra (the lyre)
Isotope has different number of neutrons, so heavier or lighter. Very sensitive equipment can detect the difference in weight?. Oxygen occurs in many isotopic forms
oxygen isotope ratio
The ratio is linked to water temperature of ancient oceans, which in turn reflects ancient climates. Cycles in the ratio mirror climate changes in geologic history.
16O / 18O
16O and 18O are commonly found in ice cores and deep-sea sediment cores. During cold, dry periods (ice ages) ocean water evaporates rapidly, settles out on land as snow, builds up glaciers?Because 16O is slightly lighter than 18O, it tends to evaporate more easily. Because 18O is heavier, when it evaporates and the clouds move toward land, tends to fall out more rapidly as rain or snow, so relatively more 16O reaches the land.
More 16O ends up on land as snow/ice, more 18O remains in the ocean .
deep-sea sediment cores
16O and 18O are commonly found in ice cores and deep-sea sediment cores. Cores record a long record of changing amounts of 18O in the ocean.
anomalies in the data. Seem to be relatively brief (~1,000-100,000 years long). Seem to occur randomly. Climate aberrations result in significantly higher or lower temperatures.
Climate aberrations cause significant changes in the global carbon cycle
Younger Dryas – ~12,000 ya, lasted 1,000 years, return of glaciers to Europe
Late Paleocene Thermal Maximum
End of the Paleocene, rapid rise in global temperatures called the Late Paleocene Thermal Maximum. 5o-6o increase in deep-sea temperatures. 8o increase in sea-surface temperatures
Medieval Warm Period
Before the Little Ice Age temperatures were above average – Medieval Warm Period. Lasted ~ 1000 – 1400 AD. During the Medieval Warm Period, European populations grew rapidly.
In the century before 1300’s, population of Europe had tripled. Europeans called it the “monde plein”, the full world – time of great cathedral building
Little Ice Age
A more dramatic climate aberration is the Little Ice Age, which lasted from about 1350-1850. 500 year period during which European temperatures fell dramatically. Decreased solar output? Increased volcanic activity?.
Temperatures were about 1o-2o C colder, (about 4o-5o F). Cold enough to cause increased snow cover, extensive glaciation. Little Ice Age had a profound effect on European history. Changed balance of power in Europe towards northern nations, away from Mediterranean. Led to radical changes in agriculture.
By 1500-1700, climax of Little Ice Age, even Atlantic fisheries were in decline as the fish sought warmer southern waters. Little Ice Age led to agricultural revolution. Better technology – windmills, better plows. Rotation of crops with legumes for fertility. Diversification of crops, more crops that grew well in cold, wet weather.
More and better animal husbandry.Social consequences: Led to distrust and suspicion between farmers and urban citizens, Led to grain hoarding, food riots, cannibalism, Social unrest, military and political upheaval, Famines and epidemics were widespread, Many settlements, villages abandonedIncrease in witchcraft trials etc… as people looked for someone to blame for the mess.Little Ice Age is a sobering example of the impact of global change on human society
climate proxy records
Instrumental records are the most reliable indicators but they are limited – why?Reliable weather instruments only go back about 200 years!Beyond that, we rely on proxy records – records of natural or cultural events influenced in some way by climate – to chart the history of climate.
Proxy records include: Historical records, Tree rings, Pollen grains, Coral growth rings, Density of stomata on living and fossil leaves, Geomorphology (land forms), Ice cores, Deep sea sediment cores. All these proxy records have problems, But together they provide a variety of tool to study past climates. Can compare them with one another to fill in gaps, resolve uncertainties in the data
Tree rings are useful for tracking annual changes in climate. Relative width of rings tells us relative growing conditions (good years, bad years). Relative width of the light part of the ring (spring wood) and the dark part (summer wood) shows seasonal contrasts.
Problems with tree rings:Growth is heavily influenced by local weather, must compare tree rings over a wide area, Not very useful in the tropics, Seasonal variations not as great, Many species like palms that lack annual rings
Pollen grains give surprisingly useful data, Pollen grains are like floral fingerprints, each shape unique to one species, Pollen grains in sediment cores show vegetation types, plant species, from which we can infer average climate, Resolution is ~ 50 years for living pollen. Date the sediments through carbon dating, dates the pollen grains by association. Extends pollen data back several million years. Beyond that we can’t reliably identify it
coral growth rings
Corals also have growth rings, analogous to tree rings. Oxygen isotope ratios in coral also usefulGood data for sea surface temperatures, sea levels, frequency of El Nino events. Coral record goes back ~ 400 years.
Snapshots from fossil coral extend back much farther.One of the few reliable sources for climate change in tropical areas. Small critters tunnel through the sediments, mix up the data a bit…
changes in the geology of the landscape – provide important climate data. Sea level features, like old barrier islands and wave-cut terraces mark the ancient shorelines. Glacial features show the path and maximum extent of glaciers, Terminal moraines, Erratic boulders dropped by retreating glaciers.
Geomorphologic features give us general information on climate going back about three billion years. Bubbles of ancient air show composition of atmospheric gases. Sediment record is damaged by marine invertebrates
Tillite deposits are made up of small pieces of sharply angled rock, resemble a rock version of particleboard.
Tillite deposits are found across the globe at 2.4 bya and 600-800 myaIn both cases, the deposits extend almost to the equator!
A terminal moraine, also called end moraine, is a moraine that forms at the end of the glacier called the snout. . Terminal moraines mark the maximum advance of the glacier. An end moraine is at the present boundary of the glacier.. It can help show the path and maximum extent of glaciers.
A glacial erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests.
Age in which the temperature drops due to changes in the Milankovitch cycles.
Carbon isotope ratios in the wood also give information about temperature, rainfall. Oxygen isotope ratios show total volume of ice
Isotope ratios reflect surface temperatures
An ice core is a core sample from the accumulation of snow and ice over many years that have recrystallized and have trapped air bubbles from previous time periods. The composition of these ice cores, especially the presence of hydrogen and oxygen isotopes, provides a picture of the climate at the time. Ice cores are increasingly used to study climate change.
Cores from glaciers and polar ice go back ~ 440,000 ya, accurate to ~ 40,000 ya. Ice cores yield a wealth of data. Oxygen isotope ratios show total volume of ice. Isotope ratios reflect surface temperatures. Deposits of dust, sea salt, pollen show wind source and strength.
Annual layers in the ice show snow accumulation rates
deep-sea sediment cores
Deep-sea sediment cores tell us: Ice volume, Salinity levels, Atmospheric CO2, Isotope ratios in sediments. Useful from 40,000 – several million ya
Atmospheric change is described in terms of climate forcing. Climate forcing is measured by the amount of energy that forces bring into the system or take out of the system. Units of climate forcing are watts / m2.
The results of climate forcing can be measured by changes in average global temperature. Climate forcing can be positive or negative, can be natural or man-induced
positive climate forcing
Positive forcing in nature: Volcanic eruptions – add large amounts of CO2 to the atmosphere. Positive forcing by humans: Burning fossil fuels, yields CO2.Southern tropical forests sit over lighter land surface.
Remove darker forest and expose land, increases reflectivity. Increased reflectivity reduces temps – negative forcingBUT – burning forests creates CO2 clouds that increase global temperatures – positive forcing
negative climate forcing
Negative forcing in nature: Volcanic eruptions! Clouds of smoke reflect light & heat back into spaceNegative forcing by humans: Burning fossil fuels! Yields reflective CO2 cloudsNorthern temperate forests sit over ice and snow, Remove darker forest and expose snow, increases reflectivity. Increased reflectivity reduces temperatures – negative forcing of ~ – 0.
Feedback loops in global warming are very complex, poorly understood. Different climate models predict different amounts of global warming mainly because of their “best guess” about the effects of feedback loops
Shrinking of polar caps, melting of ice and snow, reduces the reflectivity of the Earth’s surfaceChanges planetary albedo, ratio of amount of light the planet reflects back into space vs. amount of light that is received. Albedo = reflected light / received light. Less light reflected by ice and snow means more light and heat absorbed, more global warming – feedback loop
Methane (CH4) is far more powerful greenhouse gas. Absorbs 20-30 times as much heat per molecule as CO2 !Note the rise in methane around 500 AD – what could have caused this increase?Increase comes from cattle flatulence !!Average cow expels 200-400 lbs. of Methane/year (from both ends of the cow) Cattle flatulence (and cleared pasture land) may be a more serious problem than cars and trucks (UN 2006).
Researchers trying to reduce flatulence by altering cattle diets Methane is at its highest point in over 400,000 years, due to:Cattle flatulence, Rice cultivation and wetlands (decomposition), Coal mining (releases trapped gas pockets), Landfill gas, Termites (methanogens in their guts), We can control most or all of these activities, and solve the methane problem, Methane only stays in the air for ~ 10 years, results of our efforts to reduce it would be readily apparent
Large amounts of methane are trapped in sediments, usually as clathrates, molecular crystal lattice of methane and water (methane hydrate). Trapped in frozen tundra sediments. Trapped in ocean sediments along the continental shelf. Trapped methane has the potential for a disastrous feedback loop: Increase in global temps could bring trapped methane out of solution, into the air, global temperatures could rise very rapidly, because of the feedback loop…
EFF – environmental forcing factor
factors that are responsible for climate forcing, like greenhouse gases
residence time and removal time
Residence time of greenhouse gases is as important as their relative warming effect. Residence time is the time that greenhouse gases remain in the atmosphere (also called removal time): dioxide, nitrous oxide, CFC’s, have the longest residence times
Ozone acts as a greenhouse gas, but the ozone layer has stayed constant for millennia (now declining)
Tropospheric ozone, on the other hand, could be a serious problem. Lower-level ozone due to cars, power plants, burning of biomass. Ozone depletion is indirectly reinforced by global warming.Increased CO2 increases formation of “polar stratospheric clouds”, which tend to increase rate of ozone destruction
is a suspension of fine solid particles or iquid droplets in a gas.
Examples are smoke, oceanic haze, air pollution, smog and CS gas Both sulfate aerosols and black-soot aerosols have a relatively low residence time in the atmosphere: Gone in about 10 days…
Sulfate aerosols reflect light & heat back into space, reduce global temperaturesIronically, by cleaning up plant emissions, using higher grades of coal with lower sulfur content, we are contributing to global warming! Sulfate aerosols have a negative forcing! Sulfate aerosols come from natural and anthropogenic sources. Sulfate aerosols – natural sources – Volcanic outgassing, Marine organisms, organic aerosols. Anthropogenic sources: Coal-fired power plants, Coal-fired industrial plants. About 50% of sulfur aerosols are due to biogenic sulfur emissions
Sulfate aerosols reflect light & heat back into space, reduce global temperaturesIronically, by cleaning up plant emissions, using higher grades of coal with lower sulfur content, we are contributing to global warming! Sulfate aerosols have a negative forcing! Sulfate aerosols come from natural and anthropogenic sources. Sulfate aerosols – natural sources – Volcanic outgassing, Marine organisms, organic aerosols. Anthropogenic sources: Coal-fired power plants, Coal-fired industrial plants.
About 50% of sulfur aerosols are due to biogenic sulfur emissions
Volcanic aerosols can have a significant effect on climate, despite their short residence time – why??Repeated eruptions on a large scale release tremendous amounts of dust. Much of the dust settles out in 1-2 years, but finer particles form aerosols that reflect rays back into space for 10 years
Vegetation produces organic aerosols. Plants give off organic molecules that accumulate, form a cloudy haze. Smoky Mountains are smoky because of organic aerosols, though smokier today due to pollution
black carbon aerosol (soot)
Black soot aerosols absorb heat, directly contribute to global warming.
Formed by incomplete combustion of fossil fuels, biomass (ex. forest fires). Black aerosol clouds absorb heat directly, reduce reflection of heat back into space
Year Without a Summer (1816)
1816 was the year without a summer. Series of volcanic eruptions, culminating in 1815 with the eruption of Mount Tambora in Southeast Asia, most spectacular eruption in 15,000 years!. Dumped vast amounts of dust aerosol into the air, reflected solar energy into space.
Freeze in early June nipped flowers, crops in the bud, frost continued until June 11th, with heavy snowfallJuly 6-9, another frost hits New England, August 13-14 still more frost!. Widespread crop failures, high food prices, in US and Europe
Year Without a Summer (1816)
1816 was the year without a summer. Series of volcanic eruptions, culminating in 1815 with the eruption of Mount Tambora in Southeast Asia, most spectacular eruption in 15,000 years!.
Dumped vast amounts of dust aerosol into the air, reflected solar energy into space. Freeze in early June nipped flowers, crops in the bud, frost continued until June 11th, with heavy snowfallJuly 6-9, another frost hits New England, August 13-14 still more frost!. Widespread crop failures, high food prices, in US and Europe
A large part of the uncertainty surrounding the effects of aerosols concerns their role in cloud formation. Clouds reflect suns rays back into space, reduce global warming.
Tiny particles in aerosols form nuclei for water vapor to condense into clouds. More tiny nuclei from aerosols means smaller water droplets in clouds. Smaller droplets increase total surface area for reflection – Twomey Effect. Think of one large reflective sphere versus a dozen smaller reflective spheresSmaller droplets, get brighter, more reflective clouds. Smaller droplets also tend to inhibit rainfall, so clouds last longer, more reflectivity.Clouds are a very important variable in global warmingClouds are the least understood part of global warming, source of uncertainty in climate models
The real mystery is not whether CO2 raises global temperatures…Mystery is why temperatures aren’t even higher than they are. Amount of CO2 released in the 20th Century should have caused twice as much temperature increase as observed. Where did all the carbon go?Must be a large carbon sink in the ocean or biosphere that we have somehow failed to account for…
It has sometimes been argued that the earth’s biosphere (in large part, the terrestrial biosphere) may have the capacity to sequestor much of the increased carbon dioxide (CO2) in the atmosphere associated with human fossil fuel burning.
This effect is known as “CO2 fertilization” because, in the envisioned scenario, higher ambient CO2 concentrations in the atmosphere literally “fertilize” plant growth. Because plants in turn, in the process of photosynthesis, convert CO2 into oxygen, it is thus sometimes argued that such “co2 fertilization” could potentially provide a strong negative feedback on changing CO2 concentrations.
oceanic conveyor belt
Recent improvements in precision of data suggest that very warm or very cold climate changes can occur in relatively brief period. Maybe as little as ten years…Studies of Greenland ice sheet cores and deep-sea sediment cores suggest significant climate shifts can occur in 10-20 years! Theory centers on the oceanic conveyor belt. Ocean currents redistribute equatorial heat, help drive weather systems.
Oceanic conveyor belt is the global pattern of major currents that redistribute tropical heat from the equator to the poles. Changes in the temperature and salinity of the oceans change the way that heat is redistributed – especially in the Atlantic. These changes cause the planet to quickly shift to a climate that is much warmer or much colder.
Not a new idea – proposed in 1875 by James C. Roll (Climate and Time). Proposed that long term orbital cycles would lead to series of cold wintersWould alter surface winds that drive the Gulf Stream, shut it off, lead to an ice age. Modern version relies on a different mechanism. Changes in sea surface temps and salinity. Three stable patterns of global climate: Warm pattern – current situation, Cold pattern, Coldest pattern – extensive glaciation. Driven by changes in water temperature and salinity in the oceans. Cold water is denser, heavier, than warm water (just like air) Cold water tends to sink, warm water tends to rise .
Water heated in the tropics is pulled toward the colder poles. As it moves north, it becomes cooler, gives off heat to the surrounding air or land. Also evaporates, becomes saltier – saltier water is also heavier than fresh.
Cooler, saltier water is denser, sinks to the bottom, pulls warmer water from the tropics to replace it . Resulting warm current heats the coast of North America and Europe. During warm periods (like today), there are two vast areas of the North Atlantic where heavier cold water is sinking to the bottom of the ocean.
Sinking cold water moves along the ocean floor, wells back up in the North Pacific, completes the overall loop of the primary planetary ocean currents. During coldest periods (like Ice Age), there are no areas of the North Atlantic where heavier cold water is sinking to the bottom of the ocean. Something happens to completely shut down the oceanic conveyor belt, causing an Ice Age.
How does this relate to global warming? Increased melting of ice and snow feeds large amounts of fresh water to the oceans, which become less salty. Surface waters not heavy enough to sink, slows down or shuts off conveyor belt. Remember the Younger Dryas? Climate aberration ~12,000 ya, lasted 1,000 years, return of glaciers to Europe. Probably caused by draining of a huge glacial lake, Lake Agassiz, when glaciers melted after the last ice age
Chlorofluorocarbon: The manufacture of such compounds is being phased out by the Montreal Protocol because they contribute to ozone depletion.
water expands as it warms, causing sea levels to rise
Kyoto Conference of 1997
A landmark in environmental policy.
Conference led to a draft protocol to sharply cut back on carbon dioxide emissions. Biggest push came from LDC’s, who have to live with the mess created by the industrialized nations. Protocol sought modest goal, to cut emissions back to their pre 1990 levels. Would require substantial investment in new technologies, clean up emissions. All the nations of Earth have ratified the protocol. All that is, except for Australia and the good old USA…Al Gore signed the non-binding protocol, but Congress never ratified it. Right-wing conservative coalition has torpedoed any attempt to ratify the protocol
is the motion of a surface (usually, the Earth’s surface) as it shifts downward relative to a datum such as sea-level.
What saved us in the past from hurricanes: Deposition of new sediment by the Mississippi to build up coastal lands. All these systems are in jeopardy: Barrier islands are rapidly vanishing, deprived of new sediment from the River. Coastal marshes are rapidly disappearing, an area over 40 mi2 vanishes under the waves every year. Channels gradually widen through wave action, destabilizing and destroying huge tracts of marsh.
Marshes no longer creating new peat to build themselves up, quickly vanish…Coastal marshes are our only buffer against wind and water from the Gulf of Mexico. Army Corps rule of thumb = every 2.7 mi.
healthy marsh will dissipate one foot of tidal surge. The marshes are also vital for their bountiful seafood, home for juvenile shrimp, crabs, redfish, sea trout, and dozens of other commercially important species.
Mississippi River used to be free to go where it wanted. Wandered all over the map, changing its course entirely from time to time.
After building up a vast delta, the River would eventually find a new channel, and start to build up yet another delta. Created a series of new deltas all along the coast, all of southern Louisiana!mModern day delta is in trouble…When you force a fluid into a narrower channel, you increase its flow rate. Today, water shoots out the mouth of the Mississippi, sediment hurtles out over the edge of the continental shelf.Modern delta, instead of being built up, is being steadily eroded, starved of sediment
A dump for domestic waste. They may be convenient, single-use pits created by nomadic groups or long-term, designated dumps used by sedentary communities that accumulate over several generations.
municipal solid waste (MSW)
We throw all our old parts away. Municipal solid waste (MSW) in the USA amounts to 210 million pounds per day.
Enough to fill 80,000 garbage trucks
The dump was just a big field full of piles of rotting garbage. Lots of urban wildlife nibbling around the edges. Dumps were smelly and dangerous. Sometimes they caught fire
Incinerators weren’t much better, generated dangerous levels of air pollution. Incineration of trash still accounts for over half of trash disposal in industrialized nations
Landfills come with problems of their own: Smell, Rodents, diseases, Leachate, Biogas
As rainwater trickles down through piles of garbage, it leaches out (dissolves) a heavy load of toxic chemicals. Chemicals come from old batteries, cans of paint, bits of zinc, copper, lead, cans of cleaning solvent or pesticides…Leachate pollutes groundwater
Another potentially explosive problem is biogas from landfills. Loads of organic trash – orange peels, coffee grounds, lawn trash etc…Decomposition of organic matter in the absence of oxygen, get lots of methane.
Biogas in landfills is 2/3d’s methane, rest is carbon dioxide and hydrogen – volatile mixture!! Gas builds up, sometimes explodes, destroying entire neighborhoods!
landfill gas plant
Some smart communities exploit this resource, tap into methane with wells sunk into the landfillOver 100 landfill gas plants in the US alone
Modern landfills have a thick plastic and clay liner underneath. Catches dangerous chemicals in leachate so they don’t pollute the groundwater
Univ. of Arizona Garbage Project
University of Arizona’s Garbage Project began in 1973, has created an ever expanding database of discards. Garbologists have punctured our preconceptions about trash. Garbage is generally: diapers 1% by volume, fast food .5% , styrofoam 1% , plastics 20-24% , 40% paper
Somebody who studies garbage
Lightweighting means reducing the thickness of plastics. Amount of plastic has increased over the years, but the weight of plastic trash has stayed fairly stable.
Thinner soda bottles, thinner milk jugs, thinner garbage bags. Mid-1960’s, milk jugs weighed 120 grams, now weigh ~ 65 gramsPlastic bags used to be 30 microns thick, now ~ 15-18 microns. We’ve pushed lightweighting about as far as it could go
national bottle law
National bottle law, force the beverage industry to pay a deposit for bottle returns
Toxic Release Inventory (TRI)
In 1987, EPA started to require toxic chemical industries to report the types and amounts of pollutants they released each year. Toxic Release Inventory (TRI) is available to the public, posted online. Louisiana usually makes the top three most polluted states in every category
We have reliable toxicity data on thousands of chemicals. But no one knows what happens when you mix them together – synergistic effects.
Synergy occurs when two or more compounds produce an effect that is greater than the effect they have by themselves
Pollutants usually measured in ppm (parts per million), ppb (parts per billion), and ppt (parts per trillion)
A compound which is produced in thecourse of a chemical synthesis, which is not itself thefinal product, but is used in further reactions whichproduce the final product.
Chemical Corridor and Cancer Alley
Most of the ethylene oxide comes from a single Shell Oil chemical plant in Geismar, LAGeismar, LA sits squarely in the middle of a heavily industrialized 150 mile stretch of the Mississippi River, from Baton Rouge to New Orleans. Known in the industry as the Chemical Corridor. Most people call it Cancer Alley. Over 136 industries line the River along Cancer Alley, most of them petrochemical plants
Remember the Dead Zone? This vast area of the Gulf of Mexico is devoid of life due to eutrophication (an increase in the concentration of chemical “nutrients) caused by nutrient pollution from the River. Summer 2005 covered 4,564 mi2. Summer 2006 covered over 6,600 mi2
Many of the state’s aquifers are threatened by pollution. 2/1 drinking ratio (aquifer/river)243 mp of toxic sludge is percolating down through the soil toward the Plaquemine aquifer7,500 people rely on the Plaquemine aquifer for their drinking water.
Reports of children’s skin burning after bathing or using outdoor pools. Series of miscarriages in Myrtle Grove traced to vinyl chloride contamination in the aquifer. Residents launched a lawsuit in 2003
Injection wells – store chemicals in a deep well, with positive pressure applied to keep it from coming back up. 2005 – 39,740,931 pounds of chemicals were added to La.
injection wellsInjection well technology is not foolproof. Leaks and cracks in wells release chemicals directly to groundwater. Injected chemicals can find their way back through underground cracks, old oil wells…Need to keep pressure on constantly for thousands of years! Computer models show that wastes should not migrate back up for 100,000 years. EPA approved the technology on the basis of computer models alone
Environmental racism is the disproportionate creation of hazardous industries and toxic waste dumps in minority neighborhoods. Plant sites are chosen where land is cheap, taxes are low, water is available, workers are plentiful. Poor people live in the same places for many of the same reasonsMinority populations have historically been concentrated along the Mississippi River . Many of them were originally brought there as slaves to work on the plantations that lined the RiverPoor people have little access to technical education or legal education. Even the experts don’t always understand the health effects of toxic chemicals.
Can’t afford high-priced legal talent to square off against big corporate polluters, or get control over local zoning laws or permitsBenjamin Chavis continued to fight against environmental racism, a term he coined. Chavis led a 1987 study commissioned by the United Church of Christ. First report to conclude that environmental racism was a reality. Center for Policy Alternatives, civil rights “think tank” issued a report in 1994, co-sponsored by NAACP, United Church of Christ. Problem had worsened since Chavis’ 1987 report. Polluting industries were not intentionally targeting minority communitiesRegardless of the motives involved, report observed that minority communities were certainly bearing the brunt of toxic waste pollution.
Report found that non-white citizens of Louisiana were 44% more likely to live near a toxic waste site than white citizens. Of 12 hazardous waste sites examined in Louisiana, 10 were located in areas with greater than 25% minority population.
Everybody should share the bad effects of garbage regardless or race gender or economic power
Minorities are becoming increasingly vocal and organized about a wide range of environmental issues. Grass-roots activism has generated a strong and growing organization to protect poor communities from being used as dumping grounds
Latest battle in Louisiana was fought over a Japanese company called ShintechShintech, in Oct. 1996, proposed building a huge PVC plant (polyvinyl chloride) in a minority neighborhood in Convent, little town ~ 30 mi. upriver from New Orleans. Shintech had a relatively clean record, but manufactured a very dangerous product.
Major toxic compound produced in PVC manufacture is dioxin. In doses as low as a few ppb, dioxin causes liver damage, leukemia etc.It was easy for LA officials to overlook the potential hazards because the proposed $700 million plant would have been an economic boon for St. James Parish. Area around the proposed plant was ~ 87% African American, mostly poor and undereducated.
Citizens organized a grass roots campaign, St. James Citizens for Jobs and the Environment, collected signatures door to door – EPA had adopted a states-rights approach to new permits, so all the initial permit work was done by state and parish officials. The officials were well paid for their efforts…State DEQ approved the permit, despite a cautionary letter from the EPA that the issue of environmental racism should be carefully considered. Tulane’s Environmental Law Clinic came to the aid of the parishionersGov. Foster bounced off the ceiling at the Capitol Building, called then President Eamon Kelly and read him the riot act, implying that bad things would happen to Tulane – like removing our tax-exempt status!! State still managed to make Tulane pay a big price for its noble standState Supreme Court ruled that law clinics could no longer defend poor people in large lawsuits like that brought against Shintech.
EPA was reluctant to enter the fray. Clinton issued new regulations requiring all federal agencies to examine all new permits for impact on minority communitiesSeptember 1997, EPA finally responded to the Tulane Law Clinic’s petition and ruled that Shintech’s permit was invalid, sending the company back to square one. It was the first time in history that the federal government had ever rejected a Louisiana industrial permit!!Oddly enough, the EPA side-stepped the issue of racism, based its rejection on several minor technical issues. Shintech withdrew its proposal
carcinogenic (causes cancer)
Things you should do to help create a sustainable environment:
In the yard and garden:Don’t plant exotic species, Limit or avoid the use of pesticidesIn the marketplace:Buy products from manufacturers that contribute money to the environment, Boycott firms with bad environmental records, Buy a sensible car, Ride a bike or walk!!What can you do in the voting boothStudy the issues – inform others, Don’t blow off local electionsIn the home and office: Wash your clothes in cold water, Buy energy efficient appliances, Follow the thee R’s – Reduce, Reuse, Recycle