scholarly journals Carbon cycle extremes during the 21st century in CMIP5 models: Future evolution and attribution to climatic drivers

2014 ◽  
Vol 41 (24) ◽  
pp. 8853-8861 ◽  
Author(s):  
Jakob Zscheischler ◽  
Markus Reichstein ◽  
Jannis von Buttlar ◽  
Mingquan Mu ◽  
James T. Randerson ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
21St Century ◽  
Cmip5 Models ◽  
Future Evolution ◽  
Climatic Drivers

Time-scale dependence of climate-carbon cycle feedbacks for weak perturbations in CMIP5 models

2021 ◽  
Author(s):  
Guilherme Torres Mendonça ◽  
Julia Pongratz ◽  
Christian Reick
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Time Scales ◽  
Radiative Forcing ◽  
Global Carbon Cycle ◽  
Atmospheric Co2 ◽  
Ice Age ◽  
Cmip5 Models ◽  
Global Carbon ◽  
Different Time Scales

<p>The increase in atmospheric CO2 driven by anthropogenic emissions is the main radiative forcing causing climate change. But this increase is not only a result from emissions, but also from changes in the global carbon cycle. These changes arise from feedbacks between climate and the carbon cycle that drive CO2 into or out of the atmosphere in addition to the emissions, thereby either accelerating or buffering climate change. Therefore, understanding the contribution of these feedbacks to the global response of the carbon cycle is crucial in advancing climate research. Currently, this contribution is quantified by the α-β-γ framework (Friedlingstein et al., 2003). But this quantification is only valid for a particular perturbation scenario and time period. In contrast, a recently proposed generalization (Rubino et al., 2016) of this framework for weak perturbations quantifies this contribution for all scenarios and at different time scales. </p><p>Thereby, this generalization provides a systematic framework to investigate the response of the global carbon cycle in terms of the climate-carbon cycle feedbacks. In the present work we employ this framework to study these feedbacks and the airborne fraction in different CMIP5 models. We demonstrate (1) that this generalization of the α-β-γ framework consistently describes the linear dynamics of the carbon cycle in the MPI-ESM; and (2) how by this framework the climate-carbon cycle feedbacks and airborne fraction are quantified at different time scales in CMIP5 models. Our analysis shows that, independently of the perturbation scenario, (1) the net climate-carbon cycle feedback is negative at all time scales; (2) the airborne fraction generally decreases for increasing time scales; and (3) the land biogeochemical feedback dominates the model spread in the airborne fraction at all time scales. This last result therefore emphasizes the need to improve our understanding of this particular feedback.</p><p><strong>References:</strong></p><p>P. Friedlingstein, J.-L. Dufresne, P. Cox, and P. Rayner. How positive is the feedback between climate change and the carbon cycle? Tellus B, 55(2):692–700, 2003.</p><p>M. Rubino, D. Etheridge, C. Trudinger, C. Allison, P. Rayner, I. Enting, R. Mulvaney, L. Steele, R. Langenfelds, W. Sturges, et al. Low atmospheric CO2 levels during the Little Ice Age due to cooling-induced terrestrial uptake. Nature Geoscience, 9(9):691–694, 2016.</p>

scholarly journals Role of volcanic forcing on future global carbon cycle

2011 ◽  
Vol 2 (1) ◽  
pp. 133-159
Author(s):  
J. F. Tjiputra ◽  
O. H. Otterå
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
21St Century ◽  
Volcanic Eruptions ◽  
Future Climate Change ◽  
Small Scale ◽  
Carbon Uptake ◽  
Carbon Cycle Model ◽  
Large Volcanic Eruptions

Abstract. Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller but more frequent eruptions, such as Pinatubo, would have a stronger impact on future climate change. In a scenario where the volcanic external forcings are prescribed with a five-year frequency, the induced cooling immediately lower the global temperature by more than one degree before return to the warming trend. Therefore, the climate change is approximately delayed by several decades and by the end of the 21st century, the warming is still below two degrees when compared to the present day period. The cooler climate reduces the terrestrial heterotrophic respiration in the northern high latitude and increases net primary production in the tropics, which contributes to more than 45% increase in accumulated carbon uptake over land. The increased solubility of CO2 gas in seawater associated with cooler SST is offset by reduced CO2 partial pressure gradient between ocean and atmosphere, which results in small changes in net ocean carbon uptake. Similarly, there is nearly no change in the seawater buffer capacity simulated between the different volcanic scenarios. Our study shows that even in the relatively extreme scenario where large volcanic eruptions occur every five-years period, the induced cooling only leads to a reduction of 46 ppmv atmospheric CO2 concentration as compared to the reference projection of 878 ppmv, at the end of the 21st century. With respect to sulphur injection geoengineering method, our study suggest that small scale but frequent mitigation is more efficient than the opposite. Moreover, the longer we delay, the more difficult it would be to counteract climate change.

scholarly journals Simulations of changes to Glaciar Zongo, Bolivia (16° S), over the 21st century using a 3-D full-Stokes model and CMIP5 climate projections

2015 ◽  
Vol 56 (70) ◽  
pp. 89-97 ◽  
Author(s):  
Marion Réveillet ◽  
Antoine Rabatel ◽  
Fabien Gillet-Chaulet ◽  
Alvaro Soruco
Keyword(s):  
Mass Balance ◽  
21St Century ◽  
Coupled Model ◽  
Cmip5 Models ◽  
Climate Projections ◽  
Surface Mass Balance ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
Temperature Changes ◽  
Intercomparison Project

AbstractBolivian glaciers are an essential source of fresh water for the Altiplano, and any changes they may undergo in the near future due to ongoing climate change are of particular concern. Glaciar Zongo, Bolivia, located near the administrative capital La Paz, has been extensively monitored by the GLACIOCLIM observatory in the last two decades. Here we model the glacier dynamics using the 3-D full-Stokes model Elmer/Ice. The model was calibrated and validated over a recent period (1997–2010) using four independent datasets: available observations of surface velocities and surface mass balance were used for calibration, and changes in surface elevation and retreat of the glacier front were used for validation. Over the validation period, model outputs are in good agreement with observations (differences less than a small percentage). The future surface mass balance is assumed to depend on the equilibrium-line altitude (ELA) and temperature changes through the sensitivity of ELA to temperature. The model was then forced for the 21st century using temperature changes projected by nine Coupled Model Intercomparison Project phase 5 (CMIP5) models. Here we give results for three different representative concentration pathways (RCPs). The intermediate scenario RCP6.0 led to 69 ± 7% volume loss by 2100, while the two extreme scenarios, RCP2.6 and RCP8.5, led to 40 ± 7% and 89 ± 4% loss of volume, respectively.

Amazonian forest dieback under climate-carbon cycle projections for the 21st century

2004 ◽  
Vol 78 (1-3) ◽  
Author(s):  
P. M. Cox ◽  
R. A. Betts ◽  
M. Collins ◽  
P. P. Harris ◽  
C. Huntingford ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
21St Century ◽  
Amazonian Forest ◽  
Forest Dieback

Simulation and Projection of the Southern Hemisphere Annular Mode in CMIP5 Models

2013 ◽  
Vol 26 (24) ◽  
pp. 9860-9879 ◽  
Author(s):  
Fei Zheng ◽  
Jianping Li ◽  
Robin T. Clark ◽  
Hyacinth C. Nnamchi
Keyword(s):  
Southern Hemisphere ◽  
Coupled Model ◽  
Austral Summer ◽  
Cmip5 Models ◽  
Spatial And Temporal Variability ◽  
Positive Trend ◽  
Annular Mode ◽  
Future Evolution ◽  
Asymmetric Component ◽  
The Future

Abstract Climate variability in the Southern Hemisphere (SH) extratropical regions is dominated by the SH annular mode (SAM). Future changes in the SAM could have a large influence on the climate over broad regions. In this paper, the authors utilized model simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) to examine projected future changes in the SAM during the austral summer [December–February (DJF)]. To start off, first, the ability of the models in reproducing the recently observed spatial and temporal variability was assessed. The 12 CMIP5 models examined were found to reproduce the SAM's spatial pattern reasonably well in terms of both the symmetrical and the asymmetric component. The CMIP5 models show an improvement over phase 3 of CMIP (CMIP3) in simulating the seesaw structure of the SAM and also give improvements in the recently observed positive SAM trend. However, only half the models appeared to be able to capture two major recent decadal SAM phases. Then, the future SAM trends and its sensitivity to greenhouse gas (GHG) concentrations using simulations based on the representative concentration pathways 4.5 (RCP4.5) and 8.5 (RCP8.5) were explored. With RCP4.5, a very weak negative trend for this century is found. Conversely, with RCP8.5, a significant positive trend was projected, with a magnitude similar to the recently observed trend. Finally, model uncertainty in the future SAM projections was quantified by comparing projections from the individual CMIP5 models. The results imply the response of SH polar region stratospheric temperature to GHGs could be a significant controlling factor on the future evolution of the SAM.

scholarly journals Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models

2013 ◽  
Vol 10 (2) ◽  
pp. 3627-3676 ◽  
Author(s):  
L. Bopp ◽  
L. Resplandy ◽  
J. C. Orr ◽  
S. C. Doney ◽  
J. P. Dunne ◽  
...  
Keyword(s):  
21St Century ◽  
Primary Productivity ◽  
Multiple Stressors ◽  
Sea Surface ◽  
Marine Phytoplankton ◽  
Global Ocean ◽  
Cmip5 Models ◽  
Regional Patterns ◽  
Ocean Ecosystems ◽  
The Tropics

Abstract. Ocean ecosystems are increasingly stressed by human-induced changes of their physical, chemical and biological environment. Among these changes, warming, acidification, deoxygenation and changes in primary productivity by marine phytoplankton can be considered as four of the major stressors of open ocean ecosystems. Due to rising atmospheric CO2 in the coming decades, these changes will be amplified. Here, we use the most recent simulations performed in the framework of the Coupled Model Intercomparison Project 5 to assess how these stressors may evolve over the course of the 21st century. The 10 Earth System Models used here project similar trends in ocean warming, acidification, deoxygenation and reduced primary productivity for each of the IPCC's representative concentration parthways (RCP) over the 21st century. For the "business-as-usual" scenario RCP8.5, the model-mean changes in 2090s (compared to 1990s) for sea surface temperature, sea surface pH, global O2 content and integrated primary productivity amount to +2.73 °C, −0.33 pH unit, −3.45% and −8.6%, respectively. For the high mitigation scenario RCP2.6, corresponding changes are +0.71 °C, −0.07 pH unit, −1.81% and −2.0% respectively, illustrating the effectiveness of extreme mitigation strategies. Although these stressors operate globally, they display distinct regional patterns. Large decreases in O2 and in pH are simulated in global ocean intermediate and mode waters, whereas large reductions in primary production are simulated in the tropics and in the North Atlantic. Although temperature and pH projections are robust across models, the same does not hold for projections of sub-surface O2 concentrations in the tropics and global and regional changes in net primary productivity.

scholarly journals Projected 21st century decrease in marine productivity: a multi-model analysis

2009 ◽  
Vol 6 (4) ◽  
pp. 7933-7981 ◽  
Author(s):  
M. Steinacher ◽  
F. Joos ◽  
T. L. Frölicher ◽  
L. Bopp ◽  
P. Cadule ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Particulate Organic Carbon ◽  
21St Century ◽  
Mixed Layer Depth ◽  
The Arctic ◽  
Nutrient Concentrations ◽  
Export Production ◽  
Model Average ◽  
Marine Productivity

Abstract. Changes in marine net primary productivity and export of particulate organic carbon are projected over the 21st century with three global coupled carbon cycle-climate models. These include representations of marine ecosystems and the carbon cycle of different structure and complexity. All three models show a decrease in global mean marine productivity and export production between 7 and 20% by 2100 relative to preindustrial conditions, for the SRES A2 emission scenario. Two different regimes for productivity changes are consistently identified in all three models. The first chain of mechanisms is dominant in the low- and mid-latitude ocean and in the North Atlantic: reduced input of macro-nutrients into the euphotic zone related to enhanced stratification, reduced mixed layer depth, and slowed circulation causes a decrease in macro-nutrient concentrations and in productivity and export of particulate organic carbon. The second regime is projected for parts of the Southern Ocean: an alleviation of light and/or temperature limitation leads to an increase in primary and export production as productivity is fueled by a sustained nutrient input. A region of disagreement among the models is the Arctic, where two models project an increase in productivity while one model projects a decrease. Projected changes in seasonal and interannual variability are modest in most regions. Regional model skill metrics are proposed to generate multi-model mean fields that show an improved skill in representing observations compared to a simple multi-model average. Model results are compared to recent productivity projections with three different algorithms, usually applied to infer primary production from satellite observations.

scholarly journals Drought assessment and trends analysis from 20th century to 21st century over China

2015 ◽  
Vol 371 ◽  
pp. 89-94 ◽  
Author(s):  
X. L. Yang ◽  
L. L. Ren ◽  
R. Tong ◽  
Y. Liu ◽  
X. R. Cheng ◽  
...  
Keyword(s):  
20Th Century ◽  
21St Century ◽  
Climate Models ◽  
Local Economic Development ◽  
Standardized Precipitation Index ◽  
Cmip5 Models ◽  
Climate Projections ◽  
Future Period ◽  
Drought Assessment ◽  
The Future

Abstract. Droughts are becoming the most expensive natural disasters in China and have exerted serious impacts on local economic development and ecological environment. The fifth phase of the Coupled Model Intercomparison Project (CMIP5) provides a unique opportunity to assess scientific understanding of climate variability and change over a range of historical and future period. In this study, fine-resolution multimodel climate projections over China are developed based on 7 CMIP5 climate models under RCP8.5 emissions scenarios by means of Bilinear Interpolation and Bias Correction. The results of downscaled CMIP5 models are evaluated over China by comparing the model outputs with the England Reanalysis CRU3.1 from 1951 to 2000. Accordingly, the results from the output of downscaled models are used to calculate the Standardized Precipitation Index (SPI). Time series of SPI has been used to identify drought from 20th century to 21st century over China. The results show that, most areas of China are projected to become wetter as a consequence of increasing precipitation under RCP8.5 scenarios. Detailed examination shows that the SPI show a slightly increasing trend in the future period for the most parts of China, but drought in Southwest region of China will become the norm in the future RCP8.5 scenarios.

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