How can a temperature graph begin before thermometers?
A temperature graph can extend beyond thermometer records because other records preserve clues about past conditions. Those clues need calibration against measured climate before they become a temperature reconstruction. Combining them is more than averaging tree rings, ice, or other raw measurements: the reconstruction must account for what each record represents and how uncertain the estimate is.
Questions you could explore
- How could an overlap with thermometer records help test a proxy?
Start reading
- NOAA NCEI / Wahl and colleaguesNOAA Paleoclimatology Reconstructions Network
The archive’s dataset abstract introduces calibrated proxy reconstructions and their greater uncertainty, with links onward to the underlying studies.
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