EEPS After Midterm 2

Milky Way

The galaxy that contains our solar system; a barred spiral galaxy made of hundreds of billions of stars

Solar system

The Sun and all objects gravitationally bound to it: planets

Sun

Luminous sphere of plasma held together by its own gravity composed mainly of hydrogen and helium; the primary source of energy for the solar system. Its among 100 of billions stars in our galaxy

Terrestrial planets

small, dense, rocky planets with solid surfaces, composed mainly of silicate rocks and metals (like iron), such as Mercury, Venus, Earth, and Mars.

Earth & the Moon

A planet-moon system where Earth is a habitable terrestrial planet and the Moon is its rocky natural satellite.

Mercury

The closest planet to the Sun; small, heavily cratered, with extreme temperature variations due to no atmosphere.

Venus

A terrestrial planet with a thick CO₂ atmosphere that creates extreme greenhouse warming due to the atmosphere.

Mars

A cold, dry terrestrial planet with a thin atmosphere, past water activity, and many volcanic and impact features.

Asteroids

Small rocky bodies that orbit the Sun  mostly found in the asteroid belt between Mars and Jupiter.

Meteorites

Pieces of rock or metal from space that survive passage through Earth's atmosphere and land on the surface.

Gas planets

Large planets composed mostly of hydrogen and helium—Jupiter and Saturn.

Spectroscopy

A technique that analyzes the light emitted or reflected by an object to determine its composition.

Doppler effect

The change in wavelength of light (or sound) from a moving source; used to detect motion of stars and planets.

Sidereal day

The time it takes a planet to rotate once relative to distant stars.

Solar day

The time it takes for the Sun to return to the same position in the sky (e.g. noon to noon).

Axial tilt (obliquity)

The angle between a planet's rotation axis and its orbital plane; responsible for seasons.

PSR (permanent shadow region)

Areas—usually in craters near the poles—that never receive sunlight; extremely cold and able to trap ice.

How is the chemical composition of the Sun and other planets determined?

Can be determined by looking at its spectrum. Spectroscopy: By matching the observed spectral lines to known elements

What are the main compositional differences (top 2-3 chemical components) between the Sun Earth and other terrestrial planets?

The Sun is composed mostly of hydrogen and helium, while Earth and the other terrestrial planets are rocky and metal-rich, dominated by iron, oxygen, and silicon. Earth particularly iron rich core

Sun composition

~70% hydrogen (H), 28% helium

Earth (bulk composition)

~32% iron (Fe) — mainly in the core; ~30% oxygen (O). Earth (and other terrestrial planets) are rocky/metallic

Why does the Moon have a near side and far side?

tidal locking, a gravitational dance where the Moon rotates on its axis exactly once for every orbit around Earth

How can we use radioactive dating to understand the ages of different planetary surfaces?

measures decay of isotopes, gives absolute ages

How can we use crater counting to understand the ages of different planetary surfaces?

Surfaces accumulate impact craters over time; more craters indicate an older surface and is used when physical samples can't be collected.

How is rotational speed of a planetary body determined?

Determined by tracking surface or atmospheric features or using Doppler Spectroscopy or transit-related observations; the size of the Doppler shift reveals rotation rate.

Why is there an extreme temperature difference on the surface of Mercury?

Due to its lack of atmosphere

Understand the importance of permanent shadow regions (PSRs)

They act as natural cold traps preserving water ice and other volatiles

How is radar used to study the topography of other planets?

By sending radio waves and measuring return time and signal strength to map heights and surface roughness

How do we detect objects unable to be visibly observed (ie asteroids)?

Using reflected sunlight and infrared emission

Upwelling

 upward movement of deep, cold, and nutrient-rich water to the surface

Thermohaline circulation

Global conveyor belt driven by density differences from temperature and salinity where cold salty water sinks and warm water rises.

Insolation

Incoming solar radiation reaching Earth's surface depending on latitude

Radiative forcing

Change in Earth's energy balance caused by factors like GHGs or aerosols; positive warms and negative cools.

Albedo

Fraction of solar energy reflected by a surface; high for snow and ice

Climate commitment / warming in the pipeline

Even if emissions stop today, Earth will keep warming for decades due to ocean heat inertia and existing GHG concentrations.

Photosynthesis

Plants convert CO₂ and sunlight into organic carbon and O₂

Respiration

Organisms convert organic carbon into CO₂ and energy

Decomposition

Breakdown of dead organic matter releasing CO₂ and CH₄ in anaerobic conditions.

Henry's law

At equilibrium the amount of gas dissolved in a liquid is proportional to its pressure above it; warm water holds less CO₂.

Tipping point

A threshold where a small change triggers a large irreversible shift like ice sheet collapse.

Carbon capture and storage/sequestration

Capturing CO₂ from emissions or air and storing it underground or in materials.

Representative concentration pathway (RCP)

Standardized IPCC climate scenarios projecting future greenhouse gas concentrations and radiative forcing by 2100.

Shared socioeconomic pathway (SSP)

Scenarios describing societal development that drive emissions and are combined with RCPs for modeling.

Chemtrails

A conspiracy theory claiming aircraft create harmful chemicals; actually contrails made of ice crystals.

Where does the energy for the climate system dominantly come from?

The Sun.

Why is the equator warmer than the poles?

Sunlight is more direct at the equator and more spread out and filtered at the poles.

Why do we have seasons?

Earth's 23.5° axial tilt causes varying sunlight by hemisphere through the year.

What causes air and water movements (e.g. winds and currents)?

Uneven heating creates pressure differences

Why is the Gulf Stream important for European climate?

It transports warm tropical water to the North Atlantic

What drives thermohaline circulation? Why might this movement of water stop?

Driven by cold salty water sinking; freshwater input from melting ice can reduce salinity and slow circulation.

How do we attribute an observed change in climate to a particular cause?

Using observations

What are the three basic reasons why the earth's climate might change?

Changes in solar output

Why do we not attribute recent warming to variation in solar output?

Solar radiation has been flat or decreasing while warming continues.

Why do we not attribute recent warming to variation in the earth's orbit (Milankovitch cycles)?

Orbital changes are too slow and should currently cause cooling

Feedback vs forcing difference

Forcing is an external push to climate while feedback is an internal response that amplifies or dampens change

Know examples of some high and low albedo natural earth surface materials.

snow/ice, clouds vs ocean, forests, asphalt.

How do humans affect the albedo of earth's surface? (Local vs global effects)

Local: cities (asphalt)

Be able to describe the basic physics of the greenhouse effect.

Sunlight (shortwave) passes through the atmosphere. Earth emits infrared (longwave) radiation. GHGs absorb and re-emit longwave → traps heat → warms surface.

How would earth's climate change if we stopped greenhouse gas emissions?

warming to continue for decades

How would earth's climate change if we stopped All emissions to the atmosphere (including aerosols)?

Aerosol cooling disappears → short-term temperature spike.

How would earth's climate change if we stopped All human impact (including land use change)? Why?

Some slow recovery but still decades of elevated temperatures because GHGs stay in the atmosphere.

Know the relative size of the main carbon cycle reservoirs (atmosphere, biosphere, ocean, lithosphere).

Lithosphere (rocks): largest

Ocean: huge

Biosphere: moderate
Atmosphere: smallest but most rapidly changing

Understand the main processes whereby carbon is moved between the atmosphere and the biosphere

photosynthesis removes CO₂ while respiration and decomposition add CO₂.

Understand the main processes whereby carbon is moved between the atmosphere and the ocean

gas exchange (Henry's law) solubility pump allows cold water to absorb more CO₂.

Understand the role of the biological pump in moving carbon from the shallow to deep ocean and how it relates to overall atmosphere/ocean exchange of carbon

Phytoplankton photosynthesize → organic matter sinks → moves carbon from surface to deep ocean, storing it for centuries.

If you take the amount of CO2 in the atmosphere in 1850, and add the contributions from human activity over the last ~120 years, you would predict a current atmospheric concentration of CO2 that is significantly higher (>600ppm) than current measurements (~430 ppm). Explain the difference.

assumes all human-emitted CO₂ stays in the atmosphere, but in reality large natural sinks remove a substantial fraction of emissions.

If emissions of greenhouse gasses and warming continue what changes would we expect to see in the nature of the carbon cycle feedback to warming and why?

Warmer oceans release more CO₂, droughts fires and soil carbon loss turn land into a CO₂ source, permafrost thaw releases methane and CO₂ accelerating warming.

Why does scientific consensus attribute the warming of the past ~50 years to human causes?

The observed warming pattern matches greenhouse gas forcing the rate of warming is unprecedented natural factors cannot explain the trend and climate models only reproduce recent warming when human emissions are included.

What are the major changes in climate (temperature rainfall) we expect to see in the future under different scenarios? Why are the polar regions expected to warm more than the rest of the earth?

higher temperatures, more intense rainstorms and droughts, stronger heatwaves and sea level rise, polar regions warm more due to polar amplification where ice loss reduces albedo.

Understand the differences between the emissions paths we would need to take to limit warming to 1.5-2 degrees and the path we're on.

Limiting warming to 1.5-2 degrees requires rapid emissions decline starting now with net-zero around 2050 while the current path significantly overshoots these targets.

What are some advantages of carbon capture and storage?

reducing emissions from hard-to-decarbonize industries and potential negative emissions through direct air capture

What are some disadvantages of carbon capture and storage?

high cost high energy use storage risks and not replacing emissions cuts.

What are the two main categories of geoengineering/climate intervention (carbon dioxide removal and solar geoengineering (sometimes called albedo modification))

Carbon dioxide removal removes CO₂ from the air through methods like direct air capture afforestation and enhanced weathering Solar geoengineering reflects sunlight using techniques like stratospheric aerosols or cloud brightening.

What are some proposed mechanisms for global scale solar geoengineering?

stratospheric sulfate aerosols marine cloud brightening and space mirrors

Arguments for Solar Geoengineering

Rapid cooling, Reduces extreme weather risks

Arguments against Solar Geoengineering

Side effects on rainfall & ozone, political ethical issues, doesn't fix ocean acidification, risk of termination shock if stopped suddenly