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1.
The non-CO2 climate impact of aviation (NOx and contrails) is assessed and emissions weighting factors (EWFs) i.e., the factor by which aviation CO2 emissions should be multiplied to get the CO2-equivalent emissions for annual fleet average conditions are estimated. The EWFs are estimated using two economic metrics. One is based on the relative damage cost between non-CO2 forcers and CO2. The other is based on the cost-effective valuation between the non-CO2 forcers and CO2 given an upper ceiling on the global annual average surface temperature (set at 2?K above pre-industrial levels). We also estimate EWFs using three physical metrics, Global Warming Potential (GWP), Global Temperature change Potential (GTP) and Sustained GTP (SGTP) and compare our results with the economics based metrics. Given best estimates on the forcing contributions from CO2, contrails and NOx from aviation and by using a discount rate of 3%/year, the RDC based metric gives an EWF equal to 1.4 (slightly higher than EWFs based on GWP and SGTP using a 100?year time horizon). EWF using the cost-effective approach depends on the time that remains before stabilization occurs. It is roughly equal to unity until a few years before the temperature reaches its ceiling, and approximately 2 when stabilization has taken place. EWFs based on GTP resemble those based on CETO when the time left to when stabilization occurs is sufficiently large. Once stabilization has occurred CETO values resemble RDC based values. If aviation-induced cirrus clouds are included, uncertainties increase and the EWFs for GWP, SGTP and RDC based metrics end up in the range 1.3–2.9, while EWFs for GTP and CETO remain close to unity in the near term. 相似文献
2.
Uncertainty and learning: implications for the trade-off between short-lived and long-lived greenhouse gases 总被引：1，自引：1，他引：0
The economic benefits of a multi-gas approach to climate change mitigation are clear. However, there is still a debate on how to make the trade-off between different greenhouse gases (GHGs). The trade-off debate has mainly centered on the use of Global Warming Potentials (GWPs), governing the trade-off under the Kyoto Protocol, with results showing that the cost-effective valuation of short-lived GHGs, like methane (CH4), should be lower than its current GWP value if the ultimate aim is to stabilize the anthropogenic temperature change. However, contrary to this, there have also been proposals that early mitigation mainly should be targeted on short-lived GHGs. In this paper we analyze the cost-effective trade-off between a short-lived GHG, CH4, and a long-lived GHG, carbon dioxide (CO2), when a temperature target is to be met, taking into consideration the current uncertainty of the climate sensitivity as well as the likelihood that this will be reduced in the future. The analysis is carried out using an integrated climate and economic model (MiMiC) and the results from this model are explored and explained using a simplified analytical economic model. The main finding is that the introduction of uncertainty and learning about the climate sensitivity increases the near-term cost-effective valuation of CH4 relative to CO2. The larger the uncertainty span, the higher the valuation of the short-lived gas. For an uncertainty span of ±1°C around an expected climate sensitivity of 3°C, CH4 is cost-effectively valued 6.8 times as high as CO2 in year 2005. This is almost twice as high as the valuation in a deterministic case, but still significantly lower than its GWP100 value. 相似文献
3.
M. Ahadi M. Saber Tehrani P. Aberoomand Azar S. Waqif Husain 《International Journal of Environmental Science and Technology》2016,13(12):2797-2804
Sensitized ZnS nanoparticles were synthesized by chemical precipitation method using anthocyanin as the capping agent and sensitizer. X-ray diffractometer, field-emission scanning electron microscope, transmission electron microscopy, UV visible spectrophotometer, Fourier transform infrared spectroscopy and photoluminescence spectrometry methods were used for the characterization of nanoparticles. The electron microscopy studies of nanoparticles showed that the size of crystallites is in the range of 35–80 nm and optical studies showed a blue shift in the absorption edge by adding capping agent. The effective band gap energy was increased with decrease in the particle size. Photocatalytic activities of sensitized ZnS and pure ZnS were evaluated by degradation of tetracycline in aqueous solution under visible light irradiation, and progress of the reaction was monitored spectrophotometrically. The different parameters affecting degradation such as the pH of solution, amount of semiconductor and reusability of catalyst for three cycles and the photocatalytic degradation kinetics of tetracycline were studied. More than 80% degradation was achieved within 5 h under visible light. 相似文献
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5.
The capture and storage of CO2 from combustion of fossil fuels is gaining attraction as a means to deal with climate change. CO2 emissions from biomass conversion processes can also be captured. If that is done, biomass energy with CO2 capture and storage (BECS) would become a technology that removes CO2 from the atmosphere and at the same time deliver CO2-neutral energy carriers (heat, electricity or hydrogen) to society. Here we present estimates of the costs and conversion efficiency of electricity, hydrogen and heat generation from fossil fuels and biomass with CO2 capture and storage. We then insert these technology characteristics into a global energy and transportation model (GET 5.0), and calculate costs of stabilizing atmospheric CO2 concentration at 350 and 450 ppm. We find that carbon capture and storage technologies applied to fossil fuels have the potential to reduce the cost of meeting the 350 ppm stabilisation targets by 50% compared to a case where these technologies are not available and by 80% when BECS is allowed. For the 450 ppm scenario, the reduction in costs is 40 and 42%, respectively. Thus, the difference in costs between cases where BECS technologies are allowed and where they are not is marginal for the 450 ppm stabilization target. It is for very low stabilization targets that negative emissions become warranted, and this makes BECS more valuable than in cases with higher stabilization targets. Systematic and stochastic sensitivity analysis is performed. Finally, BECS opens up the possibility to remove CO2 from the atmosphere. But this option should not be seen as an argument in favour of doing nothing about the climate problem now and then switching on this technology if climate change turns out to be a significant problem. It is not likely that BECS can be initiated sufficiently rapidly at a sufficient scale to follow this path to avoiding abrupt and serious climate changes if that would happen. 相似文献
6.
Greenhouse gas abatement policies will increase the demand for renewable sources of energy, including bioenergy. In combination
with a global growing demand for food, this could lead to a food-fuel competition for bio-productive land. Proponents of bioenergy
have suggested that energy crop plantations may be established on less productive land as a way of avoiding this potential
food-fuel competition. However, many of these suggestions have been made without any underlying economic analysis. In this
paper, we develop a long-term economic optimization model (LUCEA) of the U.S. agricultural and energy system to analyze this
possible competition for land and to examine the link between carbon prices, the energy system dynamics and the effect of
the land competition on food prices. Our results indicate that bioenergy plantations will be competitive on cropland already
at carbon taxes about US $20/ton C. As the carbon tax increases, food prices more than double compared to the reference scenario
in which there is no climate policy. Further, bioenergy plantations appropriate significant areas of both cropland and grazing
land. In model runs where we have limited the amount of grazing land that can be used for bioenergy to what many analysts
consider the upper limit, most of the bioenergy plantations are established on cropland. Under the assumption that more grazing
land can be used, large areas of bioenergy plantations are established on grazing land, despite the fact that yields are assumed
to be much lower (less than half) than on crop land. It should be noted that this allocation on grazing land takes place as
a result of a competition between food and bioenergy production and not because of lack of it. The estimated increase in food
prices is largely unaffected by how much grazing land can be used for bioenergy production. 相似文献
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8.
Christian Azar 《Climatic change》2000,47(3):233-238
9.
The effect of the Zagros Mountains on the formation and maintenance of the Iran Anticyclone using RegCM4 总被引：3，自引：0，他引：3
Azar Zarrin Hooshang Ghaemi Majid Azadi Abbas Mofidi Ebrahim Mirzaei 《Meteorology and Atmospheric Physics》2011,112(3-4):91-100
Iran anticyclone is one of the main features of the summer circulation over the Middle East in the middle and upper troposphere. To examine the effect of the Zagros Mountains on the formation and maintenance of the Iran anticyclone, an experiment was conducted by Regional Climate Model (RegCM4) in an area between 22°?C44°N and 35°?C70°E with a 40?km horizontal grid spacing. The NCEP/NCAR re-analysis data set were used to provide the initial and lateral boundary conditions in a control run and in a simulation run by removing the Zagros Mountains. The result reveals that the Zagros Mountains have an important effect on the formation and maintenance of the low-level cyclonic circulation and mid-level anticyclonic circulation in summer. Examining the diabatic heating shows that the elimination of the Zagros Mountains causes a significant change in the heating values and its spatial distributions over the study area. Comparing the diabatic heating terms, the vertical advection term has the main contribution to the total heating. In the absence of the Zagros Mountains, the vertical advection and the mid-troposphere anticyclonic circulation are apparently weak and, therefore, the Iran subtropical anticyclone vanishes over the west of Iran. The study indicates that the Zagros Mountains as an elevated heat source have the main impact in the formation of a thermally driven circulation over the Middle East. 相似文献
10.
Beyranvand Azar Azizi Ghasem Alizadeh-Choobari Omid Darvishi Boloorani Ali 《Natural Hazards》2019,98(1):229-249
Large near-field tsunamis pose a significant threat to the Canadian West Coast due to its proximity to the circum-Pacific belt where a significant tsunami-inducing earthquake event from the Cascadia subduction zone is expected. This study investigated the risks associated with such an event in terms of pedestrian evacuation needs and plans for the Town of Tofino, a small community located on the West Coast of Vancouver Island. The population-at-risk within the hazard zone and its ability to evacuate to safety is evaluated using anisotropic path-distance modelling. Mitigation measures, such as vertical evacuation buildings, are quantitatively evaluated. Site-specific inundation modelling was not performed as part of this study; tsunami hazard and safe zones were computed using a range of run-ups varying between 3 and 25 m. It was established that up to 80% of the population is within the maximum hazard zone considered. This evacuation modelling exercise indicates that a maximum of 13% of the population would have insufficient time to reach safety when using a mobility-impaired ambulatory speed. The use of three vertical evacuation buildings can reduce the risk of losing population in this category by 99%. Although some conservative assumptions were used (vertical datum at higher high water, reductions in safe zones by generalization process and mobility-impaired evacuation speeds), the evacuation potential is likely overestimated due to the coarseness of the topographic data used in the evacuation modelling and from an overestimated first wave arrival time. This is the first Canadian study which used anisotropic evacuation modelling to evaluate the vulnerability of a Canadian community to tsunami inundation.
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