@InProceedings{LapolaSSGACDRVR:2021:BeEfEC,
               author = "Lapola, David and Sampaio, Gilvan and Shimizu, Mar{\'{\i}}lia 
                         Harumi and Guimar{\~a}es J{\'u}nior, Carlos Augusto and 
                         Alexandre, Felipe and Cardoso, Manoel Ferreira and Domingues, 
                         Tomas and Rammig, Anja and Von Randow, Celso and Rezende, Luiz 
                         Felipe Campos de",
          affiliation = "{Universidade Estadual de Campinas (UNICAMP)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {} and {} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)}",
                title = "Beta effect of eCO2 can cause as much rainfall decrease as 
                         large-scale deforestation in the Amazon",
                 year = "2021",
         organization = "EGU General Assembly",
            publisher = "EGU",
             abstract = "Amazon regions climate is particularly sensitive to surface 
                         processes and properties such as heat fluxes and vegetation 
                         coverage. Rainfall is a key expression of such 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 CO2 concentration (eCO2) on plant physiology (i.e. the 
                         \β effect), for example on canopy transpiration and 
                         rainfall, are scarcer. Here we make a systematic comparison of the 
                         plant physiological effects of eCO2 and deforestation on Amazon 
                         rainfall. We use the CPTEC-Brazilian Atmospheric Model (BAM) with 
                         dynamic vegetation under a 1.5xCO2 and a 100% substitution of the 
                         forest by pasture grassland, with all other conditions held 
                         similar between the two scenarios. We find that both scenarios 
                         result in equivalent average annual rainfall reductions 
                         (Physiology: -252 mm,-12%; Deforestation: -292 mm, -13%) that are 
                         well above observed Amazon rainfall interannual variability of 
                         5.1%. Rainfall decrease in the two scenarios are caused by a 
                         reduction of approximately 20% of canopy transpiration, but for 
                         different reasons: eCO2-driven reduction of stomatal conductance 
                         in the Physiology run; decreased leaf area index of pasture (-66%) 
                         and its dry-season lower surface vegetation coverage in the 
                         Deforestation run. Walker circulation is strengthened in the two 
                         scenarios (with enhanced convection over the Andes and a weak 
                         subsidence branch over east Amazon) but, again, through different 
                         mechanisms: enhanced west winds from the Pacific and reduced 
                         easterlies entering the basin in Physiology, and strongly 
                         increased easterlies in Deforestation. Although our results for 
                         the Deforestation scenario are in agreement with previous 
                         observational and modelling studies, the lack of direct 
                         field-based ecosystem-level experimental evidence on the effect of 
                         eCO2 in moisture fluxes of tropical forests confers a substantial 
                         level of uncertainty to this and any other projections on the 
                         physiological effect of eCO2 on Amazon rainfall. Furthermore, our 
                         results denote the incurred 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 (to be tackled by Amazonian countries) or global CO2 
                         emissions (to be handled by all countries).",
  conference-location = "Online",
      conference-year = "19-30 apr.",
                  doi = "10.5194/egusphere-egu21-8739",
                  url = "http://dx.doi.org/10.5194/egusphere-egu21-8739",
             language = "en",
           targetfile = "EGU21-8739-print.pdf",
        urlaccessdate = "20 maio 2024"
}