The Community Earth System Model Version 2 (CESM2)

Journal of Advances in Modeling Earth Systems, Год журнала: 2020, Номер 12(2)

Опубликована: Янв. 17, 2020

An overview of the Community Earth System Model Version 2 (CESM2) is provided, including a discussion challenges encountered during its development and how they were addressed. In addition, an evaluation pair CESM2 long preindustrial control historical ensemble simulations presented. These performed using nominal 1° horizontal resolution configuration coupled model with both "low-top" (40 km, limited chemistry) "high-top" (130 comprehensive versions atmospheric component. contains many substantial science infrastructure improvements new capabilities since previous major release, CESM1, resulting in improved comparison to CESM1 available observations. include reductions low-latitude precipitation shortwave cloud forcing biases; better representation Madden-Julian Oscillation; El Niño-Southern Oscillation-related teleconnections; global land carbon accumulation trend that agrees well observationally based estimates. Most tropospheric surface features low- high-top are very similar each other, so these present configurations. has equilibrium climate sensitivity 5.1–5.3 °C, larger than primarily due combination relatively small changes microphysics boundary layer parameters. contrast, CESM2's transient response 1.9–2.0 °C comparable CESM1. The outputs from other research community, represent contributions Coupled Intercomparison Project Phase 6.

Язык: Английский

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The Community Land Model Version 5: Description of New Features, Benchmarking, and Impact of Forcing Uncertainty

Journal of Advances in Modeling Earth Systems, Год журнала: 2019, Номер 11(12), С. 4245 - 4287

Опубликована: Окт. 19, 2019

The Community Land Model (CLM) is the land component of Earth System (CESM) and used in several global regional modeling systems. In this paper, we introduce model developments included CLM version 5 (CLM5), which default for CESM2. We assess an ensemble simulations, including prescribed prognostic vegetation state, multiple forcing data sets, CLM4, CLM4.5, CLM5, against a range metrics from International Benchmarking (ILAMBv2) package. CLM5 includes new updated processes parameterizations: (1) dynamic units, (2) parameterizations structure hydrology snow (spatially explicit soil depth, dry surface layer, revised groundwater scheme, canopy interception processes, fresh density, simple firn model, Scale Adaptive River Transport), (3) plant hydraulics hydraulic redistribution, (4) nitrogen cycling (flexible leaf stoichiometry, N optimization photosynthesis, carbon costs uptake), (5) crop with six types time-evolving irrigated areas fertilization rates, (6) urban building energy, (7) isotopes, (8) stomatal physiology. New optional features include demographically structured (Functionally Assembled Terrestrial Ecosystem Simulator), ozone damage to plants, fire trace gas emissions coupling atmosphere. Conclusive establishment improvement or degradation individual variables challenged by uncertainty, parametric structural complexity, but multivariate presented here suggest general broad CLM4 CLM5.

Язык: Английский

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Plant responses to rising vapor pressure deficit

New Phytologist, Год журнала: 2020, Номер 226(6), С. 1550 - 1566

Опубликована: Фев. 17, 2020

Summary Recent decades have been characterized by increasing temperatures worldwide, resulting in an exponential climb vapor pressure deficit (VPD). VPD has identified as increasingly important driver of plant functioning terrestrial biomes and established a major contributor recent drought‐induced mortality independent other drivers associated with climate change. Despite this, few studies isolated the physiological response to high VPD, thus limiting our understanding ability predict future impacts on ecosystems. An abundance evidence suggests that stomatal conductance declines under transpiration increases most species up until given threshold, leading cascade subsequent including reduced photosynthesis growth, higher risks carbon starvation hydraulic failure . Incorporation photosynthetic traits ‘next‐generation’ land‐surface models greatest potential for improved prediction responses at plant‐ global‐scale, will yield more mechanistic simulations changing climate. By providing fully integrated framework evaluation function, improvements forecasting long‐term projections can be made.

Язык: Английский

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Pervasive shifts in forest dynamics in a changing world

Science, Год журнала: 2020, Номер 368(6494)

Опубликована: Май 28, 2020

Forest dynamics arise from the interplay of environmental drivers and disturbances with demographic processes recruitment, growth, mortality, subsequently driving biomass species composition. However, forest subsequent recovery are shifting global changes in climate land use, altering these dynamics. Changes drivers, disturbance regimes forcing forests toward younger, shorter stands. Rising carbon dioxide, acclimation, adaptation, migration can influence impacts. Recent developments Earth system models support increasingly realistic simulations vegetation In parallel, emerging remote sensing datasets promise qualitatively new more abundant data on underlying consequences for structure. When combined, advances hold improving scientific understanding demographics disturbances.

Язык: Английский

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Climate-driven risks to the climate mitigation potential of forests

Science, Год журнала: 2020, Номер 368(6497)

Опубликована: Июнь 18, 2020

Risks to mitigation potential of forests Much recent attention has focused on the trees and mitigate ongoing climate change by acting as sinks for carbon. Anderegg et al. review growing evidence that forests' is increasingly at risk from a range adversities limit forest growth health. These include physical factors such drought fire biotic factors, including depredations insect herbivores fungal pathogens. Full assessment quantification these risks, which themselves are influenced climate, key achieving science-based policy outcomes effective land management. Science , this issue p. eaaz7005

Язык: Английский

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Perspectives on the Future of Land Surface Models and the Challenges of Representing Complex Terrestrial Systems

Journal of Advances in Modeling Earth Systems, Год журнала: 2020, Номер 12(4)

Опубликована: Март 11, 2020

Abstract Land surface models (LSMs) are a vital tool for understanding, projecting, and predicting the dynamics of land its role within Earth system, under global change. Driven by need to address set key questions, LSMs have grown in complexity from simplified representations biophysics encompass broad interrelated processes spanning disciplines biophysics, biogeochemistry, hydrology, ecosystem ecology, community human management, societal impacts. This vast scope complexity, while warranted problems designed solve, has led enormous challenges understanding attributing differences between LSM predictions. Meanwhile, wide range spatial scales that govern heterogeneity, spectrum timescales dynamics, create tractably representing LSMs. We identify three “grand challenges” development use LSMs, based around these issues: managing process parametric across asked changing world. In this review, we discuss progress been made, as well promising directions forward, each challenges.

Язык: Английский

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Soil moisture–atmosphere feedback dominates land carbon uptake variability

Nature, Год журнала: 2021, Номер 592(7852), С. 65 - 69

Опубликована: Март 31, 2021

Abstract Year-to-year changes in carbon uptake by terrestrial ecosystems have an essential role determining atmospheric dioxide concentrations 1 . It remains uncertain to what extent temperature and water availability can explain these variations at the global scale 2–5 Here we use factorial climate model simulations 6 show that variability soil moisture drives 90 per cent of inter-annual land uptake, mainly through its impact on photosynthesis. We find most this ecosystem response occurs indirectly as moisture–atmosphere feedback amplifies humidity anomalies enhances direct effects stress. The strength mechanism explains why coupled models indicate has a dominant 4 , which is not readily apparent from surface observational analyses 2,5 These findings highlight need account for between dryness when estimating cycle climatic change globally 5,7 well conducting field-scale investigations droughts 8,9 Our results modelled driven vapour pressure deficit are controlled moisture.

Язык: Английский

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Mechanisms of woody-plant mortality under rising drought, CO2 and vapour pressure deficit

Nature Reviews Earth & Environment, Год журнала: 2022, Номер 3(5), С. 294 - 308

Опубликована: Март 29, 2022

Язык: Английский

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Climate Change Risks to Global Forest Health: Emergence of Unexpected Events of Elevated Tree Mortality Worldwide

Annual Review of Plant Biology, Год журнала: 2022, Номер 73(1), С. 673 - 702

Опубликована: Март 1, 2022

Recent observations of elevated tree mortality following climate extremes, like heat and drought, raise concerns about change risks to global forest health. We currently lack both sufficient data understanding identify whether these represent a trend toward increasing mortality. Here, we document events sudden unexpected drought in ecosystems that previously were considered tolerant or not at risk exposure. These underscore the fact may affect forests with force future. use as examples highlight current difficulties challenges for realistically predicting such uncertainties future condition. Advances remote sensing technology greater availably high-resolution data, from field assessments satellites, are needed improve prediction responses change. Expected final online publication date Annual Review Plant Biology, Volume 73 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates revised estimates.

Язык: Английский

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Ghosts of the past: how drought legacy effects shape forest functioning and carbon cycling

Ecology Letters, Год журнала: 2020, Номер 23(5), С. 891 - 901

Опубликована: Март 10, 2020

Multi-year lags in tree drought recovery, termed 'drought legacy effects', are important for understanding the impacts of on forest ecosystems, including carbon (C) cycle feedbacks to climate change. Despite ubiquity large uncertainties remain regarding mechanistic basis effects and their importance C cycle. In this review, we identify approaches used study effects, from rings whole forests. We then discuss key knowledge gaps pertaining causes how various mechanisms that may contribute these recovery could have contrasting implications Furthermore, conduct a novel data synthesis find differ drastically both size length across US depending if they identified versus gross primary productivity. Finally, highlight promising future research improve our capacity model predict impact health. emphasise holistic view - tissues forests will advance stimulate efforts investigate via experimental, observational modelling approaches.

Язык: Английский

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