scholarly journals Greenhouse Gas Policy Influences Climate via Direct Effects of Land-Use Change

2013 ◽  
Vol 26 (11) ◽  
pp. 3657-3670 ◽  
Author(s):  
Andrew D. Jones ◽  
William D. Collins ◽  
James Edmonds ◽  
Margaret S. Torn ◽  
Anthony Janetos ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Radiative Forcing ◽  
Climate Impacts ◽  
Earth System Model ◽  
Assessment Model ◽  
System Model ◽  
Earth System ◽  
Alternative Scenario

Abstract Proposed climate mitigation measures do not account for direct biophysical climate impacts of land-use change (LUC), nor do the stabilization targets modeled for phase 5 of the Coupled Model Intercomparison Project (CMIP5) representative concentration pathways (RCPs). To examine the significance of such effects on global and regional patterns of climate change, a baseline and an alternative scenario of future anthropogenic activity are simulated within the Integrated Earth System Model, which couples the Global Change Assessment Model, Global Land-Use Model, and Community Earth System Model. The alternative scenario has high biofuel utilization and approximately 50% less global forest cover than the baseline, standard RCP4.5 scenario. Both scenarios stabilize radiative forcing from atmospheric constituents at 4.5 W m−2 by 2100. Thus, differences between their climate predictions quantify the biophysical effects of LUC. Offline radiative transfer and land model simulations are also utilized to identify forcing and feedback mechanisms driving the coupled response. Boreal deforestation is found to strongly influence climate because of increased albedo coupled with a regional-scale water vapor feedback. Globally, the alternative scenario yields a twenty-first-century warming trend that is 0.5°C cooler than baseline, driven by a 1 W m−2 mean decrease in radiative forcing that is distributed unevenly around the globe. Some regions are cooler in the alternative scenario than in 2005. These results demonstrate that neither climate change nor actual radiative forcing is uniquely related to atmospheric forcing targets such as those found in the RCPs but rather depend on particulars of the socioeconomic pathways followed to meet each target.

Reduced effective radiative forcing from cloud-aerosol interactions with improved modelling of early aerosol growth in an Earth System Model

2021 ◽  
Author(s):  
Sara Marie Blichner ◽  
Moa Kristina Sporre ◽  
Terje Koren Berntsen
Keyword(s):  
Radiative Forcing ◽  
Particle Growth ◽  
Particle Formation ◽  
Climate Impacts ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
New Particle Formation ◽  
Secondary Aerosol ◽  
Effective Radiative Forcing

<p>Cloud-aerosol interactions are responsible for much of the uncertainty in forcing estimates from pre-industrial times and thus also climate sensitivity and future projections. Maybe the most important factor in this is our lack of knowledge about pre-industrial aerosols, their sources and their ability to act as cloud condensation nuclei (CCN). The number of CCN is highly dependent on secondary aerosol formation and in particular how much of this secondary aerosol mass that goes to new particle formation (NPF) and early particle growth, versus growing already large particles even larger. <br>Earth system models which seek to model this, face a challenge because we need to represent processes at a very fine scale (nanometers) to a sufficient accuracy, while simultaneously keeping computational costs low. A common approach is to use log-normal modes to represent the sizedistribution, while more computationally expensive sectional schemes are considered closer to first principles. </p><p>In this study, we investigate the effect of a newly developed scheme for early particle growth on the effective radiative forcing from cloud-aerosol interactions (ERF<sub>aci</sub>)  in the Norwegian Earth System Model v2 (NorESMv2). The new scheme, referred to as OsloAeroSec, presented in  Blichner et al. (2020), combines a sectional scheme for the growth of the smallest particles (5 - 39.6 nm), with the original semi-modal aerosol scheme which would simply parameterize the growth up to the smallest mode with Lehtinen et al. (2007). This was shown to to improve the representation of CCN relevant particle concentrations, when compared to measurement data.  </p><p>We find that ERF<sub>aci</sub> is weakened by approximately 10 % with the new scheme (from -1.29  to -1.16 Wm<sup>-2</sup>). The weakening originates from OsloAeroSec (the new scheme) reducing particle formation in regions with high aerosol concentrations while increasing it in very pristine regions. We find, perhaps surprisingly, that an important factor for the overall forcing, is that  NPF inhibits aerosol activation into cloud droplets in high-aerosol-concentration regions, while the opposite is true in pristine regions. <br>This is because the NPF particles act as a condensation sink, and if they cannot activate directly themselves, they may reduce the growth of the larger particles which would otherwise activate. <br>Furthermore, we find that the increase in particle hygroscopicity with present day emissions of sulphate pre-cursors, decreases the size of the activated particles, and thus makes NPF particles more relevant for cloud droplet activation. </p><p><strong>References: </strong></p><p>Lehtinen, Kari E. J., Miikka Dal Maso, Markku Kulmala, and Veli-Matti Kerminen. “Estimating Nucleation Rates from Apparent Particle Formation Rates and Vice Versa: Revised Formulation of the Kerminen–Kulmala Equation.” Journal of Aerosol Science (2007): https://doi.org/10.1016/j.jaerosci.2007.06.009.</p><p>Blichner, Sara M., Moa K. Sporre, Risto Makkonen, and Terje K. Berntsen. “Implementing a sectional scheme for early aerosol growth from new particle formation in the Norwegian Earth System Model v2: comparison to observations and climate impacts.” Geoscientific Model Development Discussions (2020): https://doi.org/10.5194/gmd-2020-357</p>

scholarly journals A model-based constraint of CO<sub>2</sub> fertilisation

2012 ◽  
Vol 9 (7) ◽  
pp. 9425-9451 ◽  
Author(s):  
P. B. Holden ◽  
N. R. Edwards ◽  
D. Gerten ◽  
S. Schaphoff
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Co2 Concentration ◽  
Earth System Model ◽  
Atmospheric Co2 ◽  
System Model ◽  
Model Parameters ◽  
Earth System ◽  
Atmospheric Co2 Concentration ◽  
Post Industrial

Abstract. We derive a constraint on the strength of CO2 fertilisation of the terrestrial biosphere through a "top-down" approach, calibrating Earth System Model parameters constrained only by the post-industrial increase of atmospheric CO2 concentration. We derive a probabilistic prediction for the globally averaged strength of CO2 fertilisation in nature, implicitly net of other limiting factors such as nutrient availability. The approach yields an estimate that is independent of CO2 enrichment experiments and so provides a new constraint that can in principal be combined with data-driven priors. To achieve this, an essential requirement was the incorporation of a Land Use Change (LUC) scheme into the GENIE earth system model, which we describe in full. Using output from a 671-member ensemble of transient GENIE simulations we build an emulator of the change in atmospheric CO2 concentration change over the preindustrial period (1850 to 2000). We use this emulator to sample the 28-dimensional input parameter space. A Bayesian calibration of the emulator output suggests that the increase in Gross Primary Productivity in response of a doubling of CO2 from preindustrial values is likely to lie in the range 11 to 53%, with a most likely value of 28%. The present-day land-atmosphere flux (1990–2000) is estimated at −0.6 GTC yr−1 (likely in the range 0.9 to −2.0 GTC yr−1). The present-day land-ocean flux (1990–2000) is estimated at −2.2 GTC yr−1 (likely in the range −1.6 to −2.8 GTC yr−1). We estimate cumulative net land emissions over the post-industrial period (land use change emissions net of the CO2 fertilisation sink) to be 37 GTC, likely to lie in the range 130 to −20 GTC.

scholarly journals Present and future aerosol impacts on Arctic climate change in the GISS-E2.1 Earth system model

2021 ◽  
Vol 21 (13) ◽  
pp. 10413-10438
Author(s):  
Ulas Im ◽  
Kostas Tsigaridis ◽  
Gregory Faluvegi ◽  
Peter L. Langen ◽  
Joshua P. French ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Impacts ◽  
Earth System Model ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Anthropogenic Aerosols ◽  
Emission Reductions ◽  
Air Temperatures ◽  
Arctic Surface

Abstract. The Arctic is warming 2 to 3 times faster than the global average, partly due to changes in short-lived climate forcers (SLCFs) including aerosols. In order to study the effects of atmospheric aerosols in this warming, recent past (1990–2014) and future (2015–2050) simulations have been carried out using the GISS-E2.1 Earth system model to study the aerosol burdens and their radiative and climate impacts over the Arctic (>60∘ N), using anthropogenic emissions from the Eclipse V6b and the Coupled Model Intercomparison Project Phase 6 (CMIP6) databases, while global annual mean greenhouse gas concentrations were prescribed and kept fixed in all simulations. Results showed that the simulations have underestimated observed surface aerosol levels, in particular black carbon (BC) and sulfate (SO42-), by more than 50 %, with the smallest biases calculated for the atmosphere-only simulations, where winds are nudged to reanalysis data. CMIP6 simulations performed slightly better in reproducing the observed surface aerosol concentrations and climate parameters, compared to the Eclipse simulations. In addition, simulations where atmosphere and ocean are fully coupled had slightly smaller biases in aerosol levels compared to atmosphere-only simulations without nudging. Arctic BC, organic aerosol (OA), and SO42- burdens decrease significantly in all simulations by 10 %–60 % following the reductions of 7 %–78 % in emission projections, with the Eclipse ensemble showing larger reductions in Arctic aerosol burdens compared to the CMIP6 ensemble. For the 2030–2050 period, the Eclipse ensemble simulated a radiative forcing due to aerosol–radiation interactions (RFARI) of -0.39±0.01 W m−2, which is −0.08 W m−2 larger than the 1990–2010 mean forcing (−0.32 W m−2), of which -0.24±0.01 W m−2 was attributed to the anthropogenic aerosols. The CMIP6 ensemble simulated a RFARI of −0.35 to −0.40 W m−2 for the same period, which is −0.01 to −0.06 W m−2 larger than the 1990–2010 mean forcing of −0.35 W m−2. The scenarios with little to no mitigation (worst-case scenarios) led to very small changes in the RFARI, while scenarios with medium to large emission mitigations led to increases in the negative RFARI, mainly due to the decrease in the positive BC forcing and the decrease in the negative SO42- forcing. The anthropogenic aerosols accounted for −0.24 to −0.26 W m−2 of the net RFARI in 2030–2050 period, in Eclipse and CMIP6 ensembles, respectively. Finally, all simulations showed an increase in the Arctic surface air temperatures throughout the simulation period. By 2050, surface air temperatures are projected to increase by 2.4 to 2.6 ∘C in the Eclipse ensemble and 1.9 to 2.6 ∘C in the CMIP6 ensemble, compared to the 1990–2010 mean. Overall, results show that even the scenarios with largest emission reductions leads to similar impact on the future Arctic surface air temperatures and sea-ice extent compared to scenarios with smaller emission reductions, implying reductions of greenhouse emissions are still necessary to mitigate climate change.

scholarly journals A model-based constraint on CO<sub>2</sub> fertilisation

2013 ◽  
Vol 10 (1) ◽  
pp. 339-355 ◽  
Author(s):  
P. B. Holden ◽  
N. R. Edwards ◽  
D. Gerten ◽  
S. Schaphoff
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Co2 Concentration ◽  
Earth System Model ◽  
Atmospheric Co2 ◽  
System Model ◽  
Model Parameters ◽  
Earth System ◽  
Atmospheric Co2 Concentration ◽  
Post Industrial

Abstract. We derive a constraint on the strength of CO2 fertilisation of the terrestrial biosphere through a "top-down" approach, calibrating Earth system model parameters constrained by the post-industrial increase of atmospheric CO2 concentration. We derive a probabilistic prediction for the globally averaged strength of CO2 fertilisation in nature, for the period 1850 to 2000 AD, implicitly net of other limiting factors such as nutrient availability. The approach yields an estimate that is independent of CO2 enrichment experiments. To achieve this, an essential requirement was the incorporation of a land use change (LUC) scheme into the GENIE Earth system model. Using output from a 671-member ensemble of transient GENIE simulations, we build an emulator of the change in atmospheric CO2 concentration change since the preindustrial period. We use this emulator to sample the 28-dimensional input parameter space. A Bayesian calibration of the emulator output suggests that the increase in gross primary productivity (GPP) in response to a doubling of CO2 from preindustrial values is very likely (90% confidence) to exceed 20%, with a most likely value of 40–60%. It is important to note that we do not represent all of the possible contributing mechanisms to the terrestrial sink. The missing processes are subsumed into our calibration of CO2 fertilisation, which therefore represents the combined effect of CO2 fertilisation and additional missing processes. If the missing processes are a net sink then our estimate represents an upper bound. We derive calibrated estimates of carbon fluxes that are consistent with existing estimates. The present-day land–atmosphere flux (1990–2000) is estimated at −0.7 GTC yr−1 (likely, 66% confidence, in the range 0.4 to −1.7 GTC yr−1). The present-day ocean–atmosphere flux (1990–2000) is estimated to be −2.3 GTC yr−1 (likely in the range −1.8 to −2.7 GTC yr−1). We estimate cumulative net land emissions over the post-industrial period (land use change emissions net of the CO2 fertilisation and climate sinks) to be 66 GTC, likely to lie in the range 0 to 128 GTC.

scholarly journals Contrasting Local versus Regional Effects of Land-Use-Change-Induced Heterogeneity on Historical Climate: Analysis with the GFDL Earth System Model

2015 ◽  
Vol 28 (13) ◽  
pp. 5448-5469 ◽  
Author(s):  
Sergey Malyshev ◽  
Elena Shevliakova ◽  
Ronald J. Stouffer ◽  
Stephen W. Pacala
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Grid Cell ◽  
Earth System Model ◽  
System Model ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Earth System ◽  
Near Surface ◽  
Historical Climate ◽  
Effects Of Land Use

Abstract The effects of land-use and land-cover change (LULCC) on surface climate using two ensembles of numerical experiments with the Geophysical Fluid Dynamics Laboratory (GFDL) comprehensive Earth System Model ESM2Mb are investigated in this study. The experiments simulate historical climate with two different assumptions about LULCC: 1) no land-use change with potential vegetation (PV) and 2) with the CMIP5 historical reconstruction of LULCC (LU). Two different approaches were used in the analysis: 1) the authors compare differences in LU and PV climates to evaluate the regional and global effects of LULCC and 2) the authors characterize subgrid climate differences among different land-use tiles within each grid cell in the LU experiment. Using the first method, the authors estimate the magnitude of LULCC effect to be similar to some previous studies. Using the second method, the authors found a pronounced subgrid signal of LULCC in near-surface temperature over majority of areas affected by LULCC. The signal is strongest on croplands, where it is detectable with 95% confidence over 68.5% of all nonglaciated land grid cells in June–July–August, compared to 8.3% in the first method. In agricultural areas, the subgrid signal tends to be stronger than LU–PV signal by a factor of 1.3 in tropics in both summer and winter and by 1.5 in extratropics in winter. This analysis for the first time demonstrates and quantifies the local, subgrid-scale LULCC effects with a comprehensive ESM and compares it to previous global and regional approaches.

scholarly journals Climate Change Projection in the Twenty-First Century Simulated by NIMS-KMA CMIP6 Model Based on New GHGs Concentration Pathways

2021 ◽  
Author(s):  
Hyun Min Sung ◽  
Jisun Kim ◽  
Sungbo Shim ◽  
Jeong-byn Seo ◽  
Sang-Hoon Kwon ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Changes ◽  
Scientific Information ◽  
Earth System Model ◽  
First Century ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Future Projections ◽  
Twenty First Century

AbstractThe National Institute of Meteorological Sciences-Korea Meteorological Administration (NIMS-KMA) has participated in the Coupled Model Inter-comparison Project (CMIP) and provided long-term simulations using the coupled climate model. The NIMS-KMA produces new future projections using the ensemble mean of KMA Advanced Community Earth system model (K-ACE) and UK Earth System Model version1 (UKESM1) simulations to provide scientific information of future climate changes. In this study, we analyze four experiments those conducted following the new shared socioeconomic pathway (SSP) based scenarios to examine projected climate change in the twenty-first century. Present day (PD) simulations show high performance skill in both climate mean and variability, which provide a reliability of the climate models and reduces the uncertainty in response to future forcing. In future projections, global temperature increases from 1.92 °C to 5.20 °C relative to the PD level (1995–2014). Global mean precipitation increases from 5.1% to 10.1% and sea ice extent decreases from 19% to 62% in the Arctic and from 18% to 54% in the Antarctic. In addition, climate changes are accelerating toward the late twenty-first century. Our CMIP6 simulations are released to the public through the Earth System Grid Federation (ESGF) international data sharing portal and are used to support the establishment of the national adaptation plan for climate change in South Korea.

scholarly journals Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5

2013 ◽  
Vol 40 (9-10) ◽  
pp. 2123-2165 ◽  
Author(s):  
J.-L. Dufresne ◽  
M.-A. Foujols ◽  
S. Denvil ◽  
A. Caubel ◽  
O. Marti ◽  
...  
Keyword(s):  
Climate Change ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Climate Change Projections

scholarly journals Can an Earth System Model simulate better climate change at mid-Holocene than an AOGCM? A comparison study of MIROC-ESM and MIROC3

2013 ◽  
Vol 9 (4) ◽  
pp. 1519-1542 ◽  
Author(s):  
R. Ohgaito ◽  
T. Sueyoshi ◽  
A. Abe-Ouchi ◽  
T. Hajima ◽  
S. Watanabe ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Earth System Model ◽  
Sea Surface ◽  
System Model ◽  
Earth System ◽  
Intercomparison Project ◽  
The Difference ◽  
Precipitation Enhancement

Abstract. The importance of evaluating models through paleoclimate simulations is becoming more recognized in efforts to improve climate projection. To evaluate an integrated Earth System Model, MIROC-ESM, we performed simulations in time-slice experiments for the mid-Holocene (6000 yr before present, 6 ka) and preindustrial (1850 AD, 0 ka) periods under the protocol of the Coupled Model Intercomparison Project 5/Paleoclimate Modelling Intercomparison Project 3. We first give an overview of the simulated global climates by comparing with simulations using a previous version of the MIROC model (MIROC3), which is an atmosphere–ocean coupled general circulation model. We then comprehensively discuss various aspects of climate change with 6 ka forcing and how the differences in the models can affect the results. We also discuss the representation of the precipitation enhancement at 6 ka over northern Africa. The precipitation enhancement at 6 ka over northern Africa according to MIROC-ESM does not differ greatly from that obtained with MIROC3, which means that newly developed components such as dynamic vegetation and improvements in the atmospheric processes do not have significant impacts on the representation of the 6 ka monsoon change suggested by proxy records. Although there is no drastic difference between the African monsoon representations of the two models, there are small but significant differences in the precipitation enhancement over the Sahara in early summer, which can be related to the representation of the sea surface temperature rather than the vegetation coupling in MIROC-ESM. Because the oceanic parts of the two models are identical, the difference in the sea surface temperature change is ultimately attributed to the difference in the atmospheric and/or land modules, and possibly the difference in the representation of low-level clouds.

scholarly journals Diagnosing CO2 emission-induced feedbacks between the Southern Ocean carbon cycle and the climate system: A multiple Earth System Model analysis using a water mass tracking approach

2021 ◽  
pp. 1-62
Author(s):  
Tilla Roy ◽  
Jean Baptiste Sallée ◽  
Laurent Bopp ◽  
Nicolas Metzl
Keyword(s):  
Climate Change ◽  
Southern Ocean ◽  
Water Mass ◽  
Buffering Capacity ◽  
Climate Impacts ◽  
System Model ◽  
Earth System ◽  
Local Climate ◽  
Mode Waters ◽  
Ocean Carbon

AbstractAnthropogenic CO2 emission-induced feedbacks between the carbon cycle and the climate system perturb the efficiency of atmospheric CO2 uptake by land and ocean carbon reservoirs. The Southern Ocean is a region where these feedbacks can be largest and differ most among Earth System Model projections of 21st century climate change. To improve our mechanistic understanding of these feedbacks, we develop an automated procedure that tracks changes in the positions of Southern Ocean water masses and their carbon uptake. In an idealised ensemble of climate change projections, we diagnose two carbon–concentration feedbacks driven by atmospheric CO2 (due to increasing air-sea CO2 partial pressure difference, dpCO2, and reducing carbonate buffering capacity) and two carbon–climate feedbacks driven by climate change (due to changes in the water mass surface outcrop areas and local climate impacts). Collectively these feedbacks increase the CO2 uptake by the Southern Ocean and account for one-fifth of the global uptake of CO2 emissions. The increase in CO2 uptake is primarily dpCO2-driven, with Antarctic intermediate waters making the largest contribution; the remaining three feedbacks partially offset this increase (by ~25%), with maximum reductions in Subantarctic mode waters. The process dominating the decrease in CO2 uptake is water mass-dependent: reduction in carbonate buffering capacity in Subtropical and Subantarctic mode waters, local climate impacts in Antarctic intermediate waters, and reduction in outcrop areas in circumpolar deep waters and Antarctic bottom waters. Intermodel variability in the feedbacks is predominately dpCO2–driven and should be a focus of efforts to constrain projection uncertainty.

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