scholarly journals Influence of CO2 emission rates on the stability of the thermohaline circulation

Nature ◽  
10.1038/42224 ◽  
1997 ◽  
Vol 388 (6645) ◽  
pp. 862-865 ◽  
Author(s):  
Thomas F. Stocker ◽  
Andreas Schmittner
Keyword(s):  
Co2 Emission ◽  
Thermohaline Circulation ◽  
Emission Rates ◽  
The Stability

scholarly journals Drivers of CO2 Emission Rates from Dead Wood Logs of 13 Tree Species in the Initial Decomposition Phase

Forests ◽  
2015 ◽  
Vol 6 (12) ◽  
pp. 2484-2504 ◽  
Author(s):  
Tiemo Kahl ◽  
Kristin Baber ◽  
Peter Otto ◽  
Christian Wirth ◽  
Jürgen Bauhus
Keyword(s):  
Tree Species ◽  
Co2 Emission ◽  
Dead Wood ◽  
Emission Rates ◽  
Decomposition Phase

scholarly journals Effective CO<sub>2</sub> lifetime and future CO<sub>2</sub> levels based on fit function

2013 ◽  
Vol 31 (9) ◽  
pp. 1591-1596 ◽  
Author(s):  
G. R. Sonnemann ◽  
M. Grygalashvyly
Keyword(s):  
Global Warming ◽  
Power Function ◽  
Co2 Emission ◽  
Emission Rates ◽  
Atmospheric Emissions ◽  
Atmospheric Concentration ◽  
Effective Lifetime ◽  
Global Emission ◽  
Future Global Warming ◽  
Atmospheric Co2 Concentrations

Abstract. The estimated global CO2 emission rates and the measured atmospheric CO2 concentrations show that only a certain share of the emitted CO2 accumulates in the atmosphere. For given atmospheric emissions of CO2, the effective lifetime determines its accumulation in the atmosphere and, consequently, its impact on the future global warming. We found that on average the inferred effective lifetime of CO2 decreases as its atmospheric concentration increases, reducing the rate of its accumulation in the atmosphere. We derived a power function that fits the varying lifetimes. Based on this fitting function, we calculated the increase of CO2 for different scenarios of future global emission rates.

scholarly journals Effect of Nitrogen Fertilizer on Soil CO2 Emission Depends on Crop Rotation Strategy

2020 ◽  
Vol 12 (13) ◽  
pp. 5271
Author(s):  
Dejie Kong ◽  
Nana Liu ◽  
Chengjie Ren ◽  
Huiying Li ◽  
Weiyu Wang ◽  
...  
Keyword(s):  
Crop Rotation ◽  
Co2 Emission ◽  
Management Practices ◽  
N Fertilizer ◽  
Emission Rates ◽  
Fertilizer Management ◽  
Soil Co2 ◽  
Soil Co2 Emission ◽  
The Impact ◽  
Rotation Strategy

Developing environmentally friendly and sustainable nitrogen (N) fertilizer management strategies is crucial in mitigating carbon dioxide (CO2) emission from soil. How N fertilizer management practices influence soil CO2 emission rates under different crop rotations remains unclear. The aim of this study was to assess the impact on soil CO2 emission and soil physicochemical properties of three N fertilizer treatments including traditional rate (TF), optimized rate (0.8TF), and no fertilizer (NF) under three different crop rotation treatments: wheat-fallow (WF), wheat-soybean (WS), and wheat-maize (WM) over two years in a field experiment in northwest China. The rates were 5.51, 5.60, and 5.97 μmol·m−2·s−1 of mean soil CO2 emission under the TF, 0.8TF, and NF treatments, respectively. Mean soil CO2 emission rates were 21.33 and 26.99% higher under the WM rotation compared with the WF and WS rotations, respectively. The WS rotation showed higher soil nutrient content and lower soil CO2 emissions, and reduced fertilizer application. Importantly, soil organic carbon (SOC) concentration in the topsoil can be maximized by including either a summer legume or a summer maize crop in winter wheat rotations, and by applying N fertilizer at the optimal rate. This may be particularly beneficial in the dryland cropping systems of northern China.

Can Isopycnal Mixing Control the Stability of the Thermohaline Circulation in Ocean Climate Models?

2006 ◽  
Vol 19 (21) ◽  
pp. 5637-5651 ◽  
Author(s):  
Willem P. Sijp ◽  
Michael Bates ◽  
Matthew H. England
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Climate Models ◽  
Thermohaline Circulation ◽  
Vertical Component ◽  
Coupled Model ◽  
General Circulation Models ◽  
Tracer Transport ◽  
Horizontal Diffusion ◽  
The Stability

Abstract Convective overturning arising from static instability during winter is thought to play a crucial role in the formation of North Atlantic Deep Water (NADW). In ocean general circulation models (OGCMs), a strong reduction in convective penetration depth arises when horizontal diffusion (HD) is replaced by Gent and McWilliams (GM) mixing to model the effect of mesoscale eddies on tracer advection. In areas of sinking, the role of vertical tracer transport due to convection is largely replaced by the vertical component of isopycnal diffusion along sloping isopycnals. Here, the effect of this change in tracer transport physics on the stability of NADW formation under freshwater (FW) perturbations of the North Atlantic (NA) in a coupled model is examined. It is found that there is a significantly increased stability of NADW to FW input when GM is used in spite of GM experiments exhibiting consistently weaker NADW formation rates in unperturbed steady states. It is also found that there is a significant increase in NADW stability upon the introduction of isopycnal diffusion in the absence of GM. This indicates that isopycnal diffusion of tracer rather than isopycnal thickness diffusion is responsible for the increased NADW stability observed in the GM run. This result is robust with respect to the choice of isopycnal diffusion coefficient. Also, the NADW behavior in the isopycnal run, which includes a fixed background horizontal diffusivity, demonstrates that HD is not responsible in itself for reducing NADW stability when simple horizontal diffusion is used. Our results suggest that care should be taken when interpreting the results of coarse grid models with regard to NADW sensitivity to FW anomalies, regardless of the choice of mixing scheme.

The Eco-Design Directive ErP for AHUs

2017 ◽  
Vol 21 ◽  
pp. 482-488
Author(s):  
Cătălin George Popovici
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Co2 Emission ◽  
Renewable Energies ◽  
European Economic Area ◽  
Emission Rates ◽  
European Economic ◽  
Economic Area ◽  
Air Handling Units ◽  
Reduction Of Energy Consumption

The European ErP-Directive 2009/125/EG (Energy-related-Products-Directive), also called the Eco-Design Directive, defines the minimal requirements for energy-related products. The objective of the ErP-Directive is the reduction of energy consumption and the CO2-emission rates as well as an increase of the overall share of renewable energies. This directive applies for all products placed on the market within the European Economic Area (EEA). Relevant for the AHUs is the EC-Directive 1253/2014/EG that came into force on November 26th 2014. Within the framework of this directive and as of January 1st 2016, new requirements concerning the energy efficiency of AHUs will apply within the European Economic Area (EEA). The paper analyzes the new requirements for Air Handling Units under ErP Directive and its consequences.

scholarly journals Influence of extreme events modeled by Lévy flight on global thermohaline circulation stability

2020 ◽  
Author(s):  
Daniel Tesfay ◽  
Larissa Serdukova ◽  
Yayun Zheng ◽  
Pingyuan Wei ◽  
Jinqiao Duan ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Fresh Water ◽  
Extreme Events ◽  
Thermohaline Circulation ◽  
First Passage Time ◽  
Basin Of Attraction ◽  
Compartment Model ◽  
Meridional Overturning Circulation ◽  
Escape Probability ◽  
The Stability

Abstract. How will extreme events due to human activities and climate change affect the oceanic thermohaline circulation is a key concern in climate predictions. The stability of the thermohaline circulation with respect to extreme events, such as fresh-water oscillations, greenhouse gas accumulations and collapse of the Atlantic meridional overturning circulation, is examined using a conceptual stochastic Stommel two-compartment model. The extreme fluctuations are modeled by symmetric α-stable Lévy motions whose pathways are cádlág functions with at most a countable number of jumps. The mean first passage time, escape probability and stochastic basin of attraction are used to perform the stability analysis of on (off) equilibrium states. Our results argue that for model with weak fresh-water forcing strength, the greatest threat to the stability of the on-state represents noise with low jumps and higher frequency that can be seen as civilization-induced greenhouse gas accumulation. On the other hand, the off-state stability is more vulnerable to the agitations with moderate jumps and frequencies which can be interpreted as wind- driven circulations towards higher latitudes. Under the repercussion of stochastic noise, on to off transitions are more expected in the model if the fresh-water influx is strong. Moreover, transitions from one metastable state to another are equiprobable when the fresh-water input induces a symmetric potential well.

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