Decision-making and integrated assessment models of the water-energy-food nexus

Studying trade-offs in the long-term development of water-energy-food systems requires a new family of hydroeconomic optimization models. This article reviews the central con- siderations behind these models, highlighting the importance of water infrastructure, the foundations of a theory of decision-making, and the handling of uncertainty. Integrated as- sessment models (IAMs), used in climate change policy research, provide insights that can support this development. In particular, IAM approaches to intertemporal decision-making and economic valuation can improve existing models. At the same time, IAMs have weak- nesses identified elsewhere and can benefit from the development of hydroeconomic models, which have complementary strengths

Crop switching reduces agricultural losses from climate change in the United States by half under RCP 8.5

A key strategy for agriculture to adapt to climate change is by switching crops and relocating crop production. We develop an approach to estimate the economic potential of crop reallocation using a Bayesian hierarchical model of yields. We apply the model to six crops in the United States, and show that it outperforms traditional empirical models under cross-validation. The fitted model parameters provide evidence of considerable existing climate adaptation across counties. If crop locations are held constant in the future, total agriculture profits for the six crops will drop by 31% for the temperature patterns of 2070 under RCP 8.5. When crop lands are reallocated to avoid yield decreases and take advantage of yield increases, half of these losses are avoided (16% loss), but 57% of counties are allocated crops different from those currently planted. Our results provide a framework for identifying crop adaptation opportunities, but suggest limits to their potential

Scales for scales: An open look at the open sea

Fisheries are among the most complex and tightly coupled social-ecological systems. This thesis develops new perspectives on the spatial features of fisheries, and on common pool resources in general. The central model of the work is the Distributed Commons, a commons spread across space with local and cross-boundary interactions. The model is founded in evidence from historical analysis and complexity theory, and offers insights for management and broader sustainable development policy. The second part of the thesis uses empirical analysis, applying Bayesian and econometric techniques, to study the spatial features exposed by the model. Finally, a computational model is calibrated for exploring the consequences of this theory through experiments. The implications of the Distributed Commons model are relevant to many areas of sustainable development, including atmospheric pollution, environmental degradation, and the use of ecosystem resources

Economic impacts of tipping points in the climate system

Climate scientists have long emphasized the importance of climate tipping points like thawing permafrost, ice sheet disintegration, and changes in atmospheric circulation. Yet, save for a few fragmented studies, climate economics has either ignored them or represented them in highly stylized ways. We provide unified estimates of the economic impacts of all eight climate tipping points covered in the economic literature so far using a meta-analytic integrated assessment model (IAM) with a modular structure. The model includes national-level climate damages from rising temperatures and sea levels for 180 countries, calibrated on detailed econometric evidence and simulation modeling. Collectively, climate tipping points increase the social cost of carbon (SCC) by ∼25% in our main specification. The distribution is positively skewed, however. We estimate an ∼10% chance of climate tipping points more than doubling the SCC. Accordingly, climate tipping points increase global economic risk. A spatial analysis shows that they increase economic losses almost everywhere. The tipping points with the largest effects are dissociation of ocean methane hydrates and thawing permafrost. Most of our numbers are probable underestimates, given that some tipping points, tipping point interactions, and impact channels have not been covered in the literature so far; however, our method of structural meta-analysis means that future modeling of climate tipping points can be integrated with relative ease, and we present a reduced-form tipping points damage function that could be incorporated in other IAMs

The missing risks of climate change

The risks of climate change are enormous, threatening the lives and livelihoods of millions to billions. The economic consequences of many of the complex risks associated with climate change cannot, however, currently be quantified. We argue that these unquantified, poorly understood, and often deeply uncertain risks can and should be included in economic evaluations and decision making processes. We present an overview of these unquantified risks and an ontology of them founded on the reasons behind their lack of robust evaluation. These consist of risks missing due to (a) delays in sharing knowledge and expertise across disciplines, (b) spatial and temporal variations of climate impacts, (c) feedbacks and interactions between risks, (d) deep uncertainty in our knowledge, and (e) currently unidentified risks. We highlight collaboration needs within and between the natural and social science communities to address these gaps. We also provide an qpproach for integrating assessments or speculations of these risks in a way which accounts for interdependencies, avoids double counting and makes assumptions clear. Multiple paths exist for engaging with these missing risks, with both model-based quantification and non-model-based qualitative assessments playing crucial roles

Behavioral, morphological, and ecological trait evolution in two clades of New World Sparrows (Aimophila and Peucaea, Passerellidae)

Copyright 2020 Cicero et al. The New World sparrows (Passerellidae) are a large, diverse group of songbirds that vary in morphology, behavior, and ecology. Thus, they are excellent for studying trait evolution in a phylogenetic framework. We examined lability versus conservatism in morphological and behavioral traits in two related clades of sparrows (Aimophila, Peucaea), and assessed whether habitat has played an important role in trait evolution. We first inferred a multi-locus phylogeny which we used to reconstruct ancestral states, and then quantified phylogenetic signal among morphological and behavioral traits in these clades and in New World sparrows more broadly. Behavioral traits have a stronger phylogenetic signal than morphological traits. Specifically, vocal duets and song structure are the most highly conserved traits, and nesting behavior appears to be maintained within clades. Furthermore, we found a strong correlation between open habitat and unpatterned plumage, complex song, and ground nesting. However, even within lineages that share the same habitat type, species vary in nesting, plumage pattern, song complexity, and duetting. Our findings highlight trade-offs between behavior, morphology, and ecology in sparrow diversification

Accessibility across transport modes and residential developments in Nairobi

A key goal of urban transportation planning is to provide people with access to a greater number of opportunities for interaction with people and places. Measures of accessibility are gaining attention globally for use in planning, yet few studies measure accessibility in cities in low-income countries, and even fewer incorporate semi-formal bus systems, also called paratransit. Drawing on rich datasets available for Nairobi, Kenya this analysis quantifies place-based accessibility for walking, paratransit, and driving using three different measures: a mobility measure quantifying how many other locations in Nairobi can be reached in 60 min, a contour measure quantifying the number of health facilities that can be reached in 60 min, and a gravity measure quantifying the number of health facilities weighted by a time-decay function. Health facilities are used because they are an essential service that people need physical access to and as a representation of the spatial distribution of activities more broadly. The findings show that place-based accessibility is highest for driving, then paratransit, then walking, and that there are high levels of access to health facilities near the Central Business District (CBD) for all modes. Additionally, paratransit accessibility is comparatively better in the contour and gravity measures, which may mean that paratransit is efficiently providing access based on the spatial distribution of services. The contour measure results are also compared across different residential levels, which are grouped based on neighborhood characteristics and ordered by income. Counterintuitively, the wealthiest areas have very low levels of place-based accessibility for all modes, while poor areas have comparatively better walking access to health facilities. Interestingly, the medium low residential level, characterized in part by tenement apartment buildings, has significantly higher accessibility than other residential types. One way to reduce inequality in access across income groups is to increase spatial accessibility for the modes used by low- and middle-income households, for example with policies that prioritize public transport and non-motorized travel, integrate paratransit with land use development, and provide safe, efficient, and affordable options

Challenges and innovations in the economic evaluation of the risks of climate change

A large discrepancy exists between the dire impacts that most natural scientists project we could face from climate change and the modest estimates of damages calculated by mainstream economists. Economic assessments of climate change risks are intended to be comprehensive, covering the full range of physical impacts and their associated market and non-market costs, considering the greater vulnerability of poor people and the challenges of adaptation. Available estimates still fall significantly short of this goal, but alternative approaches that have been proposed attempt to address these gaps. This review seeks to provide a common basis for natural scientists, social scientists, and modellers to understand the research challenges involved in evaluating the economic risks of climate change. Focusing on the estimation processes embedded in economic integrated assessment models and the concerns raised in the literature, we summarise the frontiers of research relevant to improving quantitative damage estimates, representing the full complexity of the associated systems, and evaluating the impact of the various economic assumptions used to manage this complexity

Ensuring Economic Viability and Sustainability of Coffee Production

Coffee, the world’s favorite beverage, provides livelihoods for at least 60 million people across dozens of countries. Yet this beloved drink is experiencing a sustainability crisis. A sustained decline in world coffee prices has squeezed coffee producers, and thrown a tremendous number of producers below the global extreme poverty line. This report presents our research into sustainability within the coffee sector, including the results of our analytical and empirical modeling, and provides several recommendations