Anthropogenic Era Research Articles

Risk assessment and seasonal variation of atmospheric ammonia in Ondo State, Nigeria

The environment is impacted by atmospheric ammonia (NH3) in a number of ways, including the global nitrogen cycle, ecology, and the production of secondary particles. Our findings present an unparalleled depiction of the temporal and geographical properties of atmospheric NH3 in and around this megacity, based on long-term, continuous measurements of NH3 at various locations in Ondo State. The increase in atmospheric ammonia during this anthropogenic era is believed to pose a significant threat to humanity, with scientists linking it to a rise in global warming and climate change. KP-826 multiple gas detector was used to investigate ammonia gas in five locations within Ondo state and its correlation with meteorological parameters was examined in this study. The selection of Dumpsite, Cattle rearing farm and Poultry farm was purposeful because of their involvement in the production of ammonia gas. The mean concentration of NH3 (ppm) during wet season was 3.87 ± 1.60 and for dry season was 5.87 ± 1.60. The mean temperature (°C) in wet conditions is 32.51 ± 1.27, which is a little lower than the mean (33.51 ± 1.25) in dry conditions. The mean wind speed (in m/s) during wet conditions is 1.21 ± 0.32, which is greater than the mean wind speed (in m/s) during dry conditions of 1.11 ± 0.32. The mean value of humidity for wet situations is 72.08 ± 2.31, which is a little lower than the mean value for dry conditions, which is 76.07 ± 2.31. This work evaluated the potential health risks associated with NH3. The total hazard quotient (THQ) for adult was 1.30 × 10–6 for children 1.50 × 10–6. The children's HQ ranged from 2.41 to 4.15. The adult's ranged from 8.70 to 15.13. However, it was discovered that the health risk posed by breathing in atmospheric NH3 was far higher than the USEPA limits, where HQ > 1.

Socioeconomic prerequisites determine national long-term biomonitoring efforts

In the current anthropogenic era characterised by human-induced environmental changes, long-term biomonitoring has become a crucial component for understanding ecological patterns and detecting shifts in biodiversity. However, spatiotemporal inconsistencies in biomonitoring efforts hinder transboundary progress in understanding and mitigating global environmental change effectively. The International Long-Term Ecosystem Research (ILTER) network is one of the largest standardised biomonitoring initiatives worldwide, encompassing 44 countries globally, including 26 European countries that are part of the European Long-Term Ecosystem Research network (eLTER). To better understand the establishment and development of such long-term biomonitoring efforts, we analysed spatial and temporal trends within the eLTER network. Additionally, we evaluated the environmental, social, and economic factors influencing engagement in biomonitoring activities within this European network. Our findings reveal a spatial imbalance, with biomonitoring efforts concentrated in Central and Western European countries, where monitoring initiatives have typically been established for a longer duration. Furthermore, our analyses underscore the complex interplay of economic, geographic, and cultural factors in the development of long-term ecological research infrastructures. Countries with greater geographic connectivity, slower economic growth, and higher research activity are more likely to be involved in the eLTER network. The intensity of biomonitoring significantly increased with greater research investments, economic growth, and elevated levels of tourism. In contrast, it decreased in countries that are more inward-facing and exhibit a belief in their ability to control environmental outcomes independently. Addressing spatial gaps in monitoring necessitates enhanced support and funding to ensure comprehensive ecological monitoring over extended time periods. This is essential for achieving transboundary sustainability and effective biodiversity conservation in the face of global change drivers.

Contribution to Environmental Perchlorate by Stratospheric Volcanic Eruptions

AbstractPerchlorate in the environment originates from both natural and anthropogenic sources. A previous study of a 300‐year Greenland ice core perchlorate record found that anthropogenic impact on environmental perchlorate became significant starting around 1980, while natural formation is the only significant source of environmental perchlorate prior to that. The study also found increased perchlorate deposition in the Arctic following certain volcanic eruptions and suggested that at least some volcanic eruptions could enhance natural perchlorate production. Here we compare the perchlorate record with the volcanic record from sulfate in the same Greenland ice core and find that only stratospheric eruptions—large eruptions injecting volcanic substances directly into the stratosphere—enhance perchlorate production. No contribution to naturally formed perchlorate is detected from non‐stratospheric eruptions. The high‐resolution ice core perchlorate data are used to quantify contributions from volcanic eruptions, non‐volcanic natural processes, as well as from human activities during different periods. For the location in the Arctic in the perchlorate Pre‐Anthropogenic Era (1701–1979), the magnitude (0.26 μg m−2 yr−1 on average) of perchlorate produced during sporadic stratospheric eruptions is comparable to that (0.23 μg m−2 yr−1) produced by non‐volcanic natural processes. In the Anthropogenic Era (1980–2006), the magnitude of both the volcanic and non‐volcanic natural perchlorate production is similar to the enhancement (0.29 μg m−2 yr−1) by human activities.

Hydrological model skills change with drought severity; insights from multi-variable evaluation

Hydrological models often do not properly simulate streamflow (Q) during extreme events, including droughts. Limited abilities in simulating Q during droughts may arise from a misrepresentation of Q generating processes during these periods, but little research has focused on distributed, process-based models over human-affected areas and extreme events. To shed more light into model consistency during these periods, we evaluated the ability of the hydrological model Continuum in simulating Q over the human-affected Po river basin in Italy during droughts of different severity over the last 13 years, including the severe 2022 event. To investigate the causes for potential model deterioration during severe droughts, we assessed the simulation of evapotranspiration (ET) and Terrestrial Water Storage (TWS) against independent remote sensing-based benchmarks, and possible inconsistencies in forcing and benchmark data. Finally, we included a moderate drought in the calibration period, as potential strategy to improve model performances during severe droughts. The model represented well Q (KGE = 0.81 for the outlet of the basin), ET (r = 0.94) and TWS (r = 0.76) over the whole study period. Focusing on Q and specific sub-periods, model performances were comparable during wet years (2014 and 2020) and moderate droughts (2012 and 2017), with KGE across the 38 study sub-catchments of 0.59±0.32 (mean ±standard deviation) during wet years and 0.55±0.25 during moderate droughts. The model simulated Q well for the outlet section of the basin also during the severe 2022 drought (KGE = 0.82). However, performances across the sub-catchments declined in 2022 (KGE = 0.18±0.69). For the severe drought, we detected a decrease in model performances for ET, in particular over human-affected croplands (mean decrease in r by 105% and mean increase in nRMSE by 86%). Furthermore, calibrating during a moderate drought did not improve model performances in 2022 (KGE = 0.18±0.63), pointing to the fairly unique conditions of this period in terms of hydrological processes and human interference on them. Our study highlighted decreased model skills specifically during a severe drought and identified the neglection of irrigation as the most plausible cause for this. Given projected increases in severe droughts and the frequent modelling simplification of human activities, despite their heavy interference in many regions, our findings are highly relevant to move towards more robust hydrological modelling in a changing climate and the Anthropogenic era, to support management and adaptation strategies.

Reading The Book of Jonah through the Eco-Spiritual Perspective

Whether one chooses to acknowledge or disregard its significance, nature has always been part of us. In an anthropogenic era, the dire state of the environment has made it an increasingly concerning topic of discussion among us. Nature has been extensively examined in numerous scholarly discussions ranging from secular to religious perspectives. This paper examines how nature plays a crucial role in helping us understand the relationship between God and humans, as portrayed in the Bible. The Bible being a religious text exists with very specific purposes. That being said, elements of nature were also used very specifically in the Bible. Most presently available scholarly research focuses on reading the significance of nature elements from religious perspectives. However, this research employs the eco-spirituality theory to examine the book of Jonah from the Bible to determine the relationship between Jonah, God, and nature. Through this secular perspective, the aim is to show that elements of nature have been carefully woven into narratives to signify various meanings. Furthermore, this research aims to identify how God communicates with humans through nature, which eventually helps to establish various forms of relationships between humans and nature. Through these newly formed relationships, we can understand the authority of a Creator and the consequences of obedience and submission. All these highlight the importance of co-existence between humans and nature, and examining the Bible through the lens of eco-spirituality perpetuates the relevance of the Bible to 21st-century readers.

Risk and resilience in a changing climate: a diachronic analysis in the press across the globe

AbstractBuilding on our previous work investigating discourses of climate-induced mobility in the UK and US press, this paper addresses the overarching theme of environmental issues and the anthropocene by looking into representations of migration as adaptation in the context of climate change. In particular, drawing on corpus-assisted discourse analysis methodologies, the paper will focus on, and critically explore, meaning patterns of “risk” and “resilience” in a purpose-built diachronic corpus of quality newspapers from the Global North and the Global South between 2010 and 2017. Risk and resilience may in fact be regarded as the defining – though problematic – terms of our anthropogenic era. The investigation focuses on whether and how any significant discursive shifts may be identified in newspaper discourse across the globe and the extent to which the mainstream press reflects this problematicity. Our main findings show that not only is mention of risk more frequent in the Global North throughout than in the Global South media outlets, whereas the opposite is observed for resilience, but also that distinct meaning patterns emerge over time across the different areas of the world under investigation.

Lacustrine leaf wax hydrogen isotopes indicate strong regional climate feedbacks in Beringia since the last ice age

The Late-Quaternary climate of Beringia remains unresolved despite the region's role in modulating glacial-interglacial climate and as the likely conduit for human dispersal into the Americas. Here, we investigate Beringian temperature change using an ∼32,000-year lacustrine record of leaf wax hydrogen isotope ratios (δ2Hwax) from Arctic Alaska. Based on Monte Carlo iterations accounting for multiple sources of uncertainty, the reconstructed summertime temperatures were ∼3 °C colder (range: −8 to +3 °C) during the Last Glacial Maximum (LGM; 21-25 ka) than the pre-industrial era (PI; 2–0.1 ka). This ice-age summer cooling is substantially smaller than in other parts of the Arctic, reflecting altered atmospheric circulation and increased continentality which weakened glacial cooling in the region. Deglacial warming was punctuated by abrupt events that are largely synchronous with events seen in Greenland ice cores that originate in the North Atlantic but which are also controlled locally, such as by the opening of the Bering Strait between 13.4 and 11 ka. Our reconstruction, together with climate modeling experiments, indicates that Beringia responds more strongly to North Atlantic freshwater forcing under modern-day, open-Bering Strait conditions than under glacial conditions. Furthermore, a 2 °C increase (Monte Carlo range: −1 to +5 °C) over the anthropogenic era reverses a 6 °C decline (Monte Carlo range: −10 to 0 °C) through the Holocene, indicating that recent warming in Arctic Alaska has not surpassed peak Holocene summer warmth.

Contemporary systematics of vadose zone nitrate capture by speleothem carbonate

The movement of nitrate through the vadose zone has major implications for environmental and human health. This issue is particularly prevalent in karst terrain where agricultural activity, thin soils and dual permeability compound the problem of high nitrate loading to the overlying ecosystem. However, a paucity of records which document vadose zone nitrate concentrations prior to the 21st century render legacy nitrate dynamics, source attribution and baseline conditions to be poorly parameterised. Speleothems growing within karst cave settings may provide an opportunity to obtain records of vadose zone nitrate contamination which extend throughout the anthropogenic era. Here, we use dual isotope analysis of δ15NNO3 and δ18ONO3 in a contemporary study at Cueva-cubío del Llanío, N. Spain, designed to examine the transformation of nitrate between surface to cave environment, taking account of biogeochemical transformation, karst hydrology and partitioning as controls on the delivery of nitrate to the speleothem record. Concentrations of nitrate within speleothem calcite are low (measured range of 0.05 mM to 0.37 mM) due to partitioning (DNO3) across the dripwater-calcite interface. Values of δ15NNO3 extracted from cave waters in Cueva-cubío del Llanío (range +2.0 to +7.0‰) are shown to be excellent indicators of nitrate source and demonstrate no fractionation during incorporation into speleothem carbonate (range of δ15NNO3 in speleothem carbonate +1.6‰ to +6.4‰). Values of δ18ONO3 contained within cave waters (range −2.5‰ to +6.0‰) and speleothem carbonate (range +12.3‰ to +32.3‰) reflect a mixed signal of source, biogeochemical processing and hydrological pathway, providing critical insight into the behaviour of the karst aquifer. Contemporary systematics at Cueva-cubío del Llanío therefore confirm speleothem carbonate contains an excellent record of vadose zone nitrate. Analysis of nitrate contained within speleothem carbonate from other regions confirms the ubiquitous nature of partitioning across the water‑carbonate interface and the use of speleothem nitrate isotopes for recording surface ecosystem processes and vadose zone behaviour. Application of these principles to dated speleothem records should provide critical timeseries of nitrate loading, enabling understanding and remediation against the presence of vadose zone legacy nitrate.

Destination Anthropocene: Science and Tourism in The Bahamas by Amelia Moore

Reviewed by: Destination Anthropocene: Science and Tourism in The Bahamas by Amelia Moore Matthew Lauer Amelia Moore, Destination Anthropocene: Science and Tourism in The Bahamas. Oakland: University of California Press, 2019. 216 pp. During a boisterous academic conference in the late 1990s Paul Crutzen, an atmospheric chemist, made an off-the-cuff comment that we no longer live in the Holocene, but have entered the age of humans and are living in the Anthropocene geologic epic. The scientists were reviewing the growing evidence that human beings had fundamentally altered the geologic record to the extent that they could now declare that we had entered a new geologic anthropogenic era. Although defining this new geohistorical period continues to be controversial within geology, the concept has overrun its original boundaries, capturing the attention of scientists across the social and natural sciences as well as the humanities. In her lively and highly readable book, Amelia Moore explores the Anthropocene not as a concept to be contemplated or debated, but its effects in a particulate locale—the Bahamas. Rather than detailing Bahamian environmental degradation, the loss of species, or efforts to mitigate sea level rise, she instead describes how the idea of the Anthropocene has propelled the rise of "Global Change Science" (GCS), a burgeoning conglomeration of natural and social science disciplines focused on characterizing anthropologic change occurring to the earth system. She then asks a provocative question: What are the effects of GCS knowledge and practice in the lives of Bahamians? To answer this, Moore adeptly draws on series a of ethnographic accounts highlighting GCS field work at sites across the Bahamas. We learn that GCS researchers are descending on the islands in increasing [End Page 181] numbers, herself included, to document their environmental fragility as anthropogenic pressures mount. In each case she explores the intersection of GCS knowledge and the Bahamian tourist industry. The Bahamas, of course, have a long history as a global tourism destination. With its gorgeous coastlines, idyllic beaches, and close geographic proximity to the United States, tourism has formed the basis of the islands' economy for decades. In Moore's account, she details how the tourist industry has adeptly repositioned the islands' imaginary over time to attract tourists. The most recent form of repackaging involves leveraging GCS scientific discoveries and concepts into profitable tourist attractions. Thus a paradox lies at the heart of what Moore calls "Anthropocene tourism" (21): as GCS attempts to understand and protect critical habitats and threatened species on the island, the tourism industry capitalizes on their knowledge and practices to attract more tourists and perpetuate the damaging anthropogenic effects of the tourism industry. In the opening chapter, which also serves as the now requisite ethnographic "entrance story," Moore provides a personal and nuanced account from the frontlines of GCS research in action. Moore was introduced to the Bahamas as an undergraduate student employed by an interdisciplinary funded GCS project. As a ground-level field researcher conducting pilot surveys in a rural fishing community, she describes ethnographically how concepts such as "individual," "stakeholder," "livelihood," and the "social" tend to be produced rather than explained by GCS research. More broadly, she makes that point that GCS conceives of sociality in specific ways that enables its legibility. "Local people" people are framed as objects that need to be enumerated and described rather than project collaborators or knowledge producers who can contribute their own insights. Armed with "social" data, her project was also tasked with providing scientific input into the placement of marine protected areas (MPAs). The project was a means to validate environmental management in the region, which in this case was the creation of an MPA suitable for marine tourism. Moore's account uniquely contributes to the literature about the impacts of MPAs by suggesting that they not only extend the state apparatus, including tourism interests, but also the reach of GCS research itself. The second chapter, "Educational Islands," describes another manifestation of the Anthropocene: the entangling of science, tourism, and education. Here we become acquainted with a small island where a defunct, large-scale hotel was converted into an elite high school academy that [End Page 182] trains mainly US students in environmental science and...

Morphodynamic couplings between the Biandan Shoal and Xinqiao Channel, Changjiang (Yangtze) Estuary

Channel-shoal systems (CSS) are some of the significant morphodynamic cells in estuaries, which provide immeasurable economic, ecological and environmental value. However, most CSS in mega-estuaries of the world are facing great challenges from serious risk of degradation due to intensive human activities and sea-level rise. Here, we focus on the tradeoff between the Biandan Shoal (BDS) and Xinqiao Channel (XQC), which is the largest CSS of the South Branch, Changjiang Estuary. The results show that the BDS area above the 5 m water depth had an observable increasing tendency with an interannual increasing rate of 1.43 km2/yr during 1996–2016. The corresponding XQC volume exhibited an obvious reduction trend with an annual decreasing rate of 3.79 × 106 m3/yr. Meanwhile, the BDS presented lateral and downward extension with more than 4.7 km of downward movement, while the XQC indicated shrinking with the width of the upper reaches decreasing by nearly half since 1998. Furthermore, the morphodynamic evolution of the BDS-XQC system during 1998–2016 could be divided into four stages: preflood stage with the joint extension of the BDS and XQC (1996–1998); conversion stage due to impacts from the extreme flood (1998–2000); development stage with obvious deposition throughout the system (2000–2009); stabilization stage with deposition on the high flats but no lateral expansion of the BDS, and continuous shrinkage of the XQC (2009–2016). The dynamic balance of the BDS-XQC system was mainly determined by the tradeoffs between the BDS and XQC, even though the occasional extreme hydrological events disrupted the coupling of the BDS-XQC. Meanwhile, the local channel blocked by the construction of the Dongfengxisha Reservoir induced a decrease in water discharge into the XQC, which was responsible for the recent XQC recession. In light of the impact of future climate change and increasing human interference in the anthropogenic era, fragile CSS distributed in estuaries should be holistically considered with policies to support sustainable integrated coastal zone management.

Revised records of atmospheric trace gases CO<sub>2</sub>, CH<sub>4</sub>, N<sub>2</sub>O, and <i>δ</i><sup>13</sup>C-CO<sub>2</sub> over the last 2000 years from Law Dome, Antarctica

Abstract. Ice core records of the major atmospheric greenhouse gases (CO2, CH4, N2O) and their isotopologues covering recent centuries provide evidence of biogeochemical variations during the Late Holocene and pre-industrial periods and over the transition to the industrial period. These records come from a number of ice core and firn air sites and have been measured in several laboratories around the world and show common features but also unresolved differences. Here we present revised records, including new measurements, performed at the CSIRO Ice Core Extraction LABoratory (ICELAB) on air samples from ice obtained at the high-accumulation site of Law Dome (East Antarctica). We are motivated by the increasing use of the records by the scientific community and by recent data-handling developments at CSIRO ICELAB. A number of cores and firn air samples have been collected at Law Dome to provide high-resolution records overlapping recent, direct atmospheric observations. The records have been updated through a dynamic link to the calibration scales used in the Global Atmospheric Sampling LABoratory (GASLAB) at CSIRO, which are periodically revised with information from the latest calibration experiments. The gas-age scales have been revised based on new ice-age scales and the information derived from a new version of the CSIRO firn diffusion model. Additionally, the records have been revised with new, rule-based selection criteria and updated corrections for biases associated with the extraction procedure and the effects of gravity and diffusion in the firn. All measurements carried out in ICELAB–GASLAB over the last 25 years are now managed through a database (the ICElab dataBASE or ICEBASE), which provides consistent data management, automatic corrections and selection of measurements, and a web-based user interface for data extraction. We present the new records, discuss their strengths and limitations, and summarise their main features. The records reveal changes in the carbon cycle and atmospheric chemistry over the last 2 millennia, including the major changes of the anthropogenic era and the smaller, mainly natural variations beforehand. They provide the historical data to calibrate and test the next inter-comparison of models used to predict future climate change (Coupled Model Inter-comparison Project – phase 6, CMIP6). The datasets described in this paper, including spline fits, are available at https://doi.org/10.25919/5bfe29ff807fb (Rubino et al., 2019).

Human influence on the temporal dynamics and spatial distribution of forest biomass carbon in China.

Global carbon cycles are impacted by human activity primarily via fossil fuel combustion and forest carbon budget alterations. In this study, the temporal dynamics and spatial distribution of forest biomass carbon (FBC) stock and density in China were analyzed to assess the large‐scale effects of humans on FBC. The results indicated that from 1977 to 2013, the FBC stock increased by 62.9%, from 4,335 to 7,064 Tg C, owing to human‐driven forestation and ecological restoration programs. Because of intensive human impacts, 44.2%–54.6% of the FBC stock was concentrated in four provinces (Heilongjiang, Yunnan, Inner Mongolia, and Sichuan) and the FBC density increased from the densely populated southeastern provinces to the sparsely populated northeastern and western provinces. On a spatial scale, the FBC density was significantly negatively related to population density, and the degree of the dependence of the FBC density on population density has been declining since 1998. This improvement in human–forest relations is related to economic development and programs in China that have promoted forestation and reduced deforestation. These results suggest that human impacts, including forestation, deforestation, population density, and economic development, have played significant roles in determining the temporal and spatial variations of FBC in the anthropogenic era. Moreover, our findings have implications for forest management and improvement of the forest carbon sink in China.

Cognate and cognitive ecopharmacognosy — in an anthropogenic era

The vibrant future of pharmacognosy is discussed in terms of sustainable development. The future role of biologically active natural products is presented with respect to the time and consciousness required to contemplate the continuing future strategies for ecopharmacognosy to be impactful. Integration of allied sciences and technologies through regulatory harmonization, international collaboration, and translation of holistic quality control techniques to manufacturers, is essential to achieve higher levels of quality, safe, effective, and consistent (QSEC) traditional medicine products in global primary health care. Structured and highly focused research and development initiatives are needed to address chasmal gaps in global health care, particularly in light of ongoing changes in climate and the implications for disease demographics.

Increased threat of tropical cyclones and coastal flooding to New York City during the anthropogenic era

In a changing climate, future inundation of the United States' Atlantic coast will depend on both storm surges during tropical cyclones and the rising relative sea levels on which those surges occur. However, the observational record of tropical cyclones in the North Atlantic basin is too short (A.D. 1851 to present) to accurately assess long-term trends in storm activity. To overcome this limitation, we use proxy sea level records, and downscale three CMIP5 models to generate large synthetic tropical cyclone data sets for the North Atlantic basin; driving climate conditions span from A.D. 850 to A.D. 2005. We compare pre-anthropogenic era (A.D. 850-1800) and anthropogenic era (A.D.1970-2005) storm surge model results for New York City, exposing links between increased rates of sea level rise and storm flood heights. We find that mean flood heights increased by ∼1.24 m (due mainly to sea level rise) from ∼A.D. 850 to the anthropogenic era, a result that is significant at the 99% confidence level. Additionally, changes in tropical cyclone characteristics have led to increases in the extremes of the types of storms that create the largest storm surges for New York City. As a result, flood risk has greatly increased for the region; for example, the 500-y return period for a ∼2.25-m flood height during the pre-anthropogenic era has decreased to ∼24.4 y in the anthropogenic era. Our results indicate the impacts of climate change on coastal inundation, and call for advanced risk management strategies.

Dendroclimatic studies: tree growth and climate change in northern forests

Preface v Acknowledgments vii 1. Introduction 1 1.1. Overview 1 1.2. Basic Tree-Ring Principles 1 1.3. Polar Amplification of Global Warming and Impacts on Forests 3 1.4. ?Northern Archive? Synthesis 6 2. Tree-Ring Investigations at Northern Latitudes 7 2.1. Initial Studies 7 2.2. Site Selection 8 2.3. Tree-Ring Parameters and Processing: Ring Width and Maximum Latewood Density 9 3. Selected Local to Regional TRL-LDEO Northern Tree-Ring Studies 13 4. The Broader Context of Northern Dendroclimatic Studies 19 4.1. North America 19 4.2. Eurasia 21 4.3. Tree-Ring Chronology Networks 21 5. Temperature Reconstructions for the Northern Hemisphere 23 5.1. Initial Attempts 23 5.2. Evolution of NH Temperature Reconstructions 25 5.3. Reconstructed NH Temperature Trends 31 5.4. Standardization of NH Tree-Ring Temperature Reconstructions 33 6. Tree Growth Issues in the Anthropogenic Era: CO2 Fertilization and the ?Divergence Problem? 37 6.1. CO2 Fertilization 37 6.2. The Divergence Problem 38 7. Conclusions and Future Challenges 43 Glossary 51 References 57 Core TRL-LDEO Publications on Northern Forests 67 Index 75 Color plate section is located between pages 36 and 37.

The Soil Health-Human Health Nexus

Soils can beneficially or adversely affect human health, and likewise human activity can improve or destroy soil health. In the new anthropogenic era, it is worth examining the soil health–human health nexus. To do this, the author evaluates soil from the perspective of what infects us, what heals us, what contaminates us, what nourishes us, and what we breathe. Likewise, the author examines the impact of humans on soil using a similar matrix and suggests strategies to improve human health by maintaining or improving soil health.

Towards Sustainability of the Earth System

Earth system is endowed with unique characteristics and geophysical conditions to support life [1] and ecosystem services. Its ecological and social subsystems, individual processes, and their interactions forming the earth system determine the fate of biota and humans [2]. While the earth system has survived for billions of years, the Holocene era has seen unprecedented impacts from an anthropogenic influences [3], some have called this an anthropogenic era [4]. Climate change and rapid resource use to feed the burgeoning population are changing the nature and stability of the earth system. Current levels of human impacts can inadvertently alter the earth system in ways that it may prove irreversible [5]. Some examples of these impacts are Atlantic thermohaline circulation, Amazon forest dieback, and decay of Greenland ice sheet [6]. Continuation of status quo levels of resource use and environmental impacts without consideration of system limits [7] can lead to unsustainable trajectories of the earth system. The need to understand and work within the limits imposed by natural systems for achieving growth is a major emphasis in achieving sustainability of the earth system. This reflects the equilibrium that is within the boundaries of ecosystem services and the carrying capacity [8] of the earth system. The socioeconomic activities for human well-being need to balance with conservation of life support systems provided by the earth system.

Effects of syn-pandemic fire reduction and reforestation in the tropical Americas on atmospheric CO 2 during European conquest

A new reconstruction of Late Holocene biomass burning in the tropical Americas is consistent with the expansion of fire use by Mesoamerican and Amazonian agriculturalists and a subsequent period of fire reduction beginning ∼ 500 years BP. The marked reduction of biomass burning after ∼ 500 years BP, a unique feature of the fire history of the tropical Americas relative to other regions of the globe, is synchronous with the collapse of the American indigenous population during pandemics accompanying European conquest. We predict that fire reduction contemporaneous with pandemics in the tropical Americas was associated with massive forest regeneration on ∼ 5 × 10 5 km 2 of land and sequestration of 5–10 Gt C into the terrestrial biosphere, which contributed to the ∼ 2% global reduction in atmospheric CO 2 levels and the 0.1‰ increase in δ 13C of atmospheric CO 2 from 1500 to 1750 A.D. This study 1) builds upon prior fire history reconstructions by synthesizing a substantially greater number of stratigraphic charcoal accumulation records and soil charcoal 14C dates to resolve features of the Late Holocene biomass burning record in the tropical Americas; and 2) corroborates the hypothesis advanced by Ruddiman [Ruddiman, W.F., 2003. The Anthropogenic Era began thousands of years ago. Climatic Change 61, 261–293, Ruddiman, W.F., 2005. Plows, Plagues, and Petroleum. Princeton University Press, Princeton, New Jersey] that biospheric carbon sequestration via reforestation of cropland abandoned during pandemics contributed to changes in atmospheric CO 2 concentration during the past millennium.

What Drives the Climate: Man or Nature?

Traditionally, human-environment interactions are discussed in terms of the influence of climatic changes and catastrophes on civilizations (Battarbee et al., 2004; Yasuda and Shinde, 2004). Recently, a hypothesis suggesting the onset of the “anthropogenic greenhouse era” about 8 ka ago as a result of forest clearance and agriculture was proposed to explain the pre-industrial rise in CO2 and CH4 concentrations (Ruddiman, 2003; see also PAGES News 2004/1). Consequently, man was deemed the “rescuer” of the Earth from a new Ice Age, otherwise predicted at about 4 ka ago. Opponents of this hypothesis argued that natural forces were responsible for the pre-industrial increase in greenhouse gases (Broecker and Clark, 2003, Joos et al., 2004). These contradictory views and the current discussion they have provoked (Claussen et al. 2005; Crucifix et al. 2005; Ruddiman, 2005; Broecker and Stocker, 2005) are far more than a scholastic debate with only theoretical value. We regard integrative palynological and archeological studies in combination with modeling as a promising path towards a better understanding of the mechanisms and forces driving the Holocene climate. This understanding is crucial for reliable projections of climate in the future.

Commentary on “The Anthropogenic Greenhouse Era Began Thousands of Years Ago”

Bill Ruddiman (Climatic Change, 61, 261-293, 2003) recently suggested that early civilisations could have saved us from an ice age because land management over substantial areas caused an increase in atmospheric CO2 concentration. Ruddiman suggests a decreasing "natural course" of the Holocene greenhouse gases concentrations and sea-level by referring to analogous situations in the past, namely the last three interglacials. An examination of marine isotopic stage 11 would perhaps make Ruddiman's argument even more thought-challenging. Yet, the hypothesis of a natural lowering of CO2 during the Holocene contradicts recent numerical simulations of the Earth carbon cycle during this period. We think that the only way to resolve this conflict is to properly assimilate the palaeoclimate information in numerical climate models. As a general rule, models are insufficiently tested with respect to the wide range of climate situations that succeeded during the Pleistocene. In this comment, we present three definitions of palaeoclimate information assimilation with relevant examples. We also present original results with the Louvain-la-Neuve climate-ice sheet model suggesting that if, indeed, the Holocene atmospheric CO2 increase is anthropogenic, a late Holocene glacial inception is plausible, but not certain, depending on the exact time evolution of the atmospheric CO2 concentration during this period.