Climate change is perhaps the central challenge that faces humanity. If the concept of green growth is to be anything more than a mere rebranding of the concept of sustainability, then it must elucidate the relationship between economic activity and pollution and provide a more detailed economic account of it. The articles in this Special Issue focus on ways in which GHG emissions may be reduced while satisfying the increasing demand for energy: from global, technological or economic solutions, to sub-national, financial or regulatory ones. Although the wide disparity in income between the least and most wealthy makes it difficult to reach a consensus on the best way to achieve a low-carbon society, the scale and potential effects of climate change make it imperative that one is reached.

© 2013 Taylor & Francis

Climate changes affect the ocean's biological carbon pumps by modifying the sources of macro- and micro-nutrients to the euphotic zone, cloud cover, surface alkalinity, and phytoplankton assemblages. We use a global model of coupled oceanic cycles of carbon, phosphorus and iron to investigate controls on global productivity and the ocean carbon cycle. We use the adjoint of the model to comprehensively and efficiently map the sensitivity of biological productivity and air-sea carbon fluxes to decadal perturbations in the external sources of iron and photosynthetically active radiation (PAR), the availability of phosphate, and the relative export of particulate organic and particulate inorganic carbon (rain ratio). Productivity and air-sea carbon flux in the high nitrate, low chlorophyll regions are most sensitive to perturbations in the iron source while the Atlantic ocean is most sensitive to additional sources of phosphorus and the high latitudes are most sensitive to perturbations in PAR. Air-sea carbon fluxes are most sensitive to variations of the rain-ratio in the equatorial oceans.

This paper surveys and interprets the attitudes of scientists to the use of flux adjustments in climate projections with coupled Atmosphere Ocean General Circulation Models. The survey is based largely on the responses of 19 climate modellers to several questions and a discussion document circulated in 1995. We interpret the responses in terms of the following factors: the implicit assumptions which scientists hold about how the environmental policy process deals with scientific uncertainty over human-related global warming; the different scientific styles that exist in climate research; and the influence of organisations, institutions, and policy upon research agendas. We find evidence that scientists' perceptions of the policy process do play a role in shaping their scientific practices. In particular, many of our respondents expressed a preference for keeping discussion of the issue of flux adjustments within the climate modeling community, apparently fearing that climate contrarians would exploit the issue in the public domain. While this may be true, we point to the risk that such an approach may backfire. We also identify assumptions and cultural commitments lying at a deeper level which play at least as important a role as perceptions of the policy process in shaping scientific practices. This leads us to identify two groups of scientists, 'pragmatists' and 'purists,' who have different implicit standards for model adequacy, and correspondingly are or are not willing to use flux adjustments.

Considerations regarding the roles of advanced technologies are crucial in energy-economic modeling, as these technologies, while usually not yet commercially viable, could substitute for fossil energy when relevant policies are in place. To improve the representation of the penetration of advanced technologies, we present a formulation that is parameterized based on observations, while capturing elements of rent and real cost increases if high demand suddenly appears due to large policy shock. The formulation is applied to a global economy-wide model to study the roles of low carbon alternatives in the power sector. While other modeling approaches often adopt specific constraints on expansion, our approach is based on the assumption and observation that these constraints are not absolute—the rate at which advanced technologies will expand is endogenous to economic incentives. The policy simulations are designed to illustrate the response under sudden increased demand for the advanced technologies, and are not intended to represent necessarily realistic price paths for greenhouse gas emissions.