Geo Science *NEW PROF; NEW QUIZ STYLE* Questions

What geologic archives are used to reconstruct past changes in climate?

Tree rings, ice cores, ocean sediments, corals, lake sediments, cave deposits, and glaciers.

What is meant by a paleoclimate “proxy”?

Indirect evidence used to infer past climate conditions.

How are water isotopes used to determine changes in past ice sheet volumes?

Ratios of oxygen isotopes (¹⁶O vs ¹⁸O) show how much water is stored in ice vs oceans.

What is an isotope? (water isotopes)

Atoms of the same element with different numbers of neutrons.

How do the oceans change in terms of their isotopes and what exactly changes? (water isotopes)

Ocean water becomes enriched in ¹⁸O during ice ages.

Why do they change? (water isotopes)

Because ¹⁶O is trapped in ice sheets on land.

What drives the changes? (water isotopes)

Evaporation, precipitation, and ice sheet growth/melting.

What geologic archive is used to reconstruct past changes in oxygen isotopes?

Ocean sediments (microfossil shells).

What are Milankovitch Cycles? (Milankovitch Cycles)

Long-term changes in Earth’s orbit and tilt that affect climate.

Can you describe them? (Milankovitch Cycles)

They include eccentricity, obliquity, and precession cycles.

What causes them to change? (Milankovitch Cycles)

Gravitational interactions with other planets.

How do they influence past changes in energy input to the planet? (Milankovitch Cycles)

They redistribute solar energy across seasons and latitudes.

What is eccentricity? (Milankovitch Cycles)

Changes in Earth’s orbital shape (~100,000 years).

What is precession? (Milankovitch Cycles)

Wobble of Earth’s axis (~20,000 years).

What is obliquity? (Milankovitch Cycles)

Changes in Earth’s tilt (~40,000 years).

How do the cycles change through time? (Milankovitch Cycles)

They vary cyclically over tens to hundreds of thousands of years.

What conditions in the Milankovitch Cycles favor glaciers growing in the Northern Hemisphere? (Milankovitch Cycles)

Cool summers with reduced solar energy.

More or less eccentricity? (Milankovitch Cycles)

Higher eccentricity increases seasonal contrasts (can favor ice growth depending on alignment).

More or less tilt (obliquity)? (Milankovitch Cycles)

Less tilt favors glacier growth (cooler summers).

What precession conditions are needed? (Milankovitch Cycles)

Northern Hemisphere summer occurring farther from the Sun.

What information from ice cores provides past climate data?

Temperature (isotopes) and atmospheric gases (CO₂, methane).

What triggers ice ages and what was the main driver?

Orbital changes trigger them; CO₂ amplifies and drives global temperature change.

What information provides past sea level changes?

Corals and ocean sediment records.

What is the “Hockey Stick Graph”?

A graph showing stable temperatures for centuries followed by sharp modern warming.

Why is it important and controversial graph? (Hockey Stick Graph)

It shows unprecedented recent warming; controversial due to methods and interpretation debates.

What type of geological materials were used to reconstruct it? (Hockey Stick Graph)

Tree rings, ice cores, corals, and other proxies.

What makes tree rings valuable? (Geological Archives)

They provide precise, yearly climate records.

What about corals? (Geological Archives)

They record ocean temperature and chemistry.

What about ocean sediments? (Geological Archives)

They preserve long-term climate and isotope data.

What about ice cores? (Geological Archives)

hey trap ancient air and record temperature and gas concentrations.

How are glacier lengths used to reconstruct past changes in climate?

Advancing/retreating glaciers indicate cooling or warming.

Are temperatures today unprecedented in the last 2000 years? Why?

Yes; multiple proxy records show recent warming is much faster and higher than past variability.

What are uncertainties in reconstructing past climate?

Limited data, proxy interpretation, dating errors, and regional differences.

How does changing ocean circulation affect climate?

It redistributes heat globally, causing regional warming/cooling (e.g., bipolar seesaw).