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1.
J Environ Manage ; 269: 110686, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32560978

RESUMO

The planetary boundaries (PBs) represent a well-known concept, which helps identify whether production and consumption systems are environmentally sustainable in absolute terms, namely compared to the Earth's ecological limits and carrying capacity. In this study, the impacts of production and consumption of the European Union in 2010 were assessed by means of life cycle assessment (LCA)-based indicators and compared with the PBs. Five different perspectives were adopted for assessing the impacts: a production perspective (EU Domestic Footprint) and four distinct consumption perspectives, resulting from alternative modelling approaches including both top-down (input-output LCA) and bottom-up (process-based LCA). Life cycle impact assessment (LCIA) results were assessed against LCIA-based PBs, which adapted the PBs framework to the LCIA indicators and metrics of the Environmental Footprint method (EF). Global environmental impacts transgressed several LCIA-based PBs. When assessing the overall environmental impacts of EU consumption compared to the global LCIA-based PBs, impacts of EU consumption related to climate change, particulate matter, land use and mineral resources were close or already transgressed the global boundaries. The EU, with less than 10% of the world population, was close to transgress the global ecological limits. Moreover, when downscaling the global PBs and comparing the impacts per capita for an average EU citizen and a global one, the LCIA-PBs were significantly transgressed in many impact categories. The results are affected by uncertainty mainly due to: (a) the intrinsic uncertainties of the different LCA modelling approaches and indicators; (b) the uncertainties in estimating LCIA-based PBs, due to the difficulties in identifying limits for the Earth's processes and referring them to LCIA metrics. The results may anyway be used to define benchmarks and policy targets to ensure that consumption and production in Europe remains within safe ecological boundaries, as well as to understand the magnitude of the effort needed to reduce the impacts.


Assuntos
Conservação dos Recursos Naturais , Modelos Teóricos , Mudança Climática , Europa (Continente) , Planetas
2.
Nat Commun ; 11(1): 2731, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32518292

RESUMO

Identification of habitable planets beyond our solar system is a key goal of current and future space missions. Yet habitability depends not only on the stellar irradiance, but equally on constituent parts of the planetary atmosphere. Here we show, for the first time, that radiatively active mineral dust will have a significant impact on the habitability of Earth-like exoplanets. On tidally-locked planets, dust cools the day-side and warms the night-side, significantly widening the habitable zone. Independent of orbital configuration, we suggest that airborne dust can postpone planetary water loss at the inner edge of the habitable zone, through a feedback involving decreasing ocean coverage and increased dust loading. The inclusion of dust significantly obscures key biomarker gases (e.g. ozone, methane) in simulated transmission spectra, implying an important influence on the interpretation of observations. We demonstrate that future observational and theoretical studies of terrestrial exoplanets must consider the effect of dust.


Assuntos
Biomarcadores/análise , Poeira/análise , Exobiologia , Meio Ambiente Extraterreno , Minerais/análise , Planetas , Atmosfera , Clima , Simulação por Computador , Temperatura
3.
Anal Bioanal Chem ; 411(30): 8091-8101, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31773227

RESUMO

Sensitive and robust in situ chemical analysis of organic biomarkers is essential in the endeavor of finding chemical signatures of life either extinct or extant on our solar system bodies such as Europa, Enceladus, or Titan. Development of new analytical instruments and accompanying methodologies are needed, especially those that are compatible with unknown and diverse samples potentially found on solar system targets and that avoid complexities involved with other wet chemistry techniques (desalting, derivatization and contamination issues, etc.). In this study, we demonstrate that online supercritical fluid extraction and supercritical fluid chromatography with water-saturated CO2 can extract and separate nonpolar analytes of astrobiological interest, such as free fatty acids, polycyclic aromatic hydrocarbons, and polycyclic aromatic compounds containing nitrogen or sulfur. Silica was used as a support material to immobilize aqueous samples during extraction. A C18 stationary phase with an embedded polar functional group and efficient end-capping in combination with water in the mobile phase allowed efficient separation of both free fatty acids and basic compounds. The total analysis time was 30 min, including extraction, equilibration, and separation. Detection was performed with a UV detector and a quadrupole mass spectrometer equipped with electrospray ionization. The method was validated in terms of lower detection limits (0.02-40 µg/L), precision (repeatability 3-13%), relative standard deviation (RSD), intermediate precision 4-26% (RSD), trueness (bias ranging from - 48 to 9%), and retention time shifts (< 2% RSD) for 16 analytes in sample matrices with sodium chloride and magnesium sulfate that may be present in ocean worlds such as Europa or Enceladus. Graphical Abstract.


Assuntos
Cromatografia com Fluido Supercrítico/métodos , Planetas , Biomarcadores/metabolismo , Humanos
4.
Can J Diet Pract Res ; 80(4): 163, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31736395
6.
Nature ; 572(7769): 315-317, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31413374

Assuntos
Júpiter , Planetas
9.
Science ; 364(6439): 434-435, 2019 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-31048476
10.
EMBO Rep ; 20(3)2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30718360
11.
EMBO Rep ; 20(3)2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30718361
12.
Astrobiology ; 19(1): 64-86, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30070900

RESUMO

Understanding the impact of active M dwarf stars on the atmospheric equilibrium and surface conditions of a habitable zone Earth-like planet is key to assessing M dwarf planet habitability. Previous modeling of the impact of electromagnetic (EM) radiation and protons from a single large flare on an Earth-like atmosphere indicated that significant and long-term reductions in ozone were possible, but the atmosphere recovered. However, these stars more realistically exhibit frequent flaring with a distribution of different total energies and cadences. Here, we use a coupled 1D photochemical and radiative-convective model to investigate the effects of repeated flaring on the photochemistry and surface UV of an Earth-like planet unprotected by an intrinsic magnetic field. As input, we use time-resolved flare spectra obtained for the dM3 star AD Leonis, combined with flare occurrence frequencies and total energies (typically 1030.5 to 1034 erg) from the 4-year Kepler light curve for the dM4 flare star GJ1243, with varied proton event impact frequency. Our model results show that repeated EM-only flares have little effect on the ozone column depth but that multiple proton events can rapidly destroy the ozone column. Combining the realistic flare and proton event frequencies with nominal CME/SEP geometries, we find the ozone column for an Earth-like planet can be depleted by 94% in 10 years, with a downward trend that makes recovery unlikely and suggests further destruction. For more extreme stellar inputs, O3 depletion allows a constant ∼0.1-1 W m-2 of UVC at the planet's surface, which is likely detrimental to organic complexity. Our results suggest that active M dwarf hosts may comprehensively destroy ozone shields and subject the surface of magnetically unprotected Earth-like planets to long-term radiation that can damage complex organic structures. However, this does not preclude habitability, as a safe haven for life could still exist below an ocean surface.


Assuntos
Atmosfera , Radiação Eletromagnética , Modelos Teóricos , Planetas , Astros Celestes , Prótons
13.
Astrobiology ; 19(1): 1-27, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30346215

RESUMO

In this article, we summarize the work of the NASA Outer Planets Assessment Group (OPAG) Roadmaps to Ocean Worlds (ROW) group. The aim of this group is to assemble the scientific framework that will guide the exploration of ocean worlds, and to identify and prioritize science objectives for ocean worlds over the next several decades. The overarching goal of an Ocean Worlds exploration program as defined by ROW is to "identify ocean worlds, characterize their oceans, evaluate their habitability, search for life, and ultimately understand any life we find." The ROW team supports the creation of an exploration program that studies the full spectrum of ocean worlds, that is, not just the exploration of known ocean worlds such as Europa but candidate ocean worlds such as Triton as well. The ROW team finds that the confirmed ocean worlds Enceladus, Titan, and Europa are the highest priority bodies to target in the near term to address ROW goals. Triton is the highest priority candidate ocean world to target in the near term. A major finding of this study is that, to map out a coherent Ocean Worlds Program, significant input is required from studies here on Earth; rigorous Research and Analysis studies are called for to enable some future ocean worlds missions to be thoughtfully planned and undertaken. A second finding is that progress needs to be made in the area of collaborations between Earth ocean scientists and extraterrestrial ocean scientists.


Assuntos
Exobiologia , Oceanos e Mares , Planetas , Estados Unidos , United States National Aeronautics and Space Administration
14.
Astrobiology ; 19(1): 99-125, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30183335

RESUMO

The nearby exoplanet Proxima Centauri b will be a prime future target for characterization, despite questions about its retention of water. Climate models with static oceans suggest that Proxima b could harbor a small dayside surface ocean despite its weak instellation. We present the first climate simulations of Proxima b with a dynamic ocean. We find that an ocean-covered Proxima b could have a much broader area of surface liquid water but at much colder temperatures than previously suggested, due to ocean heat transport and/or depression of the freezing point by salinity. Elevated greenhouse gas concentrations do not necessarily produce more open ocean because of dynamical regime transitions between a state with an equatorial Rossby-Kelvin wave pattern and a state with a day-night circulation. For an evolutionary path leading to a highly saline ocean, Proxima b could be an inhabited, mostly open ocean planet with halophilic life. A freshwater ocean produces a smaller liquid region than does an Earth salinity ocean. An ocean planet in 3:2 spin-orbit resonance has a permanent tropical waterbelt for moderate eccentricity. A larger versus smaller area of surface liquid water for similar equilibrium temperature may be distinguishable by using the amplitude of the thermal phase curve. Simulations of Proxima Centauri b may be a model for the habitability of weakly irradiated planets orbiting slightly cooler or warmer stars, for example, in the TRAPPIST-1, LHS 1140, GJ 273, and GJ 3293 systems.


Assuntos
Atmosfera , Clima , Modelos Teóricos , Oceanos e Mares , Planetas , Exobiologia , Gases de Efeito Estufa , Movimentos da Água
15.
Science ; 362(6421): 1360-1361, 2018 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-30573618
16.
Proc Natl Acad Sci U S A ; 115(52): 13154-13156, 2018 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-30530695
17.
Nature ; 563(7731): 329-330, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30429560

Assuntos
Planetas , Neve , Planeta Terra
18.
PLoS One ; 13(11): e0207862, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30496230

RESUMO

While the 2016 Paris Agreement is in many ways an important attainment with the potential to represent a milestone in humanity's path towards sustainable development, and avoid thus a potential calamitous and destructive future, the achievement of the goals set in the agreement is a long way off. This paper investigates one of the most important worldwide hurdles frustrating the implementation of the policies required to limit environmental degradation and limit pollution, namely the still insufficient public support for the necessary environmental policies and their associated cost. Using a comparative database generated through an experimental study on tax compliance and policy preferences run in five countries (USA, UK, Italy, Sweden and Romania), I will evaluate five explanatory models of the degree to which people support environmentally friendly policies by accepting higher tax burdens and increased collective solidarity.


Assuntos
Atitude , Política Ambiental/economia , Planetas , Desenvolvimento Sustentável/economia , Tomada de Decisões , Humanos , Modelos Estatísticos
19.
Life Sci Space Res (Amst) ; 19: 13-16, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30482276

RESUMO

Finding life on other worlds is a fascinating area of astrobiology and planetary sciences. Presently, over 3800 exoplanets, representing a very wide range of physical and chemical environments, are known. Scientists are not only looking for traces of life outside Earth, but they are also trying to find out which of Earth's known organisms (ex: tardigrades (water bears)) would be able to survive on other planets. In our study, we have established a metric tool for distinguishing the potential survivability of active and cryptobiotic tardigrades on rocky-water and water-gas planets in our solar system and exoplanets, taking into consideration the geometrical means of six physical parameters such as radius, density, escape velocity, revolution period, surface temperature, and surface pressure of the considered planets. More than 3800 exoplanets are available as the main sample from Planetary Habitable Laboratory - Exoplanet Catalog (PHL-EC), from which we have chosen 57 exoplanets in our study including Earth and Mars, with water composition as reference. The Active Tardigrade Index (ATI) and Cryptobiotic Tardigrade Index (CTI) are two metric indices with minimum value 0 (= tardigrades cannot survive) and maximum 1 (= tardigrades will survive in their respective state). Values between 0 and 1 indicate a percentage chance of the active or cryptobiotic tardigrades surviving on a given exoplanet. Among known planets some of the exoplanets are tabulated as ATI and CTI indices for sample representation like: Kepler-100d, Kepler-48d, Kepler-289b, TRAPPIST-1 f and Kepler-106e. The results with Mars as the threshold indicates that Mars could be the only rock-water composition planet that could be more suitable for tardigrades than other considered exoplanets.


Assuntos
Exobiologia/métodos , Meio Ambiente Extraterreno , Planetas , Sistema Solar , Tardígrados , Animais , Temperatura , Água
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