Climate reconstruction from pollen and δ 13C records using inverse vegetation modeling – Implication for past and future climates
Hatté , Christine
Rousseau , Denis-Didier
Guiot , Joel
- Publisher: European Geosciences Union (EGU)
paleoclimates | pollen | [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment | inverse modeling | vegetation | carbon isotopes | [ SDE.MCG ] Environmental Sciences/Global Changes
An improved inverse vegetation model has been designed to better specify
both temperature and precipitation estimates from vegetation descriptions.
It is based on the BIOME4 vegetation model and uses both vegetation δ<sup>13</sup>C and biome as constraints. Previous inverse models based on only
one of the two proxies were already improvements over standard
reconstruction methods such as the modern analog since these did not take
into account some external forcings, for example CO<sub>2</sub> concentration.
This new approach makes it possible to describe a potential "isotopic
defined by analogy with the "climatic niche" theory. Boreal and temperate
biomes simulated by BIOME4 are considered in this study. We demonstrate the
impact of CO<sub>2</sub> concentration on biome existence domains by replacing a
"most likely biome" with another with increased CO<sub>2</sub> concentration.
Additionally, the climate imprint on δ<sup>13</sup>C between and within
biomes is shown: the colder the biome, the lighter its potential isotopic
niche; and the higher the precipitation, the lighter the δ<sup>13</sup>C.
For paleoclimate purposes, previous inverse models based on either biome or
δ<sup>13</sup>C did not allow informative paleoclimatic reconstructions of
both precipitation and temperature. Application of the new approach to the
Eemian of La Grande Pile palynological and geochemical records reduces the
range in precipitation values by more than 50% reduces the range in
temperatures by about 15% compared to previous inverse modeling
approaches. This shows evidence of climate instabilities during Eemian
period that can be correlated with independent continental and marine