Atmosphere & Greenhouse Gases
100: Name the gas that is the primary driver of recent global warming due to human activities.
100: Carbon dioxide (CO2).
100: List one observable change that scientists cite as evidence that the climate is warming.
100: Examples: rising global average temperatures, melting glaciers, earlier spring snowmelt, sea level rise.
100: Give one example of a human activity that increases atmospheric CO2.
100: Burning coal, oil, gas for energy; deforestation.
100: Define weather in one sentence.
100: Weather = short-term conditions of the atmosphere (temperature, precipitation, wind) at a specific place/time.
100: Identify the process by which plants remove CO2 from the atmosphere.
100: Photosynthesis.
200: Explain how the greenhouse effect warms Earth's surface.
200: Greenhouse gases trap outgoing infrared radiation; incoming shortwave solar radiation passes through, warms the surface, surface emits infrared, which greenhouse gases absorb and re‑emit, warming surface and lower atmosphere.
200: Explain how tree rings or ice cores can provide evidence of past climate conditions.
200: Tree rings: width varies with growth conditions (temperature/precipitation); ice cores: trapped air bubbles record past atmospheric composition and isotopic ratios indicate past temperature.
200: Name one individual-level action and one policy-level action that can reduce greenhouse gas emissions.
200: Individual: reduce car use, conserve energy, use public transit; Policy: carbon pricing, renewable energy mandates.
200: Define climate in one sentence.
200: Climate = long-term average of weather patterns (typically 30-year averages) for a region.
200: Explain how burning fossil fuels affects the carbon cycle.
200: Burning fossil fuels transfers carbon from long-term geological reservoirs into the atmosphere, increasing atmospheric CO2 and perturbing the carbon cycle.
300: Identify two greenhouse gases other than carbon dioxide and state one major human source for each.
300: Examples: Methane (CH4) — sources: agriculture (livestock), fossil fuel extraction; Nitrous oxide (N2O) — sources: fertilizer use, industrial processes.
300: Describe how sea level measurements and coastal observations together support the conclusion that sea level is rising.
300: Tide gauges and satellite altimetry show rising mean sea level; thermal expansion of warming water and melting glaciers/ice sheets add water.
300: Explain how planting trees can help reduce atmospheric CO2 and one limitation of relying only on planting trees.
300: Trees absorb CO2 via photosynthesis and store carbon in biomass; limitation: land and time required, permanence (fires), saturation of sinks.
300: Explain why a single cold winter does not disprove global warming.
300: Weather is short-term variability; climate is long-term trend—one cold event is within natural variability and does not negate a long-term warming trend.
300: Describe how ocean uptake of CO2 changes ocean chemistry and one consequence for marine life.
300: CO2 dissolves forming carbonic acid, lowering pH (ocean acidification), which can reduce calcification in shell-forming organisms like corals and some plankton.
400: Describe how increased atmospheric greenhouse gas concentrations affect the balance of incoming and outgoing energy for Earth.
400: More greenhouse gases increase net incoming energy (less outgoing thermal IR), causing energy imbalance and warming until a new equilibrium is reached.
400: Interpret why an increase in average global temperature can lead to both stronger storms and longer droughts in different regions.
400: Warmer atmosphere holds more moisture (can intensify storms) while shifting circulation patterns can reduce precipitation in some regions, increasing drought frequency/duration.
400: Describe a technological solution for reducing emissions from electricity generation and one potential trade-off or challenge for implementing it at scale.
400: Example: wind or solar power — challenge: intermittency, storage needs, grid upgrades, resource/materials for deployment.
400: Describe how climate models differ from weather forecasts in purpose and timescale.
400: Weather forecasts predict specific conditions days ahead using high-resolution initial conditions; climate models simulate statistical properties over decades including forcings and feedbacks.
400: Explain the concept of carbon sinks and provide two examples.
400: Carbon sinks: forests (biomass), oceans (dissolved inorganic carbon), soils, peatlands.
500: Using what you know about radiative forcing, explain why methane can be a more potent greenhouse gas than carbon dioxide over short time scales even though CO2 remains longer in the atmosphere.
500: Methane has higher global warming potential (GWP) over 20 years because it absorbs more infrared per molecule and has strong near-term forcing; CO2 persists much longer, so cumulative effect differs.
500: Explain how scientists use multiple lines of evidence (e.g., instrumental records, proxy data, models) to attribute recent warming to human activities.
500: Scientists compare observed changes to models with and without human forcings; consistency across proxies, instrumental records, and physical understanding supports attribution to humans.
500: Evaluate the difference between mitigation and adaptation, and give one example of each in the context of coastal communities.
500: Mitigation = actions to reduce causes (e.g., cut emissions); Adaptation = adjust to impacts (e.g., build sea walls). Coastal mitigation example: reduce local emissions; adaptation example: elevate homes or implement managed retreat.
500: Given an area that experienced more frequent heavy rainfall and also longer dry periods over several decades, explain how both trends can be consistent with changes in climate.
500: Increased atmospheric energy can intensify the hydrologic cycle: more intense precipitation events in some places, but shifts in circulation can create longer dry spells elsewhere.
500: Using energy budget ideas, explain how changes in Earth's energy balance lead to long-term temperature change and show how increasing greenhouse gases alter that balance.
500: Earth's energy balance: incoming solar shortwave ≈ outgoing longwave IR; increased greenhouse gases reduce outgoing IR to space at given temperatures, so net energy gain warms the planet until outgoing equals incoming again at higher temperatures.