The relatively new concept of "green growth" can be fruitfully connected to concepts and theories in neoclassical economics including market externalities, Ricardian and Hotelling rents, and policies that would correct externalities such as Pigovian taxes or a cap and trade system set to achieve emissions reductions consistent with cost benefit assessment. Partial equilibrium concepts have been extended to general equilibrium models, including their realization in relatively detailed empirical models that faithfully adhere to theoretical concepts of neoclassical economics. With such models we are then able to see how resource depletion and environmental degradation are affecting the economy, and how efforts to reduce the impact of these environmental and resource constraints could improve economic growth and performance. The foundation for traditional computable general equilibrium models are the National Income and Product Accounts (NIPAs), input-output (I-O) tables, and expanded Social Accounting Matrices (SAMs). The basis for extending these to include environmental and resource assets and goods are so called Integrated Economic and Environmental Social Accounts (IEESAs). While environmental effects are often considered to be "non-market," many of the impacts of environment are often reflected in market accounts through damages that might include, for example, less labor (due to environment related health problems), reduced productivity of agroecosystems, or damage to infrastructure and other produced assets. The challenge is to make the environmental connection explicit so as to provide a guide to where changes in policies could provide benefit. However, some damages do not enter the accounts at all, and mainly this is because household labor and leisure time are generally not valued in traditional accounts. Hence the cost of illness in terms of reduced ability to contribute to household activities would be missed in the standard accounts. While the theoretical structure for expanding the accounts has been laid out in various reviews, the empirical challenge of doing so is substantial. Careful attention to expanding NIPA accounts, making it a regular part of government statistical agencies’ efforts would improve the foundation for analysis of potential "green growth" policies and measures.

Three questions with John Reilly
 

Marine ecosystem models used to investigate how global change affects ocean ecosystems and their functioning typically omit pelagic plankton diversity. Diversity, however, may affect functions such as primary production and their sensitivity to environmental changes. Here we use a global ocean ecosystem model that explicitly resolves phytoplankton diversity by defining subtypes within four phytoplankton functional types (PFTs). We investigate the model's ability to capture diversity effects on primary production under environmental change. An idealized scenario with a sudden reduction in vertical mixing causes diversity and primary-production changes that turn out to be largely independent of the number of coexisting phytoplankton subtypes. The way diversity is represented in the model provides a small number of niches with respect to nutrient use in accordance with the PFTs defined in the model. Increasing the number of phytoplankton subtypes increases the resolution within the niches. Diversity effects such as niche complementarity operate between, but not within PFTs, and are constrained by the variety of traits and trade-offs resolved in the model. The number and nature of the niches formulated in the model, for example via trade-offs or different PFTs, thus determines the diversity effects on ecosystem functioning captured in ocean ecosystem models.

© 2014 Prowe et al.

Ninety percent of Pakistan’s agricultural output is produced in fields irrigated by the Indus basin irrigation system, the world’s largest network of canals, dams, barrages and tubewells. River flows, primarily fed by snow and glacial melt, are highly seasonal and fluctuate between intense floods and droughts. Built storage is relatively small, with withdrawals averaging at 70% of annual availability. Climate change, growth in sectoral water demands, and changes in water management infrastructure could have a profound impact on water stress in the coming decades. The interplay and contribution of these influences is explored using a model of the managed Indus River basin. To account for key hydroclimate shifts, I translate temperature rise and glacier cover scenarios into river runoff in 2050. I also project sectoral water demands to 2050. I then use an optimization model to estimate dam releases and project water stress to 2050. I find that climate change will cause decreases in peak river flows, but the changes in runoff will be comparable to current interannual variability. The most significant increase in water stress is caused by a scenario of 1-2.5°C warming and 1% annual glacial retreat. However, rises in demand have a greater impact on water stress than climate-induced changes in runoff which can be either positive or negative. The stabilization of global greenhouse gas emissions checks the rise in water demand and thus lowers future water stress. Effective adaptation options to an increase in water stress include building more storage capacity, relaxation of water allocation to allow interprovincial water trading, and adaptation of the cropping calendar to the natural hydrological cycle.

The climate impact of anthropogenic absorbing aerosols has attracted wide attentions recently. The unique forcing distribution of these aerosols displays, as instantaneous and in solar band, a significant heating to the atmosphere and a cooling in a close but smaller magnitude at the Earth's surface, leading to a positive net forcing to the Earth-atmosphere system, i.e., the forcing at the top of the atmosphere, which brings a warming tendency to the climate system. On the other hand, the atmospheric heating and surface cooling introduced by these aerosols have been demonstrated to be able to interact with dynamical processes in various scales to alter atmospheric circulation, and hence clouds and precipitation. Recent studies have suggested that the changes in precipitation caused by persistent forcing of anthropogenic absorbing aerosols through certain dynamical interactions, often appearing distant from the aerosol-laden regions, are likely more significant than those caused through aerosol–cloud microphysical connection confined locally to the aerosol concentrated areas. An active research field is forming to understand the changes in cloud and precipitation caused by anthropogenic absorbing aerosol through various dynamical linkages. This review discusses several recent findings regarding the effect of anthropogenic absorbing aerosols on cloud and precipitation, with an emphasis on works relate to the coupling between aerosol forcing and dynamical processes.

© 2013 Elsevier