Connected oceans

Dividing an elephant in half does not make two small elephants. It makes one mess.

The same is true of our oceans. Modern management of the natural environment is all about dividing up elephants, assigning the halves to different owners, and blinding ourselves to the activities beyond our halves. But just as with elephants, pieces of an ocean depend on each other: fish and currents do not respect national boundaries.

That is the starting point of a new paper Nandini Ramesh, Kimberly Oremus, and I recently published in Science, entitled “The small world of global marine fisheries: The cross-boundary consequences of larval dispersal“. We wanted to understand how national fisheries depended upon each other.

To study this, we used the same model used to study how debris from the Malaysia Airlines Flight 370 crash ended up halfway around the world:

Instead of looking at airplane debris, we looked at fish spawn. Most marine species spend a stage of their lives as plankton, either in the form of floating eggs or microscopic larvae. They can travel huge distances as they float with the currents, sometimes over the course of several months. We can use those journeys to identify the original spawning grounds of the adult fish that are eventually caught.

These connections are important, because they mean that your national fisheries depend upon neighboring countries. Spawning regions are highly sensitive, and if your national neighbors fail to protect them, the fish in your country can disappear. A country like the UK depends upon plenty of other countries for its many species.

Finally, this is not just an issue for the fishing sector. We also looked at food security and jobs. People around the world depend on the careful environmental management of their neighbors, and it is time we recognized this elephant as a whole.

Connected oceans

Dividing an elephant in half does not make two small elephants. It makes one mess.

The same is true of our oceans. Modern management of the natural environment is all about dividing up elephants, assigning the halves to different owners, and blinding ourselves to the activities beyond our halves. But just as with elephants, pieces of an ocean depend on each other: fish and currents do not respect national boundaries.

That is the starting point of a new paper Nandini Ramesh, Kimberly Oremus, and I recently published in Science, entitled “The small world of global marine fisheries: The cross-boundary consequences of larval dispersal“. We wanted to understand how national fisheries depended upon each other.

To study this, we used the same model used to study how debris from the Malaysia Airlines Flight 370 crash ended up halfway around the world:

Instead of looking at airplane debris, we looked at fish spawn. Most marine species spend a stage of their lives as plankton, either in the form of floating eggs or microscopic larvae. They can travel huge distances as they float with the currents, sometimes over the course of several months. We can use those journeys to identify the original spawning grounds of the adult fish that are eventually caught.

These connections are important, because they mean that your national fisheries depend upon neighboring countries. Spawning regions are highly sensitive, and if your national neighbors fail to protect them, the fish in your country can disappear. A country like the UK depends upon plenty of other countries for its many species.

Finally, this is not just an issue for the fishing sector. We also looked at food security and jobs. People around the world depend on the careful environmental management of their neighbors, and it is time we recognized this elephant as a whole.

Connected oceans

Dividing an elephant in half does not make two small elephants. It makes one mess.

The same is true of our oceans. Modern management of the natural environment is all about dividing up elephants, assigning the halves to different owners, and blinding ourselves to the activities beyond our halves. But just as with elephants, pieces of an ocean depend on each other: fish and currents do not respect national boundaries.

That is the starting point of a new paper Nandini Ramesh, Kimberly Oremus, and I recently published in Science, entitled “The small world of global marine fisheries: The cross-boundary consequences of larval dispersal“. We wanted to understand how national fisheries depended upon each other.

To study this, we used the same model used to study how debris from the Malaysia Airlines Flight 370 crash ended up halfway around the world:

Instead of looking at airplane debris, we looked at fish spawn. Most marine species spend a stage of their lives as plankton, either in the form of floating eggs or microscopic larvae. They can travel huge distances as they float with the currents, sometimes over the course of several months. We can use those journeys to identify the original spawning grounds of the adult fish that are eventually caught.

These connections are important, because they mean that your national fisheries depend upon neighboring countries. Spawning regions are highly sensitive, and if your national neighbors fail to protect them, the fish in your country can disappear. A country like the UK depends upon plenty of other countries for its many species.

Finally, this is not just an issue for the fishing sector. We also looked at food security and jobs. People around the world depend on the careful environmental management of their neighbors, and it is time we recognized this elephant as a whole.

An unstoppable force

Shortly after I joined LSE, Stéphane Hallegatte from the World Bank gave a presentation on their new report, “Unbreakable”. The report is about how to measure risk in the face of the potential to fall into poverty, and includes one of my favorite graphs of the last year:

Unbreakable figure
From “Unbreakable”: Estimated people driven into poverty annually by natural disasters.

I think it’s an amazing bit of modeling to be able to relate natural events to the excruciatingly chaotic process we call “falling into poverty”. But it’s the scale of the two sides of the graph that blows me away. On the left, earthquakes, storm surge, tsunamis, and windstorms all together account for about 1 million people falling into poverty every year. On the right, floods account for 10x as many, and droughts account for an additional 8x as many.

The reason is that floods and droughts are naturally huge events– covering large areas and affecting millions of people– every time they occur. The second is that they occur all the time.

This gets at the importance of water. Most of the researchers I know don’t spend much time thinking about water. They know it’s important, but in a way that’s so commonplace as to be invisible. We just said that 18 million people fall into poverty each year from floods and droughts; in 2015 there were 736 million people in poverty total. That means that if we magically got everyone out of poverty today, in 41 years, there would have already been 736 million new instances of poverty from floods and drought alone. Water is about enough to explain the stubbornness of extreme poverty all on its own.

A gallery in real life

“Elstir’s studio seemed like the laboratory out of which would come a kind of new creation of the world: from the chaos made of all things we see, he had abstracted, by painting them on various rectangles of canvas now standing about on all sides, glimpses of things, like a wave in the sea crashing its angry lilac shaded foam down on the sand, or a young man in white twill leaning on a ship’s rail. The young man’s jacket and the splash of the wave had taken on a new dignity, in virtue of the fact that they continued to exist, though now deprived of what they were believed to consist in, the wave being now unable to wet anyone, and the jacket unable to be worn.”

In the Shadow of Young Girls in Flower, Proust

I like to think I make art, sometimes, but all of my work exists only in this virtual Neverland. My works can be seen, but only through a glorified microfiche scanner, and if you choose to look to the right tiny speck. I wish I had a studio like Elstir’s where people could wander, with real hands tilting back real physical picture frames.

There’s a magic in printing things out, like a spell that reincarnates from the spirit-like 1s and 0s. Flame and I have over a dozen hand-picked photo albums from our various trips, ready should anyone care to open some memories. I want similar momentos for my projects. I thought for a while of building a converter that could represent the structures of code and data as intricate art. But no converter would see the beauty that I see in my own work.

So, I’m thinking of just printing and binding my papers (completed, whether published or not). I’m not above making them into mugs instead, or making blown-up figures etched in canvas. But the first step is to leave them leaning one on the other, and see if anyone takes a peak.

Paper Fish

I have fish! Two lovely creatures, my current obsession. I have not had an aquarium since I was 14 (when, at my height, I had tanks’ worth), but my new tank is at the center of our London flat.

Flame knows that I love animals, but her allergy to cats has killed any pet plans until recently. She finally consented to one fish per paper I publish. Since I’ve only published two papers since coming to London, I get two fish. Let me introduce them:

Paige is a Pearl Gourami. You can see her center stage, above. She’s a bit of an attention hog, but she’s beautiful and knows it. I got her for a paper on a model I helped build, named Mimi-PAGE, so it’s no surprise that she’s a model.

Robbie is a Red-tailed Black Shark (not an actual shark sadly). He’s quite shy, and you can just see his tail behind Paige. He inches along the gravel, propelled by his flaming tail, and I got him for a paper on transportation in Nairobi.

As I get more fish, I fully expected to be in a constant publication race against their perishing, but I didn’t do my research. Given the opportunity, Paige is going to grow 5 inches long and 5 years old, and Robbie is going to get 6 inches long after 9 years. And by the time Robbie comes of age, his instinct for territory is likely to be the terror of any other paper I try to publish.

23andme, Part I

Flame got me a 23andme genetic testing kit (report? procedure?) for Christmas! I’m excited to get some cliffnotes to my user manual, but I was surprised at how daunted I would feel. Preparing my saliva sample felt fatalistic, like each spit was nailing closed the possible; though, I suppose it was just a knock on the door to the actual.

I’m afraid of what I’m going to see. I got the genetic health option, and one of the items on the list is Parkinson’s, with which I watched my grandfather slowly die. That alone tells me that I have a chance that I’m predisposed– do I want to know that it’s definitely waiting in my future? I want to want to know.

On a happier note, I get to find out my paternal haplogroup. From an uncle’s genetic test, I know that my mother’s side comes from the lost land of Doggerland. And I think that my Y-chromosome comes from the east coast of England, but the story is so murky against 300 years of being American that I’m really curious what I’ll find.

Part II when I learn more!

Improving IAMs: From problems to priorities

I wrote this up over the holidays, to feed into some discussions about the failings of integrated assessment models (IAMs). IAMs have long been the point at which climate science (in a simplistic form), economics (in a fanciful form), and policy (beyond what they deserve) meet. I’m a big believer in the potential of models to bring those three together, and the hard work of improving them will be a big part of my career (see also my EAERE newsletter piece). The point of this document is to highlight some progress that’s being made, and the next steps that are needed. Thanks to D. Anthoff and F. Moore for many of the citations.


Integrated assessment models fail to accurately represent the full risks of climate change. This document outlines the challenges (section 1), recent research and progress (section 2), and priorities to develop the next generation of IAMs.

1. Problems with the IAMs and existing challenges

The problems with IAMs have been extensively discussed elsewhere (Stern 2013, Pindyck 2017). The purpose here is to highlight those challenges that are responsive to changes in near-term research priorities. I think there are three categories: scientific deficiencies, tipping points and feedbacks, and disciplinary mismatches. The calibrations of the IAMs are often decades out of date (Rising 2018) and represent empirical methods which are no longer credible (e.g. Huber et al. 2017). The IAMs also miss the potential and consequences of catastrophic feedback in both the climate and social systems, and the corresponding long-tails of risk. Difficulties in communication between natural scientists, economists, and modelers have stalled the scientific process (see previous document, Juan-Carlos et al. WP).

2. Recent work to improve IAMs

Progress is being made on each of these three fronts. A new set of scientific standards represents the environmental economic consensus (Hsiang et al. 2017). The gap between empirical economics and IAMs has been bridged by, e.g., the works of the Climate Impact Lab, through empirically-estimated damage functions, with work on impacts on mortality, energy demand, agricultural production, labour productivity, and inter-group conflict (CIL 2018). Empirical estimates of the costs and potential of adaptation have also been developed (Carleton et al. 2018). Updated results have been integrated into IAMs for economic growth (Moore & Diaz 2015), agricultural productivity (Moore et al. 2017), and mortality (Vasquez WP), resulting in large SCC changes.

The natural science work on tipping points suggest some stylized results: multiple tipping points are already at risk of being triggered, and tipping points are interdependent, but known feedbacks are weak and may take centuries to unfold (O’Neill et al. 2017, Steffen et al. 2018, Kopp et al. 2016). Within IAMs, treatment of tipping points has been at the DICE-theory interface (Lemoine and Traeger 2016, Cai et al. 2016), and feedbacks through higher climate sensitivities (Ceronsky et al. 2005, Nordhaus 2018). Separately, there are feedbacks and tipping points in the economic systems, but only some of these have been studied: capital formation feedbacks (Houser et al. 2015), growth rate effects (Burke et al. 2015), and conflict feedbacks (Rising WP).

Interdisciplinary groups remain rare. The US National Academy of Sciences has produced suggestions on needed improvements, as part of the Social Cost of Carbon estimation process (NAS 2016). Resources For the Future is engaged in a multi-pronged project to implement these changes. This work is partly built upon the recent open-sourcing of RICE, PAGE, and FUND under a common modeling framework (Moore et al. 2018). The Climate Impact Lab is pioneering better connections between climate science and empirical economics. The ISIMIP process has improved standards for models, mainly in process models at the social-environment interface.

Since the development of the original IAMs, a wide variety of sector-specific impact, adaptation, and mitigation models have been developed (see ISIMIP), alternative IAMs (WITCH, REMIND, MERGE, GCAM, GIAM, ICAM), as well as integrated earth system models (MIT IGSM, IMAGE). The latter often include no mitigation, but mitigation is an area that I am not highlighting in this document, because of the longer research agenda needed. The IAM Consortium and Snowmass conferences are important points of contact across these models.

3. Priorities for new developments

Of the three challenges, I think that significant progress in improving the science within IAMs is occurring and the path forward is clear. The need to incorporate tipping points into IAMs is being undermined by (1) a lack of clear science, (2) difficulties in bridging the climate-economic-model cultures, and (3) methods of understanding long-term long-tail risks. Of these, (1) is being actively worked on the climate side, but clarity is not expected soon; economic tipping points need much more work. A process for (2) will require the repeated, collaboration-focused covening of researchers engaged in all aspects of the problem (see Bob Ward’s proposal). Concerning (3), the focus on cost-benefit analysis may poorly represent the relevant ethical choices, even under an accurate representation of tipping points, due to their long time horizon (under Ramsey discounting), and low probabilities. Alternatives are available (e.g., Watkiss & Downing 2008), but common norms are needed.

References:

Burke, M., Hsiang, S. M., & Miguel, E. (2015). Global non-linear effect of temperature on economic production. Nature, 527(7577), 235.
Cai, Y., Lenton, T. M., & Lontzek, T. S. (2016). Risk of multiple interacting tipping points should encourage rapid CO 2 emission reduction. Nature Climate Change, 6(5), 520.
Ceronsky, M., Anthoff, D., Hepburn, C., & Tol, R. S. (2005). Checking the price tag on catastrophe: the social cost of carbon under non-linear climate response. Climatic Change.
CIL (2018). Climate Impact Lab website: Our approach. Accessible at http://bit.ly/2SKT8XB.
Houser, T., Hsiang, S., Kopp, R., & Larsen, K. (2015). Economic risks of climate change: an American prospectus. Columbia University Press.
Huber, V., Ibarreta, D., & Frieler, K. (2017). Cold-and heat-related mortality: a cautionary note on current damage functions with net benefits from climate change. Climatic change, 142(3-4), 407-418.
Kopp, R. E., Shwom, R. L., Wagner, G., & Yuan, J. (2016). Tipping elements and climate–economic shocks: Pathways toward integrated assessment. Earth’s Future, 4(8), 346-372.
Lemoine, D., & Traeger, C. P. (2016). Economics of tipping the climate dominoes. Nature Climate Change, 6(5), 514.
Moore, F. C., & Diaz, D. B. (2015). Temperature impacts on economic growth warrant stringent mitigation policy. Nature Climate Change, 5(2), 127.
Moore, F. C., Baldos, U., Hertel, T., & Diaz, D. (2017). New science of climate change impacts on agriculture implies higher social cost of carbon. Nature Communications, 8(1), 1607.
NAS (2016). Assessing Approaches to Updating the Social Cost of Carbon. Accessible at http://bit.ly/1nY5dZX
Nordhaus, W. D. (2018). Global Melting? The Economics of Disintegration of the Greenland Ice Sheet (No. w24640). National Bureau of Economic Research.
O’Neill, B. C., Oppenheimer, M., Warren, R., Hallegatte, S., Kopp, R. E., Pörtner, H. O., … & Mach, K. J. (2017). IPCC reasons for concern regarding climate change risks. Nature Climate Change, 7(1), 28.
Pindyck, R. S. (2017). The use and misuse of models for climate policy. Review of Environmental Economics and Policy, 11(1), 100-114.
Rising, J. (2018). The Future Of The Cost Of Climate Change. EAERE Newsletter. Accessible at http://bit.ly/2SLnQ2F
Steffen, W., Rockström, J., Richardson, K., Lenton, T. M., Folke, C., Liverman, D., … & Donges, J. F. (2018). Trajectories of the Earth System in the Anthropocene. Proceedings of the National Academy of Sciences, 115(33), 8252-8259.
Stern, N. (2013). The structure of economic modeling of the potential impacts of climate change: grafting gross underestimation of risk onto already narrow science models. Journal of Economic Literature, 51(3), 838-59.
Vasquez, V. (WP). Uncertainty in Climate Impact Modelling: An Empirical Exploration of the Mortality Damage Function and Value of Statistical Life in FUND. Masters Dissertation.
Watkiss, P., & Downing, T. (2008). The social cost of carbon: Valuation estimates and their use in UK policy. Integrated Assessment, 8(1).

The power of informal transit

The Journal of Transport Geography just published a study that I worked on with Kayleigh Campbell, Jacqueline Klopp, and Jacinta Mwikali Mbilo. The question address is “How important is informal transit in the developing world?” (Jump to the paper.)

What’s informal transit?

A lot of people get around Nairobi in works of art on wheels called “matatus”:

The matatu system is extensive, essential, efficient, and completely unplanned. In Nairobi’s hurry to accommodate the transport needs of a population that grows by 150,000 people a year, it has ignored this piece of infrastructure. Sometimes it has even undermined it.

The goal of this paper is to measure how important matatus are, in the context of the whole range of transportation options and income groups.

What does this paper bring to the table?

This is one of very few analyses on informal transportation networks anywhere, building upon the incredible work of the Digital Matatus Project, co-led by our co-author, Dr. Klopp.

It’s also fairly unique in looking at transport accessibility in the developing world at all (most work on accessibility is done in rich countries). Not surprisingly, transport needs in developing countries are different.

What do we find?

Some of the results are unsurprising: matatus boost measures of access by 5-15 times, compared to walking, with accessibility highest in the central business district. Of somewhat more interest:

  • Matatu access drops more quickly then driving or walking accessibility as you move away from Nairobi’s center. That’s an indication of the structure of the matatu network, helping people in Nairobi center the most.
  • Controlling for distance from the center, richer communities have low accessibility. Many people from those communities have cars, but it matters because their workers do not. In fact this communities tend to be quite isolated.
  • Tenement housing has quite strong accessibility, because matatu networks tend to organize around it.

What tools do we have for research in this area?

We developed quite an extensive body of tools for studying (1) accessibility in general, and (2) transit networks in particular. If you find yourself in the possession of a cool new transit network database, in “GTFS” format, we have code that can analyze it. Prompt me, and I can work with you to open-source it.

Enjoy the new paper! Accessibility across transport modes and residential developments in Nairobi

Made some “Rampaunt Perre” from the Pleyn Delit medieval cookbook: “Peoren ysoden (pears boiled) in water, [with] þree lyouns raumpauns [three heraldically rearing lions].” (But as beavers, naturally #mitgaard4life) #currentmiddleages #subtlety #moleculargastronomyathome

Sustainability, Engineering, and Philosophy