Response to comment on "Fairness considerations in global mitigation investments".

We welcome the analysis of Semieniuk et al. (1) as an additional sensitivity to illustrate a more extreme distribution of regional contributions to climate mitigation investments that supports our main conclusion regarding the North-South divide in mitigation investment capabilities. In response to Semieniuk et al. we would like to first point out that, in defining the required global mitigation investments for the 2020 to 2030 period, our study relies on the estimates in the sixth assessment report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) WGIII (2). These are based on diverse sources and underlying models that to varying degrees reflect regional differences in technology costs and consider both purchasing power parity (PPP) and market exchange rates (MERs). We use these IPCC estimates as a starting point and focus entirely on the question of how much of the needed regional investments, given different fairness considerations, should be financed from sources within a region.

The Double Dividend of International Cooperation for Climate Mitigation Cost Effectiveness and Public Health Cobenefits.

Current National Determined Contributions require strengthening to achieve the 2-degree target set in the Paris Agreement. Here, we contrast two mitigation effort strengthening ideas: the "burden-sharing" principle, which requires each region to meet the mitigation goal through domestic mitigation with no international cooperation, and the cooperation focused "cost effective conditional-enhancing" principle, which combines domestic mitigation with carbon trading and low-carbon investment transfer. By applying a burden-sharing model covering several equity principles, we analyze the 2030 mitigation burden for each region, then the energy system model generates the results for the carbon trade and the investment transfer for the conditional-enhancing plan, and an air pollution cobenefit model is used to analyze the cobenefit on air quality and public health. Here, we show that the conditional-enhancing plan leads to an international carbon trading volume of 339.2 billion USD per year and reduces the marginal mitigation cost of the quota-purchase regions by 25%-32%. Furthermore, the international cooperation incentivizes a faster and deeper decarbonization in developing and emerging regions, raising the air pollution health cobenefits by 18% to 731,000 avoided premature deaths annually compared to the "burden-sharing" principle, amounting to a reduction in the life value loss of 131 billion dollars per year.

Fairness considerations in global mitigation investments.

Current mitigation finance flows are inadequate and unfair.

Global roll-out of comprehensive policy measures may aid in bridging emissions gap.

Closing the emissions gap between Nationally Determined Contributions (NDCs) and the global emissions levels needed to achieve the Paris Agreement's climate goals will require a comprehensive package of policy measures. National and sectoral policies can help fill the gap, but success stories in one country cannot be automatically replicated in other countries. They need to be adapted to the local context. Here, we develop a new Bridge scenario based on nationally relevant, short-term measures informed by interactions with country experts. These good practice policies are rolled out globally between now and 2030 and combined with carbon pricing thereafter. We implement this scenario with an ensemble of global integrated assessment models. We show that the Bridge scenario closes two-thirds of the emissions gap between NDC and 2 °C scenarios by 2030 and enables a pathway in line with the 2 °C goal when combined with the necessary long-term changes, i.e. more comprehensive pricing measures after 2030. The Bridge scenario leads to a scale-up of renewable energy (reaching 52%-88% of global electricity supply by 2050), electrification of end-uses, efficiency improvements in energy demand sectors, and enhanced afforestation and reforestation. Our analysis suggests that early action via good-practice policies is less costly than a delay in global climate cooperation.

Assessing China's efforts to pursue the 1.5°C warming limit.

Given the increasing interest in keeping global warming below 1.5°C, a key question is what this would mean for China's emission pathway, energy restructuring, and decarbonization. By conducting a multimodel study, we find that the 1.5°C-consistent goal would require China to reduce its carbon emissions and energy consumption by more than 90 and 39%, respectively, compared with the "no policy" case. Negative emission technologies play an important role in achieving near-zero emissions, with captured carbon accounting on average for 20% of the total reductions in 2050. Our multimodel comparisons reveal large differences in necessary emission reductions across sectors, whereas what is consistent is that the power sector is required to achieve full decarbonization by 2050. The cross-model averages indicate that China's accumulated policy costs may amount to 2.8 to 5.7% of its gross domestic product by 2050, given the 1.5°C warming limit.

Quantification of an efficiency-sovereignty trade-off in climate policy.

The Paris Agreement calls for a cooperative response with the aim of limiting global warming to well below two degrees Celsius above pre-industrial levels while reaffirming the principles of equity and common, but differentiated responsibilities and capabilities1. Although the goal is clear, the approach required to achieve it is not. Cap-and-trade policies using uniform carbon prices could produce cost-effective reductions of global carbon emissions, but tend to impose relatively high mitigation costs on developing and emerging economies. Huge international financial transfers are required to complement cap-and-trade to achieve equal sharing of effort, defined as an equal distribution of mitigation costs as a share of income2,3, and therefore the cap-and-trade policy is often perceived as infringing on national sovereignty2-7. Here we show that a strategy of international financial transfers guided by moderate deviations from uniform carbon pricing could achieve the goal without straining either the economies or sovereignty of nations. We use the integrated assessment model REMIND-MAgPIE to analyse alternative policies: financial transfers in uniform carbon pricing systems, differentiated carbon pricing in the absence of financial transfers, or a hybrid combining financial transfers and differentiated carbon prices. Under uniform carbon prices, a present value of international financial transfers of 4.4 trillion US dollars over the next 80 years to 2100 would be required to equalize effort. By contrast, achieving equal effort without financial transfers requires carbon prices in advanced countries to exceed those in developing countries by a factor of more than 100, leading to efficiency losses of 2.6 trillion US dollars. Hybrid solutions reveal a strongly nonlinear trade-off between cost efficiency and sovereignty: moderate deviations from uniform carbon prices strongly reduce financial transfers at relatively small efficiency losses and moderate financial transfers substantially reduce inefficiencies by narrowing the carbon price spread. We also identify risks and adverse consequences of carbon price differentiation due to market distortions that can undermine environmental sustainability targets8,9. Quantifying the advantages and risks of carbon price differentiation provides insight into climate and sector-specific policy mixes.

Taking stock of national climate policies to evaluate implementation of the Paris Agreement.

Many countries have implemented national climate policies to accomplish pledged Nationally Determined Contributions and to contribute to the temperature objectives of the Paris Agreement on climate change. In 2023, the global stocktake will assess the combined effort of countries. Here, based on a public policy database and a multi-model scenario analysis, we show that implementation of current policies leaves a median emission gap of 22.4 to 28.2 GtCO2eq by 2030 with the optimal pathways to implement the well below 2 °C and 1.5 °C Paris goals. If Nationally Determined Contributions would be fully implemented, this gap would be reduced by a third. Interestingly, the countries evaluated were found to not achieve their pledged contributions with implemented policies (implementation gap), or to have an ambition gap with optimal pathways towards well below 2 °C. This shows that all countries would need to accelerate the implementation of policies for renewable technologies, while efficiency improvements are especially important in emerging countries and fossil-fuel-dependent countries.

Limited emission reductions from fuel subsidy removal except in energy-exporting regions.

Hopes are high that removing fossil fuel subsidies could help to mitigate climate change by discouraging inefficient energy consumption and levelling the playing field for renewable energy. In September 2016, the G20 countries re-affirmed their 2009 commitment (at the G20 Leaders' Summit) to phase out fossil fuel subsidies and many national governments are using today's low oil prices as an opportunity to do so. In practical terms, this means abandoning policies that decrease the price of fossil fuels and electricity generated from fossil fuels to below normal market prices. However, whether the removal of subsidies, even if implemented worldwide, would have a large impact on climate change mitigation has not been systematically explored. Here we show that removing fossil fuel subsidies would have an unexpectedly small impact on global energy demand and carbon dioxide emissions and would not increase renewable energy use by 2030. Subsidy removal would reduce the carbon price necessary to stabilize greenhouse gas concentration at 550 parts per million by only 2-12 per cent under low oil prices. Removing subsidies in most regions would deliver smaller emission reductions than the Paris Agreement (2015) climate pledges and in some regions global subsidy removal may actually lead to an increase in emissions, owing to either coal replacing subsidized oil and natural gas or natural-gas use shifting from subsidizing, energy-exporting regions to non-subsidizing, importing regions. Our results show that subsidy removal would result in the largest CO2 emission reductions in high-income oil- and gas-exporting regions, where the reductions would exceed the climate pledges of these regions and where subsidy removal would affect fewer people living below the poverty line than in lower-income regions.

Stabilization of the femoral head with a gliding screw in slipped capital femoral epiphysis.

OBJECTIVE: In situ fixation of the proximal femoral epiphysis to prevent further dislocation while maintaining the potential for longitudinal growth by insertion of a central gliding screw. Prevention of secondary coxarthrosis. INDICATIONS: Incipient and imminent slipped capital femoral epiphysis in children with a displacement angle of < 30 degrees in the axial view (ET' < 30 degrees ) and prophylactic treatment of the contralateral side. CONTRAINDICATIONS: Allergies to implant materials. SURGICAL TECHNIQUE: A Kirschner wire is inserted through a lateral proximal approach in the femur into the center of the displaced epiphysis at a right angle to its base. Overdrilling of the wire, thread tapping in the cancellous bone, insertion of the cannulated gliding screw with washer. The screw threads lie only in the epiphysis. The unthreaded part of the screw bridges the growth plate. The screw is allowed to protrude by about 2.5 cm to prevent an epiphyseodesis effect. POSTOPERATIVE MANAGEMENT: Partial weight bearing of the affected extremity up to 10 kg body weight for 6 weeks. Thrombosis prophylaxis during convalescence only for adolescents with signs of puberty (menarche/pubarche). Restriction on sports activities for 3 months. Follow-ups: clinical and radiologic examinations at 3 months postoperatively, then clinical examination every 6 months and radiologic assessment annually (possibly earlier, if there is a growth spurt). The gliding screw is removed when growth is completed. RESULTS: 63 hips (34 prophylactically and 29 therapeutically) were stabilized with the gliding screw. Clinically, the prophylactically stabilized hips showed excellent outcomes; of the therapeutically stabilized hips, the results were 19 excellent, seven good, two satisfactory, and one poor. Differences in leg length were seen in five cases, whereby the average value was 0.3 cm (0-1 cm). Chondrolysis or femoral head necrosis was not observed. Screw revision was necessary in 22 cases because contact between the screw head and the cortex would have prevented continued longitudinal growth (unintentional epiphyseodesis).

Treatment of adductor spasticity with BTX-A in children with CP: a randomized, double-blind, placebo-controlled study.

Adductor spasticity in children with cerebral palsy (CP) impairs motor function and development. In a placebo-controlled, double-blind, randomized multicentre study, we evaluated the effects of botulinum toxin A(BTX-A) in 61 children (37 males, 24 females; mean age 6 years 1 month [SD 3y 1mo]) with CP (leg-dominated tetraparesis, n=39; tetraparesis, n=22; GMFCS level I, n=3; II, n=6; III, n=17; IV, n=29; V, n=6). Four weeks after treatment, a significant superiority of BTX-A was observed in the primary outcome measure (knee-knee distance 'fast catch', p=0.002), the Ashworth scale (p=0.001), and the Goal Attainment Scale (p=0.037).

Eosinophilic granuloma of the cervical spine.

STUDY DESIGN: A meta-analysis was performed based on 53 cases of cervical eosinophilic granuloma reported in the literature and 1 in an adult treated by the authors. OBJECTIVE: To stress the clinical and radiologic differences between cervical and thoracolumbar spinal eosinophilic granuloma and to point out differences between adults and children with cervical eosinophilic granuloma to avoid false diagnosis. SUMMARY OF BACKGROUND DATA: Until now, cervical eosinophilic granuloma has been reported in 43 children and 9 adults. In 1 case the age is unknown. In previous studies, differences between adults and children with cervical eosinophilic granuloma have not been analyzed, nor has cervical eosinophilic granuloma been compared with thoracolumbar eosinophilic granuloma. METHODS: All reported cases of cervical eosinophilic granuloma were analyzed concerning age and sex distribution, clinical and radiologic presentation, therapy, and outcome. The authors' case in a 46-year-old patient is discussed. RESULTS: The presenting symptoms of cervical eosinophilic granuloma are usually pain and restricted range of motion. In contrast to eosinophilic granuloma of the thoracic spine and lumbar spine, the neurologic symptoms are less frequent, and the first radiographic sign is an osteolytic lesion. Vertebra plana is a rare sign in cervical eosinophilic granuloma. In children, the middle cervical spine is most often affected, whereas in adults it is the second vertebra. The outcome of the patients has been good in most cases, independently of treatment. CONCLUSION: In most cases of cervical eosinophilic granuloma, immobilization is an adequate therapy. If the process continuous to progress, radiotherapy is recommended. Surgical treatment should be reserved for cases with instability or neurologic defects.