Early transformation of the Chinese power sector to avoid additional coal lock-in

Emission reduction from the coal-dominated power sector is vital for achieving China's carbon mitigation targets. Although the coal expansion has been slowed down due to the cancellation of and delay in new construction, coal-based power was responsible for over one third of China's energy-related CO2 emissions by 2018. Moreover, with a technical lifetime of over 30 years, current investment in coal-based power could hinder CO2 mitigation until 2050. Therefore, it is important to examine whether the current coal-based power planning aligns with the long-term climate targets. This paper introduces China's Nationally Determined Contribution (NDC) goals and an ambitious carbon budget along with global pathways well-below 2 degrees that are divided into five integrated assessment models, which are two national and three global models. We compare the models' results with bottom-up data on current capacity additions and expansion plans to examine if the NDC targets are in line with 2-degree pathways. The key findings are: 1. NDC goals alone are unlikely to lead to significant reductions in coal-based power generation. On the contrary, more plants may be built before 2030; 2. this would require an average of 187–261 TWh of annual coal-based power capacity reduction between 2030 and 2050 to achieve a 2 °C compatible trajectory, which would lead to the stranding of large-scale coal-based power plants; 3. if the reduction in coal power can be brought forward to 2020, the average annual coal-based power reduction required would be 104–155 TWh from 2020 to 2050 and the emissions could peak earlier; 4. early regulations in coal-based power would require accelerated promotion of alternatives between 2020 and 2030, with nuclear, wind and solar power expected to be the most promising alternatives. By presenting the stranding risk and viability of alternatives, we suggest that both the government and enterprises should remain cautious about making new investment in coal-based power sector

Acute Phosphate Restriction Leads to Impaired Fracture Healing and Resistance to BMP-2

Hypophosphatemia leads to rickets and osteomalacia, the latter of which results in decreased biomechanical integrity of bones, accompanied by poor fracture healing. Impaired phosphate-dependent apoptosis of hypertrophic chondrocytes is the molecular basis for rickets. However, the underlying pathophysiology of impaired fracture healing has not been characterized previously. To address the role of phosphate in fracture repair, mice were placed on a phosphate-restricted diet 2 days prior to or 3 days after induction of a mid-diaphyseal femoral fracture to assess the effects of phosphate deficiency on the initial recruitment of mesenchymal stem cells and their subsequent differentiation. Histologic and micro-computed tomographic (µCT) analyses demonstrated that both phosphate restriction models dramatically impaired fracture healing primarily owing to a defect in differentiation along the chondrogenic lineage. Based on Sox9 and Sox5 mRNA levels, neither the initial recruitment of cells to the callus nor their lineage commitment was effected by hypophosphatemia. However, differentiation of these cells was impaired in association with impaired bone morphogenetic protein (BMP) signaling. In vivo ectopic bone-formation assays and in vitro investigations in ST2 stromal cells confirmed that phosphate restriction leads to BMP-2 resistance. Marrow ablation studies demonstrate that hypophosphatemia has different effects on injury-induced intramembranous bone formation compared with endochondral bone formation. Thus phosphate plays an important role in the skeleton that extends beyond mineralized matrix formation and growth plate maturation and is critical for endochondral bone repair. © 2010 American Society for Bone and Mineral Research

Using Sun Glint to Check the Relative Calibration of Reflected Spectral Radiances

Observations of sunlight reflected from regions of sun glint are used to check the relative calibration of spectral radiances obtained with imaging radiometers. Reflectances at different wavelengths for sun-glint regions are linearly related. Provided that the atmosphere is reasonably transparent at the wavelengths, the aerosol burden is reasonably light, 0.64-μm optical depth less than 0.2; the particles constituting the aerosol are reasonably large, as is the case for marine aerosols; and the solar zenith angle is less than about 35°, the linear relationships between reflectances at different wavelengths are rather insensitive to the factors that govern the reflectances themselves. The relationships are remarkably insensitive to atmospheric composition, surface wind speed and direction, illumination, and viewing geometry. The slopes and offsets of the linear relationships are used to assess the relative accuracies of the calibrations of the different channels. Such assessments would appear to be attractive for checks on the in-flight performance of aircraft-borne imaging radiometers. Here, observations of reflectances at 0.64, 0.84, 1.6, and 2.1 μm for regions of sun glint obtained with the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are shown to be consistent with each other. Observations of the 0.64- and 1.6-μm reflectances for the Tropical Rainfall Measuring Mission (TRMM) Visible and Infrared Scanner (VIRS) instrument are shown to be inconsistent with the MODIS observations, the VIRS 1.6-μm gain appearing to be too low by 9%. The 0.64-, 0.84-, and 1.6-μm reflectances obtained with the NOAA-16 and NOAA-17 Advanced Very High Resolution Radiometers (AVHRRs) for December 2002 are shown to be inconsistent with each other and inconsistent with the MODIS observations. Based on observations of the extensive ice sheets of Antarctica, the NOAA-16 0.64-μm gain is found to be too low by 5% and that for the 0.84-μm reflectance is too low by 12%; the NOAA-17 0.64-μm gain is found to be accurate (within 2%), but the 0.84-μm gain is too low by 15%. With the gains adjusted, the 0.64- and 0.84-μm reflectances obtained for regions of sun glint with the AVHRRs are consistent with each other and consistent with the Terra and Aqua MODIS observations. These results suggest that the gain for the NOAA-16 AVHRR 1.6-μm reflectance is accurate (within 1%) and that for the NOAA-17 AVHRR is too low by 5%. All of the observations were made with the AVHRR in the low-reflectance (high gain) mode. The accuracy of these assessments is expected to be about 5%

System integration of wind and solar power in Integrated Assessment Models: A cross-model evaluation of new approaches

Mitigation-Process Integrated Assessment Models (MP-IAMs) are used to analyze long-term transformation pathways of the energy system required to achieve stringent climate change mitigation targets. Due to their substantial temporal and spatial aggregation, IAMs cannot explicitly represent all detailed challenges of integrating the variable renewable energies (VRE) wind and solar in power systems, but rather rely on parameterized modeling approaches. In the ADVANCE project, six international modeling teams have developed new approaches to improve the representation of power sector dynamics and VRE integration in IAMs. In this study, we qualitatively and quantitatively evaluate the last years' modeling progress and study the impact of VRE integration modeling on VRE deployment in IAM scenarios. For a comprehensive and transparent qualitative evaluation, we first develop a framework of 18 features of power sector dynamics and VRE integration. We then apply this framework to the newly-developed modeling approaches to derive a detailed map of strengths and limitations of the different approaches. For the quantitative evaluation, we compare the IAMs to the detailed hourly-resolution power sector model REMIX. We find that the new modeling approaches manage to represent a large number of features of the power sector, and the numerical results are in reasonable agreement with those derived from the detailed power sector model. Updating the power sector representation and the cost and resources of wind and solar substantially increased wind and solar shares across models: Under a carbon price of 30$/tCO2 in 2020 (increasing by 5% per year), the model-average cost-minimizing VRE share over the period 2050–2100 is 62% of electricity generation, 24%-points higher than with the old model version

How much energy will buildings consume in 2100? A global perspective within a scenario framework

The demand for energy in buildings varies strongly across countries and climatic zones. These differences result from manifold factors, whose future evolution is uncertain. In order to assess buildings' energy demand across the 21st century, we develop an energy demand model—EDGE— and apply it in an analytical scenario framework—the shared socio-economic pathways (SSPs) — to take socio-economic uncertainty into consideration. EDGE projects energy demand for five energy services, four fuel categories, and eleven regions covering the world. The analysis shows that, without further climate policies, global final energy demand from buildings could increase from 116 EJ/yr in 2010 to a range of 120–378 EJ/yr in 2100. Our results show a paradigm shift in buildings' energy demand: appliances, lighting and space cooling dominate demand, while the weight of space heating and cooking declines. The importance of developing countries increases and electricity becomes the main energy carrier. Our results are of high relevance for climate mitigation studies as they create detailed baselines that define the mitigation challenge: the stress on the energy supply system stemming from buildings will grow, though mainly in the form of electricity for which a number of options to decrease GHG emissions exist

Marginalization of end-use technologies in energy innovation for climate protection

Mitigating climate change requires directed innovation efforts to develop and deploy energy technologies. Innovation activities are directed towards the outcome of climate protection by public institutions, policies and resources that in turn shape market behaviour. We analyse diverse indicators of activity throughout the innovation system to assess these efforts. We find efficient end-use technologies contribute large potential emission reductions and provide higher social returns on investment than energy-supply technologies. Yet public institutions, policies and financial resources pervasively privilege energy-supply technologies. Directed innovation efforts are strikingly misaligned with the needs of an emissions-constrained world. Significantly greater effort is needed to develop the full potential of efficient end-use technologies

Economic damages from on-going climate change imply deeper near-term emission cuts

Pathways toward limiting global warming to well below 2 ∘C, as used by the IPCC in the Fifth Assessment Report, do not consider the climate impacts already occurring below 2 ∘C. Here we show that accounting for such damages significantly increases the near-term ambition of transformation pathways. We use econometric estimates of climate damages on GDP growth and explicitly model the uncertainty in the persistence time of damages. The Integrated Assessment Model we use includes the climate system and mitigation technology detail required to derive near-term policies. We find an optimal carbon price of $115 per tonne of CO2 in 2030. The long-term persistence of damages, while highly uncertain, is a main driver of the near-term carbon price. Accounting for damages on economic growth increases the gap between the currently pledged nationally determined contributions and the welfare-optimal 2030 emissions by two thirds, compared to pathways considering the 2 ∘C limit only

Enhancing global climate policy ambition towards a 1.5 °C stabilization: a short-term multi-model assessment

The Paris Agreement is a milestone in international climate policy as it establishes a global mitigation framework towards 2030 and sets the ground for a potential 1.5 °C climate stabilization. To provide useful insights for the 2018 UNFCCC Talanoa facilitative dialogue, we use eight state-of-the-art climate-energy-economy models to assess the effectiveness of the Intended Nationally Determined Contributions (INDCs) in meeting high probability 1.5 and 2 °C stabilization goals. We estimate that the implementation of conditional INDCs in 2030 leaves an emissions gap from least cost 2 °C and 1.5 °C pathways for year 2030 equal to 15.6 (9.0–20.3) and 24.6 (18.5–29.0) GtCO2eq respectively. The immediate transition to a more efficient and low-carbon energy system is key to achieving the Paris goals. The decarbonization of the power supply sector delivers half of total CO2 emission reductions in all scenarios, primarily through high penetration of renewables and energy efficiency improvements. In combination with an increased electrification of final energy demand, low-carbon power supply is the main short-term abatement option. We find that the global macroeconomic cost of mitigation efforts does not reduce the 2020–2030 annual GDP growth rates in any model more than 0.1 percentage points in the INDC or 0.3 and 0.5 in the 2 °C and 1.5 °C scenarios respectively even without accounting for potential co-benefits and avoided climate damages. Accordingly, the median GDP reductions across all models in 2030 are 0.4%, 1.2% and 3.3% of reference GDP for each respective scenario. Costs go up with increasing mitigation efforts but a fragmented action, as implied by the INDCs, results in higher costs per unit of abated emissions. On a regional level, the cost distribution is different across scenarios while fossil fuel exporters see the highest GDP reductions in all INDC, 2 °C and 1.5 °C scenarios