scholarly journals The Joint UK Land Environment Simulator (JULES), model description – Part 2: Carbon fluxes and vegetation dynamics

2011 ◽  
Vol 4 (3) ◽  
pp. 701-722 ◽  
Author(s):  
D. B. Clark ◽  
L. M. Mercado ◽  
S. Sitch ◽  
C. D. Jones ◽  
N. Gedney ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Carbon Allocation ◽  
Carbon Sink ◽  
Carbon Fluxes ◽  
Methane Emissions ◽  
Model Description ◽  
Earth System ◽  
Ecological Processes ◽  
Living Plant

Abstract. The Joint UK Land Environment Simulator (JULES) is a process-based model that simulates the fluxes of carbon, water, energy and momentum between the land surface and the atmosphere. Many studies have demonstrated the important role of the land surface in the functioning of the Earth System. Different versions of JULES have been employed to quantify the effects on the land carbon sink of climate change, increasing atmospheric carbon dioxide concentrations, changing atmospheric aerosols and tropospheric ozone, and the response of methane emissions from wetlands to climate change. This paper describes the consolidation of these advances in the modelling of carbon fluxes and stores, in both the vegetation and soil, in version 2.2 of JULES. Features include a multi-layer canopy scheme for light interception, including a sunfleck penetration scheme, a coupled scheme of leaf photosynthesis and stomatal conductance, representation of the effects of ozone on leaf physiology, and a description of methane emissions from wetlands. JULES represents the carbon allocation, growth and population dynamics of five plant functional types. The turnover of carbon from living plant tissues is fed into a 4-pool soil carbon model. The process-based descriptions of key ecological processes and trace gas fluxes in JULES mean that this community model is well-suited for use in carbon cycle, climate change and impacts studies, either in standalone mode or as the land component of a coupled Earth system model.

scholarly journals The Joint UK Land Environment Simulator (JULES), Model description – Part 2: Carbon fluxes and vegetation

2011 ◽  
Vol 4 (1) ◽  
pp. 641-688 ◽  
Author(s):  
D. B. Clark ◽  
L. M. Mercado ◽  
S. Sitch ◽  
C. D. Jones ◽  
N. Gedney ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Carbon Allocation ◽  
Carbon Sink ◽  
Carbon Fluxes ◽  
Methane Emissions ◽  
Model Description ◽  
Earth System ◽  
Ecological Processes ◽  
Living Plant

Abstract. The Joint UK Land Environment Simulator (JULES) is a process-based model that simulates the fluxes of carbon, water, energy and momentum between the land surface and the atmosphere. Past studies with JULES have demonstrated the important role of the land surface in the Earth System. Different versions of JULES have been employed to quantify the effects on the land carbon sink of separately changing atmospheric aerosols and tropospheric ozone, and the response of methane emissions from wetlands to climate change. There was a need to consolidate these and other advances into a single model code so as to be able to study interactions in a consistent manner. This paper describes the consolidation of these advances into the modelling of carbon fluxes and stores, in the vegetation and soil, in version 2.2 of JULES. Features include a multi-layer canopy scheme for light interception, including a sunfleck penetration scheme, a coupled scheme of leaf photosynthesis and stomatal conductance, representation of the effects of ozone on leaf physiology, and a description of methane emissions from wetlands. JULES represents the carbon allocation, growth and population dynamics of five plant functional types. The turnover of carbon from living plant tissues is fed into a 4-pool soil carbon model. The process-based descriptions of key ecological processes and trace gas fluxes in JULES mean that this community model is well-suited for use in carbon cycle, climate change and impacts studies, either in standalone mode or as the land component of a coupled Earth system model.

scholarly journals Slow-down of the greening trend in natural vegetation with further rise in atmospheric CO2

2020 ◽  
Author(s):  
Alexander J. Winkler ◽  
Ranga B. Myneni ◽  
Alexis Hannart ◽  
Victor Brovkin
Keyword(s):  
Climate Change ◽  
Leaf Area ◽  
Land Surface ◽  
Scale Effects ◽  
Carbon Sink ◽  
Global Scale ◽  
Natural Vegetation ◽  
Earth System ◽  
Area Index ◽  
Probabilistic Setting

<div> <div> <div> <p>Satellite data reveal widespread changes in vegetation cover of Earth’s land surfaces. Regions intensively attended to by humans are mostly greening due to land management. Natural vegetation, on the other hand, is exhibiting patterns of both greening and browning in all continents. Factors linked to anthropogenic carbon emissions, such as CO<sub>2 </sub>fertilization, climate change and consequent episodic disturbances (<em>e.g. </em>fires and droughts) are hypothesized to be key drivers of changes in natural vegetation. A rigorous regional attribution at biome-level that can be scaled into a global picture of what is behind the observed changes is currently lacking.</p> <p>Therefore, we analyze here the longest available satellite record of global leaf area index (LAI, 1981-2017) and identify several clusters of significant long-term changes at the biome scale. Using process-based model simulations (fully-coupled MPI-M Earth system model and 13 stand-alone land surface models), we disentangle the effects of rising CO<sub>2 </sub>on LAI in a probabilistic setting applying Causal Counterfactual Theory.</p> <p>Our analysis reveals a slowing down of greening and strengthening of browning trends, particularly in the last two decades (2000-2017). The decreases in LAI are primarily concentrated in regions of high LAI (<em>i.e. </em>tropical forests), whereas the increases are in low LAI regions (<em>i.e. </em>northern and arid lands). These opposing trends are reducing the LAI texture of natural vegetation at the global scale. The analysis prominently indicates the effects of climate change on many biomes – warming in northern ecosystems and rainfall anomalies in tropical biomes. Our results do not support previously published accounts of dominant global-scale effects of CO<sub>2 </sub>fertilization. Most models largely underestimate vegetation browning, especially in the tropical rainforests. The leaf area loss in these productive ecosystems could be an early indicator of a slow-down in the terrestrial carbon sink. Models need to better account for this effect to realize plausible Earth system projections of the 21<sup>st </sup>century.</p> </div> </div> </div>

scholarly journals Resolving ecological feedbacks on the ocean carbon sink in Earth system models

2020 ◽  
Author(s):  
David I. Armstrong McKay ◽  
Sarah E. Cornell ◽  
Katherine Richardson ◽  
Johan Rockström
Keyword(s):  
Climate Change ◽  
Carbon Sink ◽  
Biological Pump ◽  
Earth System ◽  
Temperature Dependent ◽  
System Models ◽  
Plankton Ecology ◽  
Ocean Carbon ◽  
The Impact ◽  
Earth System Models

Abstract. The Earth’s oceans are one of the largest sinks in the Earth system for anthropogenic CO2 emissions, acting as a negative feedback on climate change. Earth system models predict, though, that climate change will lead to a weakening ocean carbon uptake rate as warm water holds less dissolved CO2 and biological productivity declines. However, most Earth system models do not incorporate the impact of warming on bacterial remineralisation and rely on simplified representations of plankton ecology that do not resolve the potential impact of climate change on ecosystem structure or elemental stoichiometry. Here we use a recently-developed extension of the cGEnIE Earth system model (ecoGEnIE) featuring a trait-based scheme for plankton ecology (ECOGEM), and also incorporate cGEnIE's temperature-dependent remineralisation (TDR) scheme. This enables evaluation of the impact of both ecological dynamics and temperature-dependent remineralisation on the soft-tissue biological pump in response to climate change. We find that including TDR strengthens the biological pump relative to default runs due to increased nutrient recycling, while ECOGEM weakens the biological pump by enabling a shift to smaller plankton classes. However, interactions with concurrent ocean acidification cause opposite sign responses for the carbon sink in both cases: TDR leads to a smaller sink relative to default runs whereas ECOGEM leads to a larger sink. Combining TDR and ECOGEM results in a net strengthening of the biological pump and a small net reduction in carbon sink relative to default. These results clearly illustrate the substantial degree to which ecological dynamics and biodiversity modulate the strength of climate-biosphere feedbacks, and demonstrate that Earth system models need to incorporate more ecological complexity in order to resolve carbon sink weakening.

scholarly journals Bergen Earth system model (BCM-C): model description and regional climate-carbon cycle feedbacks assessment

2010 ◽  
Vol 3 (1) ◽  
pp. 123-141 ◽  
Author(s):  
J. F. Tjiputra ◽  
K. Assmann ◽  
M. Bentsen ◽  
I. Bethke ◽  
O. H. Otterå ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Regional Climate ◽  
Earth System Model ◽  
System Model ◽  
Model Description ◽  
Earth System ◽  
Carbon Cycle Model ◽  
Enhanced Production ◽  
Positive Climate

Abstract. We developed a complex Earth system model by coupling terrestrial and oceanic carbon cycle components into the Bergen Climate Model. For this study, we have generated two model simulations (one with climate change inclusions and the other without) to study the large scale climate and carbon cycle variability as well as its feedback for the period 1850–2100. The simulations are performed based on historical and future IPCC CO2 emission scenarios. Globally, a pronounced positive climate-carbon cycle feedback is simulated by the terrestrial carbon cycle model, but smaller signals are shown by the oceanic counterpart. Over land, the regional climate-carbon cycle feedback is highlighted by increased soil respiration, which exceeds the enhanced production due to the atmospheric CO2 fertilization effect, in the equatorial and northern hemisphere mid-latitude regions. For the ocean, our analysis indicates that there are substantial temporal and spatial variations in climate impact on the air-sea CO2 fluxes. This implies feedback mechanisms act inhomogeneously in different ocean regions. In the North Atlantic subpolar gyre, the simulated future cooling of SST improves the CO2 gas solubility in seawater and, hence, reduces the strength of positive climate carbon cycle feedback in this region. In most ocean regions, the changes in the Revelle factor is dominated by changes in surface pCO2, and not by the warming of SST. Therefore, the solubility-associated positive feedback is more prominent than the buffer capacity feedback. In our climate change simulation, the retreat of Southern Ocean sea ice due to melting allows an additional ~20 Pg C uptake as compared to the simulation without climate change.

Impact of improved land model depth and hydrology on climate change projections

2020 ◽  
Author(s):  
Norman Steinert ◽  
Fidel González-Rouco ◽  
Stefan Hagemann ◽  
Philipp de Vrese ◽  
Elena García-Bustamante ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Earth System ◽  
Energy Propagation ◽  
Near Surface ◽  
Bottom Boundary ◽  
System Models ◽  
Model Component ◽  
And Storage ◽  
Earth System Models

<p>The representation of the thermal and hydrological state in the land model component of Earth System Models is crucial to have a realistic simulation of subsurface processes and the coupling between the atmo-, lito- and biosphere. There is evidence suggesting an inaccurate simulation of subsurface thermodynamics in current-generation Earth System Models, which have Land Surface Models that are too shallow. In simulations with a bottom boundary too close to the surface, the energy propagation and spatio-temporal variability of subsurface temperatures are affected. This potentially restrains the simulation of land-air interactions and subsurface phenomena, e.g. energy/moisture balance and storage capacity, freeze/thaw cycles and permafrost evolution. We introduce modifications for a deeper soil into the JSBACH soil model component of the MPI-ESM for climate projections of the 21st century. Subsurface layers are added progressively to increase the bottom boundary depth from 10m to 1400m. This leads to near-surface cooling of the soil and encourages regional terrestrial energy uptake by one order of magnitude and more. <br>The depth-changes in the soil also have implications for the hydrological regime, in which the moisture between the surface and the bedrock is sensitive to variations in the thermal regime. Additionally, we compare two different global soil parameter datasets that have major implications for the vertical distribution and availability of soil moisture and its exchange with the land surface. The implementation of supercool water and water phase changes in the soil creates a coupling between the soil thermal and hydrological regimes. In both cases of bottom boundary and water depth changes, we explore the sensitivity of JSBACH from the perspective of changes in the soil thermodynamics, energy balance and storage, as well as the effect of including freezing and thawing processes and their influence on the simulation of permafrost areas in the Northern Hemisphere high latitudes. The latter is of particular interest due to their vulnerability to long-term climate change.</p>

scholarly journals MIROC-INTEG-LAND version 1: a global biogeochemical land surface model with human water management, crop growth, and land-use change

2020 ◽  
Vol 13 (10) ◽  
pp. 4713-4747
Author(s):  
Tokuta Yokohata ◽  
Tsuguki Kinoshita ◽  
Gen Sakurai ◽  
Yadu Pokhrel ◽  
Akihiko Ito ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Management ◽  
Land Use ◽  
Land Use Change ◽  
Land Surface ◽  
Crop Yields ◽  
Land Surface Model ◽  
Climate System ◽  
Surface Model ◽  
Earth System

Abstract. Future changes in the climate system could have significant impacts on the natural environment and human activities, which in turn affect changes in the climate system. In the interaction between natural and human systems under climate change conditions, land use is one of the elements that play an essential role. On the one hand, future climate change will affect the availability of water and food, which may impact land-use change. On the other hand, human-induced land-use change can affect the climate system through biogeophysical and biogeochemical effects. To investigate these interrelationships, we developed MIROC-INTEG-LAND (MIROC INTEGrated LAND surface model version 1), an integrated model that combines the land surface component of global climate model MIROC (Model for Interdisciplinary Research on Climate) with water resources, crop production, land ecosystem, and land-use models. The most significant feature of MIROC-INTEG-LAND is that the land surface model that describes the processes of the energy and water balance, human water management, and crop growth incorporates a land use decision-making model based on economic activities. In MIROC-INTEG-LAND, spatially detailed information regarding water resources and crop yields is reflected in the prediction of future land-use change, which cannot be considered in the conventional integrated assessment models. In this paper, we introduce the details and interconnections of the submodels of MIROC-INTEG-LAND, compare historical simulations with observations, and identify various interactions between the submodels. By evaluating the historical simulation, we have confirmed that the model reproduces the observed states well. The future simulations indicate that changes in climate have significant impacts on crop yields, land use, and irrigation water demand. The newly developed MIROC-INTEG-LAND could be combined with atmospheric and ocean models to develop an integrated earth system model to simulate the interactions among coupled natural–human earth system components.

scholarly journals Oil palm modelling in the global land-surface model ORCHIDEE-MICT

2020 ◽  
Author(s):  
Yidi Xu ◽  
Philippe Ciais ◽  
Le Yu ◽  
Wei Li ◽  
Xiuzhi Chen ◽  
...  
Keyword(s):  
Oil Palm ◽  
Land Surface ◽  
Carbon Allocation ◽  
Land Surface Model ◽  
Rapid Expansion ◽  
Surface Model ◽  
Ecological Processes ◽  
Area Index ◽  
Global Land ◽  
Improved Model

Abstract. Oil palm is the most productive oil crop that provides ~40 % of the global vegetable oil supply, with 7 % of the cultivated land devoted to oil plants. The rapid expansion of oil palm cultivation is seen as one of the major cause for deforestation emissions and threatens the conservation of rain forest and swamp areas and their associated ecosystem services in tropical areas. Given the importance of oil palm in oil production and its adverse environmental consequences, it is important to understand the physiological and phenological processes of oil palm and its impacts on the carbon, water and energy cycles. In most global vegetation models, oil palm is represented by generic plant functional types (PFT) without specific representation of its morphological, physical and physiological traits. This would cause biases in the subsequent simulations. In this study, we introduced a new specific PFT for oil palm in the global land surface model ORCHIDEE-MICT (v8.4.2). The specific morphology, phenology and harvest process of oil palm were implemented, and the plant carbon allocation scheme was modified to support the growth of branch, leaf and fruit component of each phytomer. A new age-specific parameterization scheme for photosynthesis, autotrophic respiration, and carbon allocation was also developed for the oil palm PFT, based on observed physiology, and was calibrated by observations. The improved model generally reproduces the leaf area index, biomass density and fruit yield during the life cycle at 14 observation sites. Photosynthesis, carbon allocation and biomass components for oil palm also agree well with observations. This explicit representation of oil palm in global land surface model offers a useful tool for understanding the ecological processes of oil palm growth and assessing the environmental impacts of oil palm plantations.

scholarly journals Pasture degradation modifies the water and carbon cycles of the Tibetan highlands

2014 ◽  
Vol 11 (6) ◽  
pp. 8861-8923 ◽  
Author(s):  
W. Babel ◽  
T. Biermann ◽  
H. Coners ◽  
E. Falge ◽  
E. Seeber ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Surface Properties ◽  
Land Surface ◽  
Carbon Allocation ◽  
Carbon Sink ◽  
Plant Cover ◽  
The Tibetan Plateau ◽  
Onset Of Convection ◽  
Pasture Degradation ◽  
Kobresia Pygmaea

Abstract. The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments coupling changes of surface properties and processes with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan plateau. We coupled measurements of micro-lysimeter, chamber, 13C labeling, and eddy-covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyze how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while the total sum of evapotranspiration remains unaffected. The results show an earlier onset of convection and cloud generation, likely triggered by enhanced evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a~significant influence on larger scales.

scholarly journals ORCHIDEE MICT-LEAK (r5459), a global model for the production, transport, and transformation of dissolved organic carbon from Arctic permafrost regions – Part 1: Rationale, model description, and simulation protocol

2019 ◽  
Vol 12 (8) ◽  
pp. 3503-3521 ◽  
Author(s):  
Simon P. K. Bowring ◽  
Ronny Lauerwald ◽  
Bertrand Guenet ◽  
Dan Zhu ◽  
Matthieu Guimberteau ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
High Latitude ◽  
Land Surface ◽  
River Network ◽  
Model Description ◽  
Surface Model ◽  
System Modelling ◽  
Earth System ◽  
Simulation Protocol

Abstract. Few Earth system models adequately represent the unique permafrost soil biogeochemistry and its respective processes; this significantly contributes to uncertainty in estimating their responses, and that of the planet at large, to warming. Likewise, the riverine component of what is known as the “boundless carbon cycle” is seldom recognised in Earth system modelling. The hydrological mobilisation of organic material from a ∼1330–1580 PgC carbon stock to the river network results in either sedimentary settling or atmospheric “evasion”, processes widely expected to increase with amplified Arctic climate warming. Here, the production, transport, and atmospheric release of dissolved organic carbon (DOC) from high-latitude permafrost soils into inland waters and the ocean are explicitly represented for the first time in the land surface component (ORCHIDEE) of a CMIP6 global climate model (Institut Pierre Simon Laplace – IPSL). The model, ORCHIDEE MICT-LEAK, which represents the merger of previously described ORCHIDEE versions MICT and LEAK, mechanistically represents (a) vegetation and soil physical processes for high-latitude snow, ice, and soil phenomena and (b) the cycling of DOC and CO2, including atmospheric evasion, along the terrestrial–aquatic continuum from soils through the river network to the coast at 0.5 to 2∘ resolution. This paper, the first in a two-part study, presents the rationale for including these processes in a high-latitude-specific land surface model, then describes the model with a focus on novel process implementations, followed by a summary of the model configuration and simulation protocol. The results of these simulation runs, conducted for the Lena River basin, are evaluated against observational data in the second part of this study.

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