Articles

The authors examine the complexities of designing policies that can keep Earth within the biophysical limits favorable to human life.

We review the capabilities and costs of various lofting methods intended to deliver sulfates into the lower stratosphere. We lay out a future solar geoengineering deployment scenario of halving the increase in anthropogenic radiative forcing beginning 15 years hence, by deploying material to altitudes as high as ~20 km. After surveying an exhaustive list of potential deployment techniques, we settle upon an aircraft-based delivery system. Unlike the one prior comprehensive study on the topic (McClellan et al 2012 Environ. Res. Lett. 7 034019), we conclude that no existing aircraft design—even with extensive modifications—can reasonably fulfill this mission. However, we also conclude that developing a new, purpose-built high-altitude tanker with substantial payload capabilities would neither be technologically difficult nor prohibitively expensive. We calculate early-year costs of ~$1500 ton−1 of material deployed, resulting in average costs of ~$2.25 billion yr−1 over the first 15 years of deployment. We further calculate the number of flights at ~4000 in year one, linearly increasing by ~4000 yr−1. We conclude by arguing that, while cheap, such an aircraft-based program would unlikely be a secret, given the need for thousands of flights annually by airliner-sized aircraft operating from an international array of bases.

Solar geoengineering, which seeks to cool the planet by reflecting a small fraction of sunlight back into space, has drawn the attention of scientists and policymakers as climate change remains unabated. Unlike mitigation, solar geoengineering could quickly and cheaply lower global temperatures. It is also imperfect. Its environmental impacts remain unpredictable, and its low cost and immediate effects may result in "moral hazard," potentially crowding out costly mitigation efforts. There is little understanding about how the public will respond to such tradeoffs.

Decision-makers often seek to design policies that support sustainable development. Prospective evaluations of how effectively such policies are likely to meet sustainability goals have nonetheless remained relatively challenging. Evaluating policies against sustainability goals can be facilitated through the inclusive wealth framework, which characterizes development in terms of the value to society of its underlying capital assets, and defines development to be potentially sustainable if that value does not decline over time.

Indian Prime Minister Narendra Modi traveled to Washington last week, making his fourth trip to the United States since taking office just two years ago. India and South Asia Program Fellow, Ronak Desai examines the strategic approach to India's relations with the United States.

Many energy consumers, and even analysts and policymakers, confront and frame energy and climate risks in a moral vacuum, rarely incorporating broader social justice concerns. Here, to remedy this gap, we investigate how concepts from justice and ethics can inform energy decision-making by reframing five energy problems — nuclear waste, involuntary resettlement, energy pollution, energy poverty and climate change — as pressing justice concerns.

"The Intergovernmental Panel on Climate Change (IPCC) has proven its value as an institution for large-scale scientific collaboration to synthesize and assess large volumes of climate research for use by policy-makers, as well as for establishing credibility of findings among diverse national governments. But the IPCC has received considerable criticism of both its substance and process."

China is the world's largest emitter of carbon dioxide, accounting for one-quarter of the global total in 2013. Although the country has successfully lowered the rate of emissions from industry in some cities through improved technology and energy-efficiency measures, rapid economic growth means that more emissions are being added than removed. Without mitigation, China's CO2 emissions will rise by more than 50% in the next 15 years.

"Government support in the form of so-called feed-in tariff policies (FITs), which combine long-term, fixed-price electricity purchase agreements and guaranteed grid-access, has attracted large private-sector investments in sustainable electricity generation in the industrialized world. In an effort to replicate these experiences globally, a number of international organizations, NGOs, banks and donor countries are proposing mechanisms to cover part of the cost of FITs in developing countries. This paper reviews these proposals for supported FITs and then uses a case study of Thailand's Alternative Energy Development Plan 2013–2021 to investigate the opportunities and challenges of supporting FITs at a global scale."