Showing papers in "Earth’s Future in 2021"

Identifying a Safe and Just Corridor for People and the Planet

Abstract: Keeping the Earth system in a stable and resilient state, to safeguard Earth's life support systems while ensuring that Earth's benefits, risks, and related responsibilities are equitably shared, constitutes the grand challenge for human development in the Anthropocene. Here, we describe a framework that the recently formed Earth Commission will use to define and quantify target ranges for a “safe and just corridor” that meets these goals. Although “safe” and “just” Earth system targets are interrelated, we see safe as primarily referring to a stable Earth system and just targets as being associated with meeting human needs and reducing exposure to risks. To align safe and just dimensions, we propose to address the equity dimensions of each safe target for Earth system regulating systems and processes. The more stringent of the safe or just target ranges then defines the corridor. Identifying levers of social transformation aimed at meeting the safe and just targets and challenges associated with translating the corridor to actors at multiple scales present scope for future work.

The Anthropocene: comparing its meaning in geology (chronostratigraphy) with conceptual approaches arising in other disciplines

Abstract: The term Anthropocene initially emerged from the Earth System science community in the early 2000s, denoting a concept that the Holocene Epoch has terminated as a consequence of human activities. First associated with the onset of the Industrial Revolution, it was then more closely linked with the Great Acceleration in industrialization and globalization from the 1950s that fundamentally modified physical, chemical, and biological signals in geological archives. Since 2009, the Anthropocene has been evaluated by the Anthropocene Working Group, tasked with examining it for potential inclusion in the Geological Time Scale. Such inclusion requires a precisely defined chronostratigraphic and geochronological unit with a globally synchronous base and inception, with the mid-twentieth century being geologically optimal. This reflects an Earth System state in which human activities have become predominant drivers of modifications to the stratigraphic record, making it clearly distinct from the Holocene. However, more recently, the term Anthropocene has also become used for different conceptual interpretations in diverse scholarly fields, including the environmental and social sciences and humanities. These are often flexibly interpreted, commonly without reference to the geological record, and diachronous in time; they often extend much further back in time than the mid-twentieth century. These broader conceptualizations encompass wide ranges and levels of human impacts and interactions with the environment. Here, we clarify what the Anthropocene is in geological terms and compare the proposed geological (chronostratigraphic) definition with some of these broader interpretations and applications of the term “Anthropocene,” showing both their overlaps and differences. Plain Language Summary The Anthropocene concept, that modern human impacts on Earth have been sufficient to bring in a new geological epoch, is only two decades old. In that short time, its use has grown explosively, not only in the Earth sciences but also far more widely to spread through the sciences generally, to spill over into the social sciences, arts, and humanities. This has led to welcome discussions between diverse scholarly communities, though also to some very different interpretations of the Anthropocene, when interpreted through different disciplinary lenses. Notably, the geological ZALASIEWICZ ET AL. © 2021. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. The Anthropocene: Comparing Its Meaning in Geology (Chronostratigraphy) with Conceptual Approaches Arising in Other Disciplines Jan Zalasiewicz , Colin N. Waters , Erle C. Ellis , Martin J. Head , Davor Vidas , Will Steffen, Julia Adeney Thomas, Eva Horn, Colin P. Summerhayes , Reinhold Leinfelder , J. R. McNeill, Agnieszka Gałuszka , Mark Williams, Anthony D. Barnosky , Daniel de B. Richter, Philip L. Gibbard , Jaia Syvitski , Catherine Jeandel , Alejandro Cearreta , Andrew B. Cundy , Ian J. Fairchild , Neil L. Rose , Juliana A. Ivar do Sul , William Shotyk, Simon Turner , Michael Wagreich , and Jens Zinke Geography, Geology and the Environment, University of Leicester, Leicester, UK, Geography & Environmental Systems, University of Maryland, Baltimore, MD, USA, Earth Sciences, Brock University, St. Catharines, ON, Canada, The Fridtjof Nansen Institute, Lysaker, Norway, Fenner School of Environment and Society, The Australian National University, Canberra, Australia, History, University of Notre Dame, South Bend, IN, USA, German Studies, University of Vienna, Vienna, Austria, Scott Polar Research Institute, University of Cambridge, Cambridge, UK, Geological Sciences, Freie Universität, Berlin, Germany, Department of History, Georgetown University, Washington, DC, USA, Institute of Chemistry, Jan Kochanowski University, Kielce, Poland, Jasper Ridge Biological Preserve and Department of Biology, Stanford University, Stanford, CA, USA, Nicholas School of the Environment, Duke University, Durham, NC, USA, Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA, LEGOS, Université de Toulouse, CNES, CNRS, IRD, Toulouse, France, Geología, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, Bilbao, Spain, Ocean and Earth Science, University of Southampton, National Oceanography Centre (Southampton), Southampton, UK, School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK, Geography, University College London, London, UK, Leibniz Institute for Baltic Sea Research Warnemüende (IOW), Rostock, Germany, Renewable Resources, University of Alberta, Edmonton, AB, Canada, Geology, University of Vienna, Vienna, Austria Key Points: • The Anthropocene concept developed in the Earth System science community is closely consistent with its proposed chronostratigraphic (geological) definition • A wide range of other meanings of the Anthropocene subsequently emerged that represent inherently valid, but partly different, concepts • Cross-disciplinary discussion is encouraged to help resolve issues of meaning and communication in this important area

Event-Based Storylines to Address Climate Risk

Abstract: The climate science community is challenged to adopt an actionable risk perspective, which is difficult to align with the traditional focus on model-based probabilistic climate change projections. Event-based storylines can provide a way out of this conundrum by putting emphasis on plausibility rather than probability. This links directly to common practices in disaster risk management using “stress-testing” for emergency preparedness based on events that are conditional on specific and plausible assumptions. Event-based storylines allow for conditional explanations, without full attribution of every causal factor, which is crucial when some aspects of the latter are complex and highly uncertain.

Guidelines for Studying Diverse Types of Compound Weather and Climate Events

Abstract: Compound weather and climate events are combinations of climate drivers and/or hazards that contribute to societal or environmental risk. Studying compound events often requires a multidisciplinary approach combining domain knowledge of the underlying processes with, for example, statistical methods and climate model outputs. Recently, to aid the development of research on compound events, four compound event types were introduced, namely (1) preconditioned, (2) multivariate, (3) temporally compounding, and (4) spatially compounding events. However, guidelines on how to study these types of events are still lacking. Here, we consider four case studies, each associated with a specific event type and a research question, to illustrate how the key elements of compound events (e.g., analytical tools and relevant physical effects) can be identified. These case studies show that (1) impacts on crops from hot and dry summers can be exacerbated by preconditioning effects of dry and bright springs. (2) Assessing compound coastal flooding in Perth (Australia) requires considering the dynamics of a non-stationary multivariate process. For instance, future mean sea-level rise will lead to the emergence of concurrent coastal and fluvial extremes, enhancing compound flooding risk. (3) In Portugal, deep-landslides are often caused by temporal clusters of moderate precipitation events. Finally, (4) crop yield failures in France and Germany are strongly correlated, threatening European food security through spatially compounding effects. These analyses allow for identifying general recommendations for studying compound events. Overall, our insights can serve as a blueprint for compound event analysis across disciplines and sectors.

TROPOMI NO2 in the United States: A Detailed Look at the Annual Averages, Weekly Cycles, Effects of Temperature, and Correlation With Surface NO2 Concentrations.

Abstract: Observing the spatial heterogeneities of NO2 air pollution is an important first step in quantifying NOX emissions and exposures. This study investigates the capabilities of the Tropospheric Monitoring Instrument (TROPOMI) in observing the spatial and temporal patterns of NO2 pollution in the continental United States. The unprecedented sensitivity of the sensor can differentiate the fine-scale spatial heterogeneities in urban areas, such as emissions related to airport/shipping operations and high traffic, and the relatively small emission sources in rural areas, such as power plants and mining operations. We then examine NO2 columns by day-of-the-week and find that Saturday and Sunday concentrations are 16% and 24% lower respectively, than during weekdays. We also analyze the correlation of daily maximum 2-m temperatures and NO2 column amounts and find that NO2 is larger on the hottest days (>32°C) as compared to warm days (26°C-32°C), which is in contrast to a general decrease in NO2 with increasing temperature at moderate temperatures. Finally, we demonstrate that a linear regression fit of 2019 annual TROPOMI NO2 data to annual surface-level concentrations yields relatively strong correlation (R2 = 0.66). These new developments make TROPOMI NO2 satellite data advantageous for policymakers and public health officials, who request information at high spatial resolution and short timescales, in order to assess, devise, and evaluate regulations.

The COVID-19 Pandemic not only Poses Challenges, but also Opens Opportunities for Sustainable Transformation

Abstract: The COVID-19 pandemic has affected humankind worldwide, slowing down and even reversing the progress made in achieving Sustainable Development Goals (SDGs). It has negatively impacted most SDGs but...

Past Variance and Future Projections of the Environmental Conditions Driving Western U.S. Summertime Wildfire Burn Area.

Abstract: Increases in vapor pressure deficit (VPD) have been hypothesized as the primary driver of future fire changes. The Coupled Model Intercomparison Project Phase 5 (CMIP5) models agree that western U.S. surface temperatures and associated dryness of air as defined by the VPD will increase in the 21st century for Representative Concentration Pathways (RCPs) 4.5 and 8.5. However, we find that averaged over seasonal and regional scales, other environmental variables demonstrated to be relevant to flammability, moisture abundances, and aridity-such as precipitation, evaporation, relative humidity, root zone soil moisture, and wind speed-can be used to explain observed variance in wildfire burn area as well or better than VPD. However, the magnitude and sign of the change of these variables in the 21st century are less certain than the predicted changes in VPD. Our work demonstrates that when objectively selecting environmental variables to maximize predictive skill of linear regressions (minimize square error on unseen data) VPD is not always selected and when it is not, the magnitude of future increases in burn area becomes less certain. Hence, this work shows that future burn area predictions are sensitive to what environmental predictors are chosen to drive burn area.

Risky Development: Increasing Exposure to Natural Hazards in the United States

Abstract: Losses from natural hazards are escalating dramatically, with more properties and critical infrastructure affected each year. Although the magnitude, intensity, and/or frequency of certain hazards has increased, development contributes to this unsustainable trend, as disasters emerge when natural disturbances meet vulnerable assets and populations. To diagnose development patterns leading to increased exposure in the conterminous United States (CONUS), we identified earthquake, flood, hurricane, tornado, and wildfire hazard hotspots, and overlaid them with land use information from the Historical Settlement Data Compilation data set. Our results show that 57% of structures (homes, schools, hospitals, office buildings, etc.) are located in hazard hotspots, which represent only a third of CONUS area, and ∼1.5 million buildings lie in hotspots for two or more hazards. These critical levels of exposure are the legacy of decades of sustained growth and point to our inability, lack of knowledge, or unwillingness to limit development in hazardous zones. Development in these areas is still growing more rapidly than the baseline rates for the nation, portending larger future losses even if the effects of climate change are not considered.

Cascading Hazards in the Aftermath of Australia's 2019/2020 Black Summer Wildfires

Abstract: Australia's 2019/2020 “Black Summer” fire season was exceptional in terms of the number of fires, burned area, and fire severity (Baldwin & Ross, 2020; Deb et al., 2020; Hughes et al., 2020). The fires followed an unprecedented drought; 2019 was the driest year on record (Hughes et al., 2020; van Oldenborgh et al., 2021). Throughout the continent, the fires caused direct damages to humans and ecosystems, including at least 33 directly fire-related deaths, 3,100 homes lost, an area of at least 24 million hectares burned—the size of the United Kingdom—, and never before seen air pollution levels in major cities (Davey & Sarre, 2020; Hughes et al., 2020; Royal Commission into National Natural Disaster Arrangements, 2020; Vardoulakis et al., 2020). The wildfires led to the formation of a record number of pyrocumulonimbus clouds that reached the lower stratosphere over southeastern Australia (Kablick III et al., 2020).

The Greater Mekong's climate-water-energy nexus: how ENSO-triggered regional droughts affect power supply and CO2 emissions

Abstract: The Greater Mekong Subregion is a transnational area bound together by the Mekong River basin and its immense hydropower resources, historically seen as the backbone of regional economic developmen...

Reduced Complexity Model Intercomparison Project Phase 2: Synthesizing Earth System Knowledge for Probabilistic Climate Projections

Abstract: Over the last decades, climate science has evolved rapidly across multiple expert domains. Our best tools to capture state-of-the-art knowledge in an internally self-consistent modeling framework are the increasingly complex fully coupled Earth System Models (ESMs). However, computational limitations and the structural rigidity of ESMs mean that the full range of uncertainties across multiple domains are difficult to capture with ESMs alone. The tools of choice are instead more computationally efficient reduced complexity models (RCMs), which are structurally flexible and can span the response dynamics across a range of domain-specific models and ESM experiments. Here we present Phase 2 of the Reduced Complexity Model Intercomparison Project (RCMIP Phase 2), the first comprehensive intercomparison of RCMs that are probabilistically calibrated with key benchmark ranges from specialized research communities. Unsurprisingly, but crucially, we find that models which have been constrained to reflect the key benchmarks better reflect the key benchmarks. Under the low-emissions SSP1-1.9 scenario, across the RCMs, median peak warming projections range from 1.3 to 1.7°C (relative to 1850-1900, using an observationally based historical warming estimate of 0.8°C between 1850-1900 and 1995-2014). Further developing methodologies to constrain these projection uncertainties seems paramount given the international community's goal to contain warming to below 1.5°C above preindustrial in the long-term. Our findings suggest that users of RCMs should carefully evaluate their RCM, specifically its skill against key benchmarks and consider the need to include projections benchmarks either from ESM results or other assessments to reduce divergence in future projections.

Heatwaves in Southeast Asia and Their Changes in a Warmer World

Abstract: Based on the observational dataset SA-OBS and model outputs from the Community Earth System Model Large Ensemble project, this study investigates heatwaves in Southeast Asia in the current and futu...

Uncertainty and Bias in Global to Regional Scale Assessments of Current and Future Coastal Flood Risk.

Abstract: © 2021. The Authors.This study provides a literature-based comparative assessment of uncertainties and biases in global to world-regional scale assessments of current and future coastal flood risks, considering mean and extreme sea-level hazards, the propagation of these into the floodplain, people and coastal assets exposed, and their vulnerability. Globally, by far the largest bias is introduced by not considering human adaptation, which can lead to an overestimation of coastal flood risk in 2100 by up to factor 1300. But even when considering adaptation, uncertainties in how coastal societies will adapt to sea-level rise dominate with a factor of up to 27 all other uncertainties. Other large uncertainties that have been quantified globally are associated with socio-economic development (factors 2.3–5.8), digital elevation data (factors 1.2–3.8), ice sheet models (factor 1.6–3.8) and greenhouse gas emissions (factors 1.6–2.1). Local uncertainties that stand out but have not been quantified globally, relate to depth-damage functions, defense failure mechanisms, surge and wave heights in areas affected by tropical cyclones (in particular for large return periods), as well as nearshore interactions between mean sea-levels, storm surges, tides and waves. Advancing the state-of-the-art requires analyzing and reporting more comprehensively on underlying uncertainties, including those in data, methods and adaptation scenarios. Epistemic uncertainties in digital elevation, coastal protection levels and depth-damage functions would be best reduced through open community-based efforts, in which many scholars work together in collecting and validating these data.

The Value of Urban Flood Modeling

Abstract: This material is based upon work supported by the National Science Foundation under Award Numbers SES 1444755 and 1934933. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The authors draw on discussions held during a virtual workshop of the National Science Foundation funded Urban Resilience to Extremes Sustainability Research Network on April 2, 2020. This workshop was attended by UREx researchers and practitioners representing 10 United States and Latin American cities.

Climate Warming Consistently Reduces Grassland Ecosystem Productivity

Abstract: This study was funded by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB40000000), the National Natural Science Foundation of China (NSFC 41722107), the Natural Science Foundation of Qinghai Province (2020-ZJ-726), and the Open Project of the Qinghai Provincial Key Laboratory of Restoration Ecology in Cold Area (2020-KF-07).

Widespread Race and Class Disparities in Surface Urban Heat Extremes Across the United States

Abstract: Here we use 1000-m satellite land surface temperature anomaly measurements to explore the distribution of the United States' urban heating burden, both at high resolution (within cities or counties) and at scale (across the whole contiguous United States). While a rich literature has documented neighborhood-level disparities in urban heat exposures in individual cities, data constraints have precluded comparisons across locations. Here, drawing on extreme summer urban heat measurements from all 1056 U.S. counties with more than 10 developed census tracts, we find that the poorest tracts (and those with lowest average education levels) within a county are significantly hotter than the richest (and more educated) neighborhoods for 76% of these counties (54\% for education); we also find that neighborhoods with higher Black, Hispanic, and Asian population shares are hotter than the more White, non-Hispanic areas in each county. This holds in counties with both large and small spreads in these population shares, and for 71% of all counties the significant racial urban heat disparities persist even when adjusting for income. Although individual locations have different histories that have contributed to race- and class-based geographies, we find that the physical features of the urban environments driving these heat exposure gradients are fairly uniform across the country. Systematically, the disproportionate heat exposures faced by minority communities are due to higher population density, more built-up neighborhoods, and less vegetation.

Fates and Use Efficiency of Nitrogen Fertilizer in Maize Cropping Systems and Their Responses to Technologies and Management Practices: A Global Analysis on Field N-15 Tracer Studies

Abstract: Nitrogen (N) fertilization has boosted grain production during the past century, while excess N fertilization with declining N use efficiency (NUE) has led to severe pollution in many regions. To achieve the goal of sustainable food production, Technologies and Management Practices (TMPs, e.g., optimum N application rate and methods, N-transformation inhibitors) have been developed to improve crop yield and NUE and to reduce N losses. However, it remains unclear how N fate has been changed by environmental factors and TMPs. Here, we compiled a dataset of 366 field 15N tracer observations from 74 publications worldwide and conducted a meta-analysis to examine how environmental conditions and management practices influence the fertilizer-N fate one growing season after the fertilization of maize. We show that the proportion of 15N taken up by aboveground biomass (NUE15N), was significantly lower in China (33%) than that in North America (42%) and the European Union (54%). Soil organic carbon was the most critical environmental factor positively correlated with NUE15N. Among the nine selected categories of TMPs, deep placement of fertilizer and split application increased the grain yield and decreased the fertilizer-N loss consistently among studies. Reducing the fertilizer-N rate could increase the NUE15N but presents risks of yield reduction in some regions. This study demonstrates the importance of SOC and varying impacts of TMPs on the efficiency of fertilizer use in cropping systems globally and provides critical information for farmers and policymakers to improve N management for higher productivity and less pollution.