Evidence for climate change
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Flip to reveal answersWhat is the difference between direct evidence and proxy evidence for climate change?
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Question
What is the difference between direct evidence and proxy evidence for climate change?
Answer
Direct evidence comes from modern instrument measurements (e.g., thermometers, satellites). Proxy evidence comes from indirect natural records (e.g., ice cores, tree rings) that reconstruct past climate.
💡 Hint
Direct = instruments; Proxy = natural records.
Question
List two examples of proxy data used to reconstruct past climate.
Answer
Examples include ice cores, tree rings, coral bands, pollen in sediments, and ocean/lake sediments.
💡 Hint
Proxy = natural archive.
Question
State one long-term trend shown by global temperature data.
Answer
Global average temperature has increased over the long term, with the warmest years concentrated in the most recent decade.
💡 Hint
Use “overall increase” wording.
Question
What does it mean when sea level rise is “accelerating”?
Answer
It means the rate of sea level rise is increasing over time (the slope becomes steeper), not just that sea level is rising.
💡 Hint
Acceleration = rate increases.
Question
Define proxy data in climate science.
Answer
Proxy data is indirect evidence of past climate preserved in natural archives such as ice cores, tree rings, corals, and sediments.
💡 Hint
Think “climate clues” stored in nature.
Question
Why is using multiple lines of evidence stronger than relying on a single dataset?
Answer
Multiple independent datasets reduce uncertainty and make the conclusion more robust (e.g., temperature records, CO2, sea level, ice extent all point to warming).
💡 Hint
Independent sources = stronger claim.
Question
Name two indicators of climate change commonly shown in exam graphs.
Answer
Examples include atmospheric CO2 concentration, global mean temperature, sea level, Arctic sea ice extent, and glacier mass/length.
💡 Hint
Pick any two indicators.
Question
Give two examples of direct evidence for climate change.
Answer
Examples include: (1) long-term temperature records from weather stations, (2) measured atmospheric CO2 concentrations (e.g., observatory records), (3) sea-level measurements from tide gauges/satellites, (4) satellite observations of ice extent.
💡 Hint
Pick any two measured variables.
Question
In exams, what is the key difference between “describe” and “explain” when using climate data?
Answer
Describe = state what the data shows using numbers and trends. Explain = give reasons/mechanisms for the pattern shown.
💡 Hint
Describe = what; Explain = why.
Question
Why are direct measurements generally considered more reliable than proxy data?
Answer
Direct measurements are taken with calibrated instruments and have higher precision and less interpretation. Proxy data extends further back in time but requires inference (e.g., linking ring width to climate).
💡 Hint
Precision vs time depth.
Question
What does proxy data typically allow scientists to do that direct measurements cannot?
Answer
Proxy data extends climate records back beyond the instrumental period (before modern measurements), allowing reconstruction over thousands to hundreds of thousands of years.
💡 Hint
Direct ~150 years; proxy much longer.
Question
When describing a climate graph, what 3 things should you include for full marks?
Answer
Include: (1) overall trend (increase/decrease), (2) specific data values with units and time period, (3) any change in rate or notable anomalies.
💡 Hint
Trend + numbers + rate/anomalies.
Question
What is meant by a correlation between CO2 and temperature in long-term datasets?
Answer
A correlation means CO2 and temperature tend to change together over time (both rise/fall in related patterns). It does not, by itself, prove causation.
💡 Hint
Correlation ≠ causation.
Question
How do ice cores provide evidence for past climate and atmospheric composition?
Answer
Ice cores trap ancient air bubbles and preserve isotopic signals. Air bubbles show past greenhouse gas concentrations, and isotopes help infer past temperatures, allowing comparison of CO2 and temperature over long time periods.
💡 Hint
Air bubbles + isotopes.
Question
Give one reason proxy data can be less precise than direct measurements.
Answer
Proxy data requires interpretation (calibration) because the climate signal is inferred from biological/chemical indicators, which can be influenced by multiple factors.
💡 Hint
Inference adds uncertainty.
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Climate change—causes and impacts
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