scholarly journals How the Updated Earth System Models Project Terrestrial Gross Primary Productivity in China under 1.5 and 2 °C Global Warming

2021 ◽  
Vol 13 (21) ◽  
pp. 11744
Author(s):  
Chi Zhang ◽  
Shaohong Wu ◽  
Yu Deng ◽  
Jieming Chou
Keyword(s):  
Global Warming ◽  
Tibetan Plateau ◽  
Primary Productivity ◽  
Gross Primary Productivity ◽  
Ecological Indicator ◽  
The Tibetan Plateau ◽  
Earth System ◽  
Max Planck ◽  
System Models ◽  
Earth System Models

Three Earth system models (ESMs) from the Coupled Model Intercomparison Project phase 6 (CMIP6) were chosen to project ecosystem changes under 1.5 and 2 °C global warming targets in the Shared Socioeconomic Pathway 4.5 W m−2 (SSP245) scenario. Annual terrestrial gross primary productivity (GPP) was taken as the representative ecological indicator of the ecosystem. Under 1.5 °C global warming, GPP in four climate zones—i.e., temperate continental; temperate monsoonal; subtropical–tropical monsoonal; high-cold Tibetan Plateau—showed a marked increase, the smallest magnitude of which was around 12.3%. The increase was greater under 2 °C of global warming, which suggests that from the perspective of ecosystem productivity, global warming poses no ecological risk in China. Specifically, in comparison with historical GPP (1986–2005), under 1.5 °C global warming GPP was projected to increase by 16.1–23.8% in the temperate continental zone, 12.3–16.1% in the temperate monsoonal zone, 12.5–14.7% in the subtropical–tropical monsoonal zone, and 20.0–37.0% on the Tibetan Plateau. Under 2 °C global warming, the projected GPP increase was 23.0–34.3% in the temperate continental zone, 21.2–24.4% in the temperate monsoonal zone, 16.1–28.4% in the subtropical–tropical monsoonal zone, and 28.4–63.0% on the Tibetan Plateau. The GPP increase contributed by climate change was further quantified and attributed. The ESM prediction from the Max Planck Institute suggested that the climate contribution could range from −12.8% in the temperate continental zone up to 61.1% on the Tibetan Plateau; however, the ESMs differed markedly regarding their climate contribution to GPP change. Although precipitation has a higher sensitivity coefficient, temperature generally plays a more important role in GPP change, primarily because of the larger relative change in temperature in comparison with that of precipitation.

scholarly journals Evaluation of CMIP5 earth system models in reproducing leaf area index and vegetation cover over the Tibetan Plateau

2014 ◽  
Vol 28 (6) ◽  
pp. 1041-1060 ◽  
Author(s):  
Yan Bao ◽  
Yanhong Gao ◽  
Shihua Lü ◽  
Qingxia Wang ◽  
Shaobo Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Vegetation Cover ◽  
The Tibetan Plateau ◽  
Earth System ◽  
Area Index ◽  
System Models ◽  
Earth System Models

The Transient Response of the Carbon-Cycle-Climate Continuum to CO2 Emissions is Pathway Dependent 

2021 ◽  
Author(s):  
Alexander J. Winkler ◽  
Ranga B. Myneni ◽  
Markus Reichstein ◽  
Victor Brovkin
Keyword(s):  
Carbon Cycle ◽  
Emission Rate ◽  
Transient Temperature ◽  
Emission Rates ◽  
Earth System ◽  
Max Planck ◽  
System Models ◽  
The Impact ◽  
Fully Coupled ◽  
Earth System Models

<div> <div> <div> <p>The prevailing understanding of the carbon-cycle response to anthropogenic CO<sub>2 </sub>emissions suggests that it depends only on the magnitude of this forcing, not on its timing. However, a recent study (Winkler <em>et al</em>., <em>Earth System Dynamics</em>, 2019) demonstrated that the same magnitude of CO<sub>2 </sub>forcing causes considerably different responses in various Earth system models when realized following different temporal trajectories. Because the modeling community focuses on concentration-driven runs that do not represent a fully-coupled carbon-cycle-climate continuum, and the experimental setups are mainly limited to exponential forcing timelines, the effect of different temporal trajectories of CO<sub>2 </sub>emissions in the system is under-explored. Together, this could lead to an incomplete notion of the carbon-cycle response to anthropogenic CO<sub>2 </sub>emissions.</p> <p>We use the latest CMIP6 version of the Max-Planck-Institute Earth System Model (MPI-ESM1.2) with a fully-coupled carbon cycle to investigate the effect of emission timing in form of four drastically different pathways. All pathways emit an identical total of 1200 Pg C over 200 years, which is about the IPCC estimate to stay below 2 °K of warming, and the approximate amount needed to double the atmospheric CO<sub>2 </sub>concentration. The four pathways differ only in their CO<sub>2 </sub>emission rates, which include a constant, a negative parabolic (ramp-up/ramp-down), a linearly decreasing, and an exponentially increasing emission trajectory. These experiments are idealized, but designed not to exceed the observed maximum emission rates, and thus can be placed in the context of the observed system.</p> <p>We find that the resulting atmospheric CO<sub>2 </sub>concentration, after all the carbon has been emitted, can vary as much as 100 ppm between the different pathways. The simulations show that for pathways, where the system is exposed to higher rates of CO<sub>2 </sub>emissions early in the forcing timeline, there is considerably less excess CO<sub>2 </sub>in the atmosphere at the end. These pathways also show an airborne fraction approaching zero in the final decades of the simulation. At this point, the carbon sinks have reached a strength that removes more carbon from the atmosphere than is emitted. In contrast, the exponentially increasing pathway with high CO<sub>2 </sub>emission rates in the last decades of the simulation, the pathway usually studied, shows a fairly stable airborne fraction. We propose a new general framework to estimate the atmospheric growth rate of CO<sub>2 </sub>not only as a function of the emission rate, but also include the aspect of time the system has been exposed to excess CO<sub>2 </sub>in the atmosphere. As a result, the transient temperature response is a function not only of the cumulative CO<sub>2 </sub>emissions, but also of the time the system was exposed to the excess CO<sub>2</sub>. We also apply this framework to other Earth system models and observational records of CO<sub>2 </sub>concentration and emissions.</p> </div> </div> </div><div> <div> <div> <p>The Earth system is currently in a phase of increasing, nearly exponential CO<sub>2 </sub>forcing. The impact of excess CO<sub>2 </sub>exposure time could become apparent as we approach the point of maximum CO<sub>2 </sub>emission rate, affecting the achievability of the climate targets.</p> </div> </div> </div>

scholarly journals Oceanic primary production decline halved in eddy-resolving simulations of global warming

2021 ◽  
Vol 18 (14) ◽  
pp. 4321-4349
Author(s):  
Damien Couespel ◽  
Marina Lévy ◽  
Laurent Bopp
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Primary Production ◽  
Nutrient Transport ◽  
Biogeochemical Model ◽  
Earth System ◽  
System Models ◽  
Marine Biomass ◽  
Fish Catch ◽  
Earth System Models

Abstract. The decline in ocean primary production is one of the most alarming consequences of anthropogenic climate change. This decline could indeed lead to a decrease in marine biomass and fish catch, as highlighted by recent policy-relevant reports. Because of computational constraints, current Earth system models used to project ocean primary production under global warming scenarios have to parameterize flows occurring below the resolution of their computational grid (typically 1∘). To overcome these computational constraints, we use an ocean biogeochemical model in an idealized configuration representing a mid-latitude double-gyre circulation and perform global warming simulations under an increasing horizontal resolution (from 1 to 1/27∘) and under a large range of parameter values for the eddy parameterization employed in the coarse-resolution configuration. In line with projections from Earth system models, all our simulations project a marked decline in net primary production in response to the global warming forcing. Whereas this decline is only weakly sensitive to the eddy parameters in the eddy-parameterized coarse 1∘ resolution simulations, the simulated decline in primary production in the subpolar gyre is halved at the finest eddy-resolving resolution (−12 % at 1/27∘ vs. −26 % at 1∘) at the end of the 70-year-long global warming simulations. This difference stems from the high sensitivity of the sub-surface nutrient transport to model resolution. Although being only one piece of a much broader and more complicated response of the ocean to climate change, our results call for improved representation of the role of eddies in nutrient transport below the seasonal mixed layer to better constrain the future evolution of marine biomass and fish catch potential.

scholarly journals Oceanic Primary production decline halved in eddy-resolving simulations of global warming

2021 ◽  
Author(s):  
Damien Couespel ◽  
Marina Lévy ◽  
Laurent Bopp
Keyword(s):  
Global Warming ◽  
Primary Production ◽  
Nutrient Transport ◽  
Biogeochemical Model ◽  
Earth System ◽  
System Models ◽  
Coarse Resolution ◽  
Marine Biomass ◽  
Fish Catch ◽  
Earth System Models

<p>The decline in ocean primary production is one of the most alarming consequences of anthropogenic climate change. This decline could indeed lead to a decrease in marine biomass and fish catch, as highlighted by recent policy-relevant reports. Because of computational constraints, current Earth System Models used to project ocean primary production under global warming scenarios have to parameterize flows occurring below the resolution of their computational grid (typically 1°). To overcome these computational constraints, we use an ocean biogeochemical model in an idealized configuration representing a mid-latitude double-gyre circulation, and perform global warming simulations under increasing horizontal resolution  (from 1° to 1/27°) and under a large range of parameter values for the eddy parameterization employed in the coarse resolution configuration. In line with projections from Earth System Models, all our simulations project a marked decline in net primary production in response to the global warming forcing. Whereas this decline is only weakly sensitive to the eddy parameters in the eddy-parametrized coarse resolution, the simulated decline in primary production is halved at the finest eddy-resolving resolution (-12% at 1/27° vs -26 at 1°). This difference stems from the high sensitivity of the subsurface nutrient transport to model resolution. Our results call for improved representation of the role of eddies on nutrient transport below the seasonal mixed-layer to better constrain the future evolution of marine biomass and fish catch potential for decision-making.</p>

scholarly journals How Should a Global Carbon Budget be Estimated?

2021 ◽  
Author(s):  
Paul Clements
Keyword(s):  
Global Warming ◽  
Co2 Emissions ◽  
Carbon Budget ◽  
Arctic Sea Ice ◽  
Atmospheric Co2 ◽  
Earth System ◽  
Intergovernmental Panel ◽  
System Models ◽  
Climate Analysis ◽  
Earth System Models

Abstract The Intergovernmental Panel on Climate Change (IPCC), the authority for estimating a carbon budget for keeping to the Paris Agreement’s 1.5—2°C target for limiting global warming, has indicated a budget of 580—1170 gigatons (Gt) of carbon dioxide (CO2) from 2018. This budget is based largely on Earth system models using data from the instrumental record over the industrial period. During the prior 800,000 years, however, a range of 120 parts per million (ppm) in atmospheric CO2 was associated with about a 6°C change in temperature, while temperature has only risen about 1°C with the 130 ppm increase in atmospheric CO2 in the industrial period. The paleoclimate record indicates that the anthropogenic increase in CO2 up to the present commits Earth to significant additional warming, such as from reduced albedo as Arctic sea ice melts and further CO2 release from vegetative stores. Instrumental data and model updates also indicate greater warming from these sources than IPCC models predict. Additionally, reductions in CO2 emissions to meet the Paris warming target will also reduce cooling from aerosols, which the IPCC may also have underestimated. Together, these factors indicate that CO2 emissions consistent with the IPCC’s carbon budget are likely to lead to at least 2—2.5°C global warming. I draw on the sustained critique of IPCC findings by Hansen and his colleagues, who have argued that the paleoclimate should be considered on par with Earth system models in climate analysis, and for more ambitious targets for reducing CO2 emissions.

scholarly journals Improved Modeling of Gross Primary Productivity of Alpine Grasslands on the Tibetan Plateau Using the Biome-BGC Model

2019 ◽  
Vol 11 (11) ◽  
pp. 1287 ◽  
Author(s):  
Yongfa You ◽  
Siyuan Wang ◽  
Yuanxu Ma ◽  
Xiaoyue Wang ◽  
Weihua Liu
Keyword(s):  
Tibetan Plateau ◽  
Primary Productivity ◽  
Remotely Sensed ◽  
Gross Primary Productivity ◽  
Model Parameters ◽  
The Tibetan Plateau ◽  
Alpine Grasslands ◽  
Biogeochemical Models ◽  
Sensing Technology ◽  
Sensitivity Analysis Method

The ability of process-based biogeochemical models in estimating the gross primary productivity (GPP) of alpine vegetation is largely hampered by the poor representation of phenology and insufficient calibration of model parameters. The development of remote sensing technology and the eddy covariance (EC) technique has made it possible to overcome this dilemma. In this study, we have incorporated remotely sensed phenology into the Biome-BGC model and calibrated its parameters to improve the modeling of GPP of alpine grasslands on the Tibetan Plateau (TP). Specifically, we first used the remotely sensed phenology to modify the original meteorological-based phenology module in the Biome-BGC to better prescribe the phenological states within the model. Then, based on the GPP derived from EC measurements, we combined the global sensitivity analysis method and the simulated annealing optimization algorithm to effectively calibrate the ecophysiological parameters of the Biome-BGC model. Finally, we simulated the GPP of alpine grasslands on the TP from 1982 to 2015 based on the Biome-BGC model after a phenology module modification and parameter calibration. The results indicate that the improved Biome-BGC model effectively overcomes the limitations of the original Biome-BGC model and is able to reproduce the seasonal dynamics and magnitude of GPP in alpine grasslands. Meanwhile, the simulated results also reveal that the GPP of alpine grasslands on the TP has increased significantly from 1982 to 2015 and shows a large spatial heterogeneity, with a mean of 289.8 gC/m2/yr or 305.8 TgC/yr. Our study demonstrates that the incorporation of remotely sensed phenology into the Biome-BGC model and the use of EC measurements to calibrate model parameters can effectively overcome the limitations of its application in alpine grassland ecosystems, which is important for detecting trends in vegetation productivity. This approach could also be upscaled to regional and global scales.

Sign in / Sign up

Export Citation Format

Share Document