Compact Earth Research Articles

CMIP6 simulations with the compact Earth system model OSCAR v3.1

Abstract. Reduced-complexity models, also called simple climate models or compact models, provide an alternative to Earth system models (ESMs) with lower computational costs, although at the expense of spatial and temporal information. It remains important to evaluate and validate these reduced-complexity models. Here, we evaluate a recent version (v3.1) of the OSCAR model using observations and results from ESMs from the current Coupled Model Intercomparison Project 6 (CMIP6). The results follow the same post-processing used for the contribution of OSCAR to the Reduced Complexity Model Intercomparison Project (RCMIP) Phase 2 regarding the identification of stable configurations and the use of observational constraints. These constraints succeed in decreasing the overestimation of global surface air temperature over 2000–2019 with reference to 1961–1900 from 0.60±0.11 to 0.55±0.04 K (the constraint being 0.54±0.05 K). The equilibrium climate sensitivity (ECS) of the unconstrained OSCAR is 3.17±0.63 K, while CMIP5 and CMIP6 models have ECSs of 3.2±0.7 and 3.7±1.1 K, respectively. Applying observational constraints to OSCAR reduces the ECS to 2.78±0.47 K. Overall, the model qualitatively reproduces the responses of complex ESMs, although some differences remain due to the impact of observational constraints on the weighting of parametrizations. Specific features of OSCAR also contribute to these differences, such as its fully interactive atmospheric chemistry and endogenous calculations of biomass burning, wetlands CH4 and permafrost CH4 and CO2 emissions. Identified main points of needed improvements of the OSCAR model include a low sensitivity of the land carbon cycle to climate change, an instability of the ocean carbon cycle, the climate module that is seemingly too simple, and the climate feedback involving short-lived species that is too strong. Beyond providing a key diagnosis of the OSCAR model in the context of the reduced-complexity models, this work is also meant to help with the upcoming calibration of OSCAR on CMIP6 results and to provide a large group of CMIP6 simulations run consistently within a probabilistic framework.

Code for "CMIP6 simulations with the compact Earth system model OSCAR v3.1"

Code for "CMIP6 simulations with the compact Earth system model OSCAR v3.1"

Study of earth-based materials for manufacturing compaction process

The aim of this study is to develop a characterization test for the purpose of determining the consistency of the earth-based material adapted to produce compacted earth bricks (CEB). Existing tests have often been designed for plastic or fluid earth materials, which is not the case for compact earth materials of interest in the present study. This study includes the different methods of characterization for the shaping of these materials, such as: Atterberg limits, Carazas test, and dropped ball test. The earth-based mix studied has a plastic limit of 20%, a liquid limit of 42%, and a plasticity index of 22%. Therefore, the mix can be classified as a medium plasticity clay. The Carazas and dropped ball tests reveal that the manufacturing water content must be between 12% and 16% to ensure proper adaptation to shaping by compaction. However, these characterization methods are neither sufficient nor accurate enough to quantify the consistency to the manufacturing of CEB. For this purpose, to measure this consistency, a plunger penetration test with surcharge is developed. It could be shown that the plunger impact depth corresponding to the suitable consistency of CEB should be in the range of 6–10 mm. In order to confirm these results and select the suitable water content for production, the compressive strength of CEB at different water content (12%–20%) is measured; results indicate that the highest compressive strength is noted for a water content of 14%, which corresponds to a surcharged plunger impact depth of 8 mm.

Delayed use of bioenergy crops might threaten climate and food security.

The potential of mitigation actions to limit global warming within 2 °C (ref. 1) might rely on the abundant supply of biomass for large-scale bioenergy with carbon capture and storage (BECCS) that is assumed to scale up markedly in the future2-5. However, the detrimental effects of climate change on crop yields may reduce the capacity of BECCS and threaten food security6-8, thus creating an unrecognized positive feedback loop on global warming. We quantified the strength of this feedback by implementing the responses of crop yields to increases in growing-season temperature, atmospheric CO2 concentration and intensity of nitrogen (N) fertilization in a compact Earth system model9. Exceeding a threshold of climate change would cause transformative changes in social-ecological systems by jeopardizing climate stability and threatening food security. If global mitigation alongside large-scale BECCS is delayed to 2060 when global warming exceeds about 2.5 °C, then the yields of agricultural residues for BECCS would be too low to meet the Paris goal of 2 °C by 2200. This risk of failure is amplified by the sustained demand for food, leading to an expansion of cropland or intensification of N fertilization to compensate for climate-induced yield losses. Our findings thereby reinforce the urgency of early mitigation, preferably by 2040, to avoid irreversible climate change and serious food crises unless other negative-emission technologies become available in the near future to compensate for the reduced capacity of BECCS.

Climate Warming Mitigation from Nationally Determined Contributions

Individual countries are requested to submit nationally determined contributions (NDCs) to alleviate global warming in the Paris Agreement. However, the global climate effects and regional contributions are not explicitly considered in the countries’ decision-making process. In this study, we evaluate the global temperature slowdown of the NDC scenario (ΔT = 0.6°C) and attribute the global temperature slowdown to certain regions of the world with a compact earth system model. Considering reductions in CO2, CH4, N2O, BC, and SO2, the R5OECD (the Organization for Economic Co-operation and Development in 1990) and R5ASIA (Asian countries) are the top two contributors to global warming mitigation, accounting for 39.3% and 36.8%, respectively. R5LAM (Latin America and the Caribbean) and R5MAF (the Middle East and Africa) followed behind, with contributions of 11.5% and 8.9%, respectively. The remaining 3.5% is attributed to R5REF (the Reforming Economies). Carbon Dioxide emission reduction is the decisive factor of regional contributions, but not the only one. Other greenhouse gases are also important, especially for R5MAF. The contribution of short-lived aerosols is small but significant, notably SO2 reduction in R5ASIA. We argue that additional species beyond CO2 need to be considered, including short-lived pollutants, when planning a route to mitigate climate change. It needs to be emphasized that there is still a gap to achieve the Paris Agreement 2-degree target with current NDC efforts, let alone the ambitious 1.5-degree target. All countries need to pursue stricter reduction policies for a more sustainable world.

Experimental studies on natural bank type heating/cooling energy saving Air conditioning system

The present study reports air-based novel energy saving compact bank type earth air heat exchanger system (EAHE) (having only 25m2 area) fabricated from Polyvinylchloride pipes of nominal diameter 0.203 mm (8 inches) for inlet and outlet headers and main pipes and 0.150 mm (6 inches nominal diameter) for branched pipes, which is installed in Shaheed Bhagat Singh State University, Ferozepur in Punjab state, India (North West border area of India) and studied for the duration from April to August 2021 using the full factorial design with four inlet variables at multilevel to find a model equation between inlet and outlet variables, i.e., heat exchanger effectiveness and achieved temperature difference. An induced airflow mode has been used to provide near-uniform flow through all corresponding pipes of symmetrical-shaped earth air heat exchangers. The values of Dry bulb temperature (DBT) and wet bulb temperature (WBT) have been measured for air inlet, for air outlet, as well as for ambient air using resistance temperature detectors (RTD) installed at the requisite locations. Earth's undisturbed temperature (EUT) was also noted by installing RTD at a depth of 2 m, and the average measured value of EUT is found to be 28.5°C. The current system has imparted the temperature difference variation from 0.4 oC to 9.4 oC, and the effectiveness varied from 0.16 to 0.82 during the whole season. This system could give a cooling potential of 0.0523 kJ/s to 1.587 kJ/s using a mass flow rate of 0.163 kg/s.Experiments have been designed methodically to apply the full factorial technique. Most favorable parameters have been found for hot and dry and hot and humid weather. The current study is novel in terms of significantly improving the effectiveness of EAHE and addressing the central issue of space limitation in urban areas.

On the contribution of global aviation to the CO2 radiative forcing of climate

The aviation sector contributes to anthropogenic climate change through both CO2 and non-CO2 radiative effects. The CO2 effect is considered to be much more certain than the non-CO2 effects, yet there are relatively few studies that quantify it. Building on the scientific literature on burden sharing in the wake of the “Brazilian proposal”, we discuss how to best attribute a fraction of the CO2 radiative forcing to the aviation sector. For this we use the OSCAR compact Earth System model to estimate a contribution of aviation to the CO2 concentration of 2.18 ppm in 2018. We further estimate the aviation contribution to the 2018 CO2 radiative forcing to be 34.6, 32.6, 32.2 and 28.8 mW m−2 for the proportional, differential, time-sliced and marginal methods, respectively. The time-sliced method has our preference because it is invariant upon disaggregation or recombination and can differentiate the relative impacts of early and late emissions. It leads to a radiative forcing estimate that is 12% larger than the residual method that is commonly used despite not being additive. This work has implications on the total-to-CO2 RF ratio and the assessment of potential mitigation measures involving a trade-off between the CO2 and non-CO2 radiative effects of aviation.

Trade-driven black carbon climate forcing and environmental equality under China's west-east energy transmission

Given abundant energy and mineral resources in northwestern China, the west-east energy and mineral product transmission program play an increasingly important role in China's energy supply and consumption since the 2000s. Rapid growing energy and mineral products under this program might release increasing carbon emissions, causing climate and environmental consequences in northwestern China, which seems to be overlooked before. Here, a multiregional input-output analysis (MRIO) was conducted to investigate the temporal and spatial changes in black carbon (BC) emissions embodied in west-east energy and mineral product transmission from 2007 to 2012. Results were used to estimate BC's climate and environmental impact on China, focusing on northwestern China. The results show that BC emission flow patterns have been altered dramatically in China's domestic trade from 2007 through 2012. By 2012, 48%–77% of the consumption-based BC emissions from well-developed Beijing-Tianjin metropolises, East Coast, and South Coast regions were outsourced to other, primarily less-developed regions, of which northwestern China was the largest net BC emission outflow region at 48.8 Gg. The BC radiative forcing over China embodied in the west-east energy transmission was quantified using a compact Earth system model OSCAR. Model estimation shows that more than 30% of BC radiative forcing in northwestern China was related to the consumption from other regions across China. Central and eastern China were two significant contributors to the BC radiative forcing in northwestern China. Severe BC environmental inequality embodied in interprovincial trade was also identified in northwestern and central China provinces among 30 Chinese provinces. Inner Mongolia, Shaanxi, Ningxia, and Xinjiang in northwestern China experienced the most prominent climate and environmental losses via trade with well-developed provinces. These results provide references to alleviate trade-related pollution and climate impacts and to promote BC environmental equality in China.

The contributions of individual countries and regions to the global radiative forcing

Knowing the historical relative contribution of greenhouse gases (GHGs) and short-lived climate forcers (SLCFs) to global radiative forcing (RF) at the regional level can help understand how future GHGs emission reductions and associated or independent reductions in SLCFs will affect the ultimate purpose of the Paris Agreement. In this study, we use a compact Earth system model to quantify the global RF and attribute global RF to individual countries and regions. As our evaluation, the United States, the first 15 European Union members, and China are the top three contributors, accounting for 21.9 ± 3.1%, 13.7 ± 1.6%, and 8.6 ± 7.0% of global RF in 2014, respectively. We also find a contrast between developed countries where GHGs dominate the RF and developing countries where SLCFs including aerosols and ozone are more dominant. In developing countries, negative RF caused by aerosols largely masks the positive RF from GHGs. As developing countries take measures to improve the air quality, their negative contributions from aerosols will likely be reduced in the future, which will in turn enhance global warming. This underlines the importance of reducing GHG emissions in parallel to avoid any detrimental consequences from air quality policies.

Short-lived climate forcers have long-term climate impacts via the carbon–climate feedback

Short-lived climate forcers (SLCFs) like methane, ozone and aerosols have a shorter atmospheric lifetime than CO2 and are often assumed to have a short-term effect on the climate system: should their emissions cease, so would their radiative forcing (RF). However, via their climate impact, SLCFs can affect carbon sinks and atmospheric CO2, causing additional climate change. Here, we use a compact Earth system model to attribute CO2 RF to direct CO2 emissions and to climate–carbon feedbacks since the pre-industrial era. We estimate the climate–carbon feedback contributed 93 ± 50 mW m−2 (~5%) to total RF of CO2 in 2010. Of this, SLCF impacts were −13 ± 50 mW m−2, made up of cooling (−115 ± 43 mW m−2) and warming (102 ± 26 mW m−2) terms that largely cancel. This study illustrates the long-term impact that short-lived species have on climate and indicates that past (and future) change in atmospheric CO2 cannot be attributed only to CO2 emissions.

The contribution of carbon dioxide emissions from the aviation sector to future climate change

The compact Earth system model OSCARv2.2 is used to assess the climate impact of present and future civil aviation carbon dioxide (CO2) emissions. The impact of aviation CO2 on future climate is quantified over the 1940–2050 period, extending some simulations to 2100 and using different aviation CO2 emission scenarios and two background Representative Concentrations Pathways (RCP2.6 and RCP6.0) for other emission sectors. Several aviation scenarios including weak to strong mitigation options are considered with emissions ranging from 386 MtCO2/year (Factor 2 scenario) to 2338 MtCO2/year (ICAO based scenario) in 2050. As a reference, in 2000, the calculated impact of aviation CO2 emissions is 9.1 ± 2 mK (0.8% of the total anthropogenic warming associated to fossil fuel emissions). In 2050, on a climate trajectory in line with the Paris Agreement limiting the global warming below 2 °C (RCP2.6), the impact of the aviation CO2 emissions ranges from 26 ± 2 mK (1.4% of the total anthropogenic warming associated to fossil fuel emissions) for an ambitious mitigation strategy scenario (Factor 2) to 39 ± 4 mK (2.0% of the total anthropogenic warming associated to fossil fuel emissions) for the least ambitious mitigation scenario of the study (ICAO based). On the longer term, if no significant emission mitigation is implemented for the aviation sector, the associated warming could further increase and reach a value of 99.5 mK ± 20 mK in 2100 (ICAO based), which corresponds to 5.2% of the total anthropogenic warming under RCP2.6. The contribution of CO2 is estimated to represent 36%–51% of the total aviation radiative forcing of climate including short-term climate forcers. However, due to its long residence time in the atmosphere, aviation CO2 will have a major contribution on decadal time scales. These additional short-terms forcers are subject to large uncertainties and will be analysed in forthcoming studies.

Módulo de vivienda con material reciclable en la ciudad de Huánuco

La construcción de un módulo de vivienda con materiales reciclables aporta con un sistema constructivo innovador y permite cambiar la conducta ambiental. El objetivo de la investigación es la construcción de un módulo de vivienda con material reciclable en la ciudad de Huánuco, transformando los residuos sólidos en elementos útiles para la construcción de viviendas, así mismo presentar una propuesta de solución al problema de déficit de viviendas y al problema de contaminación ambiental. La metodología planteada genera nuevo conocimiento en la experiencia proyectual de un proyecto hecho o de uno a construir. Se realizó ensayos de compresión de las botellas de plásticos y se analizó la cimentación. Se concluyó que los neumáticos de aro 16 son aptos para utilizarlos en la cimentación y en las ventanas; los neumáticos de trimoviles son aptos para el sobrecimiento; las botellas (pet) de agua mineral, rellena con tierra compacta son aptos para los muros y las fajas de neumáticos son aptos para la cobertura.

Path-dependent reductions in CO2 emission budgets caused by permafrost carbon release

Emission budgets are defined as the cumulative amount of anthropogenic CO2 emission compatible with a global temperature-change target. The simplicity of the concept has made it attractive to policy-makers, yet it relies on a linear approximation of the global carbon–climate system’s response to anthropogenic CO2 emissions. Here we investigate how emission budgets are impacted by the inclusion of CO2 and CH4 emissions caused by permafrost thaw, a non-linear and tipping process of the Earth system. We use the compact Earth system model OSCAR v2.2.1, in which parameterizations of permafrost thaw, soil organic matter decomposition and CO2 and CH4 emission were introduced based on four complex land surface models that specifically represent high-latitude processes. We found that permafrost carbon release makes emission budgets path dependent (that is, budgets also depend on the pathway followed to reach the target). The median remaining budget for the 2 °C target reduces by 8% (1–25%) if the target is avoided and net negative emissions prove feasible, by 13% (2–34%) if they do not prove feasible, by 16% (3–44%) if the target is overshot by 0.5 °C and by 25% (5–63%) if it is overshot by 1 °C. (Uncertainties are the minimum-to-maximum range across the permafrost models and scenarios.) For the 1.5 °C target, reductions in the median remaining budget range from ~10% to more than 100%. We conclude that the world is closer to exceeding the budget for the long-term target of the Paris Climate Agreement than previously thought.

Uncertainty in projected climate change arising from uncertain fossil-fuel emission factors

Emission inventories are widely used by the climate community, but their uncertainties are rarely accounted for. In this study, we evaluate the uncertainty in projected climate change induced by uncertainties in fossil-fuel emissions, accounting for non-CO2 species co-emitted with the combustion of fossil-fuels and their use in industrial processes. Using consistent historical reconstructions and three contrasted future projections of fossil-fuel extraction from Mohr et al we calculate CO2 emissions and their uncertainties stemming from estimates of fuel carbon content, net calorific value and oxidation fraction. Our historical reconstructions of fossil-fuel CO2 emissions are consistent with other inventories in terms of average and range. The uncertainties sum up to a ±15% relative uncertainty in cumulative CO2 emissions by 2300. Uncertainties in the emissions of non-CO2 species associated with the use of fossil fuels are estimated using co-emission ratios varying with time. Using these inputs, we use the compact Earth system model OSCAR v2.2 and a Monte Carlo setup, in order to attribute the uncertainty in projected global surface temperature change (∆T) to three sources of uncertainty, namely on the Earth system’s response, on fossil-fuel CO2 emission and on non-CO2 co-emissions. Under the three future fuel extraction scenarios, we simulate the median ∆T to be 1.9, 2.7 or 4.0 °C in 2300, with an associated 90% confidence interval of about 65%, 52% and 42%. We show that virtually all of the total uncertainty is attributable to the uncertainty in the future Earth system’s response to the anthropogenic perturbation. We conclude that the uncertainty in emission estimates can be neglected for global temperature projections in the face of the large uncertainty in the Earth system response to the forcing of emissions. We show that this result does not hold for all variables of the climate system, such as the atmospheric partial pressure of CO2 and the radiative forcing of tropospheric ozone, that have an emissions-induced uncertainty representing more than 40% of the uncertainty in the Earth system’s response.

The compact Earth system model OSCAR v2.2: description and first results

Abstract. This paper provides a comprehensive description of OSCAR v2.2, a simple Earth system model. The general philosophy of development is first explained, followed by a complete description of the model's drivers and various modules. All components of the Earth system necessary to simulate future climate change are represented in the model: the oceanic and terrestrial carbon cycles – including a book-keeping module to endogenously estimate land-use change emissions – so as to simulate the change in atmospheric carbon dioxide; the tropospheric chemistry and the natural wetlands, to simulate that of methane; the stratospheric chemistry, for nitrous oxide; 37 halogenated compounds; changing tropospheric and stratospheric ozone; the direct and indirect effects of aerosols; changes in surface albedo caused by black carbon deposition on snow and land-cover change; and the global and regional response of climate – in terms of temperature and precipitation – to all these climate forcers. Following the probabilistic framework of the model, an ensemble of simulations is made over the historical period (1750–2010). We show that the model performs well in reproducing observed past changes in the Earth system such as increased atmospheric concentration of greenhouse gases or increased global mean surface temperature.

Spontaneous Combustion of Wasps' Nests

SOME time ago the house of General P. M. Arismendi (now Consul of Venezuela, in Port-of-Spain, Trinidad) in this city, had a rather narrow escape from being set on fire by the spontaneous combustion of a large wasps' nest (a species of Polistes) in a closet under a roof. The day was exceedingly hot; but this circumstance, I think, has a very slight connection (if any at all) with the outbreak of smoke from the nest. Roofs in this country are constructed of tiles supported by a thick layer of compact earth, which rests on the usual lath-work of dry canes (the stems of Gynerium saccharoides, or arborescent grass), both being substances that conduct heat very badly. The source of heat must therefore have been in the nest itself. In bees-hives the temperature rises sometimes as high as 38° C. (teste Newport, as cited in Girdwoyn, “Anat. et Physiol. de l'Abeille”, p. 23). We may be allowed to suppose that something similar happens occasionally also in wasps' nests. Such a heat might be caused by an alteration beginning in the wax, hydrocarbons being formed, which, on being absorbed by the paper-like, porous substance of the cell-walls, must get still more heated, so that a comparatively small access of oxygen would be sufficient to set the whole nest on fire.