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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Earth Rotation and Global Change

Global climate change, whether from natural or man-made causes, can be expected to lead to changes in the Earth's rotation. General Circulation Models (GCMs) of the atmosphere that have been used to study the effects of changes in the amount of atmospheric greenhouse gasses general predict the globally averaged temperature to increase by 1 degree to 4 degrees C during the next century. This temperature increase is not expected to occur uniformly over the globe, but should exhibit regional variations. This changing atmospheric temperature field will cause changes in the atmospheric wind field and hence in the atmospheric angular momentum (AAM). Since the angular momentum of the atmosphere-solid Earth system is conserved, a thermally-induced change in the AAM will cause consequent changes in the rotation of the solid Earth...

Dickey, J. O.↗
DOE OSTI2024

Editorial: Water supply sustainability and challenges in Asian megadeltas under global change

Globally, riverine deltas comprise barely 1% of land area, but they support the livelihoods of more than 500 million people (Moorhouse et al., 2021). The Asian megadeltas (e.g., Indus, Bengal, Mekong, Red River, and Yangtze) and their riverine floodplains are the most dynamic economic and environmental systems in the world. These low-lying coastal landforms support surface water bodies and highly productive aquifer systems. However, water resources of the Asian megadeltas are extremely vulnerable to geogenic (e.g., arsenic) and anthropogenic (e.g., bacteria) contamination, increased water salinisation from rising sea levels (Figure 1), and chemicals (e.g., fertilizers, pesticides) from land-use practices (Mukherjee et al., 2024) – all of which are threatening the sustainability of water supply and food security in the region. This Research Topic collection features five original articles that explore water chemistry including arsenic and bacteriological contamination, water salinisation, water-energy-food nexus in irrigated agriculture, and groundwater depletion resulting from irrigation, rapid urbanization, and climate change. Although the Research Topic collection does not include case studies from all the Asian Megadeltas shown in Figure 1, the relevance of multi-hazard driven water risks to all deltaic and river floodplain environments around the world is well-illustrated.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Aspen Global Change Institute: 25 Years of Interdisciplinary Global Change Science

Global environmental changes such as climate change result from the interaction of human and natural systems. Research to understand these changes and options for addressing them requires the physical, environmental, and social sciences, as well as engineering and other applied fields. In this essay, we describe how the Aspen Global Change Institute (AGCI) has provided leadership in global change science over the past 25 years—in particular how it has contributed to the integration of the natural and social sciences needed to research the drivers of change, Earth system response, natural and human system impacts, and options for risk management. We illustrate the ways the history of AGCI has been intertwined with the evolution of global change science as it has become an increasingly interdisciplinary endeavor.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Microbial community response to a decade of simulated global changes depends on the plant community

Global changes such as increased drought and atmospheric nitrogen deposition perturb both the microbial and plant communities that mediate terrestrial ecosystem functioning. However, few studies consider how microbial responses to global changes may be influenced by interactions with plant communities. To begin to address the role of microbial–plant interactions, we tested the hypothesis that the response of microbial communities to global change depends on the plant community. We characterized bacterial and fungal communities from 395 plant litter samples taken from the Loma Ridge Global Change Experiment, a decade-long global change experiment in Southern California that manipulates rainfall and nitrogen levels across two adjacent ecosystems, a grassland and a coastal sage scrubland. The differences in bacterial and fungal composition between ecosystems paralleled distinctions in plant community composition. In addition to the direct main effects, the global change treatments altered microbial composition in an ecosystem-dependent manner, in support of our hypothesis. The interaction between the drought treatment and ecosystem explained nearly 5% of the variation in bacterial community composition, similar to the variation explained by the ecosystem-independent effects of drought. Unexpectedly, we found that the main effect of drought was approximately four times as strong on bacterial composition as that of nitrogen addition, which did not alter fungal or plant composition. Overall, the findings underscore the importance of considering plant–microbe interactions when considering the transferability of the results of global change experiments across ecosystems.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

A meta-analysis of 1,119 manipulative experiments on terrestrial carbon-cycling responses to global change

Direct quantification of terrestrial biosphere responses to global change is crucial for projections of future climate change in Earth system models. Here, we synthesized ecosystem carbon-cycling data from 1,119 experiments performed over the past four decades concerning changes in temperature, precipitation, CO2 and nitrogen across major terrestrial vegetation types of the world. Most experiments manipulated single rather than multiple global change drivers in temperate ecosystems of the USA, Europe and China. The magnitudes of warming and elevated CO2 treatments were consistent with the ranges of future projections, whereas those of precipitation changes and nitrogen inputs often exceeded the projected ranges. Increases in global change drivers consistently accelerated, but decreased precipitation slowed down carbon-cycle processes. Nonlinear (including synergistic and antagonistic) effects among global change drivers were rare. Belowground carbon allocation responded negatively to increased precipitation and nitrogen addition and positively to decreased precipitation and elevated CO2. The sensitivities of carbon variables to multiple global change drivers depended on the background climate and ecosystem condition, suggesting that Earth system models should be evaluated using site-specific conditions for best uses of this large dataset. Together, this synthesis underscores an urgent need to explore the interactions among multiple global change drivers in underrepresented regions such as semi-arid ecosystems, forests in the tropics and subtropics, and Arctic tundra when forecasting future terrestrial carbon-climate feedback.

Song, Jian↗
DOE OSTI2019

Advancing global change biology through experimental manipulations: Where have we been and where might we go?

Abstract This commentary summarizes the publication history of Global Change Biology for works on experimental manipulations over the past 25 years and highlights a number of key publications. The retrospective summary is then followed by some thoughts on the future of experimental work as it relates to mechanistic understanding and methodological needs. Experiments for elevated CO 2 atmospheres and anticipated warming scenarios which take us beyond historical analogs are suggested as future priorities. Disturbance is also highlighted as a key agent of global change. Because experiments are demanding of both personnel effort and limited fiscal resources, the allocation of experimental investments across Earth's biomes should be done in ecosystems of key importance. Uncertainty analysis and broad community consultation should be used to identify research questions and target biomes that will yield substantial gains in predictive confidence and societal relevance. A full range of methodological approaches covering small to large spatial scales will continue to be justified as a source of mechanistic understanding. Nevertheless, experiments operating at larger spatial scales encompassing organismal, edaphic, and environmental diversity of target ecosystems are favored, as they allow for the assessment of long‐term biogeochemical feedbacks enabling a full range of questions to be addressed. Such studies must also include adequate investment in measurements of key interacting variables (e.g., water and nutrient availability and budgets) to enable mechanistic understanding of responses and to interpret context dependency. Integration of ecosystem‐scale manipulations with focused process‐based manipulations, networks, and large‐scale observations will aid more complete understanding of ecosystem responses, context dependence, and the extrapolation of results. From the outset, these studies must be informed by and integrated with ecosystem models that provide quantitative predictions from their embedded mechanistic hypotheses. A true two‐way interaction between experiments and models will simultaneously increase the rate and robustness of Global Change research.

Hanson, Paul J.↗
DOE OSTI2016

What are the effects of Agro-Ecological Zones and land use region boundaries on land resource projection using the Global Change Assessment Model?

Understanding the potential impacts of climate change is complicated by mismatched spatial representations between gridded Earth System Models (ESMs) and Integrated Assessment Models (IAMs), whose regions are typically larger and defined by geopolitical and biophysical criteria. In this study we address uncertainty stemming from the construction of land use regions in an IAM, the Global Change Assessment Model (GCAM), whose regions are currently based on historical climatic conditions (1961-1990). We re-define GCAM’s regions according to projected climatic conditions (2070-2099), and investigate how this changes model outcomes for land use, agriculture, and forestry. By 2100, we find potentially large differences in projected global and regional area of biomass energy crops, fodder crops, harvested forest, and intensive pasture. These land area differences correspond with changes in agricultural commodity prices and production. These results have broader implications for understanding policy scenarios and potential impacts, and for evaluating and comparing IAM and ESM simulations.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2012

Linked Open Data in the Global Change Information System (GCIS)

The U.S. Global Change Research Program (http://globalchange.gov) coordinates and integrates federal research on changes in the global environment and their implications for society. The USGCRP is developing a Global Change Information System (GCIS) that will centralize access to data and information related to global change across the U.S. federal government. The first implementation will focus on the 2013 National Climate Assessment (NCA) . (http://assessment.globalchange.gov) The NCA integrates, evaluates, and interprets the findings of the USGCRP; analyzes the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, human health and welfare, human social systems, and biological diversity; and analyzes current trends in global change, both human-induced and natural, and projects major trends for the subsequent 25 to 100 years. The NCA has received over 500 distinct technical inputs to the process, many of which are reports distilling and synthesizing even more information, coming from thousands of individuals around the federal, state and local governments, academic institutions and non-governmental organizations. The GCIS will present a web-based version of the NCA including annotations linking the findings and content of the NCA with the scientific research, datasets, models, observations, etc. that led to its conclusions. It will use semantic tagging and a linked data approach, assigning globally unique, persistent, resolvable identifiers to all of the related entities and capturing and presenting the relationships between them, both internally and referencing out to other linked data sources and back to agency data centers. The developing W3C PROV Data Model and ontology will be used to capture the provenance trail and present it in both human readable web pages and machine readable formats such as RDF and SPARQL. This will improve visibility into the assessment process, increase understanding and reproducibility, and ultimately increase credibility and trust of the resulting report. Building on the foundation of the NCA, longer term plans for the GCIS include extending these capabilities throughout the U.S. Global Change Research Program, centralizing access to global change data and information across the thirteen agencies that comprise the program.

Tilmes, Curt A.↗
NASA NTRS1992

Our Changing Planet: The FY 1993 US Global Change Research Program. A report by the Committee on Earth and Environmental Sciences, a supplement to the US President's fiscal year 1993 budget

The U.S. Global Change Reasearch Program (USGCRP) was established as a Presidential initiative in the FY-1990 Budget to help develop sound national and international policies related to global environmental issues, particularly global climate change. The USGCRP is implemented through a priority-driven scientific research agenda that is designed to be integrated, comprehensive, and multidisciplinary. It is designed explicitly to address scientific uncertainties in such areas as climate change, ozone depletion, changes in terrestrial and marine productivity, global water and energy cycles, sea level changes, the impact of global changes on human health and activities, and the impact of anthropogenic activities on the Earth system. The USGCRP addresses three parallel but interconnected streams of activity: documenting global change (observations); enhancing understanding of key processes (process research); and predicting global and regional environmental change (integrated modeling and prediction).

Source record↗
DOE OSTI2016

Enhancing Participation in the U.S. Global Change Research Program

The US Global Change Research Program (USGCRP) is a collection of 13 Federal entities charged by law to assist the United States and the world to understand, assess, predict, and respond to human-induced and natural processes of global change. As the understanding of global change has evolved over the past decades and as demand for scientific information on global change has increased, the USGCRP has increasingly focused on research that can inform decisions to cope with current climate variability and change, to reduce the magnitude of future changes, and to prepare for changes projected over coming decades. Overall, the current breadth and depth of research in these agencies is insufficient to meet the country's needs, particularly to support decision makers. This report provides a rationale for evaluating current program membership and capabilities and identifying potential new agencies and departments in the hopes that these changes will enable the program to more effectively inform the public and prepare for the future. It also offers actionable recommendations for adjustments to the methods and procedures that will allow the program to better meet its stated goals.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2016

Soybean Roots Grown under Heat Stress Show Global Changes in Their Transcriptional and Proteomic Profiles

Heat stress is likely to be a key factor in the negative impact of climate change on crop production. Heat stress significantly influences the functions of roots, which provide support, water, and nutrients to other plant organs. Likewise, roots play an important role in the establishment of symbiotic associations with different microorganisms. Despite the physiological relevance of roots, few studies have examined their response to heat stress. Here in this study, we performed genome-wide transcriptomic and proteomic analyses on isolated root hairs, which are a single, epidermal cell type, and compared their response to stripped roots. On average, we identified 1849 and 3091 genes differentially regulated in root hairs and stripped roots, respectively, in response to heat stress. Our gene regulatory module analysis identified 10 key modules that might control the majority of the transcriptional response to heat stress. We also conducted proteomic analysis on membrane fractions isolated from root hairs and compared these responses to stripped roots. These experiments identified a variety of proteins whose expression changed within 3 h of application of heat stress. Most of these proteins were predicted to play a significant role in thermo-tolerance, as well as in chromatin remodeling and post-transcriptional regulation. In conclusion, the data presented represent an in-depth analysis of the heat stress response of a single cell type in soybean.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Seed dispersal by changing frugivore assemblages: a mechanistic test of global change effects

In the face of global change it is important to understand how changes in species abundance and richness can affect ecosystem functions. Here we modelled seed dispersal by animals in a fragmented secondary forest of the Cantabrian Range (northwestern Iberian Peninsula), simulating the activity of six frugivorous bird species when dispersing three species of fleshy‐fruited trees. We calculated the density and richness of seeds deposited across a forested landscape, as well as the density of seeds arriving to open areas. We 1) study the complementarity of functional traits of each species with frugivore assemblages varying in species compositions (i.e. abundance and richness of bird assemblages), 2) identify those bird species whose functional roles are not redundant, and 3) explore the response of seed dispersal to random losses and to two non‐random bird loss scenarios (i.e. overhunting and fewer individuals from migrant species). We found that simulations with the avian composition observed in the field (i.e. with uneven abundances of six bird species) led to values of seed dispersal higher to those emerging from four bird species equally abundant. The selective removal of dominant bird species led to significant decays in seed dispersal, suggesting non‐redundant roles of abundant bird species. Seed dispersal decays were stronger under non‐random than random scenarios of bird loss. In terms of seed density, the functional decays also differed between the scenarios of overhunting and reduced arrival of migrant birds, notably beyond 50% changes in bird species composition. Our results illustrate the need to integrate species composition (controlling for bird abundance and richness) and their sensitivity to disturbances when predicting the impact of global change on ecosystem functions.

Rodríguez‐Pérez, Javier↗
DOE OSTI2024

Tropical root responses to global changes: A synthesis

Tropical ecosystems face escalating global change. These shifts can disrupt tropical forests' carbon (C) balance and impact root dynamics. Since roots perform essential functions such as resource acquisition and tissue protection, root responses can inform about the strategies and vulnerabilities of ecosystems facing present and future global changes. However, root trait dynamics are poorly understood, especially in tropical ecosystems. We analyzed existing research on tropical root responses to key global change drivers: warming, drought, flooding, cyclones, nitrogen (N) deposition, elevated (e) CO 2 , and fires. Based on tree species- and community-level literature, we obtained 266 root trait observations from 93 studies across 24 tropical countries. We found differences in the proportion of root responsiveness to global change among different global change drivers but not among root categories. In particular, we observed that tropical root systems responded to warming and eCO 2 by increasing root biomass in species-scale studies. Drought increased the root: shoot ratio with no change in root biomass, indicating a decline in aboveground biomass. Despite N deposition being the most studied global change driver, it had some of the most variable effects on root characteristics, with few predictable responses. Episodic disturbances such as cyclones, fires, and flooding consistently resulted in a change in root trait expressions, with cyclones and fires increasing root production, potentially due to shifts in plant community and nutrient inputs, while flooding changed plant regulatory metabolisms due to low oxygen conditions. The data available to date clearly show that tropical forest root characteristics and dynamics are responding to global change, although in ways that are not always predictable. This synthesis indicates the need for replicated studies across root characteristics at species and community scales under different global change factors.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Biological nitrogen fixation across major biomes in Latin America: Patterns and global change effects

We report biological nitrogen fixation (BNF) supports terrestrial primary productivity and plays key roles in mediating human-induced changes in global nitrogen (N) and carbon cycling. However, there are still critical uncertainties in our understanding of the amount of BNF occurring across terrestrial ecosystems, and of how terrestrial BNF will respond to global change. We synthesized BNF data from Latin America, a region reported to sustain some of the highest BNF rates on Earth, but that is underrepresented in previous data syntheses. We used meta-analysis and modeling approaches to estimate BNF rates across Latin America's major biomes and to evaluate the potential effects of increased N deposition and land-use change on these rates. Unmanaged tropical and subtropical moist forests sustained observed and predicted total BNF rates of 10 ± 1 and 14 ± 1 kg N ha -1 y -1 , respectively, supporting the hypothesis that these forests sustain lower BNF rates than previously thought. Free-living BNF accounted for two-thirds of the total BNF in these forests. Despite an average 30% reduction of free-living BNF in response to experimental N-addition, our results suggest free-living BNF rate responses to current and projected N deposition across tropical and subtropical moist forests are small. In contrast, the conversion of unmanaged ecosystems to crop and pasture lands increased BNF rates across all terrestrial biomes, mostly in savannas, grasslands, and dry forests, increasing BNF rates 2-fold. The information obtained here provides a more comprehensive understanding of BNF patterns for Latin America.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1991

Sunsynchronous low Earth orbit spacecraft concepts and technology requirements for global change monitoring

The Global Change Technology Initiative listing of instruments for operation in low Earth, sunsynchronous orbits contain 21 entries, of which 20 are carried aboard multi-instrument spacecraft. This list identifies the temporal requirements for repetition of measurements and also includes groups of instruments that make complementing measurements. Definitions for individual spacecraft follows the temporal and grouping requirements to establish constellations which will provide the measurement data. The definitions of constellations for multi-instrument spacecraft show two alternatives: a constellation of 10 spacecraft, each compatible with launch by a Delta booster; a constellation of 4 spacecraft, each requiring a Titan booster. Operating subsystems for the individual spacecraft can use modular concepts that are adaptations based upon current plans for improving the performance of the NASA-Goddard Multimission Modular units. The descriptions of the spacecraft and constellations begins with a compilation of instrument related requirements that define the principal system performance parameters and operating capabilities.

Garrett, L. Bernard↗
NASA NTRS2012

Provenance Representation in the Global Change Information System (GCIS)

Global climate change is a topic that has become very controversial despite strong support within the scientific community. It is common for agencies releasing information about climate change to be served with Freedom of Information Act (FOIA) requests for everything that led to that conclusion. Capturing and presenting the provenance, linking to the research papers, data sets, models, analyses, observation instruments and satellites, etc. supporting key findings has the potential to mitigate skepticism in this domain. The U.S. Global Change Research Program (USGCRP) is now coordinating the production of a National Climate Assessment (NCA) that presents our best understanding of global change. We are now developing a Global Change Information System (GCIS) that will present the content of that report and its provenance, including the scientific support for the findings of the assessment. We are using an approach that will present this information both through a human accessible web site as well as a machine readable interface for automated mining of the provenance graph. We plan to use the developing W3C PROV Data Model and Ontology for this system.

Tilmes, Curt↗
NASA NTRS1992

Our changing planet: The FY 1993 US global change research program. A supplement to the US President's fiscal year 1993 budget

An improved predictive understanding of the integrated Earth system, including human interactions, will provide direct benefits by anticipating and planning for possible impacts on commerce, agriculture, energy, resource utilization, human safety, and environmental quality. The central goal of the U.S. Global Change Research Program (USGCRP) is to help establish the scientific understanding and the basis for national and international policymaking related to natural and human-induced changes in the global Earth system. This will be accomplished through: (1) establishing an integrated, comprehensive, long-term program of documenting the Earth system on a global scale; (2) conducting a program of focused studies to improve our understanding of the physical, geological, chemical, biological, and social processes that influence the Earth system processes; and (3) developing integrated conceptual and predictive Earth system models.

Source record↗