Atmosphere and Hydrosphere
This layer of gases surrounds Earth and works with the hydrosphere to transport heat and moisture; name it.
Atmosphere.
Define a carbon sink
A natural storage location that absorbs more carbon than it emits.
Define a positive feedback loop
A positive feedback amplifies a change
Milankovitch cycles describe natural changes in which two orbital/axial properties?
Variations in eccentricity and obliquity (also precession)
What is a mass extinction? Give the percent threshold used in the unit.
Loss of 75% or more of species
What does the Keeling Curve measure?
Atmospheric CO2 concentrations.
Define combustion in the context of the carbon cycle
Combustion is the burning of organic material (fossil fuels/biomass) that releases CO2
Identify the process by which liquid water becomes vapor and moves from the surface into the atmosphere.
Evaporation
Name the largest carbon sink on Earth.
Oceans (largest active sink by mass) — oceans absorb large amounts of CO₂. (Forests and soils important too.)
Define a negative feedback loop
A negative feedback reduces or stabilizes a change
Name two types of proxy data scientists use to reconstruct past climates.
Ice cores, tree rings, sediment cores, coral records, pollen.
State one major cause believed responsible for the End-Permian extinction.
Massive volcanic eruptions (Siberian Traps) releasing greenhouse gases and triggering widespread anoxia and warming.
The Keeling Curve shows a steady upward trend in atmospheric CO2. Name the primary driver of this trend.
Human industrial activity (fossil fuel combustion, land-use change).
Give two human activities that increase atmospheric CO2
Fossil fuel burning (coal, oil, natural gas) and deforestation/land-use change.
Explain how ocean currents influence regional climate
Ocean currents redistribute heat; warm currents raise nearby air temps and increase precipitation; cold currents cool adjacent land and reduce moisture.
Describe how increased atmospheric CO2 can affect plant growth and why this may not fully offset emissions.
Higher CO2 can stimulate photosynthesis (CO₂ fertilization), increasing plant growth, but nutrient limits, water stress, and land-use change limit this uptake.
Give one example from Earth systems of a positive feedback and briefly explain why it amplifies change.
Example positive: Arctic ice melt → lower albedo → more solar absorption → more warming → more ice melt.
Explain why volcanic eruptions can sometimes cause short-term global cooling.
Volcanic aerosols (sulfate particles) reflect sunlight, decreasing incoming solar radiation and causing short-term cooling.
Place these events in chronological order: End-Permian extinction, rise of dinosaurs, End-Ordovician extinction.
(End-Ordovician → End-Permian → rise of dinosaurs).
Explain what the seasonal “wiggles” in the Keeling Curve represent and why they occur.
Seasonal plant growth and decay: spring/summer drawdown of CO2 in northern hemisphere growing season; fall/winter increase from decomposition and reduced photosynthesis.
Explain how deforestation both reduces a carbon sink and contributes to emissions.
Removing forests reduces photosynthetic uptake and releases stored carbon when trees are burned or decompose; it also reduces biodiversity and soil stability, further limiting regrowth.
Describe what the term “albedo” means and give one example of a surface with high albedo.
Albedo = fraction of incoming solar radiation reflected; e.g., fresh snow/ice.
Explain how soil can act as a carbon reservoir and one way it can be released back to the atmosphere.
Soil stores organic carbon as humus; decomposition and microbial respiration release CO2 back to the atmosphere.
Give one example from Earth systems of a negative feedback and briefly explain how it stabilizes the system.
Example negative: Increased CO2 → more plant growth → increased CO₂ uptake → partial reduction in atmospheric CO₂ (limited by nutrients/water).
Distinguish between a temporary climate driver (like volcanic aerosols) and a long-term driver (like continental drift).
Temporary drivers: volcanic aerosols, solar flares, ENSO; long-term drivers: plate tectonics, continental positions, gradual changes in atmospheric composition over geologic time.
Explain how fossil pollen in sediment cores can inform scientists about ancient vegetation and climate.
Pollen types and abundance indicate past plant communities and climate (temperature/moisture), because different plants thrive in specific climates.
Using the Keeling Curve as evidence, state two reasons scientists link recent CO2 increases to human activities
Two reasons: (1) timing of rapid rise matches industrialization and fossil fuel emissions records; (2) isotope ratios (carbon isotopes) show fossil carbon signature.
Describe one mitigation strategy that could reduce atmospheric CO2 and one limitation of that strategy.
Example mitigation: reforestation / afforestation increases carbon uptake; limitation: land availability, competition with food production, and slow timescale for carbon sequestration.
Explain how changes in sea surface temperature during El Niño affect global weather patterns
El Niño warms central/eastern Pacific, alters convection patterns, shifts storm tracks, often causing wetter conditions in some regions (e.g., western South America) and drought in others (e.g., Australia, Indonesia).
Describe how disrupting a major carbon sink could create a feedback that raises atmospheric CO2
Example: Deforestation reduces forest carbon uptake and releases stored carbon, increasing atmospheric CO2 and strengthening warming — a positive feedback.
Analyze a scenario where permafrost thaw leads to both amplifying and limiting effects; explain the dominant feedback.
Permafrost thaw releases methane and CO₂ (amplifying). Some increased plant growth could sequester carbon (limiting), but typically greenhouse gas release dominates, producing net positive feedback
Describe how orbital eccentricity, axial tilt (obliquity), and precession can together influence glacial–interglacial cycles.
Eccentricity changes seasonality of solar radiation; obliquity affects tilt and season intensity; precession shifts timing of seasons — combined effects alter summer insolation and can trigger glacial/interglacial cycles.
Choose one mass extinction and summarize one major cause and one major effect on biodiversity.
Example (End-Permian): Cause — massive volcanism and greenhouse gas release; Effect — catastrophic biodiversity loss across marine and terrestrial ecosystems.
Given a CO₂ graph showing rising baseline from 1960–2025 with seasonal oscillations, interpret three likely consequences for Earth systems over the next 50 years if the trend continues.
Possible consequences: stronger positive feedbacks (permafrost melt), increased frequency/intensity of extreme weather, sea level rise from thermal expansion and ice melt; disruptions to biosphere carbon sinks and altered circulation patterns.
Propose a combined policy + natural-systems approach to slow atmospheric CO2 rise; include at least one example of a carbon sink restoration and one emissions reduction policy.
Example policy + nature approach: implement a carbon pricing mechanism and strict emissions standards (policy) while funding large-scale reforestation and coastal wetland restoration (sink restoration). Limitations and co-benefits should be discussed (social equity, economic feasibility, monitoring).