27The impacts of climate and land use changes on streamflow and sediment export were evaluated 28 for a humid (São Lourenço) and a dry (Guadalupe) Mediterranean catchment, using the SWAT 29 model. SWAT was able to produce viable streamflow and sediment export simulations for both 30 catchments, which provided a baseline for investigating climate and land use changes under the 31 A1B and B1 emission scenarios for 2071-2100. Compared to the baseline scenario , 32climate change scenarios showed a decrease in annual rainfall for both catchments (humid: -12%; 33 dry: -8%), together with strong increases in rainfall during winter. Land use changes were derived 34 from a socio-economic storyline in which traditional agriculture is replaced by more profitable land 35 uses (i.e. corn and commercial forestry at the humid site; sunflower at the dry site). Climate change 36 projections showed a decrease in streamflow for both catchments, whereas sediments export 37 decreased only for the São Lourenço catchment. Land use changes resulted in an increase in 38 streamflow, but the erosive response differed between catchments. The combination of climate 39 and land use change scenarios led to a reduction in streamflow for both catchments, suggesting a 40 domain of the climatic response. As for sediments, contrasting results were observed for the humid 41 (A1B: -29%; B1: -22%) and dry catchment (A1B: +222%; B1: +5%), which is mainly due to differences 42 in the present-day and forecasted vegetation types. The results highlight the importance of climate-43 induced land-use change impacts, which could be similar to or more severe than the direct impacts 44 of climate change alone. 45 46 47

Abstract. The performance of the coupled ocean–atmosphere component of the Brazilian Earth System Model version 2.5 (BESM-OA2.5) was evaluated in simulating the historical period 1850–2005. After a climate model validation procedure in which the main atmospheric and oceanic variabilities were evaluated against observed and reanalysis datasets, the evaluation specifically focused on the mean climate state and the most important large-scale climate variability patterns simulated in the historical run, which was forced by the observed greenhouse gas concentration. The most significant upgrades in the model's components are also briefly presented here. BESM-OA2.5 could reproduce the most important large-scale variabilities, particularly over the Atlantic Ocean (e.g., the North Atlantic Oscillation, the Atlantic Meridional Mode, and the Atlantic Meridional Overturning Circulation), and the extratropical modes that occur in both hemispheres. The model's ability to simulate such large-scale variabilities supports its usefulness for seasonal climate prediction and in climate change studies.

Abstract. The main features of climate change patterns, as simulated by the coupled ocean–atmosphere version 2.5 of the Brazilian Earth System Model (BESM), are compared with those of 25 other CMIP5 models, focusing on temperature, precipitation, atmospheric circulation, and radiative feedbacks. The climate sensitivity to quadrupling the atmospheric CO2 concentration was investigated via two methods: linear regression (Gregory et al., 2004) and radiative kernels (Soden and Held, 2006; Soden et al., 2008). Radiative kernels from both the National Center for Atmospheric Research (NCAR) and the Geophysical Fluid Dynamics Laboratory (GFDL) were used to decompose the climate feedback responses of the CMIP5 models and BESM into different processes. By applying the linear regression method for equilibrium climate sensitivity (ECS) estimation, we obtained a BESM value close to the ensemble mean value. This study reveals that the BESM simulations yield zonally average feedbacks, as estimated from radiative kernels, that lie within the ensemble standard deviation. Exceptions were found in the high latitudes of the Northern Hemisphere and over the ocean near Antarctica, where BESM showed values for lapse rate, humidity feedback, and albedo that were marginally outside the standard deviation of the values from the CMIP5 multi-model ensemble. For those areas, BESM also featured a strong positive cloud feedback that appeared as an outlier compared with all analyzed models. However, BESM showed physically consistent changes in the temperature, precipitation, and atmospheric circulation patterns relative to the CMIP5 ensemble mean.

Abstract. The performance of the coupled ocean-atmosphere component of the Brazilian Earth System Model version 2.5 (BESM-OA2.5) simulating the historical period 1850–2005 is evaluated. Following climate model validation procedure, in which the atmospheric and oceanic main variabilities are validated against observation and Reanalysis datasets, the evaluation particularly focuses the mean climate state and the most important large-scale climate variability patterns simulated in the historical run, which is forced by observed greenhouse gas concentration. The most significant upgrades in the model’s components are also presented briefly. BESM-OA2.5 is able to reproduce the most important large-scale variabilities, particularly over the Atlantic (e.g. the North Atlantic Oscillation, the Atlantic Meridional Mode and the Atlantic Meridional Overturning Circulation) and the extratropical modes that occur in both hemispheres. The model's ability in simulating large-scale variabilities indicates its usefulness for seasonal climate prediction and climate change studies.

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