Half Of Earth Research Articles

In situ experimental evidences for responses of abyssal benthic biota to shifts in phytodetritus compositions linked to global climate change

Abyssal plains cover more than half of Earth's surface, and the main food source in these ecosystems is phytodetritus, mainly originating from primary producers in the euphotic zone of the ocean. Global climate change is influencing phytoplankton abundance, productivity, and distribution. Increasing importance of picoplankton over diatom as primary producers in surface oceans (especially projected for higher latitudes) is projected and hence altering the quantity of organic carbon supplied to the abyssal seafloor as phytodetritus, consequences of which remain largely unknown. Here, we investigated the in situ responses of abyssal biota from viruses to megafauna to different types of phytoplankton input (diatoms or cyanobacteria which were labeled with stable isotopes) at equatorial (oligotrophic) and temperate (eutrophic) benthic sites in the Pacific Ocean (1°N at 4277 m water depth and 39°N at 5260 m water depth, respectively). Our results show that meiofauna and macrofauna generally preferred diatoms as a food source and played a relatively larger role in the consumption of phytodetritus at higher latitudes (39°N). Contrarily, prokaryotes and viruses showed similar or even stronger responses to cyanobacterial than to diatom supply. Moreover, the response of prokaryotes and viruses was very rapid (within 1–2 days) at both 1°N and 39°N, with quickest responses reported in the case of cyanobacterial supply at higher latitudes. Overall, our results suggest that benthic deep‐sea eukaryotes will be negatively affected by the predicted decrease in diatoms in surface oceans, especially at higher latitudes, where benthic prokaryotes and viruses will otherwise likely increase their quantitative role and organic carbon cycling rates. In turn, such changes can contribute to decrease carbon transfer from phytodetritus to higher trophic levels, with strong potential to affect oceanic food webs, their biodiversity and consequently carbon sequestration capacity at the global scale.

Сильные землетрясения земного шара во II полугодии 2020 г. по данным ФИЦ ЕГС РАН

The data on the seismicity of the Earth in the second half of 2020 at the level of strong earthquakes with magnitudes mb≥6.0 are given according to the data of the Alert Service of the Geophysical Survey RAS. The review also includes information on 54 tangible earthquakes in Russia and five earthquakes in adjacent territories that were felt in the settlements of the Russian Federation. Two of 67 strong earthquakes of the Earth with mb≥6.0 for the period under consideration were registered in the territory of Russia. For 15 strong earthquakes, the Alert Service published Information Messages within one or two days after their occurrence, for 14 earthquakes the information on focal mechanisms is provided. The strongest earthquake of the Earth with MS=7.9 occurred on July, 22 in the region of the Alaska Peninsula. The maximum human casualties and material damage during the study period were the result of the catastrophic intraplate earthquake with MS=6.8, which occurred on October, 30 in the Aegean Sea, near the Samos Island. As a result of the earthquake, 117 people died, 1054 were injured. The strongest earthquake on the territory of Russia was the deep-focus one with mb=6.4, which took place on November, 30 in the Tatar Strait, separating Sakhalin Island from continental Eurasia. The crustal Bystrinsk earthquake on September, 21 with MS=5.2, which occurred in the area of Lake Baikal, was felt with a maximum intensity I=6–7 on the territory of Russia. Comparative analysis of the rate of seismic energy released in the Globe in 2010-2020 showed that its value in the second half of 2020, as well as for 2019-2020 on average, is one of the lowest for the eleven-year period and indicates a seismic calm, which should be replaced by a period of intensification of global seismic and deformation processes

Half of Earth’s Nitrogen May Be Homegrown

A new analysis of iron meteorites reveals a distinct isotopic signature that suggests nitrogen was present around early Earth.

Vulnerability of global biodiversity hotspots to climate change

AbstractMotivationMore than half of Earth's species are contained in a mere 1.4% of its land area, but the climates of many of these biodiversity hotspots are projected to disappear as a consequence of anthropogenic climate change. There is growing recognition that spatio‐temporal patterns of climate in biodiversity hotspots have shaped biological diversity over a variety of historical time‐scales, yet these patterns are rarely taken into account in assessments of the vulnerability of biodiversity hotspots to future climate change. In our review, we synthesize the climatic processes that have led to the diversification of hotspots and interpret what this means in the context of anthropogenic climate change. We demonstrate the importance of mesoclimatic processes and fine‐scale topographical heterogeneity, in combination with climatic variability, in driving speciation processes and maintaining high levels of diversity. We outline why these features of hotspots are crucial to understanding the impacts of anthropogenic climate change and discuss how recent advances in predictive modelling enable vulnerability to be understood better.LocationGlobal.Main conclusionsWe contend that many, although not all, biodiversity hotspots have climate and landscape characteristics that create fine‐scale spatial variability in climate, which potentially buffers them from climatic changes. Temporally, many hotspots have also experienced stable climates through evolutionary time, making them particularly vulnerable to future changes. Others have experienced more variable climates, which is likely to provide resilience to future changes. Thus, in order to identify risk for global biodiversity, we need to consider carefully the influence of spatio‐temporal variability in climate. However, most vulnerability assessments in biodiversity hotspots are still reliant on climate data with coarse spatial and temporal resolution. Higher‐resolution forecasts that account for spatio‐temporal variability in climate and account better for the physiological responses of organisms to this variability are much needed to inform future conservation strategies.

Analysis of Developmental Chronology of South Korean Compressed Growth as a Reference from Sustainable Development Perspectives

Global challenges including overpopulation, climate change, and income inequality have increased, and a demand for sustainability has emerged. Decision-making for sustainable development is multifaceted and interlinked, owing to the diverse interests of different stakeholders and political conflicts. Analysing a situation from all social, political, environmental, and economic perspectives is necessary to achieve balanced growth and facilitate sustainable development. South Korea was among the poorest countries following the Korean War; however, it has developed rapidly since 1955. This growth was not limited to economic development alone, and the chronology of South Korean development may serve as a reference for development in other countries. Here, we explore the compressed growth of South Korea using a narrative approach and time-series, comparative, and spatial analyses. Developmental indicators, along with the modern history of South Korea, are introduced to explain the reasons for compressed growth. The development of the mid-latitude region comprising 46 countries in this study, where nearly half of Earth’s population resides, was compared with that of South Korea; results show that the developmental chronology of South Korea can serve as a reference for national development in this region.

Identification of protected areas under the "Half Earth" target: Based on main global conservation priorities

Identification of protected areas under the "Half Earth" target: Based on main global conservation priorities

Сильные землетрясения земного шара и России в I полугодии 2020 г. по данным ФИЦ ЕГС РАН

The data on the seismicity of the Earth in the first half of 2020 at the level of strong earthquakes with mb6 are presented according to the Earthquake Early Alert Service (EEAS) of the Geo-physical Survey RAS. The review also includes information on weaker but destructive earth-quakes in the world and tangible earthquakes in Russia. In total, 64 earthquakes with mb6 were registered in the first half of the year, including four events in Russia. For 18 strong earthquakes, the EEAS published Informational messages within one or two days after their occurrence, for 16 of them the information on focal mechanisms was given. A comparative analysis of the seismic energy released in the territory of the Globe showed that in the first half of 2020 its amount corresponds to the average values for the last three years. The strongest earthquakes with MS=7.7 occurred on January 28 in the Caribbean Sea and on June 23 in Mexico, accompanied by fore- and aftershocks. The largest human casualties and material damage during the study period were caused by the catastrophic earthquake with MS=6.6 that occurred on January 24 in Turkey. As a result of the earthquake, 41 people died, 1607 were injured. On the territory of Russia, the strongest earthquake with MS=7.5 occurred on March 25 east of the Kuril Islands and was felt in Severo-Kurilsk with an intensity Ii=5–6. A total of 47 tangible earthquakes with mb=3.6–7.2 were recorded in Russia.

The hysteresis of the Antarctic Ice Sheet.

More than half of Earth's freshwater resources are held by the Antarctic Ice Sheet, which thus represents by far the largest potential source for global sea-level rise under future warming conditions1. Its long-term stability determines the fate of our coastal cities and cultural heritage. Feedbacks between ice, atmosphere, ocean, and the solid Earth give rise to potential nonlinearities in its response to temperature changes. So far, we are lacking a comprehensive stability analysis of the Antarctic Ice Sheet for different amounts of global warming. Here we show that the Antarctic Ice Sheet exhibits a multitude of temperature thresholds beyond which ice loss is irreversible. Consistent with palaeodata2 we find, using the Parallel Ice Sheet Model3-5, that at global warming levels around 2 degrees Celsius above pre-industrial levels, West Antarctica is committed to long-term partial collapse owing to the marine ice-sheet instability. Between 6 and 9 degrees of warming above pre-industrial levels, the loss of more than 70 per cent of the present-day ice volume is triggered, mainly caused by the surface elevation feedback. At more than 10 degrees of warming above pre-industrial levels, Antarctica is committed to become virtually ice-free. The ice sheet's temperature sensitivity is 1.3 metres of sea-level equivalent per degree of warming up to 2 degrees above pre-industrial levels, almost doubling to 2.4 metres per degree of warming between 2 and 6 degrees and increasing to about 10 metres per degree of warming between 6 and 9 degrees. Each of these thresholds gives rise to hysteresis behaviour: that is, the currently observed ice-sheet configuration is not regained even if temperatures are reversed to present-day levels. In particular, the West Antarctic Ice Sheet does not regrow to its modern extent until temperatures are at least one degree Celsius lower than pre-industrial levels. Our results show that if the Paris Agreement is not met, Antarctica's long-term sea-level contribution will dramatically increase and exceed that of all other sources.

Dynamical Instabilities in Systems of Multiple Short-period Planets Are Likely Driven by Secular Chaos: A Case Study of Kepler-102

We investigated the dynamical stability of high-multiplicity Kepler and K2 planetary systems. Our numerical simulations find instabilities in ~ 20% of the cases on a wide range of timescales (up to 5×109 orbits) and over an unexpectedly wide range of initial dynamical spacings. To identify the triggers of long-term instability in multi-planet systems, we investigated in detail the five-planet Kepler-102 system. Despite having several near-resonant period ratios, we find that mean motion resonances are unlikely to directly cause instability for plausible planet masses in this system. Instead, we find strong evidence that slow inward transfer of angular momentum deficit (AMD) via secular chaos excites the eccentricity of the innermost planet, Kepler-102 b, eventually leading to planet-planet collisions in ~ 80% of Kepler-102 simulations. Kepler-102 b likely needs a mass ≳ 0.1M ⊕, hence a bulk density exceeding about half Earth's, in order to avoid dynamical instability. To investigate the role of secular chaos in our wider set of simulations, we characterize each planetary system's AMD evolution with a "spectral fraction" calculated from the power spectrum of short integrations (~ 5 × 106 orbits). We find that small spectral fractions (≲ 0.01) are strongly associated with dynamical stability on long timescales (5 × 109 orbits) and that the median time to instability decreases with increasing spectral fraction. Our results support the hypothesis that secular chaos is the driver of instabilities in many non-resonant multi-planet systems, and also demonstrate that the spectral analysis method is an efficient numerical tool to diagnose long term (in)stability of multi-planet systems from short simulations.

The state of rock debris covering Earth’s glaciers

Rock debris can accumulate on glacier surfaces and dramatically reduce glacier melt. The structure of a debris cover is unique to each glacier and sensitive to climate. Despite this, debris cover has been omitted from global glacier models and forecasts of their response to a changing climate. Fundamental to resolving these omissions is a global map of debris cover and an estimate of its future spatial evolution. Here we use Landsat imagery and a detailed correction to the Randolph Glacier Inventory to show that 7.3% of mountain glacier area is debris covered and over half of Earth’s debris is concentrated in three regions: Alaska (38.6% of total debris-covered area), Southwest Asia (12.6%) and Greenland (12.0%). We use a set of new metrics, which include stage, the current position of a glacier on its trajectory towards reaching its spatial carrying capacity of debris cover, to quantify the state of glaciers. Debris cover is present on 44% of Earth’s glaciers and prominent (>1.0 km2) on 15%. Of Earth’s glaciers, 20% have a substantial percentage of debris cover for which the net stage is 36% and the bulk of individual glaciers have evolved beyond an optimal moraine configuration favourable for debris-cover expansion. Use of this dataset in global-scale models will enable improved estimates of melt over 10.6% of the global glacier domain. A global map of rock-debris cover on mountain glaciers shows its spatial distribution and evolution.

The information catastrophe

Currently, we produce ∼1021 digital bits of information annually on Earth. Assuming a 20% annual growth rate, we estimate that after ∼350 years from now, the number of bits produced will exceed the number of all atoms on Earth, ∼1050. After ∼300 years, the power required to sustain this digital production will exceed 18.5 × 1015 W, i.e., the total planetary power consumption today, and after ∼500 years from now, the digital content will account for more than half Earth’s mass, according to the mass-energy–information equivalence principle. Besides the existing global challenges such as climate, environment, population, food, health, energy, and security, our estimates point to another singular event for our planet, called information catastrophe.

Global human influence maps reveal clear opportunities in conserving Earth's remaining intact terrestrial ecosystems.

Leading up to the Convention on Biological Diversity Conference of the Parties 15, there is momentum around setting bold conservation targets. Yet, it remains unclear how much of Earth's land area remains without significant human influence and where this land is located. We compare four recent global maps of human influences across Earth's land, Anthromes, Global Human Modification, Human Footprint and Low Impact Areas, to answer these questions. Despite using various methodologies and data, these different spatial assessments independently estimate similar percentages of the Earth's terrestrial surface as having very low (20%–34%) and low (48%–56%) human influence. Three out of four spatial assessments agree on 46% of the non‐permanent ice‐ or snow‐covered land as having low human influence. However, much of the very low and low influence portions of the planet are comprised of cold (e.g., boreal forests, montane grasslands and tundra) or arid (e.g., deserts) landscapes. Only four biomes (boreal forests, deserts, temperate coniferous forests and tundra) have a majority of datasets agreeing that at least half of their area has very low human influence. More concerning, <1% of temperate grasslands, tropical coniferous forests and tropical dry forests have very low human influence across most datasets, and tropical grasslands, mangroves and montane grasslands also have <1% of land identified as very low influence across all datasets. These findings suggest that about half of Earth's terrestrial surface has relatively low human influence and offers opportunities for proactive conservation actions to retain the last intact ecosystems on the planet. However, though the relative abundance of ecosystem areas with low human influence varies widely by biome, conserving these last intact areas should be a high priority before they are completely lost.

A Modified Spheromak Model Suitable for Coronal Mass Ejection Simulations

Abstract Coronal mass ejections (CMEs) are some of the primary drivers of extreme space weather. They are large eruptions of mass and magnetic field from the solar corona and can travel the distance between Sun and Earth in half a day to a few days. Predictions of CMEs at 1 au, in terms of both its arrival time and magnetic field configuration, are very important for predicting space weather. Magnetohydrodynamic modeling of CMEs, using flux rope-based models, is a promising tool for achieving this goal. In this study, we present one such model for CME simulations, based on spheromak magnetic field configuration. We have modified the spheromak solution to allow for independent input of poloidal and toroidal fluxes. The motivation for this is the possibility of estimating these fluxes from solar magnetograms and extreme ultraviolet data from a number of different approaches. We estimate the poloidal flux of CME using post-eruption arcades and toroidal flux from the coronal dimming. In this modified spheromak, we also have the option to control the helicity sign of flux ropes, which can be derived from the solar disk magnetograms using the magnetic tongue approach. We demonstrate the applicability of this model by simulating the 2012 July 12 CME in the solar corona.

How Can Remote Sensing Help Monitor Tropical Moist Forest Degradation?—A Systematic Review

In the context of the climate and biodiversity crisis facing our planet, tropical forests playing a key role in global carbon flux and containing over half of Earth’s species are important to preserve. They are today threatened by deforestation but also by forest degradation, which is more difficult to study. Here, we performed a systematic review of studies on moist tropical forest degradation using remote sensing and fitting indicators of forest resilience to perturbations. Geographical repartition, spatial extent and temporal evolution were analyzed. Indicators of compositional, structural and regeneration criteria were noted as well as remote sensing indices and metrics used. Tropical moist forest degradation is not extensively studied especially in the Congo basin and in southeast Asia. Forest structure (i.e., canopy gaps, fragmentation and biomass) is the most widely and easily measured criteria with remote sensing, while composition and regeneration are more difficult to characterize. Mixing LiDAR/Radar and optical data shows good potential as well as very high-resolution satellite data. The awaited GEDI and BIOMASS satellites data will fill the actual gap to a large extent and provide accurate structural information. LiDAR and unmanned aerial vehicles (UAVs) form a good bridge between field and satellite data. While the performance of the LiDAR is no longer to be demonstrated, particular attention should be brought to the UAV that shows great potential and could be more easily used by local communities and stakeholders.

Protecting half of the planet could directly affect over one billion people

In light of continuing global biodiversity loss, one ambitious proposal has gained considerable traction amongst conservationists: the goal to protect half the Earth. Our analysis suggests that at least one billion people live in places that would be protected if the Half Earth proposal were implemented within all ecoregions. Taking into account the social and economic impacts of such proposals is central to addressing social and environmental justice concerns, and assessing their acceptability and feasibility. Recently, ecologists have begun discussing an idea for setting aside half of the Earth for conservation purposes. This study provides some of the first analysis of the impacts of doing so on society, based on assumptions about ecoregions and human footprint.

To Conserve Nature in the Anthropocene, Half Earth Is Not Nearly Enough

To conserve the bulk of Earth’s ecological heritage across the Anthropocene, setting aside half of Earth’s land is just a start. To conserve biodiversity over the long term across an increasingly human planet, conservation must become as integral to the human enterprise around the world as are social and economic development.

Connectivity Dynamics in Dryland Litter Cycles: Moving Decomposition beyond Spatial Stasis

AbstractDrylands (arid and semiarid ecosystems) cover nearly half of Earth's terrestrial surface, but biogeochemical pools and processes in these systems remain poorly understood. Litter can account for a substantial portion of carbon and nutrient pools in these systems, with litter decomposition exerting important controls over biogeochemical cycling. Dryland decomposition is typically treated as a spatially static process in which litter is retained and decomposed where it is initially deposited. Although this assumption is reasonable for mesic systems with continuous plant canopy cover and a stable subcanopy litter layer, dryland pools generally reflect discontinuous inputs from heterogeneous canopy cover followed by substantial litter transport. In the present article, we review horizontal and vertical transport processes that move litter from the initial deposition point and retention elements that influence litter accumulation patterns. Appreciation of the spatially dynamic litter cycle, including quantitative assessment of transport patterns, will improve estimates of the fate and distribution of organic matter in current and future drylands.

Changes in the Active, Dead, and Dormant Microbial Community Structure across a Pleistocene Permafrost Chronosequence.

Permafrost hosts a community of microorganisms that survive and reproduce for millennia despite extreme environmental conditions, such as water stress, subzero temperatures, high salinity, and low nutrient availability. Many studies focused on permafrost microbial community composition use DNA-based methods, such as metagenomics and 16S rRNA gene sequencing. However, these methods do not distinguish among active, dead, and dormant cells. This is of particular concern in ancient permafrost, where constant subzero temperatures preserve DNA from dead organisms and dormancy may be a common survival strategy. To circumvent this, we applied (i) LIVE/DEAD differential staining coupled with microscopy, (ii) endospore enrichment, and (iii) selective depletion of DNA from dead cells to permafrost microbial communities across a Pleistocene permafrost chronosequence (19,000, 27,000, and 33,000 years old). Cell counts and analysis of 16S rRNA gene amplicons from live, dead, and dormant cells revealed how communities differ between these pools, how they are influenced by soil physicochemical properties, and whether they change over geologic time. We found evidence that cells capable of forming endospores are not necessarily dormant and that members of the class Bacilli were more likely to form endospores in response to long-term stressors associated with permafrost environmental conditions than members of the Clostridia, which were more likely to persist as vegetative cells in our older samples. We also found that removing exogenous "relic" DNA preserved within permafrost did not significantly alter microbial community composition. These results link the live, dead, and dormant microbial communities to physicochemical characteristics and provide insights into the survival of microbial communities in ancient permafrost.IMPORTANCE Permafrost soils store more than half of Earth's soil carbon despite covering ∼15% of the land area (C. Tarnocai et al., Global Biogeochem Cycles 23:GB2023, 2009, https://doi.org/10.1029/2008GB003327). This permafrost carbon is rapidly degraded following a thaw (E. A. G. Schuur et al., Nature 520:171-179, 2015, https://doi.org/10.1038/nature14338). Understanding microbial communities in permafrost will contribute to the knowledge base necessary to understand the rates and forms of permafrost C and N cycling postthaw. Permafrost is also an analog for frozen extraterrestrial environments, and evidence of viable organisms in ancient permafrost is of interest to those searching for potential life on distant worlds. If we can identify strategies microbial communities utilize to survive in permafrost, it may yield insights into how life (if it exists) survives in frozen environments outside of Earth. Our work is significant because it contributes to an understanding of how microbial life adapts and survives in the extreme environmental conditions in permafrost terrains.

Half Earth or Whole Earth: What Can Natura 2000 Teach Us?

The call to set aside half of Earth's surface for nature conservation is gaining momentum across the conservation community. We propose that the experiences of Earth's most extensive conservation network, Natura 2000, offers important lessons on the challenges and opportunities of scaling up area-based conservation strategies. Natura 2000 has made unprecedented advances in implementing effective, evidence-based, internationally collaborative conservation policies and practices at continental scales. These advances have relied on strong governance frameworks, standardized policies, close integration of science and policy, flexibility in protection designations, a focus on conservation outside protected areas, economic interests and development, and the engagement and incentivization of stakeholders at different scales of reserve development and operation. Although failures and gaps remain, these hard-won lessons of Natura 2000 have much to offer those aiming to scale up conservation globally to meet the biodiversity challenges of the Anthropocene.

Towards Convivial Conservation

Environmental conservation finds itself in desperate times. Saving nature, to be sure, has never been an easy proposition. But the arrival of the Anthropocene - the alleged new phase of world history in which humans dominate the earth-system seems to have upped the ante dramatically; the choices facing the conservation community have now become particularly stark. Several proposals for revolutionising conservation have been proposed, including 'new' conservation, 'half Earth' and more. These have triggered heated debates and potential for (contemplating) radical change. Here, we argue that these do not take political economic realities seriously enough and hence cannot lead us forward. Another approach to conservation is needed, one that takes seriously our economic system's structural pressures, violent socio-ecological realities, cascading extinctions and increasingly authoritarian politics. We propose an alternative termed 'convivial conservation'. Convivial conservation is a vision, a politics and a set of governance principles that realistically respond to the core pressures of our time. Drawing on a variety of perspectives in social theory and movements from around the globe, it proposes a post-capitalist approach to conservation that promotes radical equity, structural transformation and environmental justice and so contributes to an overarching movement to create a more equal and sustainable world.