Constraining anthropogenic carbon and excess heat uptake in climate projections

2021 ◽  
Author(s):  
Timothée Bourgeois ◽  
Nadine Goris ◽  
Jörg Schwinger ◽  
Jerry Tjiputra
Keyword(s):  
Water Column ◽  
Climate Mitigation ◽  
Carbon Uptake ◽  
Climate Projections ◽  
Earth System ◽  
Excess Heat ◽  
Uptake Efficiency ◽  
Water Column Stability ◽  
Heat Uptake ◽  
Anthropogenic Carbon

<p>The North Atlantic and Southern Oceans are major sinks of anthropogenic carbon and excess heat. The Earth system model projections of these sinks provided by the CMIP5 and CMIP6 scenario experiments remain highly uncertain, hindering an effective development of climate mitigation policies for meeting the ambitious climate targets laid down in the Paris agreement. A recent study identified an emergent coupling between anthropogenic carbon and excess heat uptake, highlighting the dominant passive-tracer behavior of these two quantities under high-emission scenarios. This coupling potentially allows for the use of a single observational constraint to reduce these projection uncertainties. As a first step, we investigate the causes of these uncertainties in the Southern Ocean (30°S-55°S) by looking regionally at different contemporary physical and biogeochemical quantities. We find that the variations in model´s contemporary water-column stability over the first 2000 m is highly correlated to both its future anthropogenic carbon uptake and excess heat uptake efficiency. Using an observation-based estimate of contemporary water-column stability, this allows us to reduce the uncertainty of future estimates of (1) the cumulative anthropogenic carbon uptake by up to 50% and (2) the excess heat uptake efficiency by 23%. Our results show that improving representation of water-column stratification in Earth system models should be prioritized to constrain future carbon budget and climate change projections.</p>

Emergent constraints on the Southern Ocean anthropogenic carbon and heat uptake

2021 ◽  
Author(s):  
Thomas Frölicher ◽  
Jens Terhaar ◽  
Fortunat Joos
Keyword(s):  
Southern Ocean ◽  
Ocean Circulation ◽  
Earth System Model ◽  
System Model ◽  
Carbon Uptake ◽  
Earth System ◽  
Excess Heat ◽  
The Past ◽  
Heat Uptake ◽  
Anthropogenic Carbon

<p>The Southern Ocean south of 30°S, occupying about a third of global surface ocean area, accounts for approximately 40% of the past anthropogenic carbon uptake and about 75% of excess heat uptake by the ocean. However, Earth system models have large difficulties in reproducing the Southern Ocean circulation, and therefore its historical and future anthropogenic carbon and excess heat uptake. In the first part of the talk, we show that there exists a tight relation across two Earth system model ensembles (CMIP5 and CMIP6) between present-day sea surface salinity in the subtropical-polar frontal zone, the formation region of mode and intermediate waters, and the past and future anthropogenic carbon uptake in the Southern Ocean. By using observations and Earth system model results, we constrain the projected cumulative Southern Ocean anthropogenic carbon uptake over 1850-2100 by the CMIP6 model ensemble to 158 ± 6 Pg C under the low-emissions scenario SSP1-2.6 and to 279 ± 14 Pg C under the high emissions scenario SSP5-8.5. Our results suggest that the Southern Ocean anthropogenic carbon sink is 14-18% larger and 46-54% less uncertain than estimated by the unconstrained CMIP6 Earth system model results. The identified constraint demonstrated the importance of the freshwater cycle for the Southern Ocean circulation and carbon cycle. In the second part of the talk, potential emergent constraints for the Southern Ocean excess heat uptake will be discussed.</p>

scholarly journals Sensitivity of Global Warming to Carbon Emissions: Effects of Heat and Carbon Uptake in a Suite of Earth System Models

2017 ◽  
Vol 30 (23) ◽  
pp. 9343-9363 ◽  
Author(s):  
Richard G. Williams ◽  
Vassil Roussenov ◽  
Philip Goodwin ◽  
Laure Resplandy ◽  
Laurent Bopp
Keyword(s):  
Climate Sensitivity ◽  
Carbon Emissions ◽  
Radiative Forcing ◽  
Carbon Uptake ◽  
Earth System ◽  
Ocean Heat Uptake ◽  
Surface Warming ◽  
System Models ◽  
Heat Uptake ◽  
Earth System Models

Climate projections reveal global-mean surface warming increasing nearly linearly with cumulative carbon emissions. The sensitivity of surface warming to carbon emissions is interpreted in terms of a product of three terms: the dependence of surface warming on radiative forcing, the fractional radiative forcing from CO2, and the dependence of radiative forcing from CO2 on carbon emissions. Mechanistically each term varies, respectively, with climate sensitivity and ocean heat uptake, radiative forcing contributions, and ocean and terrestrial carbon uptake. The sensitivity of surface warming to fossil-fuel carbon emissions is examined using an ensemble of Earth system models, forced either by an annual increase in atmospheric CO2 or by RCPs until year 2100. The sensitivity of surface warming to carbon emissions is controlled by a temporal decrease in the dependence of radiative forcing from CO2 on carbon emissions, which is partly offset by a temporal increase in the dependence of surface warming on radiative forcing. The decrease in the dependence of radiative forcing from CO2 is due to a decline in the ratio of the global ocean carbon undersaturation to carbon emissions, while the increase in the dependence of surface warming is due to a decline in the ratio of ocean heat uptake to radiative forcing. At the present time, there are large intermodel differences in the sensitivity in surface warming to carbon emissions, which are mainly due to uncertainties in the climate sensitivity and ocean heat uptake. These uncertainties undermine the ability to predict how much carbon may be emitted before reaching a warming target.

scholarly journals 13 Years of Storms: An Analysis of the Effects of Storms on Lake Physics on the Atlantic Fringe of Europe

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 318 ◽  
Author(s):  
Mikkel René Andersen ◽  
Elvira de Eyto ◽  
Mary Dillane ◽  
Russell Poole ◽  
Eleanor Jennings
Keyword(s):  
Water Column ◽  
Western Europe ◽  
Thermal Structure ◽  
Winter Storms ◽  
Water Column Stability ◽  
Physical Conditions ◽  
Order Of Magnitude ◽  
Storm Frequency ◽  
Summer Storm ◽  
Lake Physics

While winter storms are generally common in western Europe, the rarer summer storms may result in more pronounced impacts on lake physics. Using long-term, high frequency datasets of weather and lake thermal structure from the west of Ireland (2005 to 2017), we quantified the effects of storms on the physical conditions in a monomictic, deep lake close to the Atlantic Ocean. We analysed a total of 227 storms during the stratified (May to September, n = 51) and non-stratified (November to March, n = 176) periods. In winter, as might be expected, changes were distributed over the entire water column, whereas in summer, when the lake was stratified, storms only impacted the smaller volume above the thermocline. During an average summer (May–September) storm, the lake number dropped by an order of magnitude, the thermocline deepened by an average of 2.8 m, water column stability decreased by an average of 60.4 j m−2 and the epilimnion temperature decreased by a factor of five compared to the average change in winter (0.5 °C vs. 0.1 °C). Projected increases in summer storm frequency will have important implications for lake physics and biological pathways.

Relationship of water column stability to the growth, condition, and survival of pink salmon (Oncorhynchus gorbuscha) in the northern coastal Gulf of Alaska and Prince William Sound

2012 ◽  
Vol 69 (5) ◽  
pp. 955-969 ◽  
Author(s):  
Sara E. Miller ◽  
Milo Adkison ◽  
Lewis Haldorson
Keyword(s):  
Water Column ◽  
Growth Condition ◽  
Pink Salmon ◽  
Gulf Of Alaska ◽  
Oncorhynchus Gorbuscha ◽  
Biological Parameters ◽  
Prince William Sound ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Fish Condition ◽  
Water Column Stability

Water column stability has been hypothesized to affect growth and ultimately survival of juvenile fish. We estimated the relationships between stability and the growth, condition, and marine survival of several stocks of pink salmon ( Oncorhynchus gorbuscha ) within Prince William Sound (PWS), Alaska, USA, and the northern coastal Gulf of Alaska (GOA) shelf. There was a stronger correlation among the biological parameters of the fish than between the biological parameters and physical conditions. While stability and fish condition during early marine residence in PWS were important to year-class survival, stability of the water column that juveniles experienced as they migrated to the open waters of the GOA did not play a key role in determining survival to adulthood. Below-average stability just prior to capture within PWS combined with positive fish condition was related to increased year-class survival. Our results are similar to previous studies that concluded that slower and weaker development of stratification with a deeper mixed layer depth may be important for juvenile pink salmon survival in PWS.

scholarly journals Simulating natural carbon sequestration in the Southern Ocean: on uncertainties associated with eddy parameterizations and iron deposition

2017 ◽  
Vol 14 (6) ◽  
pp. 1561-1576 ◽  
Author(s):  
Heiner Dietze ◽  
Julia Getzlaff ◽  
Ulrike Löptien
Keyword(s):  
Carbon Sequestration ◽  
Southern Ocean ◽  
Ocean Circulation ◽  
Spatial Scales ◽  
Carbon Uptake ◽  
Comprehensive Understanding ◽  
Biogeochemical Models ◽  
Anthropogenic Carbon ◽  
Natural Carbon ◽  
Oceanic Carbon

Abstract. The Southern Ocean is a major sink for anthropogenic carbon. Yet, there is no quantitative consensus about how this sink will change when surface winds increase (as they are anticipated to do). Among the tools employed to quantify carbon uptake are global coupled ocean-circulation–biogeochemical models. Because of computational limitations these models still fail to resolve potentially important spatial scales. Instead, processes on these scales are parameterized. There is concern that deficiencies in these so-called eddy parameterizations might imprint incorrect sensitivities of projected oceanic carbon uptake. Here, we compare natural carbon uptake in the Southern Ocean simulated with contemporary eddy parameterizations. We find that very differing parameterizations yield surprisingly similar oceanic carbon in response to strengthening winds. In contrast, we find (in an additional simulation) that the carbon uptake does differ substantially when the supply of bioavailable iron is altered within its envelope of uncertainty. We conclude that a more comprehensive understanding of bioavailable iron dynamics will substantially reduce the uncertainty of model-based projections of oceanic carbon uptake.

scholarly journals Historical and idealized climate model experiments: an intercomparison of Earth system models of intermediate complexity

2013 ◽  
Vol 9 (3) ◽  
pp. 1111-1140 ◽  
Author(s):  
M. Eby ◽  
A. J. Weaver ◽  
K. Alexander ◽  
K. Zickfeld ◽  
A. Abe-Ouchi ◽  
...  
Keyword(s):  
Land Use ◽  
Carbon Cycle ◽  
Air Temperature ◽  
Climate Model ◽  
Surface Air Temperature ◽  
Carbon Fluxes ◽  
Carbon Uptake ◽  
Earth System ◽  
Model Experiments ◽  
Earth System Models

Abstract. Both historical and idealized climate model experiments are performed with a variety of Earth system models of intermediate complexity (EMICs) as part of a community contribution to the Intergovernmental Panel on Climate Change Fifth Assessment Report. Historical simulations start at 850 CE and continue through to 2005. The standard simulations include changes in forcing from solar luminosity, Earth's orbital configuration, CO2, additional greenhouse gases, land use, and sulphate and volcanic aerosols. In spite of very different modelled pre-industrial global surface air temperatures, overall 20th century trends in surface air temperature and carbon uptake are reasonably well simulated when compared to observed trends. Land carbon fluxes show much more variation between models than ocean carbon fluxes, and recent land fluxes appear to be slightly underestimated. It is possible that recent modelled climate trends or climate–carbon feedbacks are overestimated resulting in too much land carbon loss or that carbon uptake due to CO2 and/or nitrogen fertilization is underestimated. Several one thousand year long, idealized, 2 × and 4 × CO2 experiments are used to quantify standard model characteristics, including transient and equilibrium climate sensitivities, and climate–carbon feedbacks. The values from EMICs generally fall within the range given by general circulation models. Seven additional historical simulations, each including a single specified forcing, are used to assess the contributions of different climate forcings to the overall climate and carbon cycle response. The response of surface air temperature is the linear sum of the individual forcings, while the carbon cycle response shows a non-linear interaction between land-use change and CO2 forcings for some models. Finally, the preindustrial portions of the last millennium simulations are used to assess historical model carbon-climate feedbacks. Given the specified forcing, there is a tendency for the EMICs to underestimate the drop in surface air temperature and CO2 between the Medieval Climate Anomaly and the Little Ice Age estimated from palaeoclimate reconstructions. This in turn could be a result of unforced variability within the climate system, uncertainty in the reconstructions of temperature and CO2, errors in the reconstructions of forcing used to drive the models, or the incomplete representation of certain processes within the models. Given the forcing datasets used in this study, the models calculate significant land-use emissions over the pre-industrial period. This implies that land-use emissions might need to be taken into account, when making estimates of climate–carbon feedbacks from palaeoclimate reconstructions.

scholarly journals CARACTERISTICAS FISICO-QUIMICAS DE LA BAHIA DE SANTA MARTA (AGOSTO 1980 - JULIO 1981)

2016 ◽  
Vol 13 ◽  
Author(s):  
Gustavo Ramírez T.
Keyword(s):  
Surface Water ◽  
Water Column ◽  
Annual Cycle ◽  
Water Column Stability ◽  
Physical Chemical ◽  
Chemical Conditions

Physical-chemical conditions have been studied in the Bay of Santa Marta, Colombian Caribbean, from August 1980 to July 1981. The results obtained at nine stations indicate that the surface water is rather homogeneous and of mainly oceanic character. In the period from december to april water temperatures were lowest (<25®C), salinity highest (>36°/oo) and undersaturation with oxigen occured (<91%) these factors together with pH, alcalinity and the variation of water column stability are indicating an upwelling phenomenon in this period and allow the stablishment of an approximated model for the annual cycle the bay.

scholarly journals Twenty-First-Century Compatible CO2 Emissions and Airborne Fraction Simulated by CMIP5 Earth System Models under Four Representative Concentration Pathways

2013 ◽  
Vol 26 (13) ◽  
pp. 4398-4413 ◽  
Author(s):  
Chris Jones ◽  
Eddy Robertson ◽  
Vivek Arora ◽  
Pierre Friedlingstein ◽  
Elena Shevliakova ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Climate Models ◽  
Coupled Model ◽  
Co2 Concentration ◽  
Atmospheric Composition ◽  
System Component ◽  
Anthropogenic Emissions ◽  
Carbon Uptake ◽  
Earth System ◽  
Representative Concentration Pathways

Abstract The carbon cycle is a crucial Earth system component affecting climate and atmospheric composition. The response of natural carbon uptake to CO2 and climate change will determine anthropogenic emissions compatible with a target CO2 pathway. For phase 5 of the Coupled Model Intercomparison Project (CMIP5), four future representative concentration pathways (RCPs) have been generated by integrated assessment models (IAMs) and used as scenarios by state-of-the-art climate models, enabling quantification of compatible carbon emissions for the four scenarios by complex, process-based models. Here, the authors present results from 15 such Earth system GCMs for future changes in land and ocean carbon storage and the implications for anthropogenic emissions. The results are consistent with the underlying scenarios but show substantial model spread. Uncertainty in land carbon uptake due to differences among models is comparable with the spread across scenarios. Model estimates of historical fossil-fuel emissions agree well with reconstructions, and future projections for representative concentration pathway 2.6 (RCP2.6) and RCP4.5 are consistent with the IAMs. For high-end scenarios (RCP6.0 and RCP8.5), GCMs simulate smaller compatible emissions than the IAMs, indicating a larger climate–carbon cycle feedback in the GCMs in these scenarios. For the RCP2.6 mitigation scenario, an average reduction of 50% in emissions by 2050 from 1990 levels is required but with very large model spread (14%–96%). The models also disagree on both the requirement for sustained negative emissions to achieve the RCP2.6 CO2 concentration and the success of this scenario to restrict global warming below 2°C. All models agree that the future airborne fraction depends strongly on the emissions profile with higher airborne fraction for higher emissions scenarios.

Decadal Prediction of Marine Heatwaves in MPI-ESM

2021 ◽  
Author(s):  
Laura Hövel ◽  
Sebastian Brune ◽  
Johanna Baehr
Keyword(s):  
North Atlantic ◽  
Regional Differences ◽  
Correlation Coefficients ◽  
Sea Surface ◽  
System Model ◽  
Climate Projections ◽  
Earth System ◽  
Max Planck ◽  
Circulation Patterns ◽  
Decadal Predictability

&lt;p&gt;Marine Heatwaves (MHWs) are Sea Surface Temperature (SST) extremes that can have devastating impacts on marine ecosystems but can also impact circulation patterns in the ocean and the atmosphere. The variability of MHWs has been studied in historical observations and longterm climate projections, but predictability has only been analyzed on seasonal timescales. Here, we we present the first attempt to study the decadal predictability of MHW days per year in an ensemble of decadal hindcasts based on the Max Planck Institute Earth System Model (MPI-ESM-LR).&lt;/p&gt;&lt;p&gt;Our results show that there are strong regional differences in prediction skill. While many regions show little to no skill, we find in the Subpolar North Atlantic correlation coefficients up to 0.7 for MHW days up to lead year 8. We demonstrate that these correlations mainly arise from correctly predicting the absence of MHWs in individual years. MHW days per year might be successfully predicted by only using yearly mean SST as a proxy, which also demonstrates that in the Subpolar North Atlantic, any increase in SST is accompanied by more MHWs and vice versa.&lt;/p&gt;

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