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Building Temperature Reconstructions

Learn how scientists combine multiple proxies to create reliable climate reconstructions

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The Reconstruction Process

Temperature reconstruction is detective work. Scientists must take indirect measurements (proxies) and work backwards to infer past temperatures. This requires calibrating each proxy against modern instrumental records, understanding sources of uncertainty, and combining multiple independent lines of evidence.

The famous "hockey stick" graph combines tree rings, ice cores, coral records, and historical documents to show temperatures over the past 2,000 years—revealing that recent warming is unprecedented in magnitude and speed.

🎛️Build Your Reconstruction

Select which proxy types to include in your temperature reconstruction. More proxies increase confidence but may not always improve quality if they have high uncertainty:

Reconstruction Quality

100%

⚠️ Single proxy is risky—add more for cross-validation

📉Understanding Uncertainty

High ConfidenceLow Confidence

Sources of Uncertainty

  • •Dating errors: Older samples harder to date precisely
  • •Calibration: Converting proxy signal to temperature
  • •Spatial coverage: Proxies don't cover all regions
  • •Non-climate factors: Proxies respond to multiple variables

Reducing Uncertainty

  • •Multiple proxies: Cross-validate independent measurements
  • •Better calibration: More instrumental overlap period
  • •Statistical methods: Advanced techniques account for biases
  • •Ensemble approach: Combine multiple reconstruction methods

💡 Key Insight: Even with uncertainty, the signal is clear—recent warming is rapid and large compared to natural variability over the past 2,000 years. Uncertainty ranges don't change the fundamental conclusion.

Landmark Temperature Reconstructions

Mann et al. (1999) - "Hockey Stick"

Period: Last 1,000 years
Methods:
Tree rings, ice cores, coral, historical records
Key Finding:

Late 20th century warmest in millennium; rapid recent warming

PAGES 2k Consortium (2019)

Period: Last 2,000 years
Methods:
692 proxy records from all continents
Key Finding:

Current warming unprecedented in spatial extent and coherence

Shakun et al. (2012)

Period: Last 22,000 years
Methods:
Global proxy network through last ice age
Key Finding:

CO₂ drove majority of deglacial warming; current rate 10x faster

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