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2.
Proc Natl Acad Sci U S A ; 119(17): e2118696119, 2022 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-35452307

RESUMO

SignificanceOur study of climate response to orbital variations in a Late Triassic midlatitude temperate setting in Jameson Land, East Greenland, provides robust evidence of astronomically forced grand cycles ascribed to gravitational interactions between Earth and Mars and is an Early Mesozoic record where both Mars-Earth modulation components are present and constrained with adequate chronostratigraphic controls. These findings suggest chaotic behavior of the inner Solar System and have implications as reference points in calculations of the past motions of the planets in the Solar System. Furthermore, our findings demonstrate a climate antiphasing between low and midlatitudes, which has implications for precise correlation of geological records and for validating models of Earth's climate dynamics.


Assuntos
Clima , Planetas , Planeta Terra , Evolução Planetária , Geologia , Groenlândia
3.
Int J Mol Sci ; 23(8)2022 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-35457069

RESUMO

Glycine (Gly), NH2CH2COOH, is the simplest amino acid. Although it has not been directly detected in the interstellar gas-phase medium, it has been identified in comets and meteorites, and its synthesis in these environments has been simulated in terrestrial laboratory experiments. Likewise, condensation of Gly to form peptides in scenarios resembling those present in a primordial Earth has been demonstrated experimentally. Thus, Gly is a paradigmatic system for biomolecular building blocks to investigate how they can be synthesized in astrophysical environments, transported and delivered by fragments of asteroids (meteorites, once they land on Earth) and comets (interplanetary dust particles that land on Earth) to the primitive Earth, and there react to form biopolymers as a step towards the emergence of life. Quantum chemical investigations addressing these Gly-related events have been performed, providing fundamental atomic-scale information and quantitative energetic data. However, they are spread in the literature and difficult to harmonize in a consistent way due to different computational chemistry methodologies and model systems. This review aims to collect the work done so far to characterize, at a quantum mechanical level, the chemical life of Gly, i.e., from its synthesis in the interstellar medium up to its polymerization on Earth.


Assuntos
Meio Ambiente Extraterreno , Meteoroides , Poeira Cósmica/análise , Planeta Terra , Evolução Química , Glicina
4.
Nature ; 604(7905): 304-309, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35418633

RESUMO

Over the last five years prior to the Glasgow Climate Pact1, 154 Parties have submitted new or updated 2030 mitigation goals in their nationally determined contributions and 76 have put forward longer-term pledges. Quantifications of the pledges before the 2021 United Nations Climate Change Conference (COP26) suggested a less than 50 per cent chance of keeping warming below 2 degrees Celsius2-5. Here we show that warming can be kept just below 2 degrees Celsius if all conditional and unconditional pledges are implemented in full and on time. Peak warming could be limited to 1.9-2.0 degrees Celsius (5%-95% range 1.4-2.8 °C) in the full implementation case-building on a probabilistic characterization of Earth system uncertainties in line with the Working Group I contribution to the Sixth Assessment Report6 of the Intergovernmental Panel on Climate Change (IPCC). We retrospectively project twenty-first-century warming to show how the aggregate level of ambition changed from 2015 to 2021. Our results rely on the extrapolation of time-limited targets beyond 2030 or 2050, characteristics of the IPCC 1.5 °C Special Report (SR1.5) scenario database7 and the full implementation of pledges. More pessimistic assumptions on these factors would lead to higher temperature projections. A second, independent emissions modelling framework projected peak warming of 1.8 degrees Celsius, supporting the finding that realized pledges could limit warming to just below 2 degrees Celsius. Limiting warming not only to 'just below' but to 'well below' 2 degrees Celsius or 1.5 degrees Celsius urgently requires policies and actions to bring about steep emission reductions this decade, aligned with mid-century global net-zero CO2 emissions.


Assuntos
Política Ambiental , Aquecimento Global , Cooperação Internacional , Temperatura , Planeta Terra , Política Ambiental/legislação & jurisprudência , Aquecimento Global/legislação & jurisprudência , Aquecimento Global/prevenção & controle , Aquecimento Global/estatística & dados numéricos , História do Século XXI , Cooperação Internacional/legislação & jurisprudência , Paris , Estudos Retrospectivos , Fatores de Tempo , Nações Unidas/legislação & jurisprudência
5.
Nat Commun ; 13(1): 1990, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35418121

RESUMO

The Cambrian is the most poorly dated period of the past 541 million years. This hampers analysis of profound environmental and biological changes that took place during this period. Astronomically forced climate cycles recognized in sediments and anchored to radioisotopic ages provide a powerful geochronometer that has fundamentally refined Mesozoic-Cenozoic time scales but not yet the Palaeozoic. Here we report a continuous astronomical signal detected as geochemical variations (1 mm resolution) in the late Cambrian Alum Shale Formation that is used to establish a 16-Myr-long astronomical time scale, anchored by radioisotopic dates. The resulting time scale is biostratigraphically well-constrained, allowing correlation of the late Cambrian global stage boundaries with the 405-kyr astrochronological framework. This enables a first assessment, in numerical time, of the evolution of major biotic and abiotic changes, including the end-Marjuman extinctions and the Steptoean Positive Carbon Isotope Excursion, that characterized the late Cambrian Earth.


Assuntos
Evolução Biológica , Fósseis , Isótopos de Carbono , Clima , Planeta Terra
6.
Nat Commun ; 13(1): 2000, 2022 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-35422049

RESUMO

The Atlantic Meridional Overturning Circulation (AMOC) regulates the heat distribution and climate of Earth. Here we identify a new feature of the circulation within the North Atlantic Subtropical Gyre that is associated with the northward flowing component of the AMOC. We find that 70% of the water that flows northwards as part of the AMOC circulates the Gyre at least once before it can continue northwards. These circuits are needed to achieve an increase of density and depth through a combination of air-sea interaction and interior mixing processes, before water can escape the latitudes of the Gyre and join the northern upper branch of the AMOC. This points towards an important role of the Gyre circulation in determining the strength and variability of the AMOC and the northward heat transport. Understanding this newly identified role of the North Atlantic Subtropical Gyre is needed to properly represent future changes of the AMOC.


Assuntos
Clima , Movimentos da Água , Planeta Terra , Temperatura Alta , Água
7.
Sensors (Basel) ; 22(7)2022 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-35408156

RESUMO

Resilient navigation in Global Navigation Satellite System (GNSS)-degraded and -denied environments is becoming more and more required for many applications. It can typically be based on multi-sensor data fusion that relies on alternative technologies to GNSS. In this work, we studied the potential of a low earth orbit (LEO) satellite communication system for a high-dynamic application, when it is integrated with an inertial measurement unit (IMU) and magnetometers. We derived the influence of the main error sources that affect the LEO space vehicle (SV) Doppler-based navigation on both positioning and attitude estimations. This allowed us to determine the best, intermediate and worst cases of navigation performances. We show that while the positioning error is large due to large orbit errors or high SV clock drifts, it becomes competitive with that of an inertial navigation system (INS) based on a better quality IMU if precise satellite orbits are available. On the other hand, the attitude estimation tolerates large orbit errors and high SV clock drifts. The obtained results suggest that LEO SV signals, used as signals of opportunity for navigation, are an attractive alternative in GNSS-denied environments for high dynamic vehicles.


Assuntos
Algoritmos , Comunicações Via Satélite , Planeta Terra , Projetos de Pesquisa
8.
Sci Rep ; 12(1): 5677, 2022 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-35383225

RESUMO

Impacts by small solar system bodies (meteoroids, asteroids, comets and transitional objects) are characterized by a combination of energy dynamics and chemical modification on both terrestrial and small solar system bodies. In this context, the discovery of glycine amino acid in meteorites and comets has led to a hypothesis that impacts by astronomical bodies could contribute to delivery and polymerization of amino acids in the early Earth to generate proteins as essential molecules for life. Besides the possibility of abiotic polymerization of glycine, its decomposition by impacts could generate reactive groups to form other essential organic biomolecules. In this study, the high-pressure torsion (HPT) method, as a new platform for simulation of impacts by small solar system bodies, was applied to glycine. In comparison with high-pressure shock experiments, the HPT method simultaneously introduces high pressure and deformation strain. It was found that glycine was not polymerized in the experimental condition assayed, but partially decomposed to ethanol under pressures of 1 and 6 GPa and shear strains of < 120 m/m. The detection of ethanol implies the inherent availability of remaining nitrogen-containing groups, which can incorporate to the formation of other organic molecules at the impact site. In addition, this finding highlights a possibility of the origin of ethanol previously detected in comets.


Assuntos
Glicina , Meteoroides , Aminoácidos , Planeta Terra , Meio Ambiente Extraterreno , Sistema Solar
9.
Nature ; 603(7899): 86-90, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35236974

RESUMO

The Hadean eon, following the global-scale melting of the mantle1-3, is expected to be a dynamic period, during which Earth experienced vastly different conditions. Geologic records, however, suggest that the surface environment of Earth was already similar to the present by the middle of the Hadean4,5. Under what conditions a harsh surface environment could turn into a habitable one remains uncertain6. Here we show that a hydrated mantle with small-scale chemical heterogeneity, created as a result of magma ocean solidification, is the key to ocean formation, the onset of plate tectonics and the rapid removal of greenhouse gases, which are all essential to create a habitable environment on terrestrial planets. When the mantle is wet and dominated by high-magnesium pyroxenites, the removal of carbon dioxide from the atmosphere is expected to be more than ten times faster than the case of a pyrolitic homogeneous mantle and could be completed within  160 million years. Such a chemically heterogeneous mantle would also produce oceanic crust rich in olivine, which is reactive with ocean water and promotes serpentinization. Therefore, conditions similar to the Lost City hydrothermal field7-9 may have existed globally in the Hadean seafloor.


Assuntos
Planeta Terra , Planetas , Atmosfera , Oceanos e Mares , Água
10.
Sci Rep ; 12(1): 4501, 2022 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-35296705

RESUMO

Our Moon periodically moves through the magnetic tail of the Earth that contains terrestrial ions of hydrogen and oxygen. A possible density contrast might have been discovered that could be consistent with the presence of water phase of potential terrestrial origin. Using novel gravity aspects (descriptors) derived from harmonic potential coefficients of gravity field of the Moon, we discovered gravity strike angle anomalies that point to water phase locations in the polar regions of the Moon. Our analysis suggests that impact cratering processes were responsible for specific pore space network that were subsequently filled with the water phase filling volumes of permafrost in the lunar subsurface. In this work, we suggest the accumulation of up to ~ 3000 km3 of terrestrial water phase (Earth's atmospheric escape) now filling the pore spaced regolith, portion of which is distributed along impact zones of the polar regions of the Moon. These unique locations serve as potential resource utilization sites for future landing exploration and habitats (e.g., NASA Artemis Plan objectives).


Assuntos
Lua , Água , Planeta Terra , Meio Ambiente Extraterreno , Gravitação
11.
PLoS One ; 17(3): e0265546, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35333882

RESUMO

The formation of craters is an important issue in the investigations of the surface of the earth and other planets. The aim of the study was to check whether the different textures of sand beds affect the size and dynamics of the formation of craters and ejection curtain after high-velocity impacts. The experiments were conducted using an aluminium impactor at two impact speeds (~700 and ~1300 m∙s-1) and a sand bed composed of either a broad range of sizes (<2.0 mm) or any of the three fractions obtained from it (<0.5, 0.5-1, 1-2 mm). The diameters, depths, wall slope, and rim heights of the resulting craters were measured. The ejecta curtain was characterized by the inclination angle of walls, base diameter, and expansion velocity. The mass of the transferred material and the depth of the impactor penetration were also determined. Additionally, the results were used to calculate dimensionless parameters commonly considered in crater studies (πV, π2 and α). The texture of the sand most clearly influenced the diameters of the craters, its effect could also be seen in the case of the distance covered by the ejected material. This information appears to be relevant for future research, providing some rationale to help assess in which aspects of the phenomenon the texture may be important.


Assuntos
Planetas , Areia , Planeta Terra
12.
New Phytol ; 234(5): 1863-1875, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35274308

RESUMO

The post-Miocene climatic histories of arid environments have been identified as key drivers of dispersal and diversification. Here, we investigate how climatic history correlates with the historical biogeography of the Atacama Desert genus Cristaria (Malvaceae). We analyze phylogenetic relationships and historical biogeography by using next-generation sequencing (NGS), molecular clock dating, Dispersal Extinction Cladogenesis and Bayesian sampling approaches. We employ a novel way to identify biogeographically meaningful regions as well as a rarely utilized program permitting the use of dozens of ancestral areas. Partial incongruence between the established taxonomy and our phylogenetic data argue for a complex historical biogeography with repeated introgression and incomplete lineage sorting. Cristaria originated in the central southern part of the Atacama Desert, from there the genus colonized other areas from the late Miocene onwards. The more recently diverged lineages appear to have colonized different habitats in the Atacama Desert during pluvial phases of the Pliocene and early Pleistocene. We show that NGS combined with near-comprehensive sampling can provide an unprecedented degree of phylogenetic resolution and help to correlate the historical biogeography of plant communities with cycles of arid and pluvial phases.


Assuntos
Ecossistema , Especiação Genética , Teorema de Bayes , Planeta Terra , Filogenia , Filogeografia
14.
Sci Rep ; 12(1): 3852, 2022 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-35264650

RESUMO

The Early Ordovician is a key interval for our understanding of the evolution of life on Earth as it lays at the transition between the Cambrian Explosion and the Ordovician Radiation and because the fossil record of the late Cambrian is scarce. In this study, assembly processes of Early Ordovician trilobite and echinoderm communities from the Central Anti-Atlas (Morocco), the Montagne Noire (France), and the Cordillera Oriental (Argentina) are explored. The results show that dispersal increased diachronically in trilobite communities during the Early Ordovician. Dispersal did not increase for echinoderms. Dispersal was most probably proximally triggered by the planktic revolution, the fall in seawater temperatures, changes in oceanic circulation, with an overall control by tectonic frameworks and phylogenetic constraints. The diachronous increase in dispersal within trilobite communities in the Early Ordovician highlights the complexity of ecosystem structuring during the early stages of the Ordovician Radiation. As Early Ordovician regional dispersal was followed by well-documented continental dispersal in the Middle/Late Ordovician, it is possible to consider that alongside a global increase in taxonomic richness, the Ordovician Radiation is also characterized by a gradual increase in dispersal.


Assuntos
Ecossistema , Fósseis , Animais , Evolução Biológica , Planeta Terra , Equinodermos , Filogenia
15.
Physiol Rep ; 10(6): e15214, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35347882

RESUMO

Many of us think a lot about oxygen. This includes how the normal body handles oxygen in health, but particularly how this is complicated by lung disease. Few of us are aware that as human inhabitants of the earth, we have a unique privilege. This is that as air breathers, we and most other animals on Earth, are the only living creatures in the known universe that have unlimited supply of oxygen. This situation came about through one of the greatest miracles of nature, that is photosynthesis, the ability to release oxygen from water using the energy of sunlight. One consequence of this was that the first atmospheric oxygen came from the metabolism of microorganisms, the cyanobacteria, that used photosynthesis, but for which oxygen was an unwanted by-product. In fact, the oxygen had to be discarded for the organisms to thrive. When a major increase of oxygen concentration in the atmosphere occurred some 2 billion years ago, and the partial pressure of oxygen in the air rose to perhaps 200 mmHg, this Great Oxidation Event as it was called, was a death sentence for the large population of anaerobic animals for whom oxygen was toxic. Today much of the oxygen in the atmosphere comes from photosynthesis in microorganisms, including the cyanobacteria, and the recently discovered Prochlorococcus, that discard this unwanted by-product. The result is that the PO2 in our atmosphere at sea level remains nearly constant at about 150 mm Hg, although the factors responsible for this are not understood.


Assuntos
Evolução Biológica , Oxigênio , Atmosfera , Planeta Terra , Oxigênio/metabolismo , Fotossíntese
16.
Trends Ecol Evol ; 37(4): 293-298, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35263561

RESUMO

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmental change.


Assuntos
Planeta Terra , Ecossistema , Animais , Conservação dos Recursos Naturais , Movimento
17.
PLoS One ; 17(3): e0264690, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35275949

RESUMO

A series of model tests are carried out on flexible retaining walls such as cantilevered piles, continuous walls, and sheet pile walls in the foundation pit to study the deformation, failure surface, and earth pressure distribution of soils in a passive zone. The shape, displacement, and shear strain of slip failure surface of sand in a passive area are analyzed by Particle Image Velocimetry. The slip failure surface is a broken line, the upper end slides out from the top of the soil, and the lower end is close to the zero displacements of the retaining wall. With the increase of the flexural deformation and horizontal displacement of the wall, the shear strain of the soil increases, and the shear fracture zone in the upper part of the sliding surface is more prominent. Based on the broken line rupture surface in the test results, the passive area can be divided into two zones, the limit state zone and the non-limit state zone. Then the mechanical models are set up respectively. Considering soil displacement, the upper and lower soil layer's internal friction angle and wall-soil interface friction angle mobilize differently. The relationship between mechanical parameters along the retaining wall and horizontal displacement is estimated. Finally, the earth pressure distribution is obtained by using the horizontal differential layer method. The calculation results of this paper are consistent with the existing research results and the model test results in terms of earth pressure distribution. With the increase of depth, the unit earth pressure increases in the limit state zone. Still, after entering the non-limit state zone, the unit earth pressure rises to a certain extent and decreases rapidly.


Assuntos
Planeta Terra , Solo , Fricção , Pressão
18.
Nat Commun ; 13(1): 1306, 2022 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-35288559

RESUMO

Despite tectonic conditions and atmospheric CO2 levels (pCO2) similar to those of present-day, geological reconstructions from the mid-Pliocene (3.3-3.0 Ma) document high lake levels in the Sahel and mesic conditions in subtropical Eurasia, suggesting drastic reorganizations of subtropical terrestrial hydroclimate during this interval. Here, using a compilation of proxy data and multi-model paleoclimate simulations, we show that the mid-Pliocene hydroclimate state is not driven by direct CO2 radiative forcing but by a loss of northern high-latitude ice sheets and continental greening. These ice sheet and vegetation changes are long-term Earth system feedbacks to elevated pCO2. Further, the moist conditions in the Sahel and subtropical Eurasia during the mid-Pliocene are a product of enhanced tropospheric humidity and a stationary wave response to the surface warming pattern, which varies strongly with land cover changes. These findings highlight the potential for amplified terrestrial hydroclimate responses over long timescales to a sustained CO2 forcing.


Assuntos
Planeta Terra , Camada de Gelo , Retroalimentação
19.
Astrobiology ; 22(3): 263-292, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35263189

RESUMO

The Planetary Terrestrial Analogues Library (PTAL) project aims at building and exploiting a database involving several analytical techniques, to help characterize the mineralogical evolution of terrestrial bodies, starting with Mars. Around 100 natural Earth rock samples have been collected from selected locations to gather a variety of analogs for martian geology, from volcanic to sedimentary origin with different levels of alteration. All samples are to be characterized within the PTAL project with different mineralogical and elemental analysis techniques, including techniques brought on actual and future instruments at the surface of Mars (near infrared [NIR] spectroscopy, Raman spectroscopy, and laser-induced breakdown spectroscopy). This article presents the NIR measurements and interpretations acquired with the ExoMars MicrOmega spare instrument. MicrOmega is an NIR hyperspectral microscope, mounted in the analytical laboratory of the ExoMars rover Rosalind Franklin. All PTAL samples have been observed at least once with MicrOmega using a dedicated setup. For all PTAL samples, data description and interpretation are presented. For some chosen examples, color composite images and spectra are presented as well. A comparison with characterizations by NIR and Raman spectrometry is discussed for some of the samples. In particular, the spectral imaging capacity of MicrOmega allows detections of mineral components and potential organic molecules that were not possible with other one-spot techniques. In addition, it enables estimation of heterogeneities in the spatial distribution of various mineral species. The MicrOmega/PTAL data shall support the future observations and analyses performed by MicrOmega/Rosalind Franklin instrument.


Assuntos
Exobiologia , Marte , Planeta Terra , Exobiologia/métodos , Meio Ambiente Extraterreno/química , Minerais/análise
20.
Nat Commun ; 13(1): 1196, 2022 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-35256613

RESUMO

The Sun sporadically produces eruptive events leading to intense fluxes of solar energetic particles (SEPs) that dramatically disrupt the near-Earth radiation environment. Such events have been directly studied for the last decades but little is known about the occurrence and magnitude of rare, extreme SEP events. Presently, a few events that produced measurable signals in cosmogenic radionuclides such as 14C, 10Be and 36Cl have been found. Analyzing annual 14C concentrations in tree-rings from Switzerland, Germany, Ireland, Russia, and the USA we discovered two spikes in atmospheric 14C occurring in 7176 and 5259 BCE. The ~2% increases of atmospheric 14C recorded for both events exceed all previously known 14C peaks but after correction for the geomagnetic field, they are comparable to the largest event of this type discovered so far at 775 CE. These strong events serve as accurate time markers for the synchronization with floating tree-ring and ice core records and provide critical information on the previous occurrence of extreme solar events which may threaten modern infrastructure.


Assuntos
Prótons , Atividade Solar , Planeta Terra , Alemanha , Árvores
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