David Schimel

David Schimel
California Institute of Technology | CIT · Carbon an ecosystems

About

345
Publications
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Publications

Publications (345)
Article
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The decline in biodiversity in Mediterranean-type ecosystems (MTEs) and other shrublands underscores the importance of understanding the trends in species loss through consistent vegetation mapping over broad spatial and temporal ranges, which is increasingly accomplished with optical remote sensing (imaging spectroscopy). Airborne missions planned...
Article
Remote sensing has transformed the monitoring of life on Earth by revealing spatial and temporal dimensions of biological diversity through structural, compositional and functional measurements of ecosystems. Yet, many aspects of Earth’s biodiversity are not directly quantified by reflected or emitted photons. Inclusive integration of remote sensin...
Research
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This position paper was submitted to the 2016 Earth Science Decadal Survey RFI in May 2016 and is part of the submission records
Article
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We assess the detectability of COVID‐like emissions reductions in global atmospheric CO2 concentrations using a suite of large ensembles conducted with an Earth system model. We find a unique fingerprint of COVID in the simulated growth rate of CO2 sampled at the locations of surface measurement sites. Negative anomalies in growth rates persist fro...
Conference Paper
We assess the detectability of COVID-like emissions reductions in global atmospheric CO₂ concentrations using a suite of large ensembles conducted with an Earth system model. We find a unique fingerprint of COVID in the simulated growth rate of CO₂ sampled at the locations of surface measurement sites. Negative anomalies in growth rates persist fro...
Article
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The COVID-19 global pandemic and associated government lockdowns dramatically altered human activity, providing a window into how changes in individual behavior, enacted en masse, impact atmospheric composition. The resulting reductions in anthropogenic activity represent an unprecedented event that yields a glimpse into a future where emissions to...
Article
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Live woody vegetation is the largest reservoir of biomass carbon, with its restoration considered one of the most effective natural climate solutions. However, terrestrial carbon fluxes remain the largest uncertainty in the global carbon cycle. Here, we develop spatially explicit estimates of carbon stock changes of live woody biomass from 2000 to...
Article
Photosynthesis is a keystone process for the Earth system. The emergence of photosynthesis transformed Earth’s geologic, geochemical, and biologic evolution, and today, virtually all life on Earth depends on this process as a direct or indirect food source. Photosynthesis controls a fundamental link between the global carbon, water, and energy cycl...
Article
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National Academies' Decadal Survey, Thriving on Our Changing Planet, recommended Surface Biology and Geology (SBG) as a "Designated Targeted Observable" (DO). The SBG DO is based on the need for capabilities to acquire global, high spatial resolution, visible to shortwave infrared (VSWIR; 380-2500 nm; ~30 m pixel resolution) hyperspectral (imaging...
Article
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Here we present a global and regionally resolved terrestrial net biosphere exchange (NBE) dataset with corresponding uncertainties between 2010–2018: Carbon Monitoring System Flux Net Biosphere Exchange 2020 (CMS-Flux NBE 2020). It is estimated using the NASA Carbon Monitoring System Flux (CMS-Flux) top-down flux inversion system that assimilates c...
Technical Report
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This is a response submitted to the 2016 RFI for the 2017 NRC Decadal Survey. It describes the possible use of GNSS reflectometry for the purpose of global mapping of wetlands.
Preprint
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Here we present a global and regionally-resolved terrestrial net biosphere exchange (NBE) dataset with corresponding uncertainties between 2010–2018: CMS-Flux NBE 2020. It is estimated using the NASA Carbon Monitoring System Flux (CMS-Flux) top-down flux inversion system that assimilates column CO2 observations from Greenhouse gases Observing SATel...
Chapter
Full-text available
Imaging spectroscopy is a powerful new approach for observing aspects of the biological diversity of the Earth, conveying information about plant functional traits, habitat, and plant diversity itself. For decades, spectroscopic data suitable for this application have mainly been collected by aircraft. But in the next decade, global coverage from s...
Article
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The terrestrial carbon sink has significantly increased in the past decades, but the underlying mechanisms are still unclear. The current synthesis of process-based estimates of land and ocean sinks requires an additional sink of 0.6 PgC yr−1 in the last decade to explain the observed airborne fraction. A concurrent global fire decline was observed...
Conference Paper
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Understanding the consequences of ongoing and rapid changes in the Earth system, driven by anthropogenic activities, requires novel observing strategies that span land, ocean, and coastal ecosystems. Recognizing this challenge, the US National Academies 2017 Decadal Survey recommended five Designated Observables to address science questions related...
Article
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Surface Biology and Geology, a new NASA Earth observation effort, is developing a path forward for monitoring the Earth system from space. Citation: Schneider, F. D., A. Ferraz, and D. Schimel (2019), Watching Earth’s interconnected systems at work, Eos, 100, https://doi.org/10.1029/2019EO136205. Published on 31 October 2019.
Article
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The Orbiting Carbon Observatory-2 has been on orbit since 2014, and its global coverage holds the potential to reveal new information about the carbon cycle through the use of top-down atmospheric inversion methods combined with column average CO2 retrievals. We employ a large ensemble of atmospheric inversions utilizing different transport models,...
Article
Northern hemisphere evergreen forests assimilate a significant fraction of global atmospheric CO_2 but monitoring large-scale changes in gross primary production (GPP) in these systems is challenging. Recent advances in remote sensing allow the detection of solar-induced chlorophyll fluorescence (SIF) emission from vegetation, which has been empiri...
Article
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Global ecology – the study of the interactions among the Earth's ecosystems, land, atmosphere, and oceans – depends crucially on global observations: this paper focuses on space‐based observations of global terrestrial ecosystems. Early global ecology relied on extrapolation of detailed site‐level observations, using models of increasing complexity...
Article
Full-text available
The Orbiting Carbon Observatory-2 has been on orbit since 2014, and its global coverage holds the potential to reveal new information about the carbon cycle through the use of top-down atmospheric inversion methods combined with column average CO2 retrievals. We employ a large ensemble of atmospheric inversions utilizing different transport models,...
Article
Terrestrial laser scanning (TLS) has emerged as a reference for three-dimensional measurements of forest structure as well as forest reconstruction and modeling. Ground-based measurements can be complemented by new light-weight sensors on unmanned aerial vehicles (UAVs) or laser scans from canopy cranes or towers. However, it is still largely unkno...
Article
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We have compared global carbon budgets calculated from numerical inverse models and CO2 observations, and evaluated how these systems reproduce vertical gradients in atmospheric CO2 from aircraft measurements. We found that available models have converged on near-neutral tropical total fluxes for several decades, implying consistent sinks in intact...
Article
Chevallier showed a column CO 2 ( XCO2 ) anomaly of ±0.5 parts per million forced by a uniform net biosphere exchange (NBE) anomaly of 2.5 gigatonnes of carbon over the tropical continents within a year, so he claimed that the inferred NBE uncertainties should be larger than presented in Liu et al . We show that a much concentrated NBE anomaly led...
Article
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The second NASA Earth Venture Mission, Geostationary Carbon Cycle Observatory (GeoCarb), will provide measurements of atmospheric carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and solar-induced fluorescence (SIF) from Geostationary Orbit (GEO). The GeoCarb mission will deliver daily maps of column concentrations of CO2, CH4, and CO ove...
Article
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We have compared a suite of recent global CO2 atmospheric inversion results to independent airborne observations and to each other, to assess their dependence on differences in northern extratropical vertical transport and to identify some of the drivers of model spread. We evaluate posterior CO 2 concentration profiles against observations from th...
Article
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The contemporary Arctic carbon balance is uncertain, and the potential for a permafrost carbon feedback of anywhere from 50 to 200 petagrams of carbon (Schuur et al., 2015) compromises accurate 21st-century global climate system projections. The 42-year record of atmospheric CO2 measurements at Barrow, Alaska (71.29 N, 156.79 W), reveals significan...
Article
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To protect ecosystem services and the increasing wildland urban interface in a world with fire, comprehensive maps of wildland fuels are needed to predict fire behavior and effects. Traditionally, fuels have been categorized into a classification scheme whereby a single metric represents vegetation composition and structure, which can then be param...
Article
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In 2018 technologies on the International Space Station will provide ~1 year of synchronous observations of ecosystem composition, structure and function. We discuss these instruments and how they can be used to constrain global models and improve our understanding of the current state of terrestrial ecosystems.
Conference Paper
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Current estimates of the global carbon budget are informed by surface flux estimates from atmospheric inverse models. It is essential to quantify the uncertainty in inverse flux calculations through comparison with independent observations. The most prominent community-wide inverse model intercomparison that included comparisons of posterior concen...
Data
In 2018 technologies on the International Space Station will provide ~1 year of synchronous observations of ecosystem composition, structure and function. We discuss these instruments and how they can be used to constrain global models and improve our understanding of the current state of terrestrial ecosystems.
Article
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https://www.nature.com/articles/s41559-017-0194
Article
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Recent studies have utilized coarse spatial and temporal resolution remotely sensed solar induced fluorescence (SIF) for modeling terrestrial gross primary productivity (GPP) at regional scales. Although these studies have demonstrated the potential of SIF, there have been concerns about the ecophysiological basis of the relationship between SIF an...
Poster
Detecting and quantifying plant stress is a grand challenge for remote sensing, and is important for understanding climate impacts on ecosystems broadly and also for early warning systems supporting food security. The long record from moderate resolution sensors providing frequent data has allowed using phenology to detect stress in forest and agro...
Article
Megafires have lasting social, ecological, and economic impacts and are increasing in the western contiguous United States. Because of their infrequent nature, there is a limited sample of megafires to investigate their unique behaviour, drivers and relationship to forest management practices. One approach is to characterize critical information pr...
Data
An analysis suggests that high carbon uptake by US land ecosystems during the warm spring of 2012 offset the carbon loss that resulted from severe drought over the summer — and hints that the warm spring could have worsened the drought.
Article
An analysis suggests that high carbon uptake by US land ecosystems during the warm spring of 2012 offset the carbon loss that resulted from severe drought over the summer [mdash] and hints that the warm spring could have worsened the drought.
Article
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Understanding the processes controlling terrestrial carbon fluxes is one of the grand challenges of climate science. Carbon cycle process controls are readily studied at local scales, but integrating local knowledge across extremely heterogeneous biota, landforms and climate space has proven to be extraordinarily challenging. Consequently, top-down...
Article
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Increases in atmospheric CO2 and CH4 result from a combination of forcing from anthropogenic emissions and Earth System feedbacks that reduce or amplify the effects of those emissions on atmospheric concentrations. Despite decades of research carbon-climate feedbacks remain poorly quantified. The impact of these uncertainties on future climate are...
Article
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The world's ecosystems are losing biodiversity fast. A satellite mission designed to track changes in plant functional diversity around the globe could deepen our understanding of the pace and consequences of this change, and how to manage it.
Article
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The IGBP Analysis, Integration and Modeling of the Earth System (AIMES) project has developed the notion of Earth System Science (ESS). ESS studies how the planet operates as a coupled system of interacting components, which produce emergent behaviors over and beyond the dynamics of the individual components. Many climate models used in the IPCC's...
Conference Paper
Plant physiology exerts a key control on the exchange of carbon and water between terrestrial ecosystems and the atmosphere at different spatial and temporal scales. Therefore, accurate and reliable detection of variations in plant physiological functioning is critical for modeling and monitoring terrestrial carbon and water cycle. Using data from...
Conference Paper
Recent demonstrations of the retrieval of vegetation solar-induced fluorescence (SIF) emission from satellite platforms have opened up the possibility of remotely monitoring photosynthetic function, in addition to the structural and biochemical parameters that characterize the current capabilities of vegetation observing systems. These satellite re...
Article
In his 7 August In Depth News story “The dimming of NEON” (p. [574][1]), J. Mervis reported cuts to the National Science Foundation's (NSF's) National Ecological Observatories Network (NEON) program. NEON is a highly ambitious research program that attempts to observe biological and ecological
Article
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Satellite observations reveal substantial burning during the 2007 and 2010 tropical South America fire season, with both years exhibiting similar total burned area. However, 2010 CO fire emissions, based on satellite CO concentration measurements, were substantially lower (−28%), despite the once-in-a-century drought in 2010. We use Bayesian infere...
Article
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Ecologists are increasingly tackling questions that require significant infrastucture, large experiments, networks of observations, and complex data and computation. Key hypotheses in ecology increasingly require more investment, and larger data sets to be tested than can be collected by a single investigator's or s group of investigator's labs, su...
Article
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Feedbacks from the terrestrial carbon cycle significantly affect future climate change. The CO2 concentration dependence of global terrestrial carbon storage is one of the largest and most uncertain feedbacks. Theory predicts the CO2 effect should have a tropical maximum, but a large terrestrial sink has been contradicted by analyses of atmospheric...
Article
Terrestrial ecosystem and carbon cycle feedbacks will significantly impact future climate, but their responses are highly uncertain. Models and tipping point analyses suggest the tropics and Arctic/Boreal zone carbon-climate feedbacks could be disproportionately large. In situ observations in those regions are sparse, resulting in high uncertaintie...
Article
In a recent paper (Mitchard et al. 2014, Global Ecology and Biogeography, 23, 935–946) a new map of forest biomass based on a geostatistical model of field data for the Amazon (and surrounding forests) was presented and contrasted with two earlier maps based on remote-sensing data Saatchi et al. (2011; RS1) and Baccini et al. (2012; RS2). Mitchard...
Chapter
Forests play a major role in the global carbon cycle. Deforestation is a major source of carbon to the atmosphere, and forest regrowth is a major sink for carbon from the atmosphere. This understanding comes from several decades of intense research focusing on explaining patterns of variation in atmospheric CO2 over time and space. The observed pat...
Conference Paper
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Background/Question/Methods In August 2013, a major fire in Yosemite National Park and the Stanislaus National Forest burned 104,131 hectares (257,314 acres) before extinction on October 24th, 2013 (http://inciweb.nwcg.gov/incident/3660/). One of the unique attributes of this fire is the unprecedented amount of before and after remotely sensed da...
Article
Full-text available
A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify the effectiveness of policies aiming to reduce greenhouse gas emissions and increase carbon sequestration. Building an integrated carbon observati...
Conference Paper
Background/Question/Methods Nitrogen (N) loss via gaseous emissions, erosion, and leaching from fields and pastures is a widely recognized environmental problem for modern agriculture. The mechanisms and consequences of N loss are well studied in humid and sub-humid agricultural regions, but less so in semi-arid regions, where leaching is a rare...
Conference Paper
Background/Question/Methods The peatlands of the high latitude north contain vast reservoirs of carbon, whose potential importance to planetary metabolism was first emphasized by Eville Gorham in a series of classic papers in the 1980s and 1990s. Northern peat lands have accumulated carbon, mainly in detrital forms, preserved by acidic, anaerobic...
Article
A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify the effectiveness of policies aiming to reduce greenhouse gas emissions and increase carbon sequestration. Building an integrated carbon observati...
Article
[1] Forecasting the carbon uptake potential of terrestrial ecosystems in the face of future climate change has proven challenging. Process models, which have been increasingly used to study ecosystem-atmosphere carbon and water exchanges when conditioned with tower-based eddy covariance data, have the potential to inform us about biogeochemical pro...