Journal ArticleDOI
Climate extremes and the carbon cycle
Markus Reichstein,Michael Bahn,Philippe Ciais,Dorothea Frank,Miguel D. Mahecha,Sonia I. Seneviratne,Jakob Zscheischler,Jakob Zscheischler,Christian Beer,Christian Beer,Nina Buchmann,David Frank,Dario Papale,Anja Rammig,Pete Smith,Kirsten Thonicke,Marijn van der Velde,Sara Vicca,Ariane Walz,Martin Wattenbach +19 more
TLDR
The mechanisms and impacts of climate extremes on the terrestrial carbon cycle are explored, and a pathway to improve the understanding of present and future impacts ofClimate extremes onThe terrestrial carbon budget is proposed.Abstract:
The terrestrial biosphere is a key component of the global carbon cycle and its carbon balance is strongly influenced by climate. Continuing environmental changes are thought to increase global terrestrial carbon uptake. But evidence is mounting that climate extremes such as droughts or storms can lead to a decrease in regional ecosystem carbon stocks and therefore have the potential to negate an expected increase in terrestrial carbon uptake. Here we explore the mechanisms and impacts of climate extremes on the terrestrial carbon cycle, and propose a pathway to improve our understanding of present and future impacts of climate extremes on the terrestrial carbon budget.read more
Citations
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Journal ArticleDOI
On underestimation of global vulnerability to tree mortality and forest die‐off from hotter drought in the Anthropocene
TL;DR: In this article, the authors identify ten contrasting perspectives that shape the vulnerability debate but have not been discussed collectively and present a set of global vulnerability drivers that are known with high confidence: (1) droughts eventually occur everywhere; (2) warming produces hotter Droughts; (3) atmospheric moisture demand increases nonlinearly with temperature during drought; (4) mortality can occur faster in hotter Drought, consistent with fundamental physiology; (5) shorter Drought can become lethal under warming, increasing the frequency of lethal Drought; and (6) mortality happens rapidly
Book Chapter
Agriculture, Forestry and Other Land Use (AFOLU)
Pete Smith,Mercedes M. C. Bustamante,Helal Ahammad,Harry Clark,Hongmin Dong,Elnour A. Elsiddig,Helmut Haberl,Richard J. Harper,Joanna Isobel House,Mostafa Jafari,Omar Masera,Cheikh Mbow,N. H. Ravindranath,Charles W. Rice,Carmenza Robledo Abad,Anna Romanovskaya,Frank Sperling,Francesco N. Tubiello +17 more
TL;DR: Agriculture, Forestry, and Other Land Use (AFOLU) is unique among the sectors considered in this volume, since the mitigation potential is derived from both an enhancement of removals of greenhouse gases (GHG), as well as reduction of emissions through management of land and livestock as discussed by the authors.
Journal ArticleDOI
The dominant role of semi-arid ecosystems in the trend and variability of the land CO2 sink
Anders Ahlström,Anders Ahlström,Michael R. Raupach,Guy Schurgers,Benjamin Smith,Almut Arneth,Martin Jung,Markus Reichstein,Josep G. Canadell,Pierre Friedlingstein,Atul K. Jain,Etsushi Kato,Benjamin Poulter,Stephen Sitch,Benjamin D. Stocker,Benjamin D. Stocker,Nicolas Viovy,Ying-Ping Wang,Andy Wiltshire,Soenke Zaehle,Ning Zeng +20 more
TL;DR: Using an ensemble of ecosystem and land-surface models and an empirical observation-based product of global gross primary production, it is shown that the mean sink, trend, and interannual variability in CO2 uptake by terrestrial ecosystems are dominated by distinct biogeographic regions.
Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations
Abstract: We upscaled FLUXNET observations of carbon dioxide, water, and energy fluxes to the global scale using the machine learning technique, model tree ensembles (MTE). We trained MTE to predict site-level gross primary productivity (GPP), terrestrial ecosystem respiration (TER), net ecosystem exchange (NEE), latent energy (LE), and sensible heat (H) based on remote sensing indices, climate and meteorological data, and information on land use. We applied the trained MTEs to generate global flux fields at a 0.5 degrees x 0.5 degrees spatial resolution and a monthly temporal resolution from 1982 to 2008. Cross-validation analyses revealed good performance of MTE in predicting among-site flux variability with modeling efficiencies (MEf) between 0.64 and 0.84, except for NEE (MEf = 0.32). Performance was also good for predicting seasonal patterns (MEf between 0.84 and 0.89, except for NEE (0.64)). By comparison, predictions of monthly anomalies were not as strong (MEf between 0.29 and 0.52). Improved accounting of disturbance and lagged environmental effects, along with improved characterization of errors in the training data set, would contribute most to further reducing uncertainties. Our global estimates of LE (158 +/- 7 J x 10(18) yr(-1)), H (164 +/- 15 J x 10(18) yr(-1)), and GPP (119 +/- 6 Pg C yr(-1)) were similar to independent estimates. Our global TER estimate (96 +/- 6 Pg C yr(-1)) was likely underestimated by 5-10%. Hot spot regions of interannual variability in carbon fluxes occurred in semiarid to semihumid regions and were controlled by moisture supply. Overall, GPP was more important to interannual variability in NEE than TER. Our empirically derived fluxes may be used for calibration and evaluation of land surface process models and for exploratory and diagnostic assessments of the biosphere.
Journal ArticleDOI
Triggers of tree mortality under drought
Brendan Choat,Timothy J. Brodribb,Craig R. Brodersen,Remko A. Duursma,Rosana López,Rosana López,Belinda E. Medlyn +6 more
TL;DR: This work focuses on the current understanding of tree hydraulic performance under drought, the identification of physiological thresholds that precipitate mortality and the mechanisms of recovery after drought, and the potential application of hydraulic thresholds to process-based models that predict mortality.
References
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Journal ArticleDOI
An Overview of CMIP5 and the Experiment Design
TL;DR: The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance the authors' knowledge of climate variability and climate change.
Journal ArticleDOI
Catastrophic shifts in ecosystems.
TL;DR: Recent studies show that a loss of resilience usually paves the way for a switch to an alternative state, which suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.
Journal ArticleDOI
A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests
Craig D. Allen,Alison K. Macalady,Haroun Chenchouni,Dominique Bachelet,Nate G. McDowell,Michel Vennetier,Thomas Kitzberger,Andreas Rigling,David D. Breshears,Edward H. Hogg,Patrick Gonzalez,Rod Fensham,Zhen Zhang,Jorge Castro,N.A. Demidova,Jong Hwan Lim,Gillian Allard,Steven W. Running,Akkin Semerci,Neil S. Cobb +19 more
TL;DR: In this paper, the authors present the first global assessment of recent tree mortality attributed to drought and heat stress and identify key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system.
Journal ArticleDOI
A Large and Persistent Carbon Sink in the World’s Forests
Yude Pan,Richard Birdsey,Jingyun Fang,Jingyun Fang,Richard A. Houghton,Pekka E. Kauppi,Werner A. Kurz,Oliver L. Phillips,Anatoly Shvidenko,Simon L. Lewis,Josep G. Canadell,Philippe Ciais,Robert B. Jackson,Stephen W. Pacala,A. David McGuire,Shilong Piao,Aapo Rautiainen,Stephen Sitch,Daniel J. Hayes +18 more
TL;DR: The total forest sink estimate is equivalent in magnitude to the terrestrial sink deduced from fossil fuel emissions and land-use change sources minus ocean and atmospheric sinks, with tropical estimates having the largest uncertainties.
Journal ArticleDOI
Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity
Anthony L. Westerling,Anthony L. Westerling,Hugo G. Hidalgo,Daniel R. Cayan,Daniel R. Cayan,Thomas W. Swetnam +5 more
TL;DR: It is shown that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons.
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