The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance our knowledge of climate variability and climate change. Researchers worldwide are analyzing the model output and will produce results likely to underlie the forthcoming Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Unprecedented in scale and attracting interest from all major climate modeling groups, CMIP5 includes “long term” simulations of twentieth-century climate and projections for the twenty-first century and beyond. Conventional atmosphere–ocean global climate models and Earth system models of intermediate complexity are for the first time being joined by more recently developed Earth system models under an experiment design that allows both types of models to be compared to observations on an equal footing. Besides the longterm experiments, CMIP5 calls for an entirely new suite of “near term” simulations focusing on recent decades...

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An Overview of CMIP5 and the Experiment Design

世界経済・社会統計 = World development indicators

Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO2 emissions in the atmosphere demands that holding atmospheric CO2 levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.

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Powering the planet: Chemical challenges in solar energy utilization

This paper summarizes the development process and main characteristics of the Representative Concentration Pathways (RCPs), a set of four new pathways developed for the climate modeling community as a basis for long-term and near-term modeling experiments. The four RCPs together span the range of year 2100 radiative forcing values found in the open literature, i.e. from 2.6 to 8.5 W/m 2 . The RCPs are the product of an innovative collaboration between integrated assessment modelers, climate modelers, terrestrial ecosystem modelers and emission inventory experts. The resulting product forms a comprehensive data set with high spatial and sectoral resolutions for the period extending to 2100. Land use and emissions of air pollutants and greenhouse gases are reported mostly at a 0.5×0.5 degree spatial resolution, with air pollutants also provided per sector (for well-mixed gases, a coarser resolution is used). The underlying integrated assessment model outputs for land use, atmospheric emissions and concentration data were harmonized across models and scenarios to ensure consistency with historical observations while preserving individual scenario trends. For most variables, the RCPs cover a wide range of the existing literature. The RCPs are supplemented with extensions (Extended Concentration Pathways, ECPs), which allow

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The representative concentration pathways: an overview

Advances in the science and observation of climate change are providing a clearer understanding of the inherent variability of Earth's climate system and its likely response to human and natural influences. The implications of climate change for the environment and society will depend not only on the response of the Earth system to changes in radiative forcings, but also on how humankind responds through changes in technology, economies, lifestyle and policy. Extensive uncertainties exist in future forcings of and responses to climate change, necessitating the use of scenarios of the future to explore the potential consequences of different response options. To date, such scenarios have not adequately examined crucial possibilities, such as climate change mitigation and adaptation, and have relied on research processes that slowed the exchange of information among physical, biological and social scientists. Here we describe a new process for creating plausible scenarios to investigate some of the most challenging and important questions about climate change confronting the global community.

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The next generation of scenarios for climate change research and assessment

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Accelerating emission reduction in Israel: Carbon pricing vs. policy standards

The concept of Global Energy Interconnection (GEI) proposed by Global Energy Interconnection Development and Cooperation Organization (GEIDCO) integrates smart grids, ultrahigh voltage (UHV) transmission and renewable energy access (solar, wind and hydro). Ultrahigh Voltage (UHV) lines could transmit renewable power from one world region to another with lower losses than current high voltage systems. In December 2019, the Global Energy Interconnection Development and Cooperation Organization (GEIDCO), International Institute for Applied Systems Analysis (IIASA) and World Meteorological Organization (WMO) published a report titled “Research Report on Global Energy Interconnection for Address Climate Change”. In that report, two scenarios for Global Energy Interconnection are presented, consistent with limiting climate change to 1.5 and 2 degrees. These scenarios were limited to the GEI interconnections as concretely proposed by GEIDCO.

This report provides an uncertainty analysis for the GEI scenarios, especially focusing on uncapping the GEI interconnections to explore the potential for electricity transmission between world regions. In order to further investigate the benefits of renewable electricity trade via UHV transmission lines, in this study we designed two new scenarios with uncapped transmission capacity of UHV lines by using IIASA’s integrated assessment modeling (IAM) tool, the MESSAGEix-GLOBIOM model. 

Based on these scenarios, we find several insights: first, there exits more needs of electricity trade between the model regions than what the selected UHV projects can offer. This implies that new UHV transmission projects might need to be investigated. Second, renewable electricity trade by UHV transmission lines could facilitate higher production of renewable electricity. The more trade is realized, the more renewable electricity is produced. In addition, the renewable electricity trade could help the reduction of CO2 emissions by boosting the global consumption of renewable electricity.

Global Energy Interconnection: A scenario analysis based on the MESSAGEix-GLOBIOM Model

Integrated solutions for water, energy, and land nexus management the Zambezi Basin: stakeholder engagement and modeling

This research investigates the interconnections between water, energy, and land systems in the context of a long-term assessment of transition paths to achieve the Sustainable Development Goals (SDGs). It highlights the importance of integrated methods and addresses the complexity, interdependence, and uncertainty of climate change's impacts on natural systems and technology in the water, energy, and land sectors. The research utilizes two Integrated Assessment Models (MESSAGEix-GLOBIOM and IMAGE) to assess the long-term resources, supply, and demand of these sectors, together with the regional and sectoral reforms required to achieve the SDGs. It demonstrates how various locations and sectors would be affected by climate feedback under various climate mitigation scenarios.&amp;#160; The study concludes that changes in water availability, that influence agriculture, water and sanitation access, hydropower potential, and power plant cooling technologies, constitute the largest proportion of climate impacts and the prime source of uncertainty. Furthermore, scenario analysis is used to understand the relationship between the SDGs and climate impacts in the absence of climate policies. The findings demonstrate that considerable progress towards the trajectories of the nexus SDGs resulted in strong synergies and interactions across the energy-water and land nexus components, irrespective of climate factors. Additionally, the study demonstrates that ambitious and healthy dietary modifications and a reduction in food waste can result in a decrease in global food demand, irrigation withdrawals, and emissions. Changes in the land sector can reduce overall SDG policy costs and energy and water expenditures, while strengthening the needs of the poor. Improving wastewater treatment and establishing more efficient water management technologies has socioeconomic and environmental advantages and can alleviate stress on freshwater withdrawals in locations that are water stressed.&amp;#160; The study also shows that some regions, such as the Middle East and South Asia, are more vulnerable to climate impacts on the water sector and may require more extensive investments in water efficiency. In addition, it stresses that supplying households with electricity and clean cooking services can stimulate energy demand in emerging economies, but widespread adoption would require an increase in household incomes, notably in South Asia and Sub-Saharan Africa. Overall, the study highlights the importance of exploring the effects of climate change on natural and technological systems in the water, energy, and land sectors, as well as the relevance of implementing a coordinated strategy to achieving the Sustainable Development Goals. It also demonstrates the inter - dependencies and potentials of various sectors to achieve the SDGs while addressing the challenges they face because of climate change.&amp;#160; 

Leveraging Integrated Assessment Models to access climate feedbacks on Water, Energy, and Land Systems: An Evaluation of Regional and Sectoral Transformations for Achieving the Sustainable Development Goals 

The financial system, the ecosystem of investors (e.g., banks, investment funds, insurance), markets, and instruments, is often considered to play an enabling role in climate mitigation pathways to a low-carbon transition. But it can also have a hampering role, e.g., if investors’ perceptions of low risk from a missed transition and low opportunities from a transition fail to trigger a reallocation of capital into low-carbon investments. This increases the chance of the transition not occur-ring within the time window required to stabilize the climate or occurring in a disorderly fashion. But investors, who can influence the realization of climate mitigation pathways, themselves rely upon estimates of climate mitigation pathways from process-based Integrated Assessment Models (IAMs). And IAMs do not model the financial system nor investors’ decisions, thus the feedback loop between the financial system and mitigation pathways is not taken into account by the IAMs nor by the finance community. This limitation to our understanding of the dynamics and the feasibility of the low-carbon transition weakens the ability of IAMs to inform policy and investment decisions. We propose a framework to capture the interdependence between investors’ perception of future climate risk, depending on the credibility of climate policies, and the allocation of in-vestments in the economy.

Keywan Riahi

Papers

Accelerating emission reduction in Israel: Carbon pricing vs. policy standards

Global Energy Interconnection: A scenario analysis based on the MESSAGEix-GLOBIOM Model

Integrated solutions for water, energy, and land nexus management the Zambezi Basin: stakeholder engagement and modeling

Leveraging Integrated Assessment Models to access climate feedbacks on Water, Energy, and Land Systems: An Evaluation of Regional and Sectoral Transformations for Achieving the Sustainable Development Goals

Accounting for finance is key for climate mitigation pathways