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Dendroclimatology

Dendroclimatology. Proxy Data. Climate conditions can be estimated from a variety of natural environmental records going back to well before humans existed. Information of this kind is called “proxy data” because it substitutes for, or acts as a proxy for, the actual data we are seeking.

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Dendroclimatology

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  1. Dendroclimatology

  2. Proxy Data • Climate conditions can be estimated from a variety of natural environmental records going back to well before humans existed. Information of this kind is called “proxy data” because it substitutes for, or acts as a proxy for, the actual data we are seeking.

  3. Tree-ring data are just one of type of many proxies of past climate.

  4. Reconstructed Climate Variables 1) Temperature Trends in reconstructed Northern Hemisphere temperatures.

  5. 2) Precipitation Trends in reconstructed precipitation for the American Southwest.

  6. 0.6 * * * * * * * * * * * * * * 0.4 * * * * * * * * * * 0.2 Correlation Coefficient 0 -0.2 PHDI -0.4 PDSI -0.6 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep • 3) Drought Figure 3.10: Results of correlation analysis for composite chronology: PDSI and PHDI correlated against Table Mountain pine tree growth. Statistically significant relationships are indicated by * (p < 0.05), ** (p < 0.01), and *** (p < 0.001).

  7. 4) Recent research emphasizes relationships between trends in tree-ring data and long-term climate oscillations.

  8. Normal ocean temperatures

  9. The big slosh of warm ocean temps to the eastern Pacific.

  10. Pacific Decadal Oscillation • Discovered late 1990s by salmon fisheries experts • Long-lived El Niño-like pattern of Pacific climate variability • Operates on longer 20 to 30 year periods • Note when shifts occurred…

  11. Pacific Decadal Oscillation Warm phase PDO

  12. Pacific Decadal Oscillation Cool phase PDO

  13. North Atlantic Oscillation • Large scale seesaw in atmospheric mass between the subtropical high and the polar low • Dominant mode of winter climate variability in the North Atlantic region ranging from central North America to Europe • Again, note where shifts occurred…

  14. North Atlantic Oscillation • Operates on 20 to 30 year periods, also

  15. North Atlantic Oscillation • Positive Phase: • results in warm and wet winters in Europe and in cold and dry winters in northern Canada and Greenland • Eastern US experiences mild and wet winter conditions • Negative Phase: • brings moist air into the Mediterranean and cold air to northern Europe • Eastern US experiences more cold air outbreaks and hence snowy weather conditions

  16. Atlantic Multidecadal Oscillation • A multidecadal (50-70 year timescale) pattern of North Atlantic ocean-atmosphere variability • Occurs in Atlantic between the equator and Greenland • When the AMO is positive (warm Atlantic) there is less rainfall over most of the United States • During warm phases of the AMO, the numbers of tropical storms that mature into severe hurricanes is much greater than during cool phases • Since the mid-1990s we have been in a warm phase • Again, note when shifts occurred…

  17. Atlantic Multidecadal Oscillation

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