forces big ideas

Hazards Influenced By Convection

1. Hurricanes / Tropical Storms. Forms just N and S of the equator. Don’t occur in the South Atlantic or Eastern South Pacific. they are very concentrated by the Gulf of Mexico and Caribbean, southeast Asia and Western Pacific. Convection: Warm ocean water heats the air above, causing it to rise, then cool and fall, which powers the storm.

2. Volcanoes: Concentrated at subduction and divergent tectonic boundaries, most notably the Pacific Ring of Fire. Convection currents in the asthenosphere drive the creation and eruption patterns of volcanoes, through tectonic movement.

How two forces of nature are both creative and destructive

1. Tectonic Activity in the Lithosphere:

   • Earthquakes: Kills thousands, destroys infrastructure triggers other hazards such as landslides, loosens soil,and flattens areas

   • Volcanic Eruptions: destruction of wildlife and habitats due to ash, lava, and pyroclastic flow.

   • Mountain building, convergent plates clashing together.

   • Sea floor spreading, divergent plates allow for new magma to rise up

   • Volcanic islands, like Hawai’i on a hotspot

2. Glaciers in the cryosphere

   • erosion: glaciers scour and reshape valleys, removing rock and soil. can create formations like fjords or u shaped valleys. They pluck out large chunks of rock as they freeze and grab onto them before retreating.

   • deposits: they leave behind fertile soil called till as they retreat. eroding rock from one area, depositing it in another. they create landforms like moraines and drumlin.

Formation and distribution of two different natural environments

coral reefs: found in shallow warm waters, such as the tropics (great barrier reef in australia, or coral triangle in indonesia / the philippines). also will commonly form on top of volcanoes due to the warm and shallow stability they provide. form as coral polyps build calcium carbonate skeletons, grows slowly over many centuries. earth systems contributions: mainly biological, byt the movements of the plates cna shift which areas are in the goldilocks zone, sea level changes and acidification impact development. furthermore, volcanic subsidence gives coral the chance to grow up as it sinks.

deserts: form at 30 and 60 N and S of the equator, either side of the hadley cell. and at rain shadows. contain dunes, rocky plateaus and the lowest amount of precipitation on earth. form due to the hadley cell, where the warm moist air that heads to the poles rises and creates a low pressure zone, it keeps all the moisture and precipitation there at the ITCZ, creating these deserts. also relief precipitation keeps all of the moisture concentrate on one side.

Positive Feedback Loops that involve humans

1. Arctic Ice - Albedo Feedback: fossil fuel emissions - global warming - more arctic ice melting - lower albedo - more heat - more melting - cont.

   Impacts: accelerated global warming, most notably in the poles. disruptions of ecosystems, polar bears no longer have habitats, sea level rise (displacement, water contamination, etc.)

   Mitigation: drastically reducing GHG emissions, protecting and relocating polar ecosystems, developing and sticking to climate agreements

2. Deforestation - climate

   forests cleared for agriculture - less CO2 absorbed - more GHG - warmer climate - more fires, extra loss and CO2

   Impacts: loss of biodiversity and habitat destruction, more extreme droughts and ecosystem collapse, exacerbated global warming, bad air quality, etc.

   Mitigation: Forest protection policies, reforestation efforts, indigenous land stewardship reduction in GHG emissions

Most Significant Human Impact

GHG global emissions driving climate change:

• not only impacts every sphere but how they interact with each other as well

• natural warming cycles have been hit so for out of whack it feels almost impossible to get them back on the right track

• EX> melting glaciers and ice sheets, rising sea levels by metres, drying up rivers, every year is a record breaking year, like the 2021 Pacific Northwest heat dome, wildfires, increasing danger of tropical storms, ocean acidification, food chain collapse, etc.

  These changes are constantly accelerating impact globally, and are irreversible on a human timescale. the scope is unmatched by any other action.

Settlements in Hazard Prone Areas

Near volcanoes: such as naples Italy, near mt. Vesuvius

• very rich and fertile land

• often holds lots of cultural value

• can have huge economic opportunities, like jobs

• geothermal energy

Flood plains: Like the Nile

• fertile soil and irrigation

• good for transportation and ports

• Can be harnessed for energy

EX. New Orleans

• One of the largest shipping ports in the world

• Great accesses for national and international trade

• very prone to hurricanes

• below sea level

Overall, all of these areas are incredibly dangerous but humans have adapted over time with engineered solutions. The benfits these areas bring are primarily economic, and humanity has declared that the risks are worth it.

Increasing Water Scarcity

Factors:

• Climate change / global warming, which increases drought rates and their severity. leads to unpredictable and irregular rainfall, melting glaciers which leads to river piracy.

• Overuse in agriculture

• commodification

• pollution and contaminants, natrual or chemical

• urbanization and population growth increases demand

EX. The Nile River

Ethiopia wishes to create a dam, which is making Egypt fearful of reduced flow. Huge populations rely on it, it also holds huge amounts of cultural significance, historical treaties. However ethiopia sees it as crucial for development and energy.

“There is no usch thing as a natrual disaster.”

A hazard becomes a disaster based on how it impacts society. Using the term natural implies that we have no control over that. We have methods to reduce risk and prepare. For example, the Haiti earthquake from 2010 was a magnitude 7 earthquake that killed 230,000 due to weak buildings. Versus a 7 magnitude earthquake in Chile from 2010 killed significantly less due to better construction and emergency responses. Again, Hurricane Katrina in 2005, had such a huge impact due to poor levees and neglected communities. In conclusion, disaster is shaped by human planning, poverty, and response systems.

Earth as a habitable planet

1. The moon - helps to stabilize earth’s orbit, reventing lciamte shifts and extreme tmeprature differences

2. Magnetic field - staves of cosmic rays and solar flares that would fry the earth.

3. Atmosphere - the ozone layer lets us breathe and live. The great oxygenation by early planet. also shielded early animals from lethal radiation

4. Our sun - a yellow dwarf that has 5 billion years left, that gives us plenty of time.

5. Gas Giant neighbours - they have a huge gravitational pull that grabs meteorites so they avoid our planet

6. Type of planet - the molten interior and volcanic activity gives us an atmosphere that holds in enough heat, tectonic plates leads to mountains and landforms that prevents earth from becoming one huge ocean

7. Being a twin planet - the collision with Thea increased earths size and gravity, and created the moon

Geopolitical Tensions

Syria - severe drought in the yers leading up to the syrian civil war has been cited as a huge reason behind exacerbated teniosn and soical inequalities

The arctic - melting of arctic ice is opening up new shipping routes and access to resources like oil and gas. this attracts the interest of various nations, increasing geopolitical tensions

Predictable vs Unpredictable hazards

Predictable: Hurricanes - satellite data models and tracks paths, speed, and intensity. early warnings leads to better public education and preparation, evacuations, and infrastructure can be reinforced.

Unpredictable: Earthquakes - can’t predict exact timing or location, must rely on preparation ushc as : building codes, emergency drills, evacuation plans, stockpiling resouces, accident planning, etc.

Conc: Predictability leads to proactive preparation / mitigation of impacts. You can be prepared earlier about your situation and plan accordingly. unpredictability will focus on resilience and fast responses because you never know if you will be hit/ These are much harder to prepare for, so public education is key.

Three Major Events

1. The great oxygenation - prior to this, there was no oxygen in the atmosphere. the ocean was iron rich and toxic. Plant like protists, called cyanobacteria evolved to begin performing photosynthesis, and producing boxygen. it turned the copious amounts of CO2 into oxygen, and filled the atmosphere. this paved the way for aerobic respiration, a more efficient way of producing enegu. leading to more complex life, and the formation of the ozone layer

2. the formation and breakups of supercontinents, like pangaea. rifting, subduction, plate tectonics and convection in the evtually broke it up. this brought changes to ocean currents and climate, e the interior of pangaea was very dry. these kinds of events created mountain ranges like the himalayas when india and asia smashed together.

3. the ice ages,: massive ice sheets covering much of North America, Europe and Asia, sea levels were about 120m lower, meaning land bridges connected continents.

   Milankovitch cycles: long term changes due to earth’s oblong orbit and tilt which impact how much sunlight reaches earth - cooling and warming cycles.Cooler summers, means no ice melt, meaning glaciers are bigger. More ice, higher albedo, more light reflected, etc. a positive feedback loop.

4. These growing glaceris then carved u shaped valleys, fjords, shaped landscapes, such as the great lakes. Species adapted, migrated or went extinct. such as the wooly mammoth, or sabre tooth tiger. Humans migrated over land bridges, and glacial retreat left fertile soil behind.