Lecture Notes Review

Changing Water Cycle: Hurricanes and Coastal Storms in New York

• Climate change impacts on New York:
  1. Global trends
  2. Present and future temperatures and precipitation in NY
  3. Extreme events: heatwaves, rainfall
  4. Susquehanna River flooding
  5. Lake effect snow
  6. Arctic warming and severe winter weather in New York
  7. Sea level rise, coastal storm, and hurricanes
  8. Impacts: algal blooms, invasive species, farming

Global Sea Level

• Fig 1. Time series of global sea level (1990-1999)
  • Grey shading: uncertainty in estimated long-term rate of sea level change due to lack of reliable global measurements.
  • Red line: global mean sea level from tide gauges (instruments to measure water levels); Red shading shows the range of variation from the smooth curve.
  • Green line: global mean sea level from satellite altimetry (most accurate).
  • Blue shading: beyond 2100, projections diverge significantly, depending on future emissions paths.
  • Scale note: a vertical rise of 20 cm = 8 inches, helping to visually interpret the sea level change magnitude from 20th to 21st century.
• By 2100, global sea level rise is projected to be between 1 to 8 feet, with a likely range of 1 to 4 feet.
• Sea level rise controls:
  • Global warming
  • Minor control: ocean temperature increase leading to slight expansion.
  • Most important control: melting of icecaps (water from melting glaciers and ice sheets increases the total volume of water).

Sea Level Rise Trends

• Solid black line (1920-2020): average sea level rise steadily over the past 100 years along the U.S. coast.
• Dashed black line (projected to 2050): extends the recent trend forward, based on how fast sea level has risen since 1970 (a "current trend continues" scenario).
• Colored lines (out to 2150): represent possible futures based on different assumptions about greenhouse gas emissions and ice sheet behavior.
• Stacked bar (2100): shows a range of sea level rise in 2100 depending on how much the Earth warms; higher temperature means higher seas.
• More warming = more sea level rise.

Relative Sea Level Rise

• Left map: sea level rise by 2050.
• Right map: sea level rise by 2100.
• These maps show relative sea level rise compared to land in different places.
• The U.S. coast will see higher increases than others, especially the Atlantic and Gulf coasts.
• California is slowly rising.

Sea Level Rise in New York

• Sea level rise along New York’s ocean coast and Hudson River has risen by more than one foot since 1990, or about 1.2 inches/decade.
• Seacoast and tidal portions of the Hudson River (to the federal Dam of Troy):
  • Sea level rise could be up to 30 inches by the 2050s.
  • Up to 4 feet by the 2080s.
  • Up to 6 feet by 2100.
• Rising sea levels will have major consequences for New York’s coastal communities:
  • Magnification of storm surges (caused by high winds and tides) increases the risk of flooding, beach erosion, and damage to infrastructure in low-lying areas (worst flooding during storms).
  • Increased areas of coastal inundation (flooding) during regular tidal cycles (most frequent tidal flooding).
  • Regular inundation of coastal wastewater infrastructure and transmission of pathogen and nitrogen pollution to ground and surface waters can cause flooding of sewer systems and treatment plants, leading to pollution into the groundwater.
  • Increased salinity of drinking water in communities along the Hudson due to saltwater intrusion (saltwater from the ocean pushes up the Hudson River, making it harder for communities to get freshwater for drinking).

Hurricanes, Nor'easters, and Extreme Rainfall

• Hurricanes (tropical cyclones) are low-pressure systems with organized thunderstorm activity that form over tropical and subtropical waters, gaining energy from warm ocean waters.
• Nor’easter:
  • A strong storm that happens along the East coast of the U.S., especially between September and April. The name comes from strong winds usually coming from the northeast.
  • Formation:
    • In winter, cold Arctic air moves south across land.
    • Warm air from the Atlantic Ocean moves north.
    • The clash between cold air and warm air over the ocean creates the energy for these powerful storms.
    • The Gulf Stream (a warm ocean current) keeps the coastal water warmer, adding more fuel.
• Hurricane Harvey:
  • The highest rainfall amount in a single storm for any place in the continental U.S.
  • Rainfall amounts were 48.2 inches (recorded by a rain gauge on Clear Creek and Houston).

Hurricane Trends and Indices

• Graph showing how many hurricanes formed each year in the North Atlantic Ocean from 1878 to 2022 and how many of those hurricanes hit the U.S.
  • Green curve: total number of hurricanes recorded each year.
  • Orange curve: an adjusted version of the total hurricane count that tries to make up for the fact before planes and satellites existed, we likely missed some hurricanes.
• Power Dissipation Index (PDI):
  • A way to measure how much energy hurricanes use combining:
    • How strong the storms are (wind speed).
    • How long they last.
    • How many there are.
  • Higher PDI = more powerful or more frequent storms.
  • Warmer ocean water helps fuel stronger storms.
• Accumulated Cyclone Energy (ACE) index:
  • Measure the total energy from all tropical storms and hurricanes in a season by combining:
    • Wind speed.
    • Duration of each storm.
    • Frequency.
  • Good to use for comparing storm seasons year to year (how active a hurricane season is).
  • Key differences:
    • ACE gives a broad view of hurricane activity (more about how many and how long).
    • PDI emphasizes storm intensity (more about how powerful they are).

Lake Effect Snow in New York

• Lake effect snow forms when cold air moves over warm water.
• Lake effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water.
• The lower layer of air, heated by the lake water, picks up water vapor from the lake and rises through cooler air. The vapor then freezes and is deposited on the leeward (downwind) shores.
• Steps:
  1. Cold air moves over a warmer lake.
  2. The lake warms the air just above it, and that air picks up moisture (water vapor) from the lake.
  3. As the moist air rises into colder air above, the water vapor freezes and turns into snow.
  4. The snow then falls on the downwind side of the lake (the leeward shore).
• Wind direction and physical geography are key components in determining which areas will receive lake effect snow.
• Lake effect is a type of heavy, localized snow that commonly happens in the Great Lakes region during late fall and winter.
• How it works:
  • Cold air (usually from Canada) moves over the warmer, unfrozen waters of the Great Lakes.
  • The lakes warm the air and add moisture to it.
  • The moist, warmer air rises, and as it cools, clouds form.
  • These clouds can create narrow bands of intense snow, dumping 2 or 3 inches of snow per hour or more.
• Ice coverage of the Great Lakes has decreased 8% per decade from 1973-2008 (30% decrease).
• As the world gets warmer, lake temperatures increase, and lakes remain ice-free longer.
• As long as cold air blows over lakes, there will be increased lake effect snow with increasing temperatures.

Lake Effect Snowstorms

• On January 6, 2017, a major lake effect snowstorm hit parts of the Great Lakes region, dropping record-breaking amounts of snow in some areas.
  • Key snowfall totals:
    • Erie, PA: 22.6 inches.
    • Gaylord, MI: 24.8 inches.
    • Perrysburg, NY: 30.6 inches.
• Satellite image from 2014 of Great Lakes: Ice-covered lakes drastically reduce the amount of lake effect snow.
• When the lakes are frozen, there’s less open water to add moisture and warmth to the air, meaning there’s less fuel for lake-effect snow to form.
• Ice-covered lakes = much less lake effect snow.

Lake Ice Coverage Trends

• Lake Erie (top chart):
  • Most winters, it was almost completely frozen.
  • Since 1998, there have been 6 years where it barely froze at all, a sign of warmer winters.
• Lake Ontario (bottom chart):
  • It has rarely frozen over, even in earlier years.
  • Since 2006, it’s had less than 40% ice cover almost every year, except during two very cold winters (2013-14 & 2014-15).
• Why does Lake Erie freeze more than Lake Ontario?
  • Lake Erie is shallower, so it freezes more easily; deeper lakes like Lake Ontario take more time to freeze.

Snowfall Changes Over Time

• Figure comparing how snowfall has changed over time at two types of places from 1931 to 2001:
  • a) Lake effect sites: Places near the Great Lakes, where snowfall is often boosted by lake effect snow.
    • The graph shows how snowfall changed each year from October to April.
    • The grey line shows the long-term trend (whether snowfall has gone up or down over time).
  • b) Non-lake effect sites: These are places farther from the lakes, where snowfall doesn’t depend on lake-effect.
    • It shows the same kind of snowfall data and trend for comparison.
• Are we getting more lake effect with climate change?
  • Lake effect has increased over the years.

Winter Precipitation Increase

• Figure shows how much winter precipitation (rain and snow) is expected to increase in New York State by the middle of the century (around 2050) if greenhouse gas emissions keep rising quickly.
  • Southern New York: 10-15% more winter precipitation.
  • Northern New York: 15-20% more.
• Three things control lake effects:
  1. Ice cover.
  2. Water temperature.
  3. Difference in temperature between lake and air blowing over it.
• As climate warms, ice coverage on the Great Lakes decreases.

Climate Change and Lake Effect Snow

• As the climate gets warmer, the Great Lakes freeze less in winter.
• From 1932 to 2008, ice cover on the lakes dropped by about 8% per decade—that’s a 30% total drop over 35 years.
• Less ice = more open water, which means the lakes can add more moisture to the air, leading to more lake-effect snow in the near future.
• But over the long term, as temperatures keep rising, it may get too warm for snow, and instead of snow, the extra moisture will fall as rain.
• Lake effect snow—what’s happening now (observed):
  • Lake effect snow happens when cold Arctic air moves over the warmer water of lakes like Lake Erie and Lake Ontario.
  • The air picks up moisture and heat from the lake, then cools down again, causing heavy snow to fall near the lakes.
  • These snowstorms can be very intense, sometimes dropping up to 4 feet (48 inches) of snow in one storm and lasting a few hours to several days.
  • As the climate has warmed, the Great Lakes freeze less—since 1973, lake ice has dropped by about 30%.
  • With more open water, there’s been an increase in lake-effect snowfall since 1950, especially on the south and east sides of the Great Lakes.
• What's expected in the future (projected):
  • In the next few decades, we may see even more intense lake-effect snow, like the huge storm that hit western New York in 2014.
  • Why? Because less ice means more water vapor going into the air.
  • But in the longer term, as temperatures keep rising, it may get too warm for snow, so instead of snow, we’ll see more rain during those same conditions.
  • Lake effect snow can potentially affect New York to increase in the future.

Crisis of Salt Lakes: Decline of the World's Saline Lakes

• Graph tracks how much water volume (amount of water) has been lost from several major salty lakes around the world over the past 140 years.
  • All the lakes have shrunk over time by a lot.
  • Data shown using a 5-year average to smooth out short-term changes and highlight long-term trends.
  • The Dead Sea hasn't lost as much volume compared to others, but that is because it is very deep. Even a small volume loss has caused its water level to drop by more than 28 meters.
  • Lake Urmia in Iran has lost water very quickly in recent years, mostly because of irrigation and water use for farming (agriculture).

Owens Lake

• Owens Lake used to be a natural, full lake for hundreds of years, but in the early 1900s, water from the Owens Lake was diverted to supply LA, and by 1926, the lake became completely dry.
• What happened after the lake dried?
  • The dry lake bed turned into a huge source of dust storms.
  • This dust contains tiny harmful particles called PM10 (particles small enough to get deep into your lungs and cause health problems).
• Why is the dust dangerous?
  • The dust carries arsenic, a toxic metal that can cause serious health issues when inhaled.
  • People living nearby (like Keeler and Ridgecrest) are exposed to unhealthy air many days a year.
• What’s the issue?
  • Dry Owens Lake in California’s Owens Valley is causing serious air pollution, which is tiny dust particles that can damage your lungs and cause serious health problems.
  • The dust from the dry lake bed gets picked up by strong winds and blown into the air.
• What’s being done about it?
  • The state of California created a plan (called a State Implementation Plan or SIP) to clean up the air and meet federal air quality standards.
  • The EPA has approved this plan and gave the area more time to meet the clean air goals.
  • The plan includes three main ways to control the dust:
    1. Shallow flooding parts of the dry lake to keep dust down.
    2. Growing plants (managed vegetation) to hold the solid in place.
    3. Spreading gravel on the ground to cover up dust sources.
• The Great Salt Lake in Utah has even more exposed dry lakebed than Owens—over 7 times more.
• The Wasatch Front, where lots of people live (like Salt Lake City), is nearby, with a population 85 times bigger near Owens Lake.
• This means the potential for harmful dust and health risk is much greater.
• Some of the dust contains toxic metals like arsenic and lithium, which can be dangerous to breathe.
• The drying of the Great Salt Lake is damaging the environment (messes up bird migrations).
• Water development in the Owen Valley has exposed 2100 \text{ km}^2 of lake bed, causing the generation of fine dust for the harm of humans and agriculture.

Aral Sea and Dead Sea

• Lower Jordan River and Yarmouk River has significantly reduced the amount of water flowing into the Dead Sea, with current inflow only about 10% of its natural level.
• Environmentalists say that the drying up of the Dead Sea is a human-made problem:
  • In a water-scarce region, Israel, Jordan, and Syria have diverted the rivers that feed the Dead Sea for drinking water and irrigation.
  • Mineral extraction by Israeli and Jordanian companies and dams are contributing to the Dead Sea depletion.

Aral Sea

• In the 1960s, the Soviet Union built canals and dams to take water from two big rivers in Central Asia (the Syr Darya and Amu Darya) and use it to grow crops, especially cotton, in the desert.
• Before this, those rivers flowed naturally into the Aral Sea, which was a huge lake, the 4th largest in the world.
• But after the water was redirected for farming, less and less water reached the lake, and over time, the Aral Sea began to dry up.
  • Even though irrigation (using water to grow crops) helped turn desert areas into farmland, it caused the Aral Sea to shrink badly.
  • It had split into two parts: the North Aral Sea (smaller) and the South Aral Sea (larger).
  • The South Aral Sea then broke into two separate parts, an eastern and a western lobe.
  • The eastern half started drying up and vanished by 2014.
• When the Aral Sea dried up, it caused serious problems for both the environment and local communities:
  • Fishing collapsed because the water became too salty and polluted to support fish.
  • Pesticides and fertilizers from farms got into the water and contaminated the lakebed.
  • As the lake dried up, the wind blew salty, toxic dust from the exposed lake bottom into towns and onto farmland, making the soil worse for growing crops.
  • Farmers had to use more and more water to wash salt out of their fields.
  • The climate around the lake changed—winters became colder, and summers hotter and drier because the lake was no longer there to help balance the temperatures.
• The Aral Sea has lost more than half of its size since 1985 because water that used to flow into it from two big rivers (the Syr Darya and Amu Darya) is now used for farming, especially growing cotton.
  • Less water reaching the lake is keeping dried up.
  • A long drought in the region has made the problem worse.
  • As the water disappears, the bottom of the lake is exposed.
  • Then the exposed lakebed is full of fine dust and chemicals (like fertilizers and pesticides from farming).
  • Strong winds blow across the dry area, picking up the dust and creating dust storms.
  • Astronauts on the International Space Station saw a big dust storm blowing from the Aral Sea in June 2001.

Cryosphere: Frozen Parts of Earth

• The Cryosphere is all parts of the Earth that are frozen:
  • Snow
  • Ice on rivers and lakes
  • Sea ice
  • Glaciers
  • Ice sheets (larger than glaciers)
  • Frozen ground (called permafrost)
• Glaciers exist only in Antarctica or Greenland

Glaciers

• A glacier is a large mass of ice and snow that moves slowly over land.
• Mountain glaciers are like frozen rivers of ice that flow slowly down mountains into valleys.
• Ice sheets are much bigger and are found in Greenland and Antarctica. They spread out like big ice domes in all directions.
• How do glaciers form?
  • The evolution of snow into glacial ice.

Glacier Features and Movement

• How do we get the lines in the middle of the mountain glaciers?
  • Each smaller glacier carries rock and dirt (sediment) along the edges.
  • When the glaciers join, the rock from their edges gets squeezed into the middle of the new, larger glacier.
  • This makes a dark line of rock and dirt running down the center of the combined glacier.
  • Lines represent those loose materials like rock and soil, is either falling onto the glacier from the surrounding valley walls or when two glaciers merge bring their debris together.
• How do glaciers move?
  • Glaciers move because of pressure and gravity.
• Glaciers are melting due to a warmer climate.

Glacier Melt and Global Temperature Rise

• Since 1970, glaciers have lost a lot of ice.
• This loss comes from:
  • Less snow falling and sticking into the glaciers.
  • More ice melting, evaporating, or breaking off into the ocean.
• Water equivalent meaning:
  • Ice and water have different densities, meaning water is denser; ice is less dense, extends when it freezes, and floats on water.
  • It is used to measure ice & snow to compare its volume to the amount of liquid water it would produce.
• Nearly half of the world’s mountain glaciers are expected to melt away by the end of this century.
• If the global temperature increases by 1.5°C, about 104,000 glaciers will disappear, and the sea level will rise about 3.5 inches.
• The Paris Climate Agreement aims to keep global temps within 1.5°C higher than they were before industrial times, but we are getting close to that limit.
• How much has global temperature risen in the last 1,000 years?
  • 1.5° Celsius
  • 1. 5° Celsius of global warming would wipe out around 104,000 glaciers and raise sea levels by 3.5 inches.
• Ice refracts sunlight, and sea ice helps keep the Earth cool by refracting most sunlight.
• Open water absorbs heat; when ice melts, dark ocean water is exposed, which absorbs more heat.
• Warming speeds up; this extra heat makes it harder for new ice to form, causing more melting. This loop is called ice-albedo feedback.
• The Arctic is warming faster; the Arctic is heating up 4 times faster than the rest of the planet.
• Melting permafrost releases gases: As more ice and ground thaw (becomes liquid), carbon dioxide and methane are released, adding more greenhouse gases to the atmosphere.

Ice Sheets, Permafrost, and Sea Level Rise

• There are over 200,000 glaciers around the world (not counting big ice sheets in Greenland & Antarctica).
• If all of those glaciers melted, the sea would rise about 1.6 feet.
• If the Greenland ice sheet melted, the sea would rise by about 24 feet.
• If the Antarctic ice sheet melted, the sea would rise by almost 200 feet.
• So big ice sheets hold much more water than all the other glaciers combined.

Vostok Ice Core

• Vostok ice core: (measures tiny bubbles past temps and greenhouse gas levels)
  1. There is a decline in both temperature and greenhouse gas concentrations during glacial periods.
     • During ice ages (glacial periods), both temperatures and greenhouse gases (like CO2) went down.
  2. And a rapid rise during deglaciation.
     • When the ice ages ended (deglaciation), both temperature and greenhouse gases went up quickly.
  3. Climate has been relatively warm and stable during the last 10,000 years—the Holocene interglacial period.
     • For the last 10,000 years, the climate has been warmer and more stable—this time is called the Holocene, and it’s the period we’re living in now.

Greenland Ice Mass Loss

• Recent loss of Greenland ice mass since 2002: Each year, the ice is getting smaller, making it melt faster.
• 300 gigatons per year

Changes in Greenland Ice Sheet Height

• Scientists used satellites and aircraft data to measure how the height of the ice surface on the Greenland ice sheet changes between about 1998 and 2005. They looked at over 16,000 places using special laser equipment.
• In some areas near the edges, ice is getting thinner quickly.
• Outlet glaciers: ice rapidly thinning.
• Why are most of the changes/actions seen in the margins?
  • Where the flow of the glaciers goes.
  • The center of the glaciers is where ice accumulates because the climate is cold.
• As the ocean and air around Greenland get warmer, the ice on Greenland is melting faster. This causes:
  • More surface melting (on top of the ice).
  • More water running off into the ocean, and
  • Glaciers near the coast (called outlet glaciers) to move faster and become thinner.

Antarctic Ice Sheet Instability

• The image compares Marine Ice Sheet Instability (MISI) and Marine Ice Cliff Instability (MICI)—two ways that large parts of Antarctic ice could break apart and cause sea levels to rise faster.
• Ice from the middle of Greenland and Antarctica slowly moves outward in fast-moving rivers of ice called ice streams.
• These streams flow toward the edges of the ice sheets, where the ice spreads out over the ocean in big floating platforms called ice shelves.
• As the ocean gets warmer, these ice shelves can melt or break apart. When that happens, the ice behind them (in the ice streams) can slide faster into the ocean, which adds more water to the sea and raises sea levels.

Marine Ice Sheet Instability (MISI) and Marine Ice Cliff Instability (MICI)

• MISI:
  • Where it starts: ice that is resting on land but extends into the ocean, often grounded below sea level.
  • What causes instability: happens when the bedrock beneath the ice slopes downward inland. As the ice front retreats into deeper water, the ice becomes thicker and flows faster.
  • Trigger: melting at the base from warmer ocean water → faster flow → more retreat (a feedback loop).
  • Type of melting: mostly from below, driven by warm water under the ice sheet.
• MICI:
  • Where it starts: If the floating ice shelf that holds back land ice breaks apart (due to things like melting from above and below), tall cliffs of ice are exposed at the edge.
  • Trigger: These cliffs can’t support their own weight and collapse, causing more ice to fall into the ocean.
  • Type of melting: driven by both surface melt (above) and the ocean melt (below), weakening the shelf.
• Both of these processes show how ice can suddenly become unstable and melt quickly, speeding up sea level rise.

Permafrost

• Soil or underwater sediment that stays frozen (below 0°C or 32°F) continuously for at least 2 years.
  • The earliest permafrost has been frozen for about 700,00 years.
• "Perma" means permanent and "frost" refers to frozen ground.
• It doesn’t just freeze sometimes—it stays frozen all year, for multiple years.
• It can be shallow or extremely deep.
• Found mostly in cold regions, like the Arctic or high mountains.
• NOT the same as the ground water under the glaciers or ice sheet—those aren’t considered permafrost.
• On land, it usually lies beneath an active layer of soil that freezes and thaws with the season.

Permafrost Layers

• Layer in the soil profile (from top to bottom):
  1. Active layer:
     • The topmost soil layer.
     • Freezes in winter and thaws in summer, so the temperature fluctuates a lot.
     • The curved red line at the top shows the seasonal maximum and minimum temperatures in this layer.
     • This layer is not permafrost because it doesn’t stay frozen year-round.
  2. Permafrost zone:
     • The middle layer remains below 0°C (32°F) all year.
     • Stays frozen for at least 2 years.
     • It sits below the active layer and above warmer ground deeper down.
     • The red dotted to solid line shows the average temperature of the soil getting colder with depth until it warms again near the bottom.
  3. Bottom layer (thawed ground):
     • Deep underground, geothermal heat from the Earth’s interior raises the temperature.
     • Eventually, the soil warms above freezing, even though it’s very deep.
     • This sets the lower boundary of the permafrost.
     • Below there is no permafrost.
• Why is there no permafrost deep down?
  • The Earth constantly gives off geothermal heat from its core and mantle.
  • As you go deeper underground, the temperature rises, even in cold places.
    • On average temperature increases by about 25-30°C per kilometer.
• Permafrost holds ancient dead plant and animals (biomass).
  • For thousands of years, dead stuff (like roots, leaves, and animals) has gotten buried in the frozen ground.
  • Because the soil stays frozen, it didn’t rot or break down.
  • This made tundra soil a carbon sink, meaning it stored carbon instead of releasing it into the air.

Thawing Permafrost and Carbon Release

• But when permafrost thaws, that carbon is released.
• Global warming is heating the Arctic, causing permafrost to thaw.
• Once it thaws, the dead material starts to decompose, which releases greenhouse gases like carbon dioxide (CO2) or methane (CH4) into the atmosphere.
• Why would methane and carbon dioxide be released from decomposition?
  • Anaerobic conditions—if there’s little or no oxygen like in thawed permafrost, different microbes take over.
• This again creates a feedback loop.
• Yedoma is a kind of permafrost that's rich in frozen organic matter—things like dead plants and animals.
  • It’s especially packed with carbon.
  • When Yedoma thaws, it releases a lot of greenhouse gases.

Permafrost Carbon Storage

• Total permafrost carbon:
• A bar section representing 1,400-1,650 billion tons of carbon stored in Arctic permafrost.
• Comparison of bars or lines:
  • Atmospheric carbon—showing that it’s about half the amount in permafrost.
  • Human carbon emissions since the industrial revolution—about ¼ of permafrost.
• Carbon release under warming scenarios:
• A downwards trend or loss curve showing permafrost volume (especially the upper 3m) shrinks with each 1°C of global warming.
• Under RCP8.5 (high emissions scenario), it might show:
  • 5-15% of total permafrost carbon potentially being released over time.
• Human activities release about 40 million tons of carbon (fossil fuels, deforestation).
• Permafrost is getting warmer by about 0.29°C (0.5°F).
• Arctic permafrost holds a lot of carbon.

Thawing Permafrost and Slope Instability

• Thawing permafrost and melting glaciers are causing slope instability.
• In mountain regions, as glaciers shrink and permafrost thaws, the ground becomes less stable.
• As permafrost thaws, the ground can become soft or unstable, causing things like:
  • Roads to crack or sink
  • Buildings to tilt or collapse
  • Pipelines to break
• Places in Alaska and Russia are shown to be especially vulnerable.

Geothermal Energy: Coso Volcanic Field

• Geothermal energy = heat from inside the Earth.
  • It is energy that comes from the natural heat stored underground.
• Where does it come from?
  • Deep underground, there are hot rocks and water.
  • This heat can be found naturally or made more accessible by drilling.
• How do we use it?
  • People drill wells (like very deep holes) to reach hot water or steam underground.
  • This heat can be used in two main ways:
    1. Electricity generation:
       • The steam or hot water powers turbines, which generate electricity.
    2. Heating and cooling:
       • Geothermal systems can heat buildings in the winter and cool them in the summer by using underground temperatures.

How Geothermal Energy Makes Electricity

• 1. Deep underground:
  • There are hot rocks and fluids (like water) under the Earth’s surface.
  • These fluids can move through cracks and spaces in the rock (called permeability).
• 2. Drill wells to reach the heat:
  • Wells are drilled deep down to let the hot fluid flow up to the surface.
  • As it moves through the hot rock, the fluid absorbs heat.
• 3. The heat turns to steam:
  • At the surface, pressure drops suddenly, and the hot water “flashes” into steam.
  • This happens in a flash steam power plant.
• 4. Steam spins a turbine:
  • The steam blows through a turbine.
• The spinning turbine powers a generator, which creates electricity.

Coso Geothermal Facility

• The Coso geothermal facility has 9 power plants located on U.S. Navy land near China Lake, California.
• These plants make electricity using steam from underground.
• Coso generates enough power for about 145,000 homes.
• Electricity at Coso:
  • Has hot rock underground; water seeps deep into the ground and gets heated by the hot rocks (volcanic rocks).
  • Engineers drill deep wells to bring the hot water and steam to the surface.
  • At the surface, the pressure drops, and some of the hot water turns into steam.
  • The stream spins a turbine, just like wind or stream in other power plants.
• How much electricity does it provide?
  • It generates about 145 megawatts (MW).

Geothermal Power in the U.S.

• The U.S. is #1 in geothermal electricity.
• The U.S. produces the most geothermal electricity (over 4 gigawatts).
  • Enough to power 3 million homes.
• To generate geothermal power, you need 3 things:
  1. Heat—from hot rock deep underground.
  2. Fluid—usually water, which soaks up the heat.
  3. Permeability—cracks or spaces in the rock that let the hot water move around.
• Sometimes the rocks are hot, but they don’t have water or cracks.
  • In those cases, engineers create Enhanced Geothermal Systems (EGS).
    • They inject water into the rock.
    • This creates or opens up