Articles

The extraordinary complexity of today’s advanced weapons systems has significantly reduced the ability of states to imitate other states’ military technology. Consequently, U.S. rivals such as China will continue to struggle to develop indigenous capabilities that can match those of the United States.

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.

Sovereign wealth funds (SWFs) have traditionally been created to recycle excess reserves from natural resource or non‐commodity revenues. However, in recent years funds are being established under conditions of capital scarcity with objectives to contribute domestic economic development, often through the buildout of national infrastructure programs. Such trends in new fund creation represent a fundamental shift in the sovereign wealth fund paradigm and raise serious questions about how these entities are to be capitalized and also the implications of capitalization models on their sustainability. This study examines the recent evolution of SWF models focused on economic development. Its analytic focus is drawn, in particular, to countries that are neither endowed with oil wealth, nor otherwise enjoy export surpluses to be used to capitalize a development‐oriented SWF. While this study is relevant to and expands the scope of the broad literature on SWFs, its specific contribution is as a focused analysis of how SWF funding sources impact achieving long‐term financial and socio‐economic development objectives.