Pr Pre-Columbian Columbian def defor oresta estation as an tion - - PowerPoint PPT Presentation

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Pr Pre-Columbian Columbian def defor oresta estation as an tion - - PowerPoint PPT Presentation

Apr 16, 2023 138 likes •248 views

Pr Pre-Columbian Columbian def defor oresta estation as an tion as an amplifier amplifier of of dr drought in Cent ought in Central al America America Benjamin I Cook Jed O Kaplan, Kevin J Anchukaitis, Michael Puma, Maxwell Kelly Pr

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SLIDE 1

Pr Pre-Columbian Columbian def defor

  • resta

estation as an tion as an amplifier amplifier of

  • f dr

drought in Cent

  • ught in Central

al America America

Benjamin I Cook Jed O Kaplan, Kevin J Anchukaitis, Michael Puma, Maxwell Kelly

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SLIDE 2

Pr Pre-Columbian Columbian Centr Central al America America

  • Home to over 19 million

people

  • Sedentary agricultural

societies

  • Major population crash

after European conquest

  • Landscape probably

looked less like this 

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SLIDE 3

And more like this. . .

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SLIDE 4

Pre-Columbian Droughts

  • Impacted Maya, Toltec,

Aztec…

  • Causes?
  • Solar forcing, random

variability

  • Could deforestation

have contributed?

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SLIDE 5

Land Cover Reconstruction

  • Based on population
  • Varying per capita land

use; arable land restriction

  • More extensive/intensive

land use than previous reconstructions

  • New input for climate

models

a) 800-950 C.E. (approx.) b) 1500-1650 C.E. (approx.) c) 2000 C.E.

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SLIDE 6

Experiments

  • NATVEG: Natural vegetation only; no

crops or anthropogenic land cover

  • DEFOREST: pre-Columbian land cover
  • REGROWTH: post-Columbian land

cover

  • Compared against paleorecords from

the Yucatán

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SLIDE 7

a) Precipitation b) Surface Temperature

a) 800-950 C.E. (approx.) b) 1500-1650 C.E. (approx.) c) 2000 C.E.

NATVEG minus DEFOREST

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SLIDE 8

a) 800-950 C.E. (approx.) b) 1500-1650 C.E. (approx.) c) 2000 C.E.

NATVEG minus DEFOREST

a) Net Radiation, TOA b) Convection

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SLIDE 9

Yuca ucatán: tán: 800 800-950 C 950 C.E. .E. vs vs 1500 1500-1650 C 1650 C.E. .E.

  • Paleo-records indicate regional

water balance changes precipitation minus evaporation

  • Lake records, cave records
  • Drier Classic/Post-Classic era

relative to the Colonial regrowth period

  • Hard to convert most to

quantitative estimates

  • Tzanab Speleothem
  • 14% decline in P-E
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SLIDE 10

Conclusions

  • Warmer/Drier average conditions with pre-Columbian

deforestation (higher albedo, less energy available for convection and precipitation)

  • DEFOREST minus REGROWTH:
  • 18% decline in JJA P-E (-6%, annual), comparable to

Tzanab (-14%)

  • Future deforestation in the Yucatán?

Modern Pre-Columbus