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Relying on real options theory, we employ a multistage decision model to analyze the effect of delaying the introduction of emission trading systems (ETS) on power plant investments in carbon capture and storage (CCS) retrofits, on plant operation, and on carbon dioxide (CO2) abatement. Unlike previous studies, we assume that the investment decision is made before the ETS is in place, and we allow CCS operating flexibility for new power plant investments. Thus, the plant may be run in CCS-off mode if carbon prices are low. We employ Monte Carlo simulation methods to account for uncertainties in the prices of CO2 certificates, other inputs, and output prices, relying on a realistic parameterization for a supercritical pulverized coal plant in China. We find that CCS operating flexibility lowers the critical carbon price needed to support CCS investment because it renders CCS investment less irreversible. For a low carbon price path, operating flexibility also implies that delaying the introduction of an ETS hardly affects plant CO2 abatement since the plant operator is better off purchasing emission certificates rather than operating the plant in CCS mode. Interestingly, for low carbon prices we find a U-shaped relation between the length of the delay and the economic value of the plant. Thus, delaying the introduction of an ETS may make investors worse off.

Relying on a recent survey of more than 3400 participants from China, Germany, and the US, this article empirically analyses citizens' perceptions of key guiding principles for sharing mitigation costs across countries, justification of climate policy and trust in climate policy. Our findings suggest that the ranking of the main principles for burden-sharing is identical in China, Germany, and the US: accountability followed by capability, egalitarianism, and sovereignty. Thus, on a general level, citizens across these countries seem to have a common (normative) understanding of fairness. We therefore find no evidence that citizens' (stated) fairness preferences are detrimental to future burden-sharing agreements. In all three countries a majority of citizens considers international climate policy to be justified, but citizens' perceptions differ across specific items and countries. Finally, a substantial portion of citizens in all countries exhibit a lack of trust in international climate agreements.

The impact of a global phase-out of nuclear energy is assessed for the costs of meeting international climate policy targets for 2020. The analysis is based on simulations with the Prospective Outlook on Long-term Energy Systems (POLES) global energy systems model. The phase-out of nuclear power increases GHG emissions by 2% globally and 7% for Annex I countries. The price of certificates increases by 24% and total compliance costs of Annex I countries rise by 28%. Compliance costs increase most for Japan (+58%) and the US (+28%). China, India, and Russia benefit from a global nuclear phase-out because revenues from higher trading volumes of certificates outweigh the costs of losing nuclear power as a mitigation option. Even for countries that face a relatively large increase in compliance costs, such as Japan, the nuclear phase-out implies a relatively small overall economic burden. When trading of certificates is available only to countries that committed to a second Kyoto period, the nuclear phase-out results in a larger increase in the compliance costs for the group of Annex I countries (but not for the EU and Australia). Results from sensitivity analyses suggest that the findings are fairly robust to alternative burden-sharing schemes and emission target levels.Policy relevanceNew calculations show that the impact of a global phase-out of nuclear energy on global mitigation costs is quite modest, but that there are substantial differences for countries. Total compliance costs increase the most for Japan and the US, but these are rather marginal if measured in terms of GDP. China, India, and Russia benefit from a nuclear phase-out because their additional revenues from selling certificates outweigh the additional costs of losing nuclear power as a mitigation option. The findings also highlight the importance of certificate trading to achieving climate targets in a cost-efficient way. If Japan or the US were to be banned from certificate trading, along with other countries, because of their non-participation in a second Kyoto period, then their compliance costs would increase substantially under a nuclear phase-out. The EU, however, would benefit because certificate prices would be lower.

The German Federal Climate Change Act includes binding annual greenhouse gas (GHG) emission targets for the economic sectors energy, industry, buildings, transport, agriculture and waste. For sectors that fail to meet their targets, climate policy measures have to be implemented immediately. However, some sectors may only have achieved their targets thanks to the COVID-19 pandemic, while others may have missed their targets because of COVID-19. For policy making, it is therefore important to disentangle the effects of the COVID-19 pandemic from the effects of policy and other drivers on emissions. In this paper, the effects of the pandemic on GHG emissions in Germany in 2020 are estimated at the national level and at the levels of the economic sectors. Counterfactual emissions are estimated here based on autoregressive econometric models, thereby distinguishing between different factors of emissions based on decomposition analysis. The findings at the national level suggest that the COVID-19 pandemic lowered GHG emissions in 2020 in Germany by about 41 Mt CO2-eq (5.15%) compared to counterfactual emissions. Accordingly, about 58% of the reduction in emissions between 2019 and 2020 in Germany may be attributed to the pandemic. The findings at the sectoral level imply that without the COVID-19 pandemic, all sectors with the exception of the transport sector, would have met their emissions target in 2020 as set in the Federal Climate Change Act. The transport sector would have missed its emission target in 2020 without COVID-19, suggesting that existing policies were not strong enough to bend the curve of emissions trends sufficiently down. In contrast, the buildings sector failed to meet its target in 2020 because of COVID-19, prompting immediate climate policy measures in this sector. The COVID-19 pandemic lowered greenhouse gas (GHG) emissions in Germany in 2020 by 5.5% compared to counterfactual emissions and accounted for about 58% of total estimated reductions between 2019 and 2020.Without COVID-19, all sectors but the transport sector would have met their emissions targets.Climate policy response should take into account the effects of extraordinary events like COVID-19 suppressing GHG emissions based on counterfactual emissions because failure to implement measures early on may turn out to be costly in the medium term once the transitory emissions reductions no longer occur.Counterfactual emissions should be considered prior to crediting emissions surplus or deficit to subsequent years. The COVID-19 pandemic lowered greenhouse gas (GHG) emissions in Germany in 2020 by 5.5% compared to counterfactual emissions and accounted for about 58% of total estimated reductions between 2019 and 2020. Without COVID-19, all sectors but the transport sector would have met their emissions targets. Climate policy response should take into account the effects of extraordinary events like COVID-19 suppressing GHG emissions based on counterfactual emissions because failure to implement measures early on may turn out to be costly in the medium term once the transitory emissions reductions no longer occur. Counterfactual emissions should be considered prior to crediting emissions surplus or deficit to subsequent years.

It remains unclear whether biodiversity buffers ecosystems against climate extremes, which are becoming increasingly frequent worldwide. Early results suggested that the ecosystem productivity of diverse grassland plant communities was more resistant, changing less during drought, and more resilient, recovering more quickly after drought, than that of depauperate communities. However, subsequent experimental tests produced mixed results. Here we use data from 46 experiments that manipulated grassland plant diversity to test whether biodiversity provides resistance during and resilience after climate events. We show that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. Across all studies and climate events, the productivity of low-diversity communities with one or two species changed by approximately 50% during climate events, whereas that of high-diversity communities with 16-32 species was more resistant, changing by only approximately 25%. By a year after each climate event, ecosystem productivity had often fully recovered, or overshot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events. Anthropogenic environmental changes that drive biodiversity loss thus seem likely to decrease ecosystem stability, and restoration of biodiversity to increase it, mainly by changing the resistance of ecosystem productivity to climate events.

Hyperthermia is a cancer treatment modality in which body tissue is exposed to elevated temperatures to destroy cancerous cells. Hyperthermia treatment planning refers to the use of computational models to optimize the heating protocol with the goal of isolating thermal damage to predetermined treatment areas. This paper presents an algorithm to optimize a hyperthermia treatment protocol using the conjugate gradient method with the adjoint problem. The output of the minimization algorithm is a heating protocol that will cause a desired amount of thermal damage. The transient temperature distribution in a cylindrical region is simulated using the bioheat transfer equation. Temperature and time are integrated to calculate the extent of thermal damage in the region via a first-order rate process based on the Arrhenius equation. Several validation experiments are carried out by applying the results of the minimization algorithm to an albumen tissue phantom. Comparisons of metrics describing the damage region (the height and radius of the volume of thermally ablated phantom) show good agreement between the desired extent of damage and the measured extent of damage. The sensitivity of the bioheat transfer model and the Arrhenius damage model to their constituent parameters is calculated to create a tolerable range of error between the desired and measured extent of damage. The measured height and radius of the ablated region fit well within the tolerable range of error found in the sensitivity analysis.

AbstractIn many regions across the globe, extreme weather events such as storms have increased in frequency, intensity, and duration due to climate change. Ecological theory predicts that such extreme events should have large impacts on ecosystem structure and function. High winds and precipitation associated with storms can affect lakes via short‐term runoff events from watersheds and physical mixing of the water column. In addition, lakes connected to rivers and streams will also experience flushing due to high flow rates. Although we have a well‐developed understanding of how wind and precipitation events can alter lake physical processes and some aspects of biogeochemical cycling, our mechanistic understanding of the emergent responses of phytoplankton communities is poor. Here we provide a comprehensive synthesis that identifies how storms interact with lake and watershed attributes and their antecedent conditions to generate changes in lake physical and chemical environments. Such changes can restructure phytoplankton communities and their dynamics, as well as result in altered ecological function (e.g., carbon, nutrient and energy cycling) in the short‐ and long‐term. We summarize the current understanding of storm‐induced phytoplankton dynamics, identify knowledge gaps with a systematic review of the literature, and suggest future research directions across a gradient of lake types and environmental conditions.