Climate and the [historical] slave trade

This is an interesting data set and a neat reduced-form result, although I think the mechanism is less clear than the authors suggest. I also like that the authors are drawing from a wider body of literature than is usual (and from their references, I can't but help get the creeping feeling that they might be reading FE).

Climate, ecosystem resilience and the slave trade

James Fenske and Namrata Kala
African societies exported more slaves in colder years. Lower temperatures reduced mortality and raised agricultural yields, lowering the cost of supplying slaves. Our results help explain African participation in the slave trade, which is associated with adverse outcomes today. We merge annual data on African temperatures with a panel of port-level slave exports to show that a typical port exported fewer slaves in a year when the local temperature was warmer than normal. This result is strongest where African ecosystems are least resilient to climate change, and is robust to several alternative specifications and robustness checks. We support our interpretation using evidence from the histories of Whydah, Benguela, and Mozambique.

h/t Ted Miguel


Diarrhoea in Bangladesh: displaying results from fixed effects models

I ran into this 2008 paper doing hurricane work with Jesse. The results are not extremely surprising, but I really liked how they displayed their result.  Many of us use high-dimensional data and multiple regression models to try and account for the many different processes that occur in social data, but it is often difficult to clearly display the effect of just one process while also being clear about all the other controls in the model. I like the approach of this team: they show predictions form the complex model (eg. with week and month fixed effects, socioeconomic controls, etc.) overlaid with the real data.

Factors determining vulnerability to diarrhoea during and after severe floods in Bangladesh
Masahiro Hashizume, Yukiko Wagatsuma, Abu S. G. Faruque, Taiichi Hayashi, Paul R. Hunter, Ben Armstrong and David A. Sack

Abstract: This paper identifies groups vulnerable to the effect of flooding on hospital visits due to diarrhoea during and after a flood event in 1998 in Dhaka, Bangladesh. The number of observed cases of cholera and non-cholera diarrhoea per week was compared to expected normal numbers during the flood and post-flood periods, obtained as the season-specific average over the two preceding and subsequent years using Poisson generalised linear models. The expected number of diarrhoea cases was estimated in separate models for each category of potential modifying factors: sex, age, socio-economic status and hygiene and sanitation practices. During the flood, the number of cholera and non-cholera diarrhoea cases was almost six and two times higher than expected, respectively. In the post-flood period, the risk of non-cholera diarrhoea was significantly higher for those with lower educational level, living in a household with a non- concrete roof, drinking tube-well water (vs. tap water), using a distant water source and unsanitary toilets. The risk for cholera was significantly higher for those drinking tube-well water and those using unsanitary toilets. This study confirms that low socio-economic groups and poor hygiene and sanitation groups were most vulnerable to flood-related diarrhoea.


Only the finest in Swiss data visualiation

The data visualization specialists over at Chart Porn point us to Datavisualization.ch's Selected Tools page. From their blog post announcing it:
When I meet with people and talk about our work, I get asked a lot what technology we use to create interactive and dynamic data visualizations. [...] That’s why we have put together a selection of tools that we use the most and that we enjoy working with. We called it selection.datavisualization.ch. It includes libraries for plotting data on maps, frameworks for creating charts, graphs and diagrams and tools to simplify the handling of data. Even if you’re not into programming, you’ll find applications that can be used without writing one single line of code. We will keep this list as a living repository and add / remove things as technology develops. We hope this will help you find the best tool for your next job.
Guess it's time to learn a little javascript...


Why we aren't so great at "climate management"

I ran into this today:

This Global Map of Science is based on research-front data for the six-year period ending in December 2009. The map shows the major subject areas within fields linked together in a network based on the same principles as our research-front maps showing highly cited papers. To create a map of science, we start with all research fronts in Essential Science IndicatorsSM from Thomson Reuters, and compute the links between fronts based on how often they are co-cited—that is, the frequency that current papers jointly cite two given fronts. Successive applications of a clustering process then groups fronts into larger aggregates. Each circle on the map represents a cluster or aggregate of research fronts on a broad topic within that field. Annotations have been added to this map which represent the main research themes. These appear as labels attached to specific regions on the maps. Additional information about Research Fronts.
Us interdisciplinary folks have something to learn from the hepatitisologists...


Elinor Ostrom on cities and sustainability

Elinor Ostrom passed away this week, and in doing so deprives the world of one its great political economists. To wit: this thought provoking op-ed, published post-humously, on the role of decentralized policy making in sustainability:
Much is riding on the United Nations Rio+20 summit. Many are billing it as Plan A for Planet Earth and want leaders bound to a single international agreement to protect our life-support system and prevent a global humanitarian crisis. 
Inaction in Rio would be disastrous, but a single international agreement would be a grave mistake. We cannot rely on singular global policies to solve the problem of managing our common resources: the oceans, atmosphere, forests, waterways, and rich diversity of life that combine to create the right conditions for life, including seven billion humans, to thrive.  
We have never had to deal with problems of the scale facing today’s globally interconnected society. No one knows for sure what will work, so it is important to build a system that can evolve and adapt rapidly. 
Decades of research demonstrate that a variety of overlapping policies at city, subnational, national, and international levels is more likely to succeed than are single, overarching binding agreements. Such an evolutionary approach to policy provides essential safety nets should one or more policies fail.
Emphasis is my own. The rest is worthwhile.


Another reason to love/hate elections

While reading about different reasons why climate might influence conflict, I ran into this interesting find from PNAS 2010:

Irrelevant events affect voters’ evaluations of government performance
Andrew J. Healy, Neil Malhotrab, and Cecilia Hyunjung Mo
Abstract: Does information irrelevant to government performance affect voting behavior? If so, how does this help us understand the mechanisms underlying voters’ retrospective assessments of candidates’ performance in office? To precisely test for the effects of irrel- evant information, we explore the electoral impact of local college football games just before an election, irrelevant events that government has nothing to do with and for which no government response would be expected. We find that a win in the 10 d before Election Day causes the incumbent to receive an additional 1.61 percentage points of the vote in Senate, gubernatorial, and presidential elections, with the effect being larger for teams with stronger fan support. In addition to conducting placebo tests based on postelection games, we demonstrate these effects by using the betting market’s estimate of a team’s probability of winning the game before it occurs to isolate the surprise component of game outcomes. We corroborate these aggregate-level results with a survey that we conducted during the 2009 NCAA men’s college basketball tournament, where we find that surprising wins and losses affect presidential approval. An experiment embedded within the survey also indicates that personal well-being may influence voting decisions on a subconscious level. We find that making people more aware of the reasons for their current state of mind reduces the effect that irrelevant events have on their opinions. These findings underscore the subtle power of irrelevant events in shaping important real-world decisions and suggest ways in which decision making can be improved.

Reminds me of this one on beliefs regarding global warming, and this one on whether to go to college.


Nature on Rio+20

Johannes points out that Nature is running a special issue on the environment in honor of Rio +20. Of special interest is the following by Barnosky et al.:
Approaching a state shift in Earth’s biosphere 
Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence. The plausibility of a planetary-scale ‘tipping point’ highlights the need to improve biological forecasting by detecting early warning signs of critical transitions on global as well as local scales, and by detecting feedbacks that promote such transitions. It is also necessary to address root causes of how humans are forcing biological changes.
There's a nice discussion article over at the NY Times' Green blog:
In interviews, scientists involved in writing the paper acknowledged that the 50 percent threshold was simply a best guess, based on extrapolating the earlier research. But they said they were deeply concerned about many of the trends on the planet and the seeming inability of the world’s political leadership to grapple with them. 
The situation “scares the hell out of me,” said one author of the paper, James H. Brown, who is a macroecologist at the University of New Mexico and a member of the National Academy of Sciences. “We’ve created this enormous bubble of population and economy. If you try to get the good data and do the arithmetic, it’s just unsustainable. It’s either got to be deflated gently, or it’s going to burst.”
These sorts of articles come out sufficiently frequently that I think we may need to call in some science historians to do a lit review of eschatology in ecology...


Climate Change and Sustainable Development: Key Contributions Since May 2011

[This is the last in a four-part series of guest posts by first year students in Columbia's Sustainable Development program]

Climate Change and Sustainable Development: Key Contributions Since May 2011
By: Meg Sutton, Matthias Pfaff, and Anthony Louis D'Agostino

This past March, the US registered the warmest average March temperature on record, while more than 15,000 warm temperature records were broken.  Far from an anomaly, global temperature records over the last two decades have been marching upward with "nine of the ten warmest years [occurring] in the 21st century."

Rising temperature trends, alongside other anticipated effects of climate change, will pose formidable challenges to development.  To be effective, policy responses require the most current and reliable science available.  Since this knowledge is continually evolving, we reviewed research published over the last year on the link between climate change and sustainable development, and have composed this summary of what we think will become key papers on this topic.  


Butting Heads: A Year’s Review of Research in the Context of the Global Energy Paradox

[This is the third in a four-part series of guest posts by first year students in Columbia's Sustainable Development program]

Butting Heads: A Year’s Review of Research in the Context of the Global Energy Paradox
By: Aaron Baum, Pablo Egaña and Erin McNally.

Today, the energy sector emits around two-thirds of global greenhouse gas emissions; yet, around one-quarter of the world's population has basic energy needs that are not being met and are rising.  There is a paradox in the pursuit of the dual goal to curb emissions by meeting demand via technology, which was impressively discerned by William S. Jevons more than a hundred years ago: technological progress that achieves higher levels of efficiency and decreased negative environmental effects tends to be accompanied by a decrease in the price of the resource, with a consequent increase in consumption rates.  Jevons’s paradox obliges us to scrutinize the view that the dual problem of rising emissions and demand can be simply resolved through the increased efficiency that technological progress yields.

In what direction is the research into viability – in terms of costs and feasibility – of carbon capture as well as generation and storage of sustainable energy headed?  In the following, we briefly explore answers to this question from selected investigations in leading scientific journals (Nature, Science and PNAS), focusing on the role that technology can play in sustainable development and the role of natural disasters in investment.


The Global Food System and Water Crisis: 10 Science Papers from the Past Year

[This is the second in a four-part series of guest posts by first year students in Columbia's Sustainable Development program]

The Global Food System and Water Crisis: 10 Science Papers from the Past Year

To get caught up on the latest research on the global food system and water crisis we did a survey of the must-read articles from the last twelve months.  The requirements to make our list were simple.  First, the article had to be from the Research Articles or Reports sections of Science or the Review, Articles, or Letters sections of Nature published between May 2011 and April 2012.  Then we picked the ones that we thought would have the most significant impact on humans, were the most immediate or critical concerns, or were the most unique solutions to the current crises faced.  And here they are…