@Article{SampaioSGAGCDRVRL:2021:COPhEf,
               author = "Sampaio, Gilvan and Shimizu, Mar{\'{\i}}lia Harumi and 
                         Guimar{\~a}es J{\'u}nior, Carlos Augusto and Alexandre, Felipe 
                         Ferreira and Guatura, Marcelo Barbosa da Silva and Cardoso, Manoel 
                         Ferreira and Domingues, Tomas F. and Ramming, Anja and Von Randow, 
                         Celso and Rezende, Luiz Felipe Campos de and Lapola, David M.",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {Instituto Nacional de Pesquisas Espaciais 
                         (INPE)} and {Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Universidade de S{\~a}o Paulo (USP)} and {Technical University 
                         of Munich} and {Instituto Nacional de Pesquisas Espaciais (INPE)} 
                         and {Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Universidade Estadual de Campinas (UNICAMP)}",
                title = "CO2 physiological effect can cause rainfall decrease as strong as 
                         large-scale deforestation in the Amazon",
              journal = "Biogeosciences",
                 year = "2021",
               volume = "18",
               number = "8",
                pages = "2511--2525",
                month = "Apr.",
             abstract = "The climate in the Amazon region is particularly sensitive to 
                         surface processes and properties such as heat fluxes and 
                         vegetation coverage. Rainfall is a key expression of the land 
                         surface atmosphere interactions in the region due to its strong 
                         dependence on forest transpiration. While a large number of past 
                         studies have shown the impacts of large-scale deforestation on 
                         annual rainfall, studies on the isolated effects of elevated 
                         atmospheric CO2concentrations (eCO2) on canopy transpiration and 
                         rainfall are scarcer. Here, for the first time, we systematically 
                         compare the plant physiological effects of eCO2and deforestation 
                         on Amazon rainfall. We use the CPTEC Brazilian Atmospheric Model 
                         (BAM) with dynamic vegetation under a 1.5CO2experiment and a 100% 
                         substitution of the forest by pasture grasslands, with all other 
                         conditions held similar between the two scenarios. We find that 
                         both scenarios result in equivalent average annual rainfall 
                         reductions (Physiology: 257 mm, 12 %; Deforestation: 183 mm, 9 %) 
                         that are above the observed Amazon rainfall interannual 
                         variability of 5 %. The rainfall decreases predicted in the two 
                         scenarios are linked to a reduction of approximately 20% in canopy 
                         transpiration but for different reasons: The eCO2-driven reduction 
                         of stomatal conductance drives the change in the Physiology 
                         experiment, and the smaller leaf area index of pasturelands (72% 
                         compared to tropical forest) causes the result in the 
                         Deforestation experiment. The Walker circulation is modified in 
                         the two scenarios: in Physiology due to a humidity-enriched free 
                         troposphere with decreased deep convection due to the heightening 
                         of a drier and warmer (C2.1 C) boundary layer, and in 
                         Deforestation due to enhanced convection over the Andes and a 
                         subsidence branch over the eastern Amazon without considerable 
                         changes in temperature (0.2 C in 2m air temperature and C0.4 C in 
                         surface temperature). But again, these changes occur through 
                         different mechanisms: strengthened west winds from the Pacific and 
                         reduced easterlies entering the basin affect the Physiology 
                         experiment, and strongly increased easterlies influence the result 
                         of the Deforestation experiment. Although our results for the 
                         Deforestation scenario agree with the results of previous 
                         observational and modelling studies, the lack of direct 
                         field-based ecosystem-level experimental evidence regarding the 
                         effect of eCO2on moisture fluxes in tropical forests confers a 
                         considerable level of uncertainty to any projections of the 
                         physiological effect of eCO2on Amazon rainfall. Furthermore, our 
                         results highlight the responsibilities of both Amazonian and 
                         non-Amazonian countries to mitigate potential future climatic 
                         change and its impacts in the region, driven either by local 
                         deforestation or global CO2emissions.",
                  doi = "10.5194/bg-18-2511-2021",
                  url = "http://dx.doi.org/10.5194/bg-18-2511-2021",
                 issn = "1726-4170",
             language = "en",
           targetfile = "sampaio_co2.pdf",
        urlaccessdate = "20 maio 2024"
}