Geol 142 final

How will climate change impact NY?

Heatwaves, flooding, lake effect snow, sea level rise, coastal storms, algal blooms, invasive species, farming

What is the range of projected sea level rise by 2100?

220-500 mm (1-8 ft)

Why is the Mississippi Delta expected to have a greater relative sea level rise?

River sediment makes the land sink, so relative sea level rise is higher

How much has sea level risen along NY's coast and Hudson River since 1900?

>1 ft; about 1.2 in/decade

Impact of higher sea levels

Worse storm surges, increased area of coastal flooding during tides, increased coastal wastewater after flooding, increased salinity of drinking water (saltwater intrusion)

By 2050, how many people in NYC are expected to live in a 100-year floodplain?

800,000 (previous: 400,000)

What are hurricanes?

Low-pressure systems with organized thunderstorm activity that form over tropical and subtropical waters

What is a Nor'easter?

When polar jet streams transport cold arctic air southward over the US, then eastward towards the Atlantic, where warm air from the Gulf of Mexico and Atlantic moves northward

Which hurricane caused the highest rainfall amount for any single storm on the continental US?

Hurricane Harvey, 8/23/17. Rainfall was 48.2 in. near Huston

Since 1860, what is the trend of the number of hurricanes that reach the US?

No trend—average has stayed about the same

Since 1950, what is the trend of hurricane intensity?

Hurricanes are becoming more intense/powerful

Why are hurricanes becoming more powerful?

Increased ocean temperatures provide more energy for hurricane systems, making them more intense

Since 1950, what year had the most number of strong hurricanes?

2005

What causes lake effect snow?

A cold air mass moves across warm lake water, picking up water vapor from the lake, which then freezes and is deposited as snow on downwind shores of the lake

Variables that affect how much lake effect snow falls in a given region

Wind, geography of land and water, ice cover on the lakes

Since 1930, what is the trend in the amount of lake effect snow fallen?

Increase

Since 1930, what is the trend in the amount of regular snow fallen?

No change

What regions of the US will experience increased winter snowfall with climate change?

North

What regions of the US will experience decreased winter snowfall with climate change?

South

What will be the effect of climate change on lake effect snow?

Warmer waters and less ice coverage mean more lake effect snow, until the air becomes too warm for snow, when it will fall as rain

Where does lake effect snow typically occur in the US?

East of the Great Lakes

Which Great Lake creates the least amount of lake effect snow, and why?

Lake Erie, because it is the shallowest and cools down the fastest

Health concern of salt lakes drying

Metals and dust become airborne and can affect human health: Owens Lake is the single largest source of PM10 in the US, and dust contains arsenic

What are three potential control methods to contain the dust from the lakes?

Shallow flooding, managed vegetation, gravel cover

Are larger lakes losing their water faster or slower than smaller lakes?

Faster—more surface area = more evaporation

Since 2007, what is the trend in the elevation of the Great Salt Lake?

It has been decreasing

Since 1840, what is the trend in the amount of water flowing into the Great Salt Lake? What is the significance?

There has been no difference, meaning the lake drying has nothing to do with water input

What do the two images of the Great Salt lake, taken in 1985 and 2022, reveal?

How much smaller the lake is in 2022 compared to 1985; the pale coloration in the 2022 image is where the lake waters used to cover

What is the largest consumption of water use?

Agriculture

If people weren't using water, what is the predicted trend of lake elevation?

No trend, no change

Why is the Jordan River so small when it reaches the Dead Sea?

Overused for agriculture and drinking, and water is evaporated to harvest minerals for export & fertilizer

How much elevation does the Dead Sea lose each year?

About 3 ft

What happens to the land when the Dead Sea level drops?

The land collapses

What were the rivers, Syr Darya and Amu Darya, that led to the Aral Sea, used for?

Farms for cotton and other crops

How has the Aral Sea changed over time?

Used to be connected, but by 2001 the east and west was separated, then began shrinking. Water levels fluctuate annually between wet and dry years. By 2014 the east was gone

Effects of the Aral Sea drying up

Fishing communities collapsed, salt water became polluted with fertilizers, dust became a health hazard, croplands had to be flushed with increasing amounts of water

Climate effect from losing so much water to agriculture

Winters are colder and summers hotter & drier

What was Kazakhstan's solution to save the Aral Sea?

They built a dam in 2005, preventing flow out of the North Aral Sea to the South Aral. Fisheries and water level rebounded

What is the cryosphere?

Solid precipitation, snow, sea ice, lake and river ice, icebergs, mountain glaciers, ice caps, ice shelves, and permafrost (literally anything that has to do with snow and ice)

What is a glacier?

An accumulation of ice and slowly flows over land due to its own weight; an ice river

Where do ice sheets exist?

Greenland and Antarctica

What is the speed of glacier flow?

1-100 ft/day

How do glaciers form?

Snow (90% air) gets packed into granular ice (50% air), then firn (20-30% air), then glacial ice (20% air as bubbles)

Why does the Juneau, Alaskan glacier have a line down the middle?

It's the seam between two glaciers that joined; the discoloration is glacial debris gathered from the edges of the two glaciers

How is the flow of a glacier accomplished?

By small slips along the microscopic planes of ice crystals

When does the glacier retreat?

When accumulation < loss

When does the glacier remain in the same position?

When accumulation = loss

When does the glacier advance?

When accumulation > loss

What is the average retreat of mountain glaciers since 1850?

1.5 km

What is glacier mass balance?

The annual balance between how much snow accumulates and how much ice is lost

What is water equivalent?

The measurement of how much ice is lost if it was water, since they don't have the same densities

In 2022, how much water equivalent did glaciers lose?

26 meters (94 ft of ice)

What happened to the Pedersen Glacier in Alaska?

The once glacier-filled valley melted, leaving behind sediment that created a grassland

What has happened to the Sólheimajökull glacier in Iceland?

1930-1970 = over 1 km loss

1970-2000 = 0.5 km gain

2000-now = more than 1.5 km loss

how many glaciers are expected to disappear within the century?

About half

At what temperatures are certain percentages of glaciers predicted to melt?

1.5°C = 50%

2°C = 60%

3°C = >70% (sea levels would rise 5 in)

What is sea ice?

Frozen seawater that floats on the ocean surface

About how much Arctic sea ice has been lost since 1980?

14,000 km2

How does ice loss make ice loss worse? (ice-albedo feedback)

Ice reflects about 90% of sunlight; water absorbs about 90%

What do large amounts of ice do to the land underneath?

The ice is so heavy that it compresses the land

How much would sea levels rise if Greenland's >200,000 glaciers melted? How much if the Greenland Ice Sheet melted? How much if the Antarctic Ice Sheet melted?

0.5 m (1.6 ft); 7.4 m (24.3 ft); 60 m (197 ft)

What does the Vostok ice core show about greenhouse gases over the last 400,000 years?

There are natural fluctuations in CO2, methane, and temperatures, and pre-industrialization climate was relatively warm and stable

What is the glacial-interglacial time period?

100,000 years

How much ice is Greenland losing per year?

300 gigatons

Why is Greenland's ice melting faster on the coasts?

It's closest to the ocean, which makes the air warmer

Why is ice flow velocity increasing in Greenland?

Warming ocean and air temps destabilize the ice sheet, resulting in enhanced surface melt and run-off and ice discharge

How much ice (mass) has been lost since 2000?

Over 2500 gigatons

What are ice shelves vulnerable to?

Rising ocean temperatures, which accelerates flow in ice streams

Ice shelf vs ice sheet vs sea ice

Ice shelves are ticker than sea ice and connect to the ice sheet, which is glacial ice on land. Sea is not attached to anything and floats freely

What is a retrograde slope, and why is it bad for ice sheet melting?

The earth slopes away from the ocean because the ice compressed the land, which leads to thicker ice connecting to ocean water and more surface area to melt (feedback loop)

What is permafrost?

Soil that is continuously below 0°C for two or more years. Land under glaciers and ice sheets is NOT permafrost

What is the "active layer" in the ground?

Soil that freezes and thaws depending on the season

How much land surface in the Northern Hemisphere and globally has permafrost?

15%, 11% (most is in the Arctic, Canada, and Russia)

Why is there a bottom layer to permafrost?

Natural heat from the earth makes the ground temperature rise above 0°C due to the geothermal gradient

What is the geothermal gradient?

25°C / km

What is the climate danger to melting permafrost?

Dead biomass accumulated over millennia, previously frozen, can thaw enough to decompose and release carbon dioxide or methane, making the air warmer and increasing the amount of permafrost melting (feedback loop)

What are permafrost emissions comparable to?

Global emissions from deforestation or annual emissions from countries like Russia, the US, or China

How much carbon dioxide is stored in permafrost? How much is in the atmosphere?

Permafrost: 1,400 gigatons; atmosphere: 850 gigatons

If all global permafrost melted, how much would sea levels rise?

3-10 cm (1-4 in)

How much organic carbon do Arctic and Boreal permafrost contain?

1460-1600 gigatons

Immediate human danger to melting permafrost

Land compression leads to infrastructure damage

What is geothermal energy?

Heat energy created by the Earth

What are geothermal resources?

Reservoirs of hot water that exist (or are human-made) at varying temperatures and depths below the earth's surface

Conditions from which geothermal electricity can be generated

Presence of hot rocks, fluid, and permeability

How is geothermal energy extracted?

The fluid flows through the hot rocks, absorbing heat, which is then drawn up through wells to Earth's surface where it converted to steam and drive turbines

What are flash steam plants?

Fluids at temps of >182°C from deep underground travel under high pressures to a low-pressure tank at the surface. The change in pressure causes some of the fluid to rapidly transform ("flash") into vapor

Coso Operating Company in California

Produces about 145 MW of power; geothermal reservoir is about 600°C

How much geothermal energy goes the US generate?

About 4 gigawatts (largest in the world)

Enhanced geothermal systems

Human-made reservoirs to create conditions for electricity generation by injecting fluids into hot rocks, creating fractures and opening existing ones

How many homes could enhanced geothermal systems power by 2050?

>40 million homes

How do geothermal heat pumps work?

They provide heating/cooling by using the stable temperature of the ground as a heat sink in the summer, when the ground is cooler than the air, or as a heat source, when the ground is warmer than the air

What are district heating and cooling systems?

One or more geothermal system (like heat pumps) to heat and cool groups of buildings, campuses, or entire communities

What is hydroelectricity?

Electricity generated from hydropower. Supplies 15% of the world's electricity (~1410 TWh in 2023), more than all other renewable resources combined

How do hydroelectric dams work?

Water from a reservoir flows downgrade through a dam in the penstock where it spins a turbine that generates electricity

Percentage of renewable energy in the US generated from hydropower

10%

Effect of the Three Gorges Dam, China

Flood control, hydroelectricity to fuel economic growth, increased risk of landslides

Largest dam in the world

Three Gorges Dam, China

Largest dam in the US

Oroville Dam, CA

Itaipu Dam

Located on the Paraná River between Brazil and Paraguay; third largest in the world

Hoover Dam

Generates about 4 billion KWh each year; was once the largest in the world and now one of the largest in the US BUT NOT the largest