Ethnic Groups in Conflict

Corruption and Growth

The state of desalination and brine production: A global outlook.

For centuries, thinkers have considered whether and how climatic conditions-such as temperature, rainfall, and violent storms-influence the nature of societies and the performance of economies. A multidisciplinary renaissance of quantitative empirical research is illuminating important linkages in the coupled climate-human system. We highlight key methodological innovations and results describing effects of climate on health, economics, conflict, migration, and demographics. Because of persistent "adaptation gaps," current climate conditions continue to play a substantial role in shaping modern society, and future climate changes will likely have additional impact. For example, we compute that temperature depresses current U.S. maize yields by ~48%, warming since 1980 elevated conflict risk in Africa by ~11%, and future warming may slow global economic growth rates by ~0.28 percentage points per year. In general, we estimate that the economic and social burden of current climates tends to be comparable in magnitude to the additional projected impact caused by future anthropogenic climate changes. Overall, findings from this literature point to climate as an important influence on the historical evolution of the global economy, they should inform how we respond to modern climatic conditions, and they can guide how we predict the consequences of future climate changes.

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Social and economic impacts of climate

The 3 most often-used performance measures in the cognitive and decision sciences are choice, response or decision time, and confidence. We develop a random walk/diffusion theory-2-stage dynamic signal detection (2DSD) theory-that accounts for all 3 measures using a common underlying process. The model uses a drift diffusion process to account for choice and decision time. To estimate confidence, we assume that evidence continues to accumulate after the choice. Judges then interrupt the process to categorize the accumulated evidence into a confidence rating. The model explains all known interrelationships between the 3 indices of performance. Furthermore, the model also accounts for the distributions of each variable in both a perceptual and general knowledge task. The dynamic nature of the model also reveals the moderating effects of time pressure on the accuracy of choice and confidence. Finally, the model specifies the optimal solution for giving the fastest choice and confidence rating for a given level of choice and confidence accuracy. Judges are found to act in a manner consistent with the optimal solution when making confidence judgments.

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Two-stage dynamic signal detection: a theory of choice, decision time, and confidence.

It was the summer of 1969 and the Cuyahoga River was on fire. This wasn’t the first time the river in northern Ohio had burned, it wasn’t even the tenth. Every few years, an errant spark would ignite the river, threatening nearby buildings or passing ships. The fire of 1969 was not especially notable for the damage it caused or the duration of its blaze. But it did ignite the tinderbox of environmental unrest that had already been smoldering across the country. Within six months of the fire, the U.S. Congress passed the National Environmental Policy Act, establishing the U.S. Environmental Protection Agency (EPA). One of the first acts of the EPA was to implement the Clean Water Act of 1972, which mandated that all waterways must be of sufficient quality to be safe for swimming and aquatic life by 1983. Fifty years on, water quality issues remain a challenge. Like the Cuyahoga River in 1969, many other water bodies are on fire, some literally, like the Meiyu River in eastern China or Bellandur Lake in Bangalore, India, which has rained ash onto buildings up to six miles away. Yet most burn imperceptibly, with bacteria, sewage, chemicals, and plastics sucking out the dissolved oxygen much like a raging inferno and transforming water into poison for humans and ecosystems alike. Understanding of this problem has been impaired not just by a lack of information, but also by the complexity of issues that often transcend discipline boundaries, environmental science, health, hydrology, and economics, with each offering different insights. This report brings forth new results that illuminate the impacts of the hidden dangers that lie beneath the water’s surface and elucidate strategies for combating them. The main, though not exclusive, focus is on the parameters that are tracked in the water quality Sustainable Development Goal (SDG) 6.3.2, with its focus on nutrient loads, salt balances, and overall environmental health of water bodies. The report demonstrates that the parameters identified in SDG 6.3.2 have impacts that are wider, deeper, and larger than previously known, suggesting the need for a broader focus on water quality beyond indicators of sanitation-related contaminants such as fecal coliforms and Escherichia coli. Recognizing the scope of the problem, identifying the magnitude of the impacts, and formulating ways to address these will be critical to improving public health, preserving ecosystems, and sustaining economic growth throughout the twenty-first century.

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Quality Unknown: The Invisible Water Crisis

The 21st century will witness the collision of two powerful forces, burgeoning population growth, together with a changing climate. With population growth, water scarcity will proliferate to new areas across the globe. And with climate change, rainfall will become more fickle, with longer and deeper periods of droughts and deluges. This report presents new evidence to advance understanding on how rainfall shocks coupled with water scarcity, impacts farms, firms, and families. On farms, the largest consumers of water in the world, impacts are channeled from declining yields to changing landscapes. In cities, water extremes especially when combined with unreliable infrastructure can stall firm production, sales, and revenue. At the center of this are families, who feel the impacts of this uncertainty on their incomes, jobs, and long-term health and welfare. Although a rainfall shock may be fleeting, its consequences can become permanent and shape the destiny of those who experience it. Pursuing business as usual will lead many countries down a “parched path” where droughts shape destinies. Avoiding this misery in slow motion will call for fundamental changes to water policy around the globe. Building resilience to rainfall variability will require using different policy instruments to address the multifaceted nature of water. A key message of this report is that water has multiple economic attributes, each of which entail distinct policy responses. If water is not managed more prudently, from source, to tap, and back to source, the crises observed today will become the catastrophes of tomorrow.

Uncharted Waters: The New Economics of Water Scarcity and Variability

Rainfall anomalies have long occupied center stage in policy discussions, and understanding their impacts on agricultural production has become more important as climate change intensifies. However, the global scale of rainfall-induced productivity shocks on changes in cropland is yet to be quantified. Here we identify how rainfall anomalies impact observed patterns of cropped areas at a global scale by leveraging locally determined unexpected variations in rainfall. Employing disaggregated panel data at the grid level, we find that repeated dry anomalies lead to an increase in cropland expansion in developing countries. No discernible effects are detected from repeated wet events. That these effects are confined to developing countries, which are often dominated by small-holder farmers, implies that they may be in response to reduced yields. The estimates suggest that overall, in developing countries, dry anomalies account for ∼9% of the rate of cropland expansion over the past two decades. We perform several tests to check for consistency and robustness of this relationship. First, using forest cover as an alternative measure, we find comparable reductions in forest cover in the same regions where cropland expands due to repeated dry anomalies. Second, we test the relationship in regions where yields are buffered from rainfall anomalies by irrigation infrastructure and find that the impact on cropland expansion is mitigated, providing further support for our results. Since cropland expansion is a significant driver of deforestation, these results have important implications for forest loss and environmental services.

Jason Russ

Papers

Quality Unknown: The Invisible Water Crisis

Uncharted Waters: The New Economics of Water Scarcity and Variability

Rainfall anomalies are a significant driver of cropland expansion

Long-term impacts of exposure to high temperatures on human capital and economic productivity

The Road to Growth: Measuring the Tradeoffs between Economic Growth and Ecological Destruction