Publication: measuring effects of geoengineering on agriculture using volcanoes

Jon Proctor, Solomon Hsiang, and coauthors published a study in Nature estimating the effect of solar radiation management (SRM) on global agricultural production. The paper exploits the historical eruption of massive volcanoes that inject sulfate aerosols into the stratosphere to understand the effect of changing light conditions on crop yields. The paper finds that benefits from cooling, the intended effect of SRM, are fully offset by harm to yields via shading. 

Read the study ungated here.

A resource page for the article is here.

Press release here.

View fullsize

Visualization of the stratospheric sulfate aerosols injected into the atmosphere after the eruption of Mt Pinatubo. Each frame is a month. Visualization by Jon Proctor & Solomon Hsiang.

Publication: Warming increases suicides in the USA and Mexico

Felipe González, Patrick Baylis, Solomon Hsiang and colleagues published an article in Nature Climate Change demonstrating that higher temperatures increase suicide rates across the entire United States and Mexico. 

Read the article here.

Publication: letter on Ivory trade policy in Science

View fullsize

Alongside a large interdisciplinary team, Sol coauthored a letter today in Science today explaining that recommendations to limit trade in legal ivory are based on evidence-based research. This was a response to an earlier article by Biggs et al. arguing that recommendations to limit trade were based on arbitrary values. We also point out that transparency in international negotiations are an important element of the process, in contrast to the recommendation by Biggs et al. to speed up international decision-making by negotiating international trade in ivory behind closed doors. 

Read the letter here. 

Read research by the lab on the global black market for ivory and international trade policy experiments here.

Comment in Nature: Climate and conflict research can support policy decision-making

Marshall Burke and Sol Hsiang wrote a short response to a recent editorial in Nature. The editorial was itself a response to an article in Nature Climate Change that argued that climate-conflict research contained systematic sampling bias. The published Correspondence is pretty succinct:

“Your Editorial on sampling bias in studies linking climate change with civil unrest (Nature 554, 275–276; 2018) is based on an analysis that in our view provides no evidence for biased results (C. Adams et al. Nature Clim. Change 8, 200–203; 2018).

We disagree with your contention that it is “undesirable” to study risk factors for populations with a high likelihood of conflict on the grounds that it could “stigmatize” these regions as politically unstable. The same logic would argue against studying risk factors for people who have a high chance of developing cancer for fear of stigmatizing patients. In our view, such recommendations could create bias in the literature by inhibiting research.

Studies of connections between climate and conflict should instead be motivated to identify causes of human suffering so that it can be alleviated (see, for example, M. Burke et al. Annu. Rev. Econ. 7, 577–617; 2015). We do not believe that shying away from investigations in this field is an effective path towards this goal.”

— Marshall Burke & Solomon Hsiang (Nature, 2018)

You can read the original un-cut text here, or download a pdf here.

Publication: Effect of Temperature on Math performance and learning

Joshua Graff Zivin, Matthew Neidell and Sol Hsiang published a new article "Temperature and human capital in the short and long run". Analyzing over 24,000 student exams and following individual students over time, they demonstrate that cognitive performance in mathematics declines at high temperatures, but not in reading or verbal exams.

Read the article here.

Paper: Pricing climate

Tatyana Deryugina and Solomon Hsiang have a new NBER working paper out titled "The Marginal Product of Climate". The analysis develops a formal theory for how overall economic productivity due to the climate should be valued, accounting for the fact that populations adapt to changes in their climate. They apply their approach to data on the United States and estimate that "business as usual" warming is worth roughly $6.7 trillion in foregone production within the US market economy.

Read the paper here.

Paper: The Distribution of Environmental Damages

Solomon Hsiang has a new joint paper with Paulina Oliva, and Reed Walker reviewing and exploring what is known about the distributional consequences of environmental damages and the benefits of environmental policy. They provide a general framework for empiricists and explore what is known in the context of pollution, deforestation, and climate. The NBER working paper is available online here. The article is forthcoming in the Review of Environmental Economics and Policy.

Publication: Crop-damaging temperatures increase suicide rates in India

Tamma Carleton has a new paper out in PNAS linking the climate to suicide rates in India. 

View fullsize

The analysis is the first to provide large-scale empirical evidence that the climate influences suicide rates in a developing country. The study shows that temperature during India's main agricultural growing season has a substantial influence over annual suicide rates, such that heating up the country by just 1 degree C on one day causes approximately 65 annual suicides. This effect appears to materialize through an agricultural channel in which high temperatures cause crop losses and economic distress, leading some to commit suicide in response. Carleton estimates that warming trends experienced in India since 1980 are responsible for a total of over 59,000 suicides.

See the paper here.

Publication: Climate Damage in the United States

James Rising, Solomon Hsiang, and former lab member Amir Jina, along with other teammates from the Climate Impact Lab, have a new paper out in Science calculating economic damages from climate change in the United States.  

The analysis is the first to construct a "damage function" using micro-level econometric results for a large number of sectors, linked to the full suite of climate models used in CMIP5.  Because the analysis has high spatial resolution, it is able to resolve how impacts of unmitigated climate damages across the country will vary, demonstrating that it will substantially increase economic inequality.

See the paper and an interactive visualization of results.

Update: The team at the Associated Press did a really nice interactive visualization of the results:

Paper: Understanding farmer crop choice in response to climate change

James Rising has a new working paper Weather-driven adaptation in perennial crop systems:An integrated study of Brazilian coffee yields, demonstrating how farmers in Brazil cope with changing environmental conditions by altering the portfolio of coffee crops they maintain. The analysis develops a novel structural Bayesian modeling approach that embeds reduced form modeling estimates, allowing James to solve (for the first time) the well-known "problem with perennials", i.e. the fact that analysts and policy-makes cannot generally observe the number of long-live plants (perennials) that farmers maintain on a farm. The analysis is important because it demonstrates how farmers cope with a changing climate by changing their investment decisions, sometimes amplifying the economic impact of changes in climate. 

Paper: Non-linear network behavior of protesters during escalating social movements

Felipe Gonzalez has a new working paper Collective Action in Networks: Evidence from the Chilean Student Movement, demonstrating how millions of students across schools in Chile influence one another to participate in a growing social movement.  Felipe demonstrates how the number of individuals in each student's social network, in addition to each student's physical neighborhood, increases the likelihood that specific students will participate in the 2011 student movement. He finds strong evidence of a "tipping point" where if 40% of a student's class is participating, then the entire class "tips" and begins attending the protest.  This is important because it is the first empirical evidence testing classical models of social network dynamics in revolutionary environments.

Locations of over 50,000 student protesters in Santiago, Chile during the 2011 student movement

Publication: Social and economic impacts of climate

Tamma Carleton and Solomon Hsiang published an article in Science discussing and synthesizing the methods and results used to understand the impact of climate from the last decade. We demonstrate how findings across the literature and sectors are linked, identify commonalities across numerous studies, and compute how much (i) various aspects of the current climate contribute to to historical social outcomes, (ii) how much climate change to date has affected outcomes, and (iii) quantitative projections of the future. We identify that understanding "adaptation gaps" is the most important area for future research.

View fullsize

Paper: Attendance distorts standardized test scores

Felipe Gonzalez has a new working paper Distorted Quality Signals in School Markets, demonstrating that schools in Chile increase their ranking by discouraging low performing students from showing up to class on days when standardized tests are administered. This is important because standardized tests scores determine how competitive schools are ranked and how resources are allocated across schools.

Paper: Effects of legalization on black markets

Solomon Hsiang and Nitin Sekar have a new NBER Working Paper Does legalization reduce black market activity? Evidence from a global ivory experiment and elephant poaching data.

Publication: Potentially extreme migration and population concentration in the tropics

Adam Sobel and Sol Hsiang have a new paper Potentially Extreme Population Displacement and Concentration in the Tropics Under Non-Extreme Warming in Scientific Reports.

Sol describes the paper on the G-FEED blog here.