@PhDThesis{Maksic:2023:InMoSi,
author = "Maksic, Jelena",
title = "A past-present-future perspective of climate changes and
terrestrial ecosystem responses in South America: Insights from
model simulations and paleoclimate reconstructions",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2023",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2023-06-14",
keywords = "last glacial maximum, simulation, biomes, future scenario, paleo
records, ultimo m{\'a}ximo glacial, simula{\c{c}}{\~a}o,
biomas, cen{\'a}rio futuro, registros paleo.",
abstract = "The main objective of the thesis is to provide a
past-present-future perspective of climate changes and terrestrial
ecosystem responses in South America. The first part investigates
the vegetation response to a temperature increase from the Last
Glacial Maximum (LGM) to the pre-industrial era. In order to
verify the most affected biomes and explore how they might react
to future warming it was employed the Center for Weather
Forecasting and Climate Studies Potential Vegetation Model version
2 model (CPTEC PVM2). In addition, to determine the influence of
each climate parameter on biome distribution, sensitivity
experiments for both LGM and future scenario were run, considering
the anomalies of CO2, precipitation and temperature separately.
The results for the LGM indicate grassland expansion in southern
Brazilian highlands and the persistence of the Amazon rainforest
under colder and drier conditions. The western and central Amazon
forest remained due to negative temperature anomalies, while a
decrease in precipitation led to changes in the eastern portion.
The reliability of computed precipitation anomalies and simulated
potential vegetation for LGM is validated with compilation of 149
published vegetation and hydroclimate records. Results reaffirmed
paleo studies that claim that changes in monsoon intensity cannot
be used as the main driver for vegetational changes/stability
across the Amazon biome, and that lower temperatures in
combination with substantially lower CO2 are important controlling
factors during the LGM. In contrast, for the future +4°C warming
scenario, biome shifts will be driven by changes in precipitation.
Savanna/Cerrado is projected to expand, while the Amazon forest,
Tropical seasonal forest, and Caatinga may decrease. In the future
warming scenario increasing temperatures with reduction in
precipitation neutralize the potential gain in biomass from the
positive effect of CO2 fertilization. The thesis also investigates
the Atlantic Multidecadal Oscillation (AMO) as a potential main
driver of warming/cooling scenarios and changes in precipitation
in South America during the last millennium. This study evaluates
AMO influence on atmospheric dynamics, precipitation and
consequently {{\δ18O}} of precipitation in South America
using the water isotope-enabled version of the Community Earth
System Model version 1.2 (iCESM1.2) forced with cold and warm AMO
phase sea surface temperature fields. The model-derived AMO signal
for the region under the influence of the Atlantic ITCZ aligns
with proxy reconstructions, indicating changes in ITCZ during the
Little Ice Age (LIA). One implication of these findings is that a
change in the core strength of the ITCZ, caused by a persistent
cold AMO, might have contributed to dry conditions over the
northernmost part of South America and increased precipitation
along the coastal area of northeastern Brazil during the LIA.
Hydroclimatic spatiotemporal patterns during last millennium in
other regions of South America remain puzzling. The study also
warns that caution should be exercised when interpreting records
reflecting annual means, as they may actually record signals of
seasonal variability rather than ITCZ shifts. This thesis
contributes to our understanding of past and future climate
changes and terrestrial ecosystem responses in South America,
highlighting the importance of considering both simulations and
paleo records as neither available paleorecords nor state-ofthe-
art models alone are conclusive, especially under extremely
heterogeneous and complex environmental conditions. RESUMO: O
objetivo principal da tese {\'e} fornecer uma perspectiva
passado-presente-futuro das mudan{\c{c}}as clim{\'a}ticas e
respostas dos ecossistemas terrestres na Am{\'e}rica do Sul. A
primeira parte investiga a resposta da vegeta{\c{c}}{\~a}o ao
aumento da temperatura desde o {\'U}ltimo M{\'a}ximo Glacial
(UMG) at{\'e} a era pr{\'e}-industrial. Para verificar os biomas
mais afetados e explorar como eles podem reagir ao aquecimento
futuro, foi utilizado o modelo do Potencial Vegetacional do Centro
de Previs{\~a}o de Tempo e Estudos Clim{\'a}ticos (CPTEC PVM2).
Al{\'e}m disso, foram realizados experimentos de sensibilidade
para determinar a influ{\^e}ncia de cada par{\^a}metro
clim{\'a}tico na distribui{\c{c}}{\~a}o dos biomas, tanto para
o LGM quanto para cen{\'a}rios futuros. Os resultados para o LGM
indicam expans{\~a}o de campos no planalto sul brasileiro e a
persist{\^e}ncia da Floresta Amaz{\^o}nica sob
condi{\c{c}}{\~o}es mais frias e secas. A Floresta
Amaz{\^o}nica ocidental e central permaneceram devido a anomalias
negativas de temperatura, enquanto uma redu{\c{c}}{\~a}o na
precipita{\c{c}}{\~a}o causou altera{\c{c}}{\~o}es na
por{\c{c}}{\~a}o leste. Os resultados reafirmaram os estudos
paleo que afirmam que as mudan{\c{c}}as na intensidade das
mon{\c{c}}{\~o}es n{\~a}o podem ser usadas como o principal
fator para mudan{\c{c}}as/estabilidade da vegeta{\c{c}}{\~a}o
em todo o bioma Amaz{\^o}nia, e que temperaturas mais baixas em
combina{\c{c}}{\~a}o com CO2 substancialmente mais baixo
s{\~a}o fatores de controle importantes durante o LGM. A
confiabilidade das anomalias de precipita{\c{c}}{\~a}o
calculadas e da vegeta{\c{c}}{\~a}o potencial simulada para o
LGM {\'e} validada com a compila{\c{c}}{\~a}o de 149 registros
de vegeta{\c{c}}{\~a}o e hidroclima. Por outro lado, para o
cen{\'a}rio futuro de aquecimento de +4°C, as mudan{\c{c}}as nos
biomas ser{\~a}o impulsionadas por altera{\c{c}}{\~o}es na
precipita{\c{c}}{\~a}o. A savana/Cerrado {\'e} projetada para
expandir, enquanto a Floresta Amaz{\^o}nica, Floresta Tropical
sazonal e Caatinga podem diminuir. No cen{\'a}rio de aquecimento
futuro, o aumento das temperaturas com a redu{\c{c}}{\~a}o da
precipita{\c{c}}{\~a}o neutraliza o ganho potencial de biomassa
pelo efeito positivo da fertiliza{\c{c}}{\~a}o de CO2. A tese
tamb{\'e}m investiga a Oscila{\c{c}}{\~a}o Multidecenal do
Atl{\^a}ntico (AMO) como um poss{\'{\i}}vel motor principal de
cen{\'a}rios de aquecimento/resfriamento e mudan{\c{c}}as na
precipita{\c{c}}{\~a}o na Am{\'e}rica do Sul durante o
{\'U}ltimo mil{\^e}nio. Este estudo avalia a influ{\^e}ncia da
AMO usando a vers{\~a}o habilitada para is{\'o}topos do Modelo
de Sistema Terrestre da Comunidade, vers{\~a}o 1.2 (iCESM1.2). O
sinal de AMO derivado do modelo para a regi{\~a}o sob a
influ{\^e}ncia da Zona de Converg{\^e}ncia Intertropical do
Atl{\^a}ntico (ITCZ) coincide com reconstru{\c{c}}{\~o}es de
proxy, indicando mudan{\c{c}}as na ITCZ durante a Pequena Idade
do Gelo (PIG). Uma implica{\c{c}}{\~a}o dessas descobertas
{\'e} que uma mudan{\c{c}}a na for{\c{c}}a central da ITCZ,
causada por uma AMO fria persistente, pode ter
contribu{\'{\i}}do para condi{\c{c}}{\~o}es secas na parte
mais ao norte da Am{\'e}rica do Sul e aumento da
precipita{\c{c}}{\~a}o ao longo da {\'a}rea costeira do
nordeste do Brasil durante a LIA. Os padr{\~o}es
esp{\'a}cio-temporais hidroclim{\'a}ticos durante o {\'u}ltimo
mil{\^e}nio em outras regi{\~o}es da Am{\'e}rica do Sul ainda
s{\~a}o enigm{\'a}ticos. Esta tese contribui para nossa
compreens{\~a}o das mudan{\c{c}}as clim{\'a}ticas passadas e
futuras e respostas dos ecossistemas terrestres na Am{\'e}rica do
Sul, destacando a import{\^a}ncia de considerar tanto
simula{\c{c}}{\~o}es quanto registros paleo, j{\'a} que nem os
paleoregistros dispon{\'{\i}}veis nem os modelos por si s{\'o}
s{\~a}o conclusivos. Insights em escalas e estados
clim{\'a}ticos devem contribuir para uma compreens{\~a}o mais
profunda das proje{\c{c}}{\~o}es clim{\'a}ticas futuras.",
committee = "Alves, Lincoln Muniz (presidente) and Oliveira, Gilvan Sampaio de
(orientador) and Cruz, Francisco William da (orientador) and
Shimizu, Mar{\'{\i}}lia Harumi and Str{\'{\i}}kis,
Nicol{\'a}s Misailidis",
englishtitle = "Uma perspectiva passado-presente-futuro das mudan{\c{c}}as
clim{\'a}ticas e respostas do ecossistema terrestre na
Am{\'e}rica do Sul: conhecimentos de simula{\c{c}}{\~o}es de
modelos e reconstru{\c{c}}{\~o}es paleoclim{\'a}ticas",
language = "en",
pages = "134",
ibi = "8JMKD3MGP3W34T/49ATFRE",
url = "http://urlib.net/ibi/8JMKD3MGP3W34T/49ATFRE",
targetfile = "publicacao.pdf",
urlaccessdate = "09 maio 2024"
}