Nitrous oxide emissions from tropical soils

Nitrous oxide (\rm N\sb2O), the third most important greenhouse trace gas in the troposphere and one contributor to ozone destruction in the stratosphere, has its concentration in the atmosphere increasing steadily over the last few decades. This study measured sources from tropical soils, potentially the highest and least studied \rm N\sb2O production areas in the world. For two tropical volcanic soils in Costa Rica the effect of water, nitrate and glucose additions on episodic emissions of nitrous oxide were studied. Magnitudes of episodic \rm N\sb2O pulses, as well as overall \rm N\sb2O emissions, varied considerably and consistently, depending on soil texture, soil moisture, and kind and availability of substrates. Emission pulses began within 30 minutes, peaking no later than 8 hours after wetting. Production in the soil occurred mainly in the layer between 5 and 20 cm deep, but depended directly on the temporal dynamics of the water profile. Soil inorganic nitrogen was associated with soil \rm N\sb2O concentration changes. Depending on the treatment, one episodic \rm N\sb2O production event driven by one moderate rain could account for less than 15% to more than 90% of the total weekly production. Previous survey studies may have underestimated the contribution of gas emissions from tropical soils to the global budget of \rm N\sb2O, and better budgets will demand a detailed knowledge of both background emissions, and episodic emissions driven by rain events. The seasonally burned cerrados of Brazil are the largest savanna-type ecosystem of South America and their contribution to the global atmospheric \rm N\sb2O budget is unknown. Results showed that \rm N\sb2O consumption/emission for four fire-scarred savanna ecosystems, for nitrogen and carbon fertilization and for agriculture/pasture ranged from $-$0.3 to +0.7, 1.8 to 9.1, and 0.5 to 3.7 g \rm N\sb2O-\rm N\cdot ha\sp{-1}\cdot d\sp{-1}, respectively. During the wet season the cerrado biome does not appear to be a major source of \rm N\sb2O to the troposphere, even following fire events. However, conversion of the cerrado to high input agriculture, with liming and fertilization, can increase \rm N\sb2O emissions more than ten fold

Comments on "Is condensation-induced atmospheric dynamics a new theory of the origin of the winds?" by Jaramillo et al. (2018)

Our comments on paper "Is Condensation-Induced Atmospheric Dynamics a New Theory of the Origin of the Winds?" by A. Jaramillo, O. J. Mesa, and D. J. Raymond published in J. Atmos. Sci. 75, 3305 (2018).Comment: 12 pages, 1 figur

The role of ecosystem transpiration in creating alternate moisture regimes by influencing atmospheric moisture convergence

The terrestrial water cycle links the soil and atmosphere moisture reservoirs through four fluxes: precipitation, evaporation, runoff, and atmospheric moisture convergence (net import of water vapor to balance runoff). Each of these processes is essential for human and ecosystem well-being. Predicting how the water cycle responds to changes in vegetation cover remains a challenge. Recently, changes in plant transpiration across the Amazon basin were shown to be associated disproportionately with changes in rainfall, suggesting that even small declines in transpiration (e.g., from deforestation) would lead to much larger declines in rainfall. Here, constraining these results by the law of mass conservation, we show that in a sufficiently wet atmosphere, forest transpiration can control atmospheric moisture convergence such that increased transpiration enhances atmospheric moisture import and resulting water yield. Conversely, in a sufficiently dry atmosphere increased transpiration reduces atmospheric moisture convergence and water yield. This previously unrecognized dichotomy can explain the otherwise mixed observations of how water yield responds to re-greening, as we illustrate with examples from China's Loess Plateau. Our analysis indicates that any additional precipitation recycling by additional vegetation increases precipitation but decreases local water yield and steady-state runoff. Therefore, in the drier regions and early stages of ecological restoration, the role of vegetation can be confined to precipitation recycling, while once a wetter stage is achieved, additional vegetation enhances atmospheric moisture convergence and water yield. Evaluating the transition between regimes, and recognizing the potential of vegetation for enhancing moisture convergence, are crucial for characterizing the consequences of deforestation and for motivating and guiding ecological restoration.Comment: Revised version; response to the reviewers can be found in Appendix A, 39 pages, 11 figures, 2 table

Land use still matters after deforestation

Careful management of deforested Amazonian land cannot replace, but must complement, efforts to preserve the rainforest. Sustainable agricultural practices that promote diverse uses can help minimise climate and environmental impacts.Peer reviewe

O risco das falsas controvérsias científicas para as políticas ambientais brasileiras

Fake controversies have influenced policy making on health and environmental issues for decades, resulting in major implementation setbacks worldwide. As a case study, in this paper we examine fake controversies produced by a small group of active Brazilian researchers that have seriously impacted environmental conservation, particularly in issues related to deforestation and climate change. Based on the literature, we develop a typology of strategies deployed in fake controversies, which include manufacturing uncertainty, misusing scientific credentials, and disregarding scientific literature. Afterwards, we examine the influence of this group of contrarians at the National Congress. We then analyze the fake controversies promoted by these contrarians and argue that, to properly understand them, we need to consider a strategy so far overlooked in the literature: the manufacture of “pseudo-facts”, namely, affirmations at odds with the established literature but that strives to appear as scientific facts. Unlike other contexts, in which contrarians have mainly sought to cast doubt on consensual issues by arguing that there are still considerable uncertainties surrounding them, in Brazil pseudo-facts on deforestation have been produced and published outside the peer-reviewed literature. We conclude the study with recommendations on how to oppose fake scientific controversies that threaten environmental conservation in general.Falsas controvérsias têm influenciado a elaboração de políticas sobre questões ambientais e de saúde há décadas, resultando em grandes retrocessos na implementação dessas políticas em todo o mundo. Utilizando um estudo de caso, neste artigo são examinadas falsas controvérsias produzidas por um pequeno grupo de pesquisadores brasileiros que têm afetado seriamente a conservação ambiental, particularmente em questões relacionadas ao desmatamento e às mudanças climáticas. Com base na literatura, foi desenvolvida uma tipologia das estratégias empregadas em falsas controvérsias, que incluem a fabricação de incertezas, o uso indevido de credenciais científicas e a desconsideração da literatura científica. Posteriormente, foi examinada a influência desse grupo de negacionistas no Congresso Nacional. Analisam-se, então, as falsas controvérsias promovidas por esses negacionistas e argumenta-se que, para entendê-las adequadamente, é necessário considerar uma estratégia até agora negligenciada na literatura: a criação de “pseudofatos”, ou seja, afirmações em desacordo com a literatura científica já estabelecida, mas que são mascaradas para parecerem fatos científicos. Ao contrário de outros contextos, nos quais os negacionistas têm procurado principalmente lançar dúvidas sobre questões já consensuais, argumentando que ainda existem incertezas consideráveis em torno delas, no Brasil foram produzidos e publicados pseudofatos sobre o desmatamento fora do âmbito da literatura revisada por pares. Concluímos o estudo com recomendações sobre como se opor às falsas controvérsias científicas que ameaçam a conservação ambiental em geral

O risco das falsas controvérsias científicas para as políticas ambientais brasileiras

Versão traduzida do artigo “The risk of fake controversies for Brazilian environmental policies”, publicado no periódico Biological Conservation, v. 266,em fevereiro de 2022. Disponível em: .Tradução de Evandro L. T. P. Cunha e Letícia Santos de Lima.Falsas controvérsias têm influenciado a elaboração de políticas sobre questões ambientais e de saúde há décadas, resultando em grandes retrocessos na implementação dessas políticas em todo o mundo. Utilizando um estudo de caso, neste artigo são examinadas falsas controvérsias produzidas por um pequeno grupo de pesquisadores brasileiros que têm afetado seriamente a conservação ambiental, particularmente em questões relacionadas ao desmatamento e às mudanças climáticas. Com base na literatura, foi desenvolvida uma tipologia das estratégias empregadas em falsas controvérsias, que incluem a fabricação de incertezas, o uso indevido de credenciais científicas e a desconsideração da literatura científica. Posteriormente, foi examinada a influência desse grupo de negacionistas no Congresso Nacional. Analisam-se, então, as falsas controvérsias promovidas por esses negacionistas e argumenta-se que, para entende-las adequadamente, é necessário considerar uma estratégia até agora negligenciada na literatura: a criação de “pseudofatos”, ou seja, afirmações em desacordo com a literatura científica já estabelecida, mas que são mascaradas para parecerem fatos científicos. Ao contrário de outros contextos, nos quais os negacionistas têm procurado principalmente lançar dúvidas sobre questões já consensuais, argumentando que ainda existem incertezas consideráveis em torno delas, no Brasil foram produzidos e publicados pseudofatos sobre o desmatamento fora do âmbito da literatura revisada por pares. Concluímos o estudo com recomendações sobre como se opor às falsas controvérsias científicas que ameaçam a conservação ambiental em geral