1
Q
- What is geology?
A
Geology is the study of the Earth, its materials, processes, and history, focusing on how it has evolved over time.
2
Q
- What is the scientific method and what is its purpose?
A
An objective, systematic method used to understand natural phenomenon.
3
Q
- Objective vs. subjective observations
A
- Objective observations: Based on facts, measurable, and observable.
- Subjective observations: Based on personal opinions and beliefs. True for some, but not all.
4
Q
- Be able to understand the steps involved in the scientific method
A
Identify a problem. Do some initial research. Create a test for your hypothesis. Predict test results. Test your hypothesis. Did the test confirm your predictions? Run test again either way. Did the test confirm your predictions again? If yes, publish your results so that the scientific community can test it as well. If no, modify/change hypothesis, but also publish results. If comprehensive scientific research further validates the hypothesis, you have a theory!
5
Q
- Define the following terms: hypothesis, scientific theory, scientific law. Make sure you understand the difference between all three.
A
- Hypothesis: A tentative, testable explanation of an observation.
- Scientific Theory: The best explanation of a natural phenomenon that is supported by a wide range of data.
- Scientific Law: A statement or equation that simply states a natural relationship.
6
Q
- What are the 3 rock groups and how do they differ?
A
- Igneous rocks: Formed from the cooling and solidification of magma or lava.
- Sedimentary rocks: Formed from the accumulation and compaction of sediments.
- Metamorphic rocks: Formed from the alteration of existing rocks due to heat, pressure, or chemical processes.
7
Q
- Plate tectonics: be able to explain what the theory states
A
Grand unifying theory in geology.
- The lithosphere is broken into numerous plates.
- These plates move on top of the underlying asthenosphere.
- The plates move very slowly.
- The plates interact at plate boundaries, generating geologic activity.
- The geologic activity is concentrated at plate boundaries.
8
Q
- What are the three types of plate tectonic boundaries and how do plates move relative to each other at these boundaries? What is sea-floor spreading and subduction? Where do these processes occur?
A
- Divergent boundaries: Plates move apart (e.g., mid-ocean ridges, sea-floor spreading).
- Convergent boundaries: Plates move toward each other (e.g., subduction zones, mountain ranges).
- Transform boundaries: Plates slide past each other (e.g., San Andreas Fault).
- Sea-floor spreading: Occurs at divergent boundaries where new oceanic crust is formed.
- Subduction: Occurs at convergent boundaries where one plate is forced beneath another.
9
Q
- What are some modern/currently examples of each type of boundary?
A
- Divergent: Mid-Atlantic Ridge
- Convergent: Himalayan Mountains (India and Asia plates)
- Transform: San Andreas Fault (Pacific and North American plates)
10
Q
- What type of plate tectonic boundary does the San Andreas Fault represent? What plates are interacting along the San Andreas fault? How are the plates moving relative to each other?
A
The San Andreas Fault is a transform boundary where the Pacific Plate and North American Plate slide past each other horizontally.
11
Q
- Describe continental rifting. What are some examples of modern continental rift zones? What are some examples of continental rifting from Earth’s past?
A
Continental rifting occurs when a continent breaks apart due to extensional forces, forming a rift valley.
* Modern example: East African Rift
* Past example: The breakup of Pangaea
12
Q
- Know the age of the Earth
A
Earth is approximately 4.6 billion years old.
13
Q
- Expect to relatively date rock layers, including unconformities. This will be diagram-based, like in Exams 1 and 2.
A
Relative dating involves placing rock layers in chronological order based on their position in a sequence, using principles like superposition.
14
Q
- Know how to correctly identify the different types of unconformities.
A
- Disconformity: A gap between parallel layers of sedimentary rocks.
- Angular unconformity: A surface where tilted layers meet overlying horizontal layers.
- Nonconformity: A boundary between sedimentary rocks and older, eroded igneous or metamorphic rocks.
15
Q
- Be able to use (and discuss how you used) the following relative age dating principles:
A
- Superposition: Younger rocks are deposited on top of older rocks.
- Lateral continuity: Layers of rock extend laterally unless interrupted by a barrier.
- Original horizontality: Layers of sediment are initially deposited horizontally.
- Cross-cutting relationships: A feature that cuts through existing layers is younger than the layers it disrupts.
- Inclusions: Inclusions are older than the rock that contains them.
16
Q
- Recall how to use overlapping ages of fossils to determine the numerical age of the rock.
A
Fossils in different rock layers can be compared to determine the relative ages of the layers. Overlapping fossil ages can help establish a numerical age through correlation with known fossil records.
17
Q
- What is numerical age dating?
A
Numerical age dating (or absolute dating) involves determining the actual age of a rock or fossil in years, often using radiometric techniques like carbon dating or uranium-lead dating.
18
Q
- What does the Law of Radioactivity state?
A
The Law of Radioactivity states that the rate of decay is proportional to the number of parent present.
The decay of an atom is spontaneous.
19
Q
- What is radioactive decay?
A
Radioactive decay is the process by which unstable atomic nuclei lose energy by emitting radiation, transforming into a more stable form.
20
Q
- What is an isotope? What is a stable isotope; what is an unstable isotope?
A
- Isotope: Atoms of the same element that have the same number of protons but a different number of neutrons.
- Stable isotope: Does not undergo radioactive decay.
- Unstable isotope: Undergoes radioactive decay over time.
21
Q
- What is a half-life? How are half-lives used to numerically date rocks? Be able to apply these principles like you did in Exam 1.
A
A half-life is the time it takes for half of the parent to decay into the daughter.
By measuring the ratio of parent to daughter isotopes, you can determine the age of a rock.
22
Q
- What are the 4 Eons of the Geologic Time scale? List them in chronological order. When did each begin and end (know the numerical dates)?
A
- Hadean Eon: 4.6 billion - 4.0 billion years ago 2. Archean Eon: 4.0 billion - 2.5 billion years ago 3. Proterozoic Eon: 2.5 billion - 540 million years ago 4. Phanerozoic Eon: 540 million years ago - present
23
Q
- What are the 3 Eras of the Phanerozoic Eon? List them in chronological order. When did each begin and end (know the numerical dates)?
A
- Paleozoic Era: 540 million - 250 million years ago
- Mesozoic Era: 250 million - 66 million years ago
- Cenozoic Era: 66 million years ago - present
24
Q
- When (what Eon) did life first appear on Earth? What was the first form of life?
A
Life first appeared in the Archean Eon, around 3.2 billion years ago. The first clear evidence of life were prokaryotic cells (bacteria). Some Archean rocks contain stromatolites of cyanobacteria who lived in the early ocean and can photosynthesize.
25
25. What was the Great Oxygenation Event? When (what Eon) did it occur? How did the atmosphere become oxygenated?
The Great Oxygenation Event occurred during the Proterozoic Eon, about 2.4 billion years ago, when cyanobacteria began producing oxygen through photosynthesis, therefore increasing atmospheric oxygen levels.
26
26. What is the Cambrian Explosion?
The Cambrian Explosion occurred around 540 million years ago, with a rapid diversification of life. Hard protective shells and exoskeletons develop. Most likely due to break up of Rodinia and warmer climates and higher sea levels.
27
27. What is a trilobite?
A trilobite is an extinct marine arthropod, it had an exoskeleton and lived during the Paleozoic Era.
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28. What are the three orogenic events responsible for the generation of the Appalachian Mountains? What era did these events occur? In what order did they occur?
All orogenies occurred during the Paleozoic era.
* Taconic Orogeny during the Ordovician. Ancestral N.A. plate and oceanic plate collided.
* Acadian Orogeny during the Devonian at the southern margin of Laurentia.
* Alleghenian Orogeny during the Permian
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29. How catastrophic was the End-Permian (End-Paleozoic) extinction event in terms of the loss of life diversity? What may have caused this mass extinction?
The End-Permian Extinction was the largest mass extinction event, wiping out over 90% of marine species and 70% of land species. It may have been caused by global warming due to intensense volcanic activity, climate change, and ocean acidification.
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30. What were seafloor spreading rates like during the Mesozoic and how did these rates affect sea levels during the Mesozoic?
Seafloor spreading rates were three times higher during the Mesozoic, contributing to a rise in sea levels due to the expansion of ocean basins.
31
31. When did dinosaurs exist?
Dinosaurs existed during the Mesozoic Era, between 250 million and 66 million years ago.
32
32. What are the two main branches of dinosaurs? What skeletal feature is used to divide dinosaurs into these two branches?
The division is based on the structure of the pelvis.
* Saurischia: Lizard-hipped dinosaurs, such as theropods and sauropods.
Examples are T-Rex, Velociraptor, Brachiosaurus.
* Ornithischia: Bird-hipped dinosaurs, such as triceratops and stegosaurus.
The division is based on the structure of the pelvis.
33
33. What kind of organism was Archaeopteryx? When (what Era) did it exist? And why was its discovery so revolutionary?
Archaeopteryx was an early bird-like dinosaur that existed during the Jurassic Period. It was revolutionary because it showed evidence of the evolutionary link between dinosaurs and modern birds.
34
34. Discuss the evidence that exists to support the hypothesis that an asteroid impact occurred at the end of the Mesozoic.
* Layer of iridium-rich clay found in rocks, which is rare on Earth but common in asteroids
* “Shocked” quartz and tektites were found near the impact side at the Chicxulub crater in Mexico.
35
35. Where is the Basin and Range Province and what type of plate tectonic activity is occurring there? When did the Basin and Range tectonics begin?
The Basin and Range Province is in the western United States. It is characterized by extensional tectonics, where the crust is being stretched, forming alternating mountain ranges and valleys. This tectonic activity began around 30 million years ago.
36
36. What is the Farallon Plate? How is it related to the development of the San Andreas Fault System in North America?
The Farallon Plate was an oceanic plate that subducted beneath North America, eventually splitting into the Juan de Fuca, Pacific, and Cocos plates. The interactions between these plates contributed to the formation of the San Andreas Fault.
37
37. What is the driving force for all mass movements?
The driving force for all mass movements is gravity.
38
38. Make sure you understand how the normal and shear forces (gravity’s components) change when slopes get steeper and gentler. Draw this relationship.
As slopes become steeper, shear forces (the forces that cause sliding) increase, while normal forces (the force perpendicular to the surface) decrease.
39
39. What is water’s role in mass movements? Be able to answer this question in terms of causing mass movements (and why it can cause mass movements) and its role in promoting stability.
Water can trigger mass movements by increasing the weight of the material, reducing friction between particles, and lubricating the slope. It can also promote stability by cementing particles together.
40
40. What is undercutting? How does it lead to mass movement events?
Undercutting occurs when the base of a slope is eroded, often by water or waves, making the slope unstable and prone to sliding or collapse.
41
41. What is the angle of repose?
The angle of repose is the steepest angle at which loose material (such as sand or gravel) can remain stable without sliding.
42
42. Discuss vegetation’s role in mass movements.
Vegetation stabilizes slopes by binding soil and rock with roots, reducing the likelihood of mass movements. When vegetation is removed, slopes become more susceptible to erosion and failure.
43
43. What are the 4 factors used to classify mass wasting events?
1. Type of material (rock, debris, mud)
2. How the material is moving (fall, slide, flow, slurry)
3. Rate/speed of movement
4. Location of mass movement, above or below sea level
44
44. How can climate and tectonics influence the frequency of mass movements?
* Climate: Heavy rainfall or rapid snowmelt can increase the likelihood of mass movements.
* Tectonics: Earthquakes and volcanic activity can trigger mass movements by shaking or altering the landscape.
45
45. What are some “clues” you can look for to determine if a slope is unstable?
Clues include cracks in the ground, leaning trees or buildings, or evidence of past mass movements such as debris or scars.
46
1. What is glacial ice and how is it different from sea ice?
* Glacial ice: Glacial ice is freshwater and land based. Forms on land from compressed snow over time.
* Sea ice: Sea ice is salty and ocean based. Forms when ocean water freezes.
47
2. How is glacial ice technically a rock?
It’s a rock that is water based. Snow and ice are considered minerals. All minerals are
* solid
* inorganic
* with atoms that are organized in a crystalline structure
* that occur naturally and
* have a well-defined chemistry
48
3. What is the snowline and what influences its position?
The snowline is the lowest elevation where snow persists year-round. It varies by:
- latitude
- altitude
- temperature
- precipitation.
49
4. What are the different types of glaciers?
* Alpine (Mountain or Valley) Glaciers: flows in valleys between mountains and is constrained to the walls of the valley
* Piedmont Glacier: lobe-shaped glaciers, occupy flat areas at the base of steep mountain ranges. They spread out because they are no longer restricted to the mountain valley.
* Ice sheets (covers large portion of continent) and Caps (similiar but smaller than ice sheets)
* Outlet Glacier: valley glaciers fed by ice sheets/caps
* Ice shelves: originates and remains attached to land but flows over ocean water. In shallow waters it hits the sea floor. Very susceptible to climate change (can mmelt from top and below)
50
5. How does the weight of ice sheets affect the underlying continent?
Ice sheets depress the crust due to their weight, causing isostatic adjustment. When ice melts, the crust rebounds slowly (isostatic rebound).
51
6. Why are ice shelves particularly susceptible to climate change?
Ice shelves are glacial ice that flows over ocean waters. It originates and remains attached to the land. In shallow water, glacial ice hits the sea floor. It’s very susceptible to climate change because it can melt from top due to increasing temperatures and from below due to warmer ocean currents.
52
7. How does snow transform into glacial ice?
The weight of overlying snow exerts pressure on lower older layers.
With time, these older compacted layers undergo various states of recrystallization as they are buried progressively deeper.
1. Loose snow stage, 90% air.
2. Granular snow stage, 50% air.
3. Firn snow stage, 25% air.
4. Complete transformation of snow into interlocking crystals, less than 25% air.
53
8. What happens when a glacier experiences retreat vs. advance?
* Advance: Zone of accumulation > zone of ablation; glacier lengthens.
* Retreat: Zone of ablation > zone of accumulation; glacier shortens.
* Equilibrium line: where accumulation = ablation
* Glacial toe: lowest end of the glacier—moves forward or backward based on balance.
54
9. What are the brittle and ductile zones of a glacier?
* Brittle zone: ice breaks in response to stress. Upper 50 m/
* Ductile zone: ice flows plastically.
Boundary is based on pressure and temperature with depth. Below 50 m.
55
10. What is a crevasse? Where do they form?
A crevasse is a crack in a glacier’s surface, caused by brittle deformation. Found in the brittle zone where the ice can't deform plastically.
56
11. What is plastic (ductile) flow and basal flow?
* Plastic flow: internal deformation of ice under pressure
* Basal flow: entire glacier slides in jolts over the bed due to meltwater lubrication.
57
12. How does friction influence glacial ice flow?
* Highest friction: along valley walls and glacier base
* Lowest friction: in the glacier’s center. Friction slows ice, shaping flow patterns.
58
13. What are the three sediment loads in glacial ice?
* Surface: sediment that falls onto the surface of the glacier
* Internal: sediment imbedded within the glacier
* Bed: sediment located at the base of the glaciers. Scours continental crust.
59
14. When did the Pleistocene Ice Age occur?
It began 2.5 million years ago in the entire Pleistocene epoch. (Cenozoic – Quaternary- Pleistocene) and ended about 12,000 years ago.
60
15. How did the Isthmus of Panama trigger the Pleistocene Ice Age?
It cut off ocean circulation between Atlantic and Pacific, strengthening the Gulf Stream and increasing moisture and snow in the Arctic, leading to ice sheet growth.
61
16. How did the Pleistocene Ice Age affect sea levels, climate, and rivers in North America?
* Sea level dropped due to water locked in glaciers, exposing portions of the continental shelf.
* Colder climate shifted southward
Stream flow patterns changed—some rivers reversed or created glacial lakes.
62
17. What is the difference between weather and climate?
* Weather: day-to-day variations in temperature, air pressure, wind, humidity, precipitation.
* Climate: Result of long-term regional weather patterns. 30 years needed. Long-term (millions of years) or short-term (hundreds to 100,000 y) climate change.
63
18. What is the Earth System and what are its four components?
The Earth System is the collection of physical, chemical, and biological processes that interact across Earth's spheres. The four components are: Atmosphere, Hydrosphere, Biosphere, Geosphere.
64
19. How can a carbon atom cycle through Earth System components?
A carbon atom in the atmosphere (CO₂) can be:
* Absorbed by the biosphere during photosynthesis
* Transferred to the geosphere when plants die and become fossil fuels
* Moved into the hydrosphere as CO₂ dissolves in ocean water
* Released back to the atmosphere through respiration, decay, or combustion.
65
20. What does “residence time” mean?
It’s the average amount of time a substance (like carbon) stays in a particular component of the Earth System before moving elsewhere.
66
21. What is the greenhouse effect and what are key greenhouse gases?
The greenhouse effect is the process where certain gases trap heat in Earth’s atmosphere by absorbing and re-radiating infrared radiation.
Major greenhouse gases:
* Carbon dioxide (CO₂)
* Methane (CH₄)
* Water vapor (H₂O)
* Nitrous oxide (N₂O)
67
22. Which gases are most abundant in Earth’s atmosphere?
* Nitrogen (N₂) ~78%
* Oxygen (O₂) ~21%
* Argon (Ar) ~0.93%
* Carbon dioxide and other trace gases make up <1%.
68
23. If CO₂ is <1% of the atmosphere, why is it still a concern?
* CO₂ is a powerful greenhouse gas, meaning it strongly absorbs and re-radiates heat.
* It has a long residence time (can persist for 50–200 years), so its effects accumulate over time. Even small increases can significantly alter Earth’s energy balance and drive long-term warming.
69
24. What is an example of a climate-related feedback loop?
Positive feedback (amplifies warming): self-amplifying mechanism which occurs when change in a system result in the reinforcement of the original change.
* Melting ice → less reflection (albedo) → more heat absorption by continents → GH effects trap more heat → more ice melts.
Negative feedback (stabilizes system): self-regulating mechanism which occurs when a change in a system result in the inhabitation of the original change.
* More evaporation → more clouds → increased reflection → cooling effect.
70
25. What is uniformitarianism and how is it used in climate studies?
Uniformitarianism means that physical processes occurring today also occurred in the past at similar rates. Modern uniformitarianism states: All of the geological, biological, chemical, and physical processes that occur today, occurred in the past at roughly the same rate.
71
26. What is proxy data and why is it important for studying past climates?
Proxy data are indirect measurements that reflect past climate conditions. They’re essential because direct records only go back a few hundred years.
72
27. What are examples of climate proxy data?
* Rocks: reveal past sea levels and environments
* Glacial ice bubbles: trap ancient atmospheric gases
* Oxygen isotope ratios (δ¹⁸O): in ice cores or fossils indicate past temperatures
* Pollen: shows types of vegetation and thus climate
* Tree rings: thickness reflects yearly growth conditions (temperature, rainfall)
73
28. What’s the difference between long-term and short-term climate events?
* Long-term events: occur over millions of years (e.g., ice ages, tectonic changes)
* Short-term events: occur over years to centuries (e.g., El Niño, sunspot cycles)
74
29. What influences long-term climate change?
* Plate tectonics: shift continents and ocean currents
* Mountain building: changes atmospheric circulation
* Long-term volcanism: emits CO₂ and aerosols.
These change the Earth’s carbon cycle and surface reflectivity (albedo) over geological timescales.
75
30. What are factors that influence short-term climate events?
* Sunspots: dark, magnetic areas on the sun; more sunspots = slightly more solar output = slight warming
* Milankovitch cycles: orbital variations affecting how solar energy is distributed on Earth.
* Changes in volcanic emissions. Albedo varies with ash in atmosphere.
Important distinctions between long and short-term climate change: Both volcanic eruptions and ocean currents influence short-term and long-term climate trends.
76
31. What are the three Milankovitch cycles and their effects?
1. Eccentricity: shape of Earth’s orbit (~100,000 years)—affects distance from Sun
2. Obliquity: tilt of Earth’s axis (~41,000 years)—affects seasonal contrasts
3. Precession: wobble of Earth’s axis (~23,000 years)—affects timing of seasons.
These cycles combine to influence glacial/interglacial periods.
77
32. What are fossil fuels?
Fossil fuels are energy-rich substances formed from ancient organisms buried and altered over millions of years. They include coal, oil, and natural gas.
78
33. What is coal? What is oil/gas? How are they different and similar?
* Coal: solid carbon-rich fuel from plant material in swampy environments
* Oil/gas: liquid/gaseous hydrocarbons from marine microorganisms.
Both are fossil fuels, formed under pressure over time. Coal is from land plants; oil/gas from marine organisms.
79
34. How and where does coal form?
Coal forms in wet, low-oxygen environments like swamps, where plant material accumulates and is buried, preventing decay.
80
35. What are the types of coal, and how are they categorized?
Coal ranks (by increasing carbon content & energy):
* Peat
* Lignite
* Bituminous
* Anthracite.
Rank depends on burial depth, pressure, and temperature (i.e., metamorphism)
81
36. How and where does oil shale form?
Oil shale forms in deep, quiet-water environments (like lakes or seas) where organic-rich mud accumulates and preserves organic matter due to low oxygen.
82
37. What is kerogen and what happens in the oil and gas windows?
Kerogen is solid organic matter in rock.
* In the oil window (~60–120°C): kerogen becomes liquid oil
* In the gas window (>120°C): kerogen breaks down into natural gas.
83
38. How does fossil fuel formation relate to preservation potential?
Organic material needs to be quickly buried in low-oxygen settings to avoid decay—those are the best conditions for long-term preservation and fossil fuel formation.
84
39. What chemicals are released when fossil fuels are burned?
Combustion produces:
* CO₂ (carbon dioxide)
* H₂O (water vapor)
* Pollutants like SO₂, NOx, particulates, and CO (carbon monoxide).
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40. Which fossil fuel emits the most CO₂ per energy unit?
Coal emits more CO₂ per unit energy than oil or gas due to its higher carbon content and less efficient combustion.
86
41. What is the IPCC and what is its purpose?
IPCC = Intergovernmental Panel on Climate Change. It provides scientific assessments on climate change, its impacts, and adaptation/mitigation strategies.
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42. What’s driving modern atmospheric CO₂ increases?
Human activities—primarily the burning of fossil fuels and deforestation.
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43. Which sectors were the biggest CO₂ emitters in 2021?
* Energy production (esp. electricity & heat)
* Transportation
* Industry (e.g., cement, steel)
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44. How are CO₂ and temperature linked?
Higher CO₂ levels trap more heat, raising global temperatures. Rising temperatures can also release more CO₂ (e.g., from soils), reinforcing the effect.
90
45. What is the Keeling Curve and what does it show?
A graph showing rising atmospheric CO₂ since 1959, with seasonal variations due to plant growth cycles.
* Overall increase: from ~315 ppm to ~424 ppm in 2024
* The rate of increase is accelerating.
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46. What causes the seasonal wiggles in the Keeling Curve?
* Spring/Summer: plants absorb CO₂ (levels drop)
* Fall/Winter: plants decay (levels rise)
Trend = fossil fuel emissions. Wiggles = plant activity.
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47. What does “parts per million” mean?
424 ppm = 424 molecules of CO₂ per million molecules of air.
93
48. How do current CO₂ levels compare to the past?
* 800,000 years: never exceeded 300 ppm
* Now: ~424 ppm. During the Pleistocene, CO₂ dropped during ice ages and rose during interglacials—but much slower than now.
94
49. Which countries emit the most CO₂?
* Since 1750: USA (historically #1)
* In 2023: China (#1), USA (#2), India (#3)
95
50. How do per capita emissions compare?
* US: high per person
* China/India: lower per person. Implies rising future emissions in developing countries as they industrialize.
96
51. How are systems responding to rising CO₂?
* Atmospheric temps: increased ~1.1°C since Industrial Revolution
* Poles/High latitudes warming fastest
* Sea level: rising due to melting of glacial ice, thermal expansion of ocean waters, and contribution from continental waters.
* Ocean pH: decreasing, becoming more acidic
* Sea ice & glaciers: shrinking
* Ice shelves: melt from below due to warm water (very vulnerable)
97
52. What causes sea-level rise?
* Thermal expansion of water
* Melting land ice (glaciers & ice sheets).
Melting land ice contributes most to rise.
98
53. What is the pH scale and why is a small change in ocean pH a concern?
pH measures acidity.
* Ocean acidification is a problem for two reasons:
It decreases the pH and the hydrogen reacts with carbonate ions, making fewer carbonate ions available for ocean life.
This hurts coral reefs and shell-building organisms.
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54. What is ocean acidification and why is it harmful?
CO₂ + H₂O → carbonic acid → releases H⁺ → lowers pH. Less carbonate available for shells → weakens food webs.
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55. Why limit warming to 1.5°C?
Beyond 1.5°C, risks of heatwaves, crop loss, ecosystem collapse, sea level rise increase dramatically.
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56. Is staying below 1.5°C realistic? What about 2°C?
1.5°C is increasingly unlikely without drastic global action. We are already at 1.28°C higher. 2°C may still be possible with urgent reductions, but time is short.
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57. What is a carbon budget?
The maximum CO₂ humanity can emit to stay under a given temperature threshold (like 1.5°C).
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58. What must humanity do to limit warming?
* Drastically cut fossil fuel use
* Transition to renewables
* Enhance carbon removal (natural & technological)
* Support adaptation globally.
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59. What are renewable vs. non-renewable resources?
* Renewable: replenished naturally like solar, wind, geothermal, hydroelectric
* Non-renewable: does not replenish. Coal, oil, natural gas, uranium.
105
60. Are all renewables clean?
Not always.
* Solar and wind have low emissions, but have mining/waste impacts
* Biofuels can cause deforestation.
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61. How does nuclear energy work?
Fission: atoms split, releasing heat → generates steam → drives turbines.
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62. What prevents fission from going out of control?
Control rods absorb neutrons to regulate the reaction rate.
108
63. Pros and cons of nuclear energy?
Low CO₂, high energy output. Expensive, long build time, radioactive waste.
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64. What is carbon capture and storage (CCS)?
Technology to trap CO₂ from emissions and store it underground.
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65. What is direct air capture (DAC)? Why is it costly?
DAC pulls CO₂ from the air. Expensive because CO₂ is energy-intensive to remove and it’s mixed with other gases in the atmosphere (not concentrated). 0.042% CO₂ in atmosphere.
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66. What are afforestation and reforestation?
* Afforestation: planting trees where none grew before (from abandoned land used for agriculture)
* Reforestation: trees are replanted in locations that were deforested.
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67. What is fusion energy? Is it ready?
Replicates fusion energy from the sun = massive amounts of energy.
Does not produce Greenhouse gases.
Still in development, but there’s progress.
In 2025 a French fusion company maintained fusion stability for 22 minutes.
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68. Environmental concerns with fusion?
Mainly infrastructure: water use, land use, and material sourcing—not as severe as fission risks.
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69. If we stop emissions, will climate change stop?
No, warming will persist due to existing CO₂ and system lags (like ocean heat and ice melt). But stopping emissions limits how bad it gets.
EESC
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