Exam Study Notes: Water Cycle, Climate Change, and Energy

Changing Water Cycle: Hurricanes and Coastal Storms in New York

Climate change impacts on New York:
- Global trends
- Present and future temperatures and precipitation in NY
- Extreme events: heatwaves, rainfall
- Susquehanna River flooding
- Lake effect snow
- Arctic warming and severe winter weather in New York
- Sea level rise, coastal storms, and hurricanes
- Impacts: algal blooms, invasive species, farming

Global Sea Level

Global Sea Level Time Series (1990-1999):
- Grey shading indicates uncertainty in estimated long-term sea level change due to a lack of reliable global measurements.
- Red line represents global mean sea level from tide gauges.
- Red shading shows the range of variation from the smooth curve for tide gauges.
- Green line represents global mean sea level from satellite altimetry (most accurate).
- Blue shading indicates that projections diverge significantly beyond 2100, heavily dependent on future emission paths.
- Vertical rise of 20 cm = 8 inches, for visual interpretation of sea level change magnitude from the 20th to 21st century.
Sea Level Rise Projections by 2100:
- Projected to be between 1 to 8 feet, with a likely range of 1 to 4 feet.
Controls of Sea Level Rise:
- Global warming is the primary driver.
- Minor control: thermal expansion of warming oceans.
- Most important control: melting of ice caps, resulting in increased water volume.
Sea Level Trends and Projections:
- Solid black line (1920-2020): shows the average sea level rise along the U.S. coast over the past 100 years.
- Dashed black line (projected to 2050): extends the recent trend forward, based on sea level rise since 1970.
- Colored lines (out to 2150): represent possible futures based on different greenhouse gas emission scenarios and ice sheet behavior.
- Stacked bar (2100): shows a range of sea level rise in 2100 depending on the extent of Earth's warming.
- More warming = more sea level rise.

Relative Sea Level Rise

Maps show relative sea level rise by 2050 and 2100.
Relative sea level rise indicates how much sea level will rise relative to land in different places.
U.S. coasts, especially the Atlantic and Gulf coasts, will experience higher increases.
California is rising slowly.

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, about 1.2 inches/decade.
In seacoast and tidal portions of the Hudson River (to the Federal Dam of Troy):
- Could be up to 30 inches by the 2050s.
- Up to 4 feet by the 2080s.
- Up to 6 feet by 2100.

Consequences of Rising Sea Levels in New York

Magnification of storm surges caused by high winds and tides, increasing the risk of flooding, beach erosion, and infrastructure damage in low-lying areas.
Increased areas of coastal inundation (flooding) during regular tidal cycles.
Regular inundation of coastal wastewater infrastructure and transmission of pathogen and nitrogen pollution to ground and surface waters.
Increased salinity of drinking water in communities along the Hudson River due to saltwater intrusion.

Hurricanes

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'easters

Strong storms that occur along the East Coast of the U.S., especially between September and April.
Named for strong winds usually coming from the northeast.
Formation:
- In winter, cold Arctic air moves south across the land.
- Warm air from the Atlantic Ocean moves north.
- The clash between cold air and warm air over the ocean creates energy for powerful storms.
- The Gulf Stream keeps the coastal water warmer, adding more fuel.

Hurricane Harvey

Highest rainfall amount was 48.2 inches in Clear Creek and Houston.
Highest rainfall amount in a single storm for any place in the continental U.S.

Hurricane Trends

Graph shows the number of hurricanes formed each year in the North Atlantic Ocean from 1878 to 2022, and how many hit the U.S.
Green curve: total number of hurricanes recorded each year.
Orange curve: adjusted version of the total hurricane count to account for missed hurricanes before planes and satellites.

Power Dissipation Index (PDI)

Measures how much energy hurricanes use, combining:
- Storm strength (wind speed).
- Storm duration.
- Storm frequency.
Higher PDI = more powerful or more frequent storms.
Warmer ocean water helps fuel stronger storms.
Good for assessing storm strengths.

ACE Index

Measures the total energy from all tropical storms and hurricanes in a season by combining:
- Wind speed.
- Duration of each storm.
- Frequency.
Good for comparing storm seasons year to year.

Key Differences Between ACE and PDI

ACE gives a broad view of hurricane activity (how many and how long).
PDI emphasizes storm intensity (how powerful they are).

Lake Effect Snow in New York

Lake effect snow occurs when cold air moves over warmer lake water.
Produced during cooler atmospheric conditions.
The lower layer of air is heated by the lake water, picks up water vapor, and rises through cooler air. The vapor freezes and deposits on the leeward (downwind) shores.
Wind direction and physical geography determine which areas receive lake effect snow.
Lake effect is heavy, localized snow that commonly happens in the Great Lakes region during late fall and winter.
Cold air (usually from Canada) moves over the warmer, unfrozen waters of the Great Lakes.
The lakes warm the air and add moisture.
The moist, warmer air rises, and as it cools, clouds form.
These clouds can create narrow bands of intense snow, dumping 2-3 inches of snow per hour or more.
Ice coverage of the Great Lakes has decreased by 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.
Clouds stream off Great Lakes with lake effect snow bands visible along the southern shore of Lake Erie and eastern end of Lake Ontario.
A major lake effect snowstorm hit parts of the Great Lakes region, dropping record-breaking amounts of snow:
- Erie, PA: 22.6 inches
- Gaylord, MI: 24.8 inches
- Perrysburg, NY: 30.6 inches
Ice-covered lakes drastically reduce the amount of lake effect snow.
Less open water to add moisture and warmth to the air means less fuel for lake-effect snow to form.
Ice-covered lakes = much less lake effect snow.

Lake Erie and Lake Ontario Freezing Trends

Lake Erie:
- 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:
- 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).

Lake Depth

Lake Erie is shallower, so it freezes more easily. Deeper lakes, like Lake Ontario, take longer to freeze.

Lake Effect Trends

Lake effect sites:
- Places near the Great Lakes, where snowfall is often boosted by lake effect snow.
Non-lake effect sites:
- These are places farther from the lakes, where snowfall doesn’t depend on lake-effect.
Lake effect has increased over the years.

Winter Precipitation Increase

Southern New York: 10-15% more winter precipitation.
Northern New York: 15-20% more.

Controls of Lake Effects

Ice cover
Water temperature
Temperature difference between the lake and the air blowing over it
As climate warms, ice coverage on 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.

Observed Lake Effect Snow

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.

Projected Lake Effect Snow

In the next few decades, we may see even more intense lake-effect snow, like the huge storm that hit western in New York 2014.
Less ice means more water vapor going into the air.
But in the longer term, as temperature keeps 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, Salton Sea, Owens Lake.
Graph tracks how much water volume 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 is 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 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

Used to be a natural, full lake for hundreds of years.
In the early 1900s, water from Owens Lake was diverted to supply LA, and by 1926, the lake became completely dry.

Consequences of Owens Lake Drying

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).
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.
During dust storms, emergency rooms fill up because the air pollution makes breathing problems worse.
Dry Owens Lake in California’s Owens Valley is causing serious air pollution with 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.

Efforts to Mitigate Dust Storms

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:
- Shallow flooding parts of the dry lake to keep dust down.
- Growing plants (managed vegetation) to hold the solids in place.
- Spreading gravel on the ground to cover up dust sources.

Great Salt Lake

The Great Salt Lake in Utah has even more exposed dry lakebed than Owen- over 7 times more.
The Wasatch Front, where lots of people live (like Salt Lake City), is nearby, with a population 85 times bigger than near Owens Lake.
This means the potential for harmful dust and health risks 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 Impacts

Water development in the Owen Valley has exposed $2100 km^2$ of lake bed, causing the generation of fine dust harmful to human health and agriculture.
Similar case in the Aral Sea in central Asia, where the lake bed was exposed due to agricultural water development.

Dead Sea

The lower Jordan River and Yarmouk River have 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.

Aral Sea Division

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 parts: an eastern and a western lobe.
The eastern half started drying up and vanished by 2014.

Consequences of Aral Sea Drying

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 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 keeps it dried up.
A long drought in the region has made the problem worse.
As the water disappears, the bottom of the lake is exposed.
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

The Cryosphere is all parts of the Earth where water is frozen:
- Snow
- Ice on rivers and lakes
- Sea ice
- Glaciers
- Ice sheets (larger than glaciers)
- Frozen ground (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.

Glacier Formation

Evolution of snow into glacial ice.

Glacier Sediment Lines

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 loose material like rock and soil, either falling onto the glacier from the surrounding valley walls or when two glaciers merge, bringing their debris together.

Glacier Movement

Glaciers move because of pressure and gravity.
Glaciers are melting due to warmer climate.

Glacier Loss

Since 1970, these glaciers have lost a lot of ice.
This loss comes from:
- Less snow falling and sticking onto the glaciers.
- More ice melting, evaporating, or breaking off into the ocean.

Water Equivalent

Ice and water have different densities, meaning water is denser; ice is less dense and expands when it freezes, floating on water.
Water equivalent 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.

Global Temperature Rise

Global temp have risen 1.5°C in the last 1,000 years.
1. 5°C of global warming would wipe out around 104,000 glaciers and raise sea levels by 3.5 inches in that process.
Ice refracts sunlight- 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 (become liquid), carbon dioxide and methane are released, adding more greenhouse gases to the atmosphere.

Global Glacier Count

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.
Big ice sheets hold much more water than all the other glaciers combined.

Vostok Ice Core Analysis

The Vostok ice core contains measures of tiny bubbles from past temperatures and greenhouse gas levels

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 $CO_2$ ) went down.
There is a rapid rise during deglaciation.
- (When the ice ages ended (deglaciation), both temperature and greenhouse gases went up quickly).
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 times is called the holocene, and it’s the period we’re living in now.

Recent loss of Greenland ice mass since 2002 with ice getting smaller each year making it melt faster, roughly 300 gigatons per year

Greenland Ice Sheet Changes

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 is rapidly thinning.
Why are most of the changes/actions seen in the margins?
- Because that is where the flow of the glaciers go
- Center of the glaciers where ice accumulates because the climate is the coldest.

Impacts of Warming on Greenland

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.

Marine Ice Sheet and Ice Cliff 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 rises sea levels.

Marine Ice Sheet Instability (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.

Marine Ice Cliff Instability (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 $0^\circ$ Celsius or 32°F) continuously for at least 2 years.
The earliest permafrost has been frozen for about 700,000 years.