This month, President Jair Bolsonaro took office in Brazil. He must now lead a country that is undergoing its worst recession and political divisions in a generation—a daunting time to take up the ...reins. Unfortunately, his immediate solutions are a threat to the Amazon forest—a resource that most Brazilians want to protect. For this sentiment to continue to flourish, science and its role in policy-making must be strengthened, not reduced. Brazil must keep environmental conservation and sustainability as priorities if it wants solutions that benefit all of its people, as well as the greater Earth ecosystem, for future generations.
resumo Estamos entrando em uma era em que nosso planeta e nossa sociedade estão enfrentando crises importantes. Convivemos simultaneamente com três emergências importantes: 1) a crise na saúde, ...intensificada com a pandemia da Covid-19; 2) a crise de perda de biodiversidade; e 3) a emergência climática. Salienta-se que essas crises têm ligações profundas entre si, e diferenças também importantes, mas todas provocam impactos sociais e econômicos fortes e afetam o planeta globalmente. Elas são resultado de um modelo econômico que privilegia o desenvolvimento a qualquer custo, o lucro muito rápido, mesmo à custa da sustentabilidade. A crise da Covid-19 colocou questões importantes do ponto de vista de falta de governança global. Por sua vez, a crise climática tem potencial para danos socioeconômicos muito fortes, e seus efeitos já são facilmente visíveis. A perda de biodiversidade coloca em risco nossa segurança alimentar, bem como o equilíbrio do sistema terrestre. A Amazônia, por exemplo, contém milhares de vírus em sua fauna e flora, e a continuar o processo desenfreado de sua ocupação, novos vírus similares ao Sars-CoV-2 possivelmente entrarão em contato com nossa sociedade. Sair dessas três crises requer mudanças drásticas em nosso sistema econômico, insustentável em seu formato atual. Crescimento econômico contínuo em um planeta com recursos naturais finitos não é possível. A desigualdade em países em desenvolvimento e mesmo estre nações é explosiva e injusta. Precisaremos de um novo sistema de governança global que seja capaz de harmonizar medidas dos diferentes países, estados e municípios. A sustentabilidade em nosso planeta é possível e necessária. Teremos muito trabalho em construí-la nos próximos anos, comunidade científica, sociedade, governos e outros agentes. Não temos alternativas senão construir uma nova sociedade, mais justa e sustentável.
abstract We are entering an era in which our planet and our society face major crises. We live simultaneously with three important emergencies: 1) the health crisis, intensified by the Covid-19 pandemic; 2) the biodiversity loss crisis; and 3) the climatic emergency. It should be noted that these crises have profound links between them, and also important differences, but they all have strong social and economic impacts and affect the planet globally. They are the result of an economic model that favors development at any cost and very quick profits even at the expense of sustainability. The Covid-19 crisis posed important questions from the viewpoint of a lack of global governance. In turn, the climate crisis has the potential for very serious socio-economic damage, and its effects are already clearly visible. The loss of biodiversity puts our food security at risk, and the balance of the terrestrial system as well. The Amazon, for example, harbors thousands of viruses in its fauna and flora, and if the unrestrained process of occupation continues, new viruses similar to Sars-CoV-2 will possibly come into contact with our society. Overcoming these three crises requires drastic changes in our economic system, unsustainable in its current format. Continued economic growth on a planet with finite natural resources is not possible. Inequality in developing countries and even between nations is explosive and unfair. We will need a new system of global governance that is able to harmonize measures from different countries, states and municipalities. Sustainability on our planet is possible and necessary. We - the scientific community, society, governments and other stakeholders -will have a lot of work ahead of us in the coming years. We have no alternative but to build a new, more just and sustainable society.
Biomass burning (BB) aerosols can influence regional and global climate through interactions with radiation, clouds, and precipitation. Here, we investigate the impact of BB aerosols on the energy ...balance and hydrological cycle over the Amazon Basin during the dry season. We performed simulations with a fully coupled meteorology-chemistry model, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), for a range of different BB emission scenarios to explore and characterize nonlinear effects and individual contributions from aerosol-radiation interactions (ARIs) and aerosol-cloud interactions (ACIs). The ARIs of BB aerosols tend to suppress low-level liquid clouds by local warming and increased evaporation and to facilitate the formation of high-level ice clouds by enhancing updrafts and condensation at high altitudes. In contrast, the ACIs of BB aerosol particles tend to enhance the formation and lifetime of low-level liquid clouds by providing more cloud condensation nuclei (CCN) and to suppress the formation of high-level ice clouds by reducing updrafts and condensable water vapor at high altitudes (8 km).
Vegetation fires emit large quantities of aerosol into the
atmosphere, impacting regional air quality and climate. Previous work has
used comparisons of simulated and observed aerosol optical depth ...(AOD) in
regions heavily impacted by fires to suggest that emissions of aerosol particles
from fires may be underestimated by a factor of 2–5. Here we use surface,
aircraft and satellite observations made over the Amazon during September
2012, along with a global aerosol model to improve understanding of aerosol
emissions from vegetation fires. We apply three different satellite-derived
fire emission datasets (FINN, GFED, GFAS) in the model. Daily mean aerosol
emissions in these datasets vary by up to a factor of 3.7 over the Amazon
during this period, highlighting the considerable uncertainty in emissions.
We find variable agreement between the model and observed aerosol mass
concentrations. The model reproduces observed aerosol concentrations
over deforestation fires well in the western Amazon during dry season conditions
with FINN or GFED emissions and during dry–wet transition season conditions
with GFAS emissions. In contrast, the model underestimates aerosol
concentrations over savanna fires in the Cerrado environment east of the
Amazon Basin with all three fire emission datasets. The model generally
underestimates AOD compared to satellite and ground stations, even when the
model reproduces the observed vertical profile of aerosol mass
concentration. We suggest it is likely caused by uncertainties in the
calculation of AOD, which are as large as ∼90 %, with the
largest sensitivities due to uncertainties in water uptake and relative
humidity. Overall, we do not find evidence that particulate emissions from
fires are systematically underestimated in the Amazon region and we caution
against using comparison with AOD to constrain particulate emissions from
fires.
The human dimension of fire regimes on Earth Bowman, David M. J. S.; Balch, Jennifer; Artaxo, Paulo ...
Journal of biogeography,
December 2011, Volume:
38, Issue:
12
Journal Article
Peer reviewed
Open access
Humans and their ancestors are unique in being a fire-making species, but 'natural' (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced ...biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human-set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from ' natural' background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke-related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas-induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1 ) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding of the development and diversification of fire regimes, covering the pre-human period, human domestication of fire, and the subsequent transition from subsistence agriculture to industrial economies. All of these phases still occur on Earth, providing opportunities for comparative research.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
One of the least understood aspects in atmospheric chemistry is how urban emissions influence the formation of natural organic aerosols, which affect Earth's energy budget. The Amazon rainforest, ...during its wet season, is one of the few remaining places on Earth where atmospheric chemistry transitions between preindustrial and urban-influenced conditions. Here, we integrate insights from several laboratory measurements and simulate the formation of secondary organic aerosols (SOA) in the Amazon using a high-resolution chemical transport model. Simulations show that emissions of nitrogen-oxides from Manaus, a city of ~2 million people, greatly enhance production of biogenic SOA by 60-200% on average with peak enhancements of 400%, through the increased oxidation of gas-phase organic carbon emitted by the forests. Simulated enhancements agree with aircraft measurements, and are much larger than those reported over other locations. The implication is that increasing anthropogenic emissions in the future might substantially enhance biogenic SOA in pristine locations like the Amazon.
Despite ethanol's penetration into urban transportation, observational evidence quantifying the consequence for the atmospheric particulate burden during actual, not hypothetical, fuel-fleet shifts, ...has been lacking. Here we analyze aerosol, meteorological, traffic, and consumer behavior data and find, empirically, that ambient number concentrations of 7-100-nm diameter particles rise by one-third during the morning commute when higher ethanol prices induce 2 million drivers in the real-world megacity of São Paulo to substitute to gasoline use (95% confidence intervals: +4,154 to +13,272 cm
). Similarly, concentrations fall when consumers return to ethanol. Changes in larger particle concentrations, including US-regulated PM2.5, are statistically indistinguishable from zero. The prospect of increased biofuel use and mounting evidence on ultrafines' health effects make our result acutely policy relevant, to be weighed against possible ozone increases. The finding motivates further studies in real-world environments. We innovate in using econometrics to quantify a key source of urban ultrafine particles.The biofuel ethanol has been introduced into urban transportation in many countries. Here, by measuring aerosols in São Paulo, the authors find that high ethanol prices coincided with an increase in harmful nanoparticles by a third, as drivers switched from ethanol to cheaper gasoline, showing a benefit of ethanol.
We present a range of airborne in situ observations of biomass burning carbonaceous aerosol over tropical South America, including a case study of a large tropical forest wildfire and a series of ...regional survey flights across the Brazilian Amazon and Cerrado. The study forms part of the South American Biomass Burning Analysis (SAMBBA) project, which was conducted during September and October 2012. We find limited evidence for net increases in aerosol mass through atmospheric ageing combined with substantial changes in the chemical properties of organic aerosol (OA). Oxidation of the OA increases significantly and rapidly on the scale of 2.5-3 h based on our case study analysis and is consistent with secondary organic aerosol production. The observations of limited net enhancement in OA coupled with such changes in chemical composition imply that evaporation of OA is also occurring to balance these changes. We observe significant coatings on black carbon particles at source, but with limited changes with ageing in both particle core size and coating thickness.
Aerosol–cloud interactions (ACI) constitute the single largest uncertainty
in anthropogenic radiative forcing. To reduce the uncertainties and gain
more confidence in the simulation of ACI, models ...need to be evaluated
against observations, in particular against measurements of cloud
condensation nuclei (CCN). Here we present a data set – ready to be used for
model validation – of long-term observations of CCN number concentrations,
particle number size distributions and chemical composition from 12
sites on 3 continents. Studied environments include coastal background,
rural background, alpine sites, remote forests and an urban surrounding.
Expectedly, CCN characteristics are highly variable across site categories.
However, they also vary within them, most strongly in the coastal background
group, where CCN number concentrations can vary by up to a factor of 30
within one season. In terms of particle activation behaviour, most
continental stations exhibit very similar activation ratios (relative to
particles > 20 nm) across the range of 0.1 to 1.0 %
supersaturation. At the coastal sites the transition from particles being
CCN inactive to becoming CCN active occurs over a wider range of the
supersaturation spectrum. Several stations show strong seasonal cycles of CCN number concentrations
and particle number size distributions, e.g. at Barrow (Arctic haze in
spring), at the alpine stations (stronger influence of polluted boundary
layer air masses in summer), the rain forest (wet and dry season) or
Finokalia (wildfire influence in autumn). The rural background and urban
sites exhibit relatively little variability throughout the year, while
short-term variability can be high especially at the urban site. The average hygroscopicity parameter, κ, calculated from the
chemical composition of submicron particles was highest at the coastal site
of Mace Head (0.6) and lowest at the rain forest station ATTO (0.2–0.3).
We performed closure studies based on κ–Köhler theory
to predict CCN number concentrations. The ratio of predicted to measured CCN
concentrations is between 0.87 and 1.4 for five different types of κ.
The temporal variability is also well captured, with Pearson
correlation coefficients exceeding 0.87. Information on CCN number concentrations at many locations is important to
better characterise ACI and their radiative forcing. But long-term
comprehensive aerosol particle characterisations are labour intensive and
costly. Hence, we recommend operating “migrating-CCNCs” to conduct
collocated CCN number concentration and particle number size distribution
measurements at individual locations throughout one year at least to derive
a seasonally resolved hygroscopicity parameter. This way, CCN number
concentrations can only be calculated based on continued particle number size
distribution information and greater spatial coverage of long-term
measurements can be achieved.
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