The climate migrant is dead (and what we should do about it)

Samuel Huckstep , Reva Resstack and Helen Dempster at the CGD Blog ask, is there any point in defining a "climate migrant"? Their answer is that defining a climate migrant might not be worth the hassle. That's because it's difficult to determine whether it was climate that caused migration, or something else. They provide the example of:

Consider Joseph the farmer and his family. He could spend most of his money on irrigation, but instead chooses to send his daughter to school. When a drought decimates his crops, he decides to move to a city just across the border to generate income for his family and keep his daughter in school.

Is Joseph moving because of climate change, because of socioeconomic factors, or both?

It's a relevant question to ask. However, understanding the relationship between climate change and migration doesn't necessarily require us to discern the motives of migrants. Given data on climate, and data on migration flows, we can assess whether the two are related. That is essentially what I did in this 2017 article (ungated version here), which I discussed here.

Despite the definitional problems, lots of people (including policy makers and the media) talk about 'climate migrants' or 'climate refugees' (I've done it myself). That presents a problem. To see why, consider the argument in this 2019 article by Ingrid Boas (Wageningen University) and many (including some very high-profile) co-authors, published in the journal Nature Climate Change (ungated version here):

The UNFCCC explicitly specifies the need to avert, minimize and address climate displacement... while the UN Security Council warns of mass climate migration and the subsequent risk of aggravating conflicts... Although the potential for climate change to disrupt livelihoods and threaten lives is real, these policies reinforce a false narrative that predicts large numbers of ‘climate refugees’. This self-referencing narrative in scientific literature and policy reports has the consequence of entrenching climate migration as a looming security crisis without an empirical scientific basis...

Instead of being challenged, this emphasis on securitization (presenting climate change and migration as a security risk) is actively being perpetuated by public funding schemes for scientific research intended to inform national, regional or international policy development.

The willingness to accept a large estimate of 'climate refugees', without any critical thought whatsoever, was one thing I noticed about climate change researchers, media, and policy makers alike. This was particularly a surprise for me, since I expected the researchers to be a little more evidence-based (and the evidence base for a claim of up to one billion climate migrants by 2050 is pretty shaky, and was more so when I was working in this area [1]).

Boas et al. have a solution though. They recommend six research priorities, to help us to better understand the climate-migration relationship:

First, research and research funding must enable the assumption that climate change causes mass human migration to be interrogated, rather than simply reinforcing it. There is already considerable evidence that migration is not solely driven by climate change. It is instead influenced by a mix of climatic, socio-economic, cultural and political factors... Even when climate change does play a role, it remains difficult to determine the extent of its influence...

Second, the term migration does not capture the diverse ways in which people do or do not become mobile in response to a changing climate; the term should therefore be avoided. Some people may temporarily (or even seasonally) move, while others may permanently relocate to nearby urban centres... Regardless, mobility commonly involves relatively short distances, meaning that people typically move within their country or region...

Third, new research supported by scientific funding programmes should examine and address climate mobilities as the new normal, rather than the exception...

Fourth, it is crucial to fund and engage in research that goes beyond attempts to quantify and model new mobility resulting from climate change...

Fifth, research needs to better include affected populations in climate mobilities research...

Finally, research on climate mobilities needs to shift part of its focus from climate-sensitive sending areas to destination areas.

Some of those priorities (for example, #2 and #4), seem a bit self-serving (at least they didn't recommend radically increasing funding for migration research, or that would be a dead giveaway). However, the general point is clear. The way that research on climate and migration is being interpreted and used is not right, and needs to be addressed.

That suggests to me that there is a seventh priority that Boas et al. missed - that researchers should be funded (and expected) to better engage with media and policy makers on what any climate-migration relationship actually means in practice. Science communication is one thing that the climate researchers have learned to do really well, and which the rest of the research community could stand to do a bit better. It might not be worth it to define a 'climate migrant', but communicating why is definitely worth the hassle.

Read more:

• Climate change won't much affect internal migration in NZ
• Climate change and migration in poor and middle-income countries
• Why Tuvaluans aren't migrating due to climate change, yet
• Climate and internal migration in Kiribati, and what that might tell us about climate refugee flows

*****

[1] I haven't read in detail the methods underlying the World Bank's Groundswell Report, which projects 216 million 'climate migrants' by 2050. However, I would be very surprised if it held up to close scrutiny.

News coverage and mass shootings in the US

Does widespread media coverage of mass shootings increase the likelihood of future mass shootings? It seems intuitive that the answer could be 'yes'. Perhaps media coverage encourages 'copycat' behaviour. Perhaps, the prospect of fame motivates mass shooters, and regular media coverage provides the avenue to fame (or, rather, infamy). Maybe media coverage simply makes mass shootings seem 'more normal', as a response to some slight. Teasing out which of these explanations is correct is difficult, especially when you consider that the direction of causality isn't even established. Does media coverage lead to more mass shootings (as the theories outlined above suggest), or do more mass shootings simply lead to more media coverage?

Those are the questions that this recent article by Michael Jetter (University of Western Australia) and Jay Walker (Old Dominion University), published in the journal European Economic Review (sorry, I don't see an ungated version online), set out to address. Jetter and Walker obtain data on mass shootings (four or more victims) for the period from 2006 to 2017, from USA Today's Behind the Bloodshed database. To understand the extent of the problem, they highlight that:

...265 (or six percent) of the 4383 sample days from 2006 to 2017 experienced at least one mass shooting, whereas nine days saw two mass shootings.

Jetter and Walker then collect data on television news from the Vanderbilt Television News Archive. They count the number of news segments from ABC World News Tonight (the highest-ranked evening news programme in the US) that contain the terms 'shoot' (including 'shooter' and 'shooting'). They then filter out false positives manually (such as news items about the shooting of a movie). They find 490 news segments on shootings over the 2006 to 2017 period.

Their analysis relies on an instrumental variables (IV) approach, to avoid the reverse causality problem and obtain the causal effect of news on shootings. To achieve this, they need to identify an instrument that affects the amount of news on shootings, but doesn't directly affect the number of shootings. They suggest disasters in other countries, where large numbers of US expatriates live. Jetter and Walker collect data on disasters from the International Disaster Database, limiting the data to countries with at least 50,000 US emigrants. They note that:

In total, we capture 158 such disasters (132 earthquakes, 10 epidemics, and 16 events of volcanic activity) that span 950 days out of our 4383 sample days.

It turns out that disasters are a good predictor of shooting news (because more disaster news leaves less room in the news broadcast for shooting news). In their IV analysis, Jetter and Walker find that shooting news is:

...a positive, statistically significant, and quantitatively powerful predictor of mass shootings. The corresponding magnitude indicates a one standard deviation increase in shooting news (0.389) translates to an increase in the number of shootings by approximately 73% of a standard deviation.

Now, looking over the time after shooting news, they find that:

The derived coefficients decrease in magnitude and eventually turn statistically indistinguishable from zero after 3-4 weeks.

So, news coverage of shootings causes an increase in mass shootings, and the effect lasts for up to 3-4 weeks. The next question is, why? Jetter and Walker look further into the data, and find no causal relationship from news coverage to murder more generally. That rules out salience, or that shootings are seen as 'more normal' after news coverage of shootings. They find that the mass shootings are more likely to happen on or after the anniversary of other infamous mass shootings, which suggests a behavioural contagion (or 'copycat') effect. Finally, they find that mass shootings are no less likely to happen on days where there would be predictably less change of news coverage (such as the dates of the Super Bowl, Olympics, Academy Awards). That would seem to rule out fame as a significant motivator, since a mass shooter who wants to be famous would probably want to avoid those dates, and yet they don't. So, Jetter and Walker conclude that:

Taken together, the results... are consistent with a behavioral contagion model...

Mass shooters are copycats. And then, in terms of policy implications:

First, our results advise journalists to report less on mass shootings... Second, our results also explain (at least in part) why shootings sometimes cluster in short intervals... Thus, police and other security forces may be well advised to be alert on and after days of heightened media coverage of mass shootings.

In the Waikato Economics Discussion Group a couple of weeks ago, we discussed this paper. We decided you couldn't really replicate this analysis for New Zealand, as (thankfully) mass shootings are very rare. However, one student made mention of ram raids, which have attracted massive attention in the media, this year in particular (for example, see here). Is media coverage of ram raids driving up the number of ram raids in New Zealand? The arguments are very similar to those in the Jetter and Walker article. Whether ram raids are driven by media coverage is an interesting question, and one that may be well worth following up on in an Honours or Masters research project.

Book review: How To (Randall Munroe)

Yesterday, I gave a brief review of Randall Munroe's book What If?. To recap, Munroe is the person responsible for bringing us the online comic XKCD, and the book was at least as funny as anything you can find at XKCD, and a useful diversion from the books I typically read and review. That would be a good way to also describe Munroe's more recent (2019) book How To. The subtitle captures the flavour of the book: "Absurd scientific advice for common real-world problems".

What sort of real-world problems? Some of the highlights include: how to dig a hole; how to mail a package, and how to charge your phone. Don't be fooled by the mundane nature of the questions. When a discussion of digging a hole to find buried treasure quickly diverges into open pit mining, you know that you're reading a book along similar lines to What If?.

My personal favourite section was, how to build a lava moat. Whether you're trying to keep out burglars, ants, or pesky neighbours, or simply want a epically glowing red-hot property line, a lava moat may be for you. Of course, there are plenty of real-world challenges to having a moat filled with lava surrounding your house, so this book will become your go-to reference guide.

Munroe also tells us about the US government's war on beer. It's not what you think - the government carefully placed bottles of beer at various angles and distances from a nuclear test, to see whether the beer would be drinkable afterwards (I guess it's useful to know if you can still get drunk after a nuclear apocalypse?).

Like his other book, Munroe does make quite a bit of use of science (it is his background, after all). One quote really sums up his approach: "I really love that we can ask physics ridiculous questions like, "What kind of gas mileage would my house get on the highway?" and physics has to answer us. That pretty much summed up my approach to physics too, as I discussed yesterday.

So, this is another book that I highly recommend. Read it back-to-back with What If? for a double-dose of enjoyment. Or add in Munroe's forthcoming book What If? 2, due for release later this month, for a triple-dose!

Book review: What If? (Randall Munroe)

I didn't study economics at high school. I studied the sciences instead, and physics was my favourite among them (in fact, my first stint as a university undergraduate was as a physics major). In physics class, it was easy to get sidetracked thinking of weird and wacky ways to use the formulas we were learning. The hero of these mathematical adventures was 'Frictionless Scott', a fictitious character unaffected by friction, but seemingly able to withstand severe punishment. We once calculated how far Frictionless Scott would move the moon out of its current orbit if he struck it while moving at 10 percent of the speed of light. We also calculated how far Frictionless Scott could hit a golf ball, with his head, while tethered to a one-kilometre-long rope (also frictionless, of course) being spun around on the end of a rotating helicopter rotor. We then calculated how far he could hit a bulldozer under the same conditions. Frictionless Scott took a real beating in my physics class.

Those sorts of absurd questions kept my friends and I entertained in class (and, oftentimes, outside of class). So, I was excited to read Randall Munroe's 2014 book, What If?, which Tim Harford has recommended a few times on his blog. What If provides "serious scientific answers to absurd hypothetical questions", which is pretty much what my friends and I were doing in physics. Some of the questions that Munroe addresses in the book include, "What would happen if you tried to hit a baseball pitched at 90 percent of the speed of light" (a firestorm would engulf the entire city), "Is it possible to build a jetpack using downward-firing machine guns" (surprisingly, yes it is), and "If a bullet with the density of a neutron star were fired from a handgun (ignoring the how) at the Earth's surface, would the Earth be destroyed?" (no, but there would be some weird gravitational effects).

Munroe is the author of the wildly popular online comic XKCD, which I have also been a fan of for a number of years (and which my students may recognise, because I sometimes use those comics in my lecture slides, and there is always at least one XKCD comic posted to my office door (along with sometimes Saturday Morning Breakfast Cereal, or PhD Comics). The humour is the same, albeit in slightly longer form, and illustrated with the same endearing stick-figures.

There's even a little bit of economics in the book, explaining why aliens would be unlikely to be able to detect our radio transmissions (in short, it is expensive to beam signals into space, and advertisers have figured out that it is more effective to concentrate on beaming those signals to potential consumers on Earth).

I really enjoyed this book. Not all of the questions were equally funny - those towards the beginning of the book tended to be better than those towards the end. However, the difference in my reactions was between a mild chuckle and a loud guffaw. If you're looking for a book to break up the monotony of teaching (or learning, or working) online and in-person, then I highly recommend this one. And more to come - I've been reading Munroe's more recent book How To, and I see that there is a sequel, What If? 2, due for release this month!