Earth's Surface Temperature Research Articles

Clumped 13CH2D and 12CHD2 compositions of methyl groups from wood and synthetic monomers: Methods, experimental and theoretical calibrations, and initial results

Methyl groups are found in numerous biogenic and synthetic materials including geologically preserved materials such as wood. The carbon and hydrogen isotope compositions of methyl groups are used as tracers in biogeochemical cycles, as paleothermometers, and to determine the hydrogen isotopic composition of ancient rain. Here we present analyses of resolved 13C–D (13CH2D) and D–D (12CHD2) clumped isotope compositions of methyl groups as new variables for the study of methyl groups in the present and past. We first present chemical methods to extract, purify, and derivatize methyl groups from methoxyl (R–O–CH3) groups as CH3F and CH3Cl, and high-resolution mass spectrometric techniques to determine the clumped isotope compositions of these species. We achieve precisions for 13C–D clumping of ±0.25‰ and D–D clumping of ±2.5‰. We anchor our clumped isotopic measurements to a thermodynamic reference frame by first calculating the theoretical temperature dependences of 13C–D and D–D clumping in CH3Cl, then placing our measurements onto this reference frame through experimental internal isotopic equilibration of CH3Cl at 200 °C. Finally, we provide and analyze an initial dataset of clumped 13C–D and D–D compositions of methyl groups from various commercial/synthetic monomers and environmental woods. We observe ranges in clumped isotope compositions of ∼11‰ in 13C–D and ∼48‰ in D–D, and systematic differences within these ranges between methyl groups from commercial monomers and wood. Specifically, commercial clumped 13C–D compositions are between 0 and 3‰, which correspond to apparent equilibrium temperatures between 170 °C and the infinite temperature limit. In contrast, the clumped 13C–D compositions of wood methoxyl groups are distinctively high (9.50–11.25‰) and 3–6‰ higher than would be expected if formed in internal isotopic equilibrium at Earth-surface temperatures. Commercial/synthetic methyl and wood methoxyl clumped D–D compositions are also distinct: −5 to +13‰ in commercial monomers vs. −35 to −8‰ in wood—such negative values cannot result from formation in isotopic equilibrium and require kinetic processes to have occurred. These results indicate that wood methoxyl groups are formed out of isotopic equilibrium and that clumped isotope compositions of methyl groups may be useful tracers of methyl group sources and sinks in the environment. For instance, isotopic clumping in methyl groups may be useful for understanding controls on isotopic clumping in methane produced by methylotrophic methanogens.

Temporal variations of trends in the Central England Temperature series

Variations in trend rates of annual values of the Central England Temperature series (CET) over the period1659-2017 were analysed using moving windows of different length, to identify the minimum period in which the trend expresses a climate signal not hidden by the noise produced by natural variability. Trend rates exhibit high variability and irregular shifting from positive to negative values unless very long window lengths (of 100 years or more) are used. In general, as the duration of the length of the temporal window analysed increases, the absolute range of the trend rates decreases and the signal-to-noise (S/N) ratio increases. The relationship between the S/N ratio and the window length also depended on the total length of the series, so high S/N values are achieved faster when shorter time series are considered. This prevents suggesting a minimum window length for undertaking trend analyses.A comparison between CET and the average continental series in the Berkeley Earth Surface Temperature (BEST) database in their common period (1753-2017) repeats the patterns described for 1659-2017, although the average values of the rates, ranges and the "threshold period" in years change, and are more variable in CET than in BEST.Analysis of both series suggests that the recent warming started early and can be linked to the recovery of temperatures after the Little Ice Age. This process has characterised by progressively increasing trend rates, but also includes periods of deceleration or even negative trends spanning less than 50 years. The behaviour of the two long-term temperature records analysed agrees with a long-term persistence (LTP) process. We estimated the Hurst exponent of the CET series to be around 0.72 and 0.8, which reinforces the LTP hypothesis. This implies that the currently widespread statistical framework assuming a stationary, short-memory process in which departures from the norm can be easily assessed by monotonic trend analysis should not be accepted for long climatic series. In brief, relevant questions relative to the recent evolution of temperatures such as the distinction between natural variability and departures from stationarity; attribution of the causes of variability at different time scales; determination of the shortest window length to detect a trend; and other similar ones have still not been answered and may require adoption of an alternative analytical framework.

Modulating electrolyte structure for ultralow temperature aqueous zinc batteries

Rechargeable aqueous batteries are an up-and-coming system for potential large-scale energy storage due to their high safety and low cost. However, the freeze of aqueous electrolyte limits the low-temperature operation of such batteries. Here, we report the breakage of original hydrogen-bond network in ZnCl2 solution by modulating electrolyte structure, and thus suppressing the freeze of water and depressing the solid-liquid transition temperature of the aqueous electrolyte from 0 to –114 °C. This ZnCl2-based low-temperature electrolyte renders polyaniline||Zn batteries available to operate in an ultra-wide temperature range from –90 to +60 °C, which covers the earth surface temperature in record. Such polyaniline||Zn batteries are robust at –70 °C (84.9 mA h g−1) and stable during over 2000 cycles with ~100% capacity retention. This work significantly provides an effective strategy to propel low-temperature aqueous batteries via tuning the electrolyte structure and widens the application range of temperature adaptation of aqueous batteries.

High temperatures modify plant responses to abiotic stress conditions.

Climate change is altering environments in which plants and different crops grow and survive. We already experienced an increase in worldwide average earth surface temperatures, as well as frequency and extent of damaging heat waves. These conditions collide in the field with other abiotic stresses such as water deficit, high salinity, increased light irradiation, and so on, generating complex harmful conditions that destabilize agricultural systems. The conditions generated during these episodes of stress combination greatly differ from those occurring in the field when different stress factors occur individually; conditions that have been the focus of study for decades. Fortunately, knowledge of physiological and molecular responses to stress combinations and the cost they inflict on plant growth and yield has been exponentially increasing in the past several years. Understanding plant performance under multiple stress combinations will allow breeding crops capable of maintaining yield production under the new climatic conditions. Here, after reviewing recent data on physiological, hormonal and transcriptional responses to different stress combinations, we highlight the importance of photodamage avoidance, abscisic and jasmonic acid signaling, and the upregulation of genes involved in oxidation-reduction processes, photosynthesis and protein metabolism, for plant acclimation to conditions of high temperatures, in combination with other common abiotic stress factors such as drought or salinity. Finally, we propose new approaches to investigate the response of plants to stress combinations and discuss strategies for improving crop resilience to stress combination.

Mapping Vegetation Health Around the World

A new spaceborne sensor monitors Earth's surface temperature at a resolution higher than ever before, providing information on ecosystem responses to changes in water availability and climate stressors.

Root Involvement in Plant Responses to Adverse Environmental Conditions

Climate change is altering the environment in which plants grow and survive. An increase in worldwide Earth surface temperatures has been already observed, together with an increase in the intensity of other abiotic stress conditions such as water deficit, high salinity, heavy metal intoxication, etc., generating harmful conditions that destabilize agricultural systems. Stress conditions deeply affect physiological, metabolic and morphological traits of plant roots, essential organs for plant survival as they provide physical anchorage to the soil, water and nutrient uptake, mechanisms for stress avoidance, specific signals to the aerial part and to the biome in the soil, etc. However, most of the work performed until now has been mainly focused on aerial organs and tissues. In this review, we summarize the current knowledge about the effects of different abiotic stress conditions on root molecular and physiological responses. First, we revise the methods used to study these responses (omics and phenotyping techniques). Then, we will outline how environmental stress conditions trigger various signals in roots for allowing plant cells to sense and activate the adaptative responses. Later, we discuss on some of the main regulatory mechanisms controlling root adaptation to stress conditions, the interplay between hormonal regulatory pathways and the global changes on gene expression and protein homeostasis. We will present recent advances on how the root system integrates all these signals to generate different physiological responses, including changes in morphology, long distance signaling and root exudation. Finally, we will discuss the new prospects and challenges in this field.

ANÁLISE DE NDVI E TEMPERATURA DA SUPERFÍCIE TERRESTRE UTILIZANDO A PLATAFORMA DO GOOGLE EARTH ENGINE EM ÁREA DE SAVANA AMAZÔNICA E FLORESTA SECUNDÁRIA, NO MUNICÍPIO DE VIGIA – PA

A Savana Amazônica é um ecossistema com carência de estudos científicos sobre os efeitos das mudanças de uso da terra e da temperatura da superfície terrestre. Além disso, as florestas secundárias na Amazônia são áreas que podem ser afetadas pelas mudanças de uso da terra, haja vista o seu relacionamento fronteiriço com a savana. Neste sentido, o presente estudo teve como objetivo: i) analisar o Índice da Vegetação por Diferença Normalizada (NDVI) em regiões de Savana amazônica e floresta secundária e ii) verificar o comportamento da temperatura superficial da terra no município de Vigia, Estado do Pará utilizando a plataforma Google Earth Engine (GEE). Justifica-se a escolha do município de Vigia devido o seu território comportar ecossistemas de savana e floresta secundária e sofrer pressões humanas devido à inflexão de atividades agropecuárias ao longo dos anos. Os resultados do estudo revelaram que as temperaturas da superfície terrestre em Vigia giram em torno dos 28,91°C (mínima) e 31,71°C (máxima). Além disso, os NDVI próximos de 1 em áreas de floresta secundária, exceção do ano de 2014 (0,23) mostram que apesar das mudanças antrópicas na terra, o ecossistema conserva boa parte de sua vegetação, onde a plataforma GEE se mostra capaz de auxiliar no planejamento e monitoramento de áreas de savana e floresta secundária.

Massive formation of early diagenetic dolomite in the Ediacaran ocean: Constraints on the “dolomite problem”

Paleozoic and Precambrian sedimentary successions frequently contain massive dolomicrite [CaMg(CO3)2] units despite kinetic inhibitions to nucleation and precipitation of dolomite at Earth surface temperatures (<60 °C). This paradoxical observation is known as the "dolomite problem." Accordingly, the genesis of these dolostones is usually attributed to burial-hydrothermal dolomitization of primary limestones (CaCO3) at temperatures of >100 °C, thus raising doubt about the validity of these deposits as archives of Earth surface environments. We present a high-resolution, >63-My-long clumped-isotope temperature (TΔ47) record of shallow-marine dolomicrites from two drillcores of the Ediacaran (635 to 541 Ma) Doushantuo Formation in South China. Our T∆47 record indicates that a majority (87%) of these dolostones formed at temperatures of <100 °C. When considering the regional thermal history, modeling of the influence of solid-state reordering on our TΔ47 record further suggests that most of the studied dolostones formed at temperatures of <60 °C, providing direct evidence of a low-temperature origin of these dolostones. Furthermore, calculated δ18O values of diagenetic fluids, rare earth element plus yttrium compositions, and petrographic observations of these dolostones are consistent with an early diagenetic origin in a rock-buffered environment. We thus propose that a precursor precipitate from seawater was subsequently dolomitized during early diagenesis in a near-surface setting to produce the large volume of dolostones in the Doushantuo Formation. Our findings suggest that the preponderance of dolomite in Paleozoic and Precambrian deposits likely reflects oceanic conditions specific to those eras and that dolostones can be faithful recorders of environmental conditions in the early oceans.

Sentinel-1 Image Classification Using Machine Learning Algorithms Based on the Support Vector Machine and Random Forest

Due to concerns of recent earth climate changes such as an increase of earth surface temperature and monitoring its effect on the earth's surface, environmental monitoring is a necessity. Environmental change monitoring in earth sciences needs land use land cover change (LULCC) modeling to investigate the impact of climate change phenomena such as droughts and floods on earth surface land cover. As land cover has a direct effect on Land Surface Temperature (LST), the Land cover mapping is an essential part of climate change modeling. In this paper, for land use land cover mapping (LULCM), image classification of Sentinel-1A Synthetic Aperture Radar (SAR) Ground Range Detected (GRD) data using two machine learning algorithms including Support Vector Machine (SVM) and Random Forest (RF) are implemented in R programming language and compared in terms of overall accuracy for image classification. With seven different scenarios defined in this research, RF and SVM classification methods show their best performance with overall accuracies of 75.30 and 75.35 percent, respectively.

Solar fraction used in water heating systems for south Brazilian climate changes scenarios

Solar thermal systems consist of water heating from the global solar radiation. Increasing atmospheric concentrations of greenhouse gases tend to increase the earth's surface temperature. The main objective of this work was to estimate the solar fraction obtained by means of solar heating systems for dwellings, for eight locations in the State of Paraná, in scenarios of possible climate changes projected until the end of the 21st century. F-Chart method was used to simulate the performance of solar heating systems based on the monthly average of solar radiation data, which determines the annual solar fraction or percentage of the energy demand that is covered by the solar installation. The results showed that with the impact of the climate changes, the decrease in the percentage of energy demand average that is covered by the solar installation was on average 14.3%, for both scenarios. The simulated values showed a slight decrease trend of radiation data and an increase of the solar fraction. All localities presented a characteristic seasonal behavior, with annual values of solar fraction between 82.4 and 129.8%, according to the studied localities. In relation to the monthly solar fraction, the values between November and March presented averages of solar fraction between 104 and 147.2%. But from May to August, the percentage of energy demand served by the solar installation does not reach the totality, with values between 53.6 and 99.9%. The results prove that the State of Parana has favorable climatic conditions for the installation of solar heating systems, even if it is installed for aggregation purposes, in order to reduce the electric power consumption.

Which was the habitat of early Eocene planktic foraminifer Chiloguembelina? Stable isotope paleobiology from the Atlantic Ocean and implication for paleoceanographic reconstructions

The planktic foraminiferal genus Chiloguembelina is characterized by tiny test and biserial disposition of chambers. Largely accepted ecological interpretation ascribes biserial planktic foraminifera as eutrophic and low-oxygen tolerant forms inhabiting the Oxygen Minimum Zone (OMZ). However, this ecological interpretation does not agree with all available data from Cenozoic record. Actually, chiloguembelinid stable isotope paleobiology is highly variable through time and space as it indicates mixed-layer habitat on earliest Eocene, middle Eocene and Late Oligocene but thermocline habitat during middle Eocene from northwest Atlantic Ocean. However, chiloguembelinid stable-isotope data were so far lacking from the early Eocene. This interval includes the early Eocene Climatic Optimum (EECO, ~53–48 Ma) that is the crucial time when Earth's surface temperatures and pCO2 reached their maximum levels in the Cenozoic. We present here new chiloguembelinid oxygen and carbon stable-isotope data from early Eocene Atlantic Ocean Drilling Program (ODP) Sites 1051, 1258, 1263 and 690. We also generate new data on Chiloguembelina abundance from Site 1051 and compare our record with those previously published from sites 1263 and 1258 in order to correlate the early Eocene paleoceanographic distribution of this genus through the Atlantic Ocean. Interestingly, Chiloguembelina became virtually absent at the beginning of the EECO in the subtropical, equatorial and temperate Atlantic sites. Our findings clearly prove that early Eocene Chiloguembelina occupied a deep-water niche throughout the Atlantic Ocean as demonstrated by its stable isotope signature close to the deep-dweller Subbotina and benthic foraminifera. These evidences provide critical paleoceanographic implications suggesting that intermediate water temperatures probably rose significantly during the EECO thus becoming too warm for this genus. Elevated ocean temperatures enhanced the rate of bacterial respiration and remineralization significantly thus resulting in more efficient recycling of nutrients higher in the water column. This would have induced a restricted food supply deeper in the thermocline and cut out the chiloguembelinid niche. The agreement of the observed decline in abundance of chiloguembelinids at the study sites with recently published foraminifera-bound nitrogen isotope data suggests that enhanced oxygenation of the thermocline in the early EECO might have also played a major role in driving the disappearance of chiloguembelinids, which in itself represent a new evidence for the largely accepted view that these forms inhabited the OMZ. Very likely a combination of reduced food supply, increase in thermocline temperature and oxygen content resulted in the decline of chiloguembelinids in the early EECO.

Inversion of thermal conductivity and heat flow from borehole temperature data affected by recent variation in ground surface temperature

We inverted the thermal conductivity of earth material, heat flow, and ground surface temperature (GST) history from borehole temperature data obtained at the carbon dioxide capture and storage demonstration project site in Tomakomai, Japan, by Bayesian inverse analysis. Past GST change that had disturbed the underground temperature was treated as a heat source in inversion analysis to determine thermal conductivity of the earth material from borehole temperature and underground structure data. The inverted past GST change suggested an increase of GST by 3 K from 1800 to the present. The inverted thermal conductivity of the earth material appeared to correspond to lithology in the borehole. The inverted heat flow was consistent with those measured around the site. To invert these model parameters from borehole temperature data, underground structure data are required. For inverse analysis of borehole temperature data without underground structure data, we propose a simple method for inferring underground structure related to thermal conductivity of the earth material and report the effectiveness of this method for the inversion of model parameters from borehole temperature data only.

Sensoriamento Remoto aplicado à análise do fenômeno de Ilhas de Calor Urbano na cidade de Vitória, Espírito Santo

O crescente desenvolvimento das cidades sem o devido planejamento ambiental e urbano resultou no aumento da temperatura nas grandes cidades. Um dos principais fenômenos causados por esse aquecimento são as chamadas ilhas de calor urbano, que interferem no clima local e no conforto térmico. Além de outros fatores, a má distribuição de áreas verdes na cidade contribui para o aumento desse fenômeno. Portanto, o objetivo desse artigo é analisar a Temperatura de Superfície Terrestre (TST) e relacionar com cobertura vegetal por meio do Índice de Vegetação por Diferença Normalizada (NDVI) na cidade de Vitória, ES. Inicialmente foram obitidas as imagens orbitais, sensores OLI, (Operational Land Imager) e TIRS10 (Thermal Infrared Sensor) do Landsat 8 em United States Geological Survey (USGS) – órbita 215 e ponto 74. As imagens escolhidas para esse estudo é de 16/05/2013. Verificou-se a relação direta do vigor da biomassa (NDVI) e da urbanização com valores de temperatura de superfície e as ilhas de calor urbano na cidade de Vitória. Os ambientes que apresentaram menores valores de NDVI, com exceção o oceano, apresentaram maiores valores de temperatura, expondo a importância da vegetação para o clima urbano.

Global warming & climate change: integration of socio-scientific issues to enhance scientific literacy

Global warming and climate change are some of the greatest socio-scientific issues in recent decades. Many factors contribute to these issues, the footprint of human activities as well as natural phenomena. Human energy consumption in many sectors i.e food supply, livestock, industry, and transportation significantly increasing earth surface temperature average level and climate change. Various studies were carry out about global warming and climate change interdisciplinary. Integration of these socio-scientific issues into science learning as an effort to educate and enhance student environmental awareness and scientific literacy is necessary to do. Rational of this article is to studies global warming and climate change topics from integrative science context; biology (microbial activities, ruminants, and environmental impacts), chemistry (the various chemical reaction that causes greenhouse gases and global warming), and physics (temperature, heat, and global climate). This study is urgent because microbial activities that contribute into greenhouse gases releasing in ruminant enteric fermentation process haven’t included and connected yet in Indonesia’s science learning. Ruminant should be highlighted in these issues because Indonesia is an agricultural country which has enormous farmhouse area. In addition, students are expected to be able to solve problems and make the right decisions related to these issues. This article will discuss suggestion global warming and climate change topics in terms of microbial activities, ruminant and mitigation strategies to reduce GHG from livestock sector. This suggestion is expected to meet the Sustainable development goals.

Análise temporal da temperatura de superfície obtida por sensoriamento remoto

É crescente a preocupação com o aumento da temperatura que vem ocasionando diversos impactos à fauna e flora, neste sentindo, dados de sensoriamento remoto (SR) tem sido amplamente utilizados para a aquisição de informações sobre a temperatura da superfície terrestre. Portanto, o estudo objetivou correlacionar os dados de temperatura de uma estação automática da Companhia Ambiental do Estado de São Paulo (Cetesb), localizada no município de Sorocaba com os dados obtidos remotamente por meio do processamento digital de imagens do satélite Landsat-8 OLI entre os anos de 2013 a 2017. Para o processamento das imagens foi utilizado o software ArcGIS 10.4.1, utilizando os parâmetros fixos de conversão de níveis de cinza da imagem para radiância e posterior conversão dos dados em valores de temperatura. Para verificar a variação dos dados obtidos por SR comparados a estação de monitoramento, foi verificada a Raiz do Erro Quadrático Médio (REQM), coeficiente de correlação Pearson (r) e o índice de concordância (IC). Os valores obtidos de REQM indicam uma variação média de temperatura de 2,74 ºC, corroborando com os valores de r² igual a 0,664 que indicam que 66,4 % dos valores obtidos para a temperatura remotamente são diretamente relacionados aos valores obtidos na estação de monitoramento da Cetesb, apresentando valores de IC com concordância positiva de 0,88. Portanto, os resultados encontrados se mostraram satisfatórios para uma melhor aquisição de valores de temperatura obtidos remotamente indicando boa correlação com os dados obtidos pela estação de monitoramento da Cetesb.

Development of computational fluid dynamics model for two initial CO2 concentration in circulating fluidized bed reactor

Nowadays, the global warming is considered as a world problem because it influences the environment by increasing the average temperature of earth surface. One of the greenhouse gases that release from human activities and fossil fuels combustion in industry is CO2. Several technologies are applied to reduce the CO2 emission to atmosphere. In this study, the aim is to capture the CO2 by solid sorbent adsorption with potassium carbonate supported on gamma alumina using full loop circulating fluidized bed reactor in commercial computational fluid dynamics program, ANSYS FLUENT. This study focuses on the effect of initial CO2 concentrations from cement industry and power plant on CO2 removal efficiency. Besides, the solid volume fraction profile is also considered. The simulation results showed the hydrodynamics in circulating fluidized bed reactor that the solid sorbent was high at the reactor wall and low at the reactor center. In addition, the independent input variables were investigated which were percentage of K2CO3 loading on sorbent and gas velocity. The increasing of K2CO3 loading on sorbent and the decreasing of gas velocity increased the CO2 capture efficiency.

Assimilation of Low-Peaking Satellite Observations Using the Coupled Interface Framework

Abstract Coupled data assimilation (DA) provides a consistent framework for assimilating satellite observations that are sensitive to several components of the Earth system. In this paper, we focus on low-peaking infrared satellite channels that are sensitive to the lower atmosphere and Earth surface temperature (EST) over both ocean and land. Our atmospheric hybrid-4DVAR system [the Navy Global Environmental Model (NAVGEM)] is extended to include the following: 1) variability in the sea surface temperature (both diurnal variability and climatological perturbations to the ensemble members), 2) the coupled Jacobians of the radiative transfer model for the infrared sensors, and 3) the coupled covariances between the EST and the atmosphere. Our coupling approach is found to improve forecast accuracy and to provide corrections to the EST that are in balance with the atmospheric analysis. The largest impact of the coupling is found on near-surface atmospheric temperature and humidity in the tropics, but the impact extends all the way to the stratosphere. The role of each coupling element on the performance of the global atmospheric circulation model is investigated. Inclusion of variability in the sea surface temperature has the strongest positive impact on the forecast quality. Additional inclusion of the coupled Jacobian and ensemble-based coupled covariances led to further improvements in scores and to modification of the corrections to the ocean boundary layer. Coupled DA had significant impact on latent and sensible heat fluxes over land, locations of western boundary currents, and along the ice edge.

Cosmic Expansion: The Dynamic Force Source for All Planetary Tectonic Movements

In this paper, the relationship between the geodynamics and cosmic expansion is analyzed and demonstrated from the basic physical principles and various natural phenomena, and the conclusion is drawn that cosmic expansion is the dynamic force source of all planetary tectonic movements in the universe. The energy for the formation and change of landscape and the energy of earthquakes and volcanic eruptions all come from the cosmic expansion. With the cosmic expansion, the energy density of space is decreasing, the atoms and molecules of all matter in the universe are growing, and the magma is expanding and producing gases. As the earth’s internal pressure rises, the mechanical energy that accumulates within the magma forms the driving force of the earth’s various tectonic movements, and the release of these energy and matter (expansive magma and high-pressure gases) leads to the formation and the changes of the landform (such as orogenesis, epeirogenesis, the formation of the earth’s plates, the Earth expansion, the seafloor spreading, and the continental drift), as well as to earthquakes and volcanic eruptions. In this paper, the causes of all kinds of earthquakes, especially deep focus earthquakes, are given and almost all known seismic phenomena are explained, the basic principle and method of earthquake prediction are given, and the direction is pointed out for the elimination of earthquakes and the utilization of earthquake energy. Based on the same principle of physics, this paper also shows that the Ice-Age is caused by the acceleration of the speed of the motion of the solar system relative to the Milky Way in certain regions of the Milky Way. The greater the speed of the solar system relative to the Milky Way, the greater the drop in Earth surface temperature.

Probable Cold and Alkaline Surface Environment of the Hadean Earth Caused by Impact Ejecta Weathering

AbstractConstraining the surface environment of the early Earth is essential for understanding the origin and evolution of life. The release of cations from silicate weathering depends on climatic temperature and , and such cations sequester into carbonate minerals in or on the seafloor, providing a stabilizing feedback on climate. Previous studies have suggested that this carbonate‐silicate cycle can keep the early Earth's surface temperature moderate by increasing to compensate for the faint young Sun. However, the Hadean Earth experienced a high meteorite impactor flux, which produced ejecta that is easily weathered by carbonic acid. In this study, we estimated the histories of surface temperature and ocean pH during the Hadean and early Archean using a new model that includes the weathering of impact ejecta, empirically justified seafloor weathering, and ocean carbonate chemistry. We find that relatively low and surface temperatures are probable during the Hadean, for example, at 4.3 Ga, (in bar) is and temperature is K. Such a low would result in a circumneutral to basic pH of seawater, for example, at 4.3 Ga. A probably cold and alkaline marine environment is associated with a high impact flux. Hence, if there was an interval of an enhanced impact flux, that is, Late Heavy Bombardment, similar conditions may have existed in the early Archean. Therefore, if the origin of life occurred in the Hadean, life likely emerged in a cold global environment and probably spread into an alkaline ocean.

Comparison of the greenhouse effect between Earth and Venus using multiple atmospheric layer models

To better understand the mechanisms of global warming, we developed a one atmospheric layer model for Earth and a multiple atmospheric layer model (N = 111) for Venus. Earth’s greenhouse gas atmosphere has an average of 78.9% absorption efficiency of terrestrial radiation (f = 0.789), while we assume Venus’ atmosphere has a near 100% absorption efficiency (f = 1) due to its denser, CO2-rich atmosphere. Viewing the atmospheric layers as blackbodies, we modeled the surface temperature of Earth and Venus, both of which are able to predict the respective actual planetary temperatures. The consistency (δ &lt; 1%) between the modeled surface temperature and the observed surface temperature of these two planets suggest that the multiple layer greenhouse gas atmosphere mechanism could explain Venus’ runaway global warming and scorching temperature. The results of these two models suggest that if Earth continues to experience uncontrolled greenhouse gas emissions, global warming and its negative outcomes may be further exacerbated.