Category Archives: Peer Reviewed Article Review

bad news on pollution

The Lancet Commission on Pollution and Health has released a “landmark study” on health and economic effects of pollution worldwide. You can read it after going through a free but somewhat annoying registration process. There is also a pretty good summary in this Guardian article.

I find the results disturbing. Among them are that pollution causes an estimated 9 million premature deaths worldwide each year, with over 90% in low-income and middle-income countries. The Guardian article has a good Infographic showing that this is significantly more than deaths caused by other major causes like smoking, AIDS, and road deaths. (Although, you could think of smoking as a form of intentional pollution, and I believe tobacco countries are still up to their old immoral marketing tricks in developing countries. I also see a link between pollution and road deaths, with land use patterns and lifestyles centered around motor vehicles being the root cause of both, again with immoral practices by the auto, fossil fuel, and construction industries playing a role.) Other statistics are that pollution reduces GDP in low- and middle-income countries by 2% per year and global economic output by around 6% per year. (I don’t quite get how those last two statistics go together – even though the health impacts are primarily in lower-income countries, that somehow affects the economies of higher-income countries disproportionately? I guess maybe because people in higher-income countries spend money on medical care to partially offset the effects of pollution, while people in the poorer countries just die? But don’t we add medical spending to GDP, even though we should consider some of it a cost to society rather than a benefit?) One implication here is that the idea of accepting pollution for a period of time while your country develops may not be a very good strategy, even thinking in hard-nosed economic terms and neglecting the moral dimensions of allowing your people to suffer in exchange for the supposed longer-term gain.

They make a few more links I find interesting (not in a fun way). One is that we don’t really know how much of health care spending is offsetting the effects of pollution, because there is a lot we don’t know about links between pollution and health. And this is not just heart attacks, cancer, and asthma we are talking about, there are disturbing concerns about impacts on the fertility and intelligence of our species from both the small number of everyday chemicals we have good information on and the enormous and growing number we don’t. Finally, there are the somewhat obvious links between fossil fuel pollution and climate change.

Here is where I should probably draw some link to the Trump administration’s immoral policies to actually increase pollution. But it’s so obvious I’m not sure it even needs to be said. He is clearly one of the evil lizard people who eats babies and puppies and is trying to kill us all off as quickly as possible.

disappearing bugs

This surprising study from Germany raises the possibility that a catastrophic loss of insects is occurring and that it could lead to ecological collapse.

More than 75 percent decline over 27 years in total flying insect biomass in protected areas

Global declines in insects have sparked wide interest among scientists, politicians, and the general public. Loss of insect diversity and abundance is expected to provoke cascading effects on food webs and to jeopardize ecosystem services. Our understanding of the extent and underlying causes of this decline is based on the abundance of single species or taxonomic groups only, rather than changes in insect biomass which is more relevant for ecological functioning. Here, we used a standardized protocol to measure total insect biomass using Malaise traps, deployed over 27 years in 63 nature protection areas in Germany (96 unique location-year combinations) to infer on the status and trend of local entomofauna. Our analysis estimates a seasonal decline of 76%, and mid-summer decline of 82% in flying insect biomass over the 27 years of study. We show that this decline is apparent regardless of habitat type, while changes in weather, land use, and habitat characteristics cannot explain this overall decline. This yet unrecognized loss of insect biomass must be taken into account in evaluating declines in abundance of species depending on insects as a food source, and ecosystem functioning in the European landscape.

I knew about the frogs, elephants, tigers, bees, and loss of larger animal species and biomass in general, but I hadn’t really heard this idea that insects are disappearing. I can see a silver lining to this – I can’t really create elephant or tiger habitat around my house, and frog habitat is a little tough, but insects – I can actually help the little guys. On a larger scale, there is the question of green infrastructure – can we deliberately design habitats in cities, larger reserves, and corridors connecting them to support as much ecological function as we can? I think so, but I don’t think our public officials, engineers, urban planners, scientists, and others in a position to do this are tuned into the issue or even very open to hearing about it.

trees and public health

A new report from the Nature Conservancy makes the case for the value of urban trees to human health. They go through a number of economic valuation studies that are out there, and the literature on health benefits: air quality, heat stress, mental and physical health, climate change. Then they make a case that urban tree canopy in the U.S. is actually declining and that it is severely under-funded in most cities.

Also, on the tree front, here is a recent paper on the rate at which wood inside urban trees decays. I think one important concept with urban trees is to think of them as infrastructure that has to be maintained and replaced at some rate. They just don’t live as long as forest trees, because they are in stressful environments, performing functions for us, and getting worn out. And the cost of maintaining and replacing them is actually low, and their benefits high, compared to other types of infrastructure. But even though the engineering, planning and architecture professions have been talking a lot about green infrastructure for at least a decade, most of us still aren’t taking it seriously as infrastructure, and the construction industry, bureaucrats and politicians are not taking it seriously, if they have even absorbed the concepts at all. I think this is a case where wealthy private foundations or individuals could make an enormous difference if they wanted to, because the institutions to plant and maintain trees typically exist, but are just severely underfunded. So all I have to do is become a wealthy private individual and I will take care of this. Okay, a solution exists and I’ll get right on that.

The overlooked carbon loss due to decayed wood in urban trees

Decayed wood is a common issue in urban trees that deteriorates tree vitality over time, yet its effect on biomass yield therefore stored carbon has been overlooked. We mapped the occurrence and calculated the extent of decayed wood in standing Ulmus procera, Platanus × acerifolia and Corymbia maculata trees. The main stem of 43 trees was measured every metre from the ground to the top by two skilled arborists. All trees were micro-drilled in two to four axes at three points along the stem (0.3 m, 1.3 m, 2.3 m), and at the tree’s live crown. A total of 300 drilling profiles were assessed for decay. Simple linear regression analysis tested the correlation of decayed wood (cm2) against a vitality index and stem DBH. Decay was more frequent and extensive in U. procera, than P. acerifolia and least in C. maculata. Decay was found to be distributed in three different ways in the three different genera. For U. procera, decay did appear to be distributed as a column from the base to the live crown; whereas, decay was distributed as a cone-shape in P. acerifolia and was less likely to be located beyond 2.3 m. In C. maculata decay was distributed as pockets of variable shape and size. The vitality index showed a weak but not significant correlation with the proportion of decayed wood for P. acerifolia and C. maculata but not for U. procera. However, in U. procera, a strong and significant relationship was found between DBH and stem volume loss (R2 = 0.8006, P = 0.0046, n = 15). The actual volume loss ranged from 0.17-0.75 m3, equivalent to 5% to 25% of the stem volume. The carbon loss due to decayed wood for all species ranged between 69 to 110 kg per tree. Based on model’s calculation, the stem volume of U. procera trees with DBH ≥ 40 cm needs to be discounted by a factor of 13% due to decayed wood regardless of the vitality index. Decayed wood reduces significantly the tree’s standing volume and needs to be considered to better assess the carbon storage potential of urban forests.

what’s going on with supersonic travel

Wired has an article on the status of new supersonic travel projects.

Boom Technology, based in Denver, Colorado, is building a jet that could fly around 50 people at Mach 2.2, or 1,452 mph, more than twice the speed of sound. Nevada’s Aerion Corporation is making a pointy-nosed business jet, good for Mach 1.5. Both want to make their first deliveries by 2023.

NASA and Lockheed Martin are working on a Low Boom Flight Demonstrator to show that the thundering sound that shadowed the Concorde—and prevented flights over land—can be minimized. That plane may one day get an X designation, labeling it as the latest in a long line of experimental aircraft. It’s a fitting callback to the very first X plane.

evaporation energy

There is a lot of energy in evaporation, and there are technologies that theoretically could harvest it for human use.

About 50% of the solar energy absorbed at the Earth’s surface drives evaporation, fueling the water cycle that affects various renewable energy resources, such as wind and hydropower. Recent advances demonstrate our nascent ability to convert evaporation energy into work, yet there is little understanding about the potential of this resource. Here we study the energy available from natural evaporation to predict the potential of this ubiquitous resource. We find that natural evaporation from open water surfaces could provide power densities comparable to current wind and solar technologies while cutting evaporative water losses by nearly half. We estimate up to 325 GW of power is potentially available in the United States. Strikingly, water’s large heat capacity is sufficient to control power output by storing excess energy when demand is low, thus reducing intermittency and improving reliability. Our findings motivate the improvement of materials and devices that convert energy from evaporation.

This is interesting. Cutting evaporation losses in half could be a good thing in some situations, like reservoirs and swimming pools in arid regions. Cut too much evaporation elsewhere, and you could imagine a science fiction scenario where you have a full reservoir but nearby ecosystems or farmland turn into deserts. Or you end up pumping that reservoir and using it for irrigation using the energy you have harvested, in the end using technology to efficiently recreate the hydrologic cycle and ecosystem services nature used to provide for free.

Battlefield Casualties and Ballot Box Defeat

This surprising study from Boston University and University of Minnesota concludes that military families that suffered casualties in the Afghanistan and Iraq wars might have been the swing voters that put Trump over the top in Pennsylvania, Michigan, and Wisconsin.

Kriner, Douglas L. and Shen, Francis X., Battlefield Casualties and Ballot Box Defeat: Did the Bush-Obama Wars Cost Clinton the White House? (June 19, 2017). Available at SSRN: https://ssrn.com/abstract=2989040

America has been at war continuously for over 15 years, but few Americans seem to notice. This is because the vast majority of citizens have no direct connection to those soldiers fighting, dying, and returning wounded from combat. Increasingly, a divide is emerging between communities whose young people are dying to defend the country, and those communities whose young people are not. In this paper we empirically explore whether this divide—the casualty gap—contributed to Donald Trump’s surprise victory in November 2016. The data analysis presented in this working paper finds that indeed, in the 2016 election Trump was speaking to this forgotten part of America. Even controlling in a statistical model for many other alternative explanations, we find that there is a significant and meaningful relationship between a community’s rate of military sacrifice and its support for Trump. Our statistical model suggests that if three states key to Trump’s victory – Pennsylvania, Michigan, and Wisconsin – had suffered even a modestly lower casualty rate, all three could have flipped from red to blue and sent Hillary Clinton to the White House. There are many implications of our findings, but none as important as what this means for Trump’s foreign policy. If Trump wants to win again in 2020, his electoral fate may well rest on the administration’s approach to the human costs of war. Trump should remain highly sensitive to American combat casualties, lest he become yet another politician who overlooks the invisible inequality of military sacrifice. More broadly, the findings suggest that politicians from both parties would do well to more directly recognize and address the needs of those communities whose young women and men are making the ultimate sacrifice for the country.

I acknowledge and am willing to believe the numbers. I am not sure I buy the conclusions these authors draw from the numbers – that communities with ties to the military will vote for candidates they think are least likely to send their children off to war. On the contrary, I would hypothesize that people in these communities might respond more strongly to patriotic rhetoric, and be more likely to support military approaches to geopolitical problems.

climate change and Hurricane Harvey

Michael Mann, a climate scientist at Penn State, has posted a long (for Facebook) article on Facebook about how climate change contributes to events like this. In short, climate determines the probability of a particular weather event occurring, but ultimately any one particular weather event is a roll of the (now slightly loaded) dice. Warmer water and warmer air than in the past have both made events like this more likely, and are making events like this more destructive when they do occur. The article has links to several journal articles which would be worth reading to know something about hydrology and climate change. But right now I can’t do that because I’m late for my job where I have to convince people I know something about, among other topics, hydrology and climate change.

Sea level rise attributable to climate change (some is due to coastal subsidence due to human disturbance e.g. oil drilling) is more than half a foot over the past few decades (see http://www.insurancejournal.com/…/sou…/2017/05/31/452704.htm for a decent discussion).

That means that the storm surge was a half foot higher than it would have been just decades ago, meaning far more flooding and destruction.

In addition to that, sea surface temperatures in the region have risen about 0.5C (close to 1F) over the past few decades, from roughly 30C (86F) to 30.5C (87F), which contributed to the very warm sea surface temperatures (30.5-31 C or 87-88F). There is a simple thermodynamic relationship known as the “Clausius-Clapeyron equation (see e.g. https://en.wikipedia.org/…/Clausius%E2%80%93Clapeyron_relat…) that tells us there is a roughly 3% increase in average atmospheric moisture content for each 0.5C (~1F) of warming. Sea surface temperatures in the area where Harvey intensified were 0.5-1C warmer than current-day average temperatures, which translates to 1-1.5C warmer than the ‘average’ temperatures a few decades ago. That means 3-5% more moisture in the atmosphere.

Sowing density effects and patterns of colonization

That’s plant colonization, in case you were wondering what kind of colonization I am talking about. This study has a fairly simple premise – that in restoration you can sow the seeds that have the most trouble establishing at the highest densities, and seeds of plants that germinate and spread easily at lower densities, or even not at all.

Sowing density effects and patterns of colonization in a prairie restoration

A cost-effective approach in plant restorations could be to increase sowing density for species known to be challenging to establish, while reducing sowing density for species that easily colonize on their own. Sowing need not occur evenly across the site for rapidly dispersing species. We explored these issues using a prairie restoration experiment on a high-school campus with three treatments: plots sown only to grasses (G plots), to grasses and forbs (GF1), and to grasses and forbs with forbs sown at twice the density (GF2). In year 2, GF1 and GF2 plots had higher diversity than G plots, as expected, but GF2 treatments did not have twice the sown forb cover. However, high forb sowing density increased forb richness, probably by reducing stochastic factors in establishment. Cover of nonsown species was highest in G plots and lowest in GF2 plots, suggesting suppressive effects of native forbs on weedy species. Colonization of G plots by two sown forbs (Coreopsis tinctoria and Rudbeckia hirta) was apparent after 2.5 years, providing evidence that these species are self-sustaining. Colonization was greater in edges than in the central areas of G plots. Through construction of establishment kernels, we infer that the mean establishment distance was shorter for R. hirta (6.7 m) compared to C. tinctoria (21.1 m). Our results lead us to advocate for restoration practices that consider not only seed sowing but also subsequent dispersal of sown species. Furthermore, we conclude that restoration research is particularly amenable for outdoor education and university-high school collaborations.

200,000 annual deaths from air pollution in the U.S.

A 2013 study estimated the number of annual premature deaths due to air pollution in the U.S. at about 200,000. That’s kind of a shocking number considering it is more than deaths from other preventable causes like car accidents and suicides. An interesting (not in a good way) finding is that road transportation causes more deaths (~53,000/yr) from air pollution than from crashes. On the other hand, it means you can kill two birds with one stone when you institute policies and technologies that reduce vehicle emissions, driving, or both. Of course, a shift to electric cars just shifts the emissions to power plants in the short term, but that means many fewer centralized sources of emissions, which might be easier to deal with. A shift to more muscle-powered transportation in our cities is a huge win in terms of health (less violent death and injuries, less death from dirty air, more exercise in all that clean fresh air, probably better mental health), and a win in terms of land use and vibrancy and getting to know one another in our cities.

Air pollution and early deaths in the United States. Part I: Quantifying the impact of major sectors in 2005

Combustion emissions adversely impact air quality and human health. A multiscale air quality model is applied to assess the health impacts of major emissions sectors in United States. Emissions are classified according to six different sources: electric power generation, industry, commercial and residential sources, road transportation, marine transportation and rail transportation. Epidemiological evidence is used to relate long-term population exposure to sector-induced changes in the concentrations of PM2.5 and ozone to incidences of premature death. Total combustion emissions in the U.S. account for about 200,000 (90% CI: 90,000–362,000) premature deaths per year in the U.S. due to changes in PM2.5 concentrations, and about 10,000 (90% CI: −1000 to 21,000) deaths due to changes in ozone concentrations. The largest contributors for both pollutant-related mortalities are road transportation, causing ∼53,000 (90% CI: 24,000–95,000) PM2.5-related deaths and ∼5000 (90% CI: −900 to 11,000) ozone-related early deaths per year, and power generation, causing ∼52,000 (90% CI: 23,000–94,000) PM2.5-related and ∼2000 (90% CI: −300 to 4000) ozone-related premature mortalities per year. Industrial emissions contribute to ∼41,000 (90% CI: 18,000–74,000) early deaths from PM2.5 and ∼2000 (90% CI: 0–4000) early deaths from ozone. The results are indicative of the extent to which policy measures could be undertaken in order to mitigate the impact of specific emissions from different sectors — in particular black carbon emissions from road transportation and sulfur dioxide emissions from power generation.

eyes on the street

A group at the University of Pennsylvania looked for statistical evidence that “eyes on the street” are a deterrent to crime. The results are a bit puzzling, as real world data often can be.

ANALYSIS OF URBAN VIBRANCY AND SAFETY IN PHILADELPHIA

Statistical analyses of urban environments have been recently improved through publicly available high resolution data and mapping technologies that have adopted across industries. These technologies allow us to create metrics to empirically investigate urban design principles of the past half-century. Philadelphia is an interesting case study for this work, with its rapid urban development and population increase in the last decade. We focus on features of what urban planners call vibrancy: measures of positive, healthy activity or energy in an area. Historically, vibrancy has been very challenging to measure empirically. We explore the association between safety (violent and non-violent crime) and features of local neighborhood vibrancy such as population, economic measures and land use zoning. Despite rhetoric about the negative effects of population density in the 1960s and 70s, we find very little association between crime and population density. Measures based on land use zoning are not an adequate description of local vibrancy and so we construct a database and set of measures of business activity in each neighborhood. We employ several matching analyses within census block groups to explore the relationship between neighborhood vibrancy and safety at a higher resolution. We fi nd that neighborhoods with more vacancy have higher crime but within neighborhoods, crimes tend not to be located near vacant properties. We also find that more crimes occur near business locations but businesses that are active (open) for longer periods are associated with fewer crimes.

This is particularly fascinating to me because I live my life in the middle of this particular data set and am part of it. So it is very interesting to compare what the data seem to be saying with my own experiences and impressions.

The lack of correlation between population density and crime is not surprising. Two neighborhoods with identical density can be drastically different. The correlation between poverty and crime is not surprising – people who are not succeeding in the formal economy and who are not mobile turn to the informal economy, in other words drug dealing, loan sharking and other illegal ways of trying to earn an income. If they are successful at earning an income, they tend to have a lot of cash around, and other people who know about the cash will take advantage of them, knowing they will not go to the police. Other than going to the police, the remaining options are to be taken advantage of repeatedly, or to retaliate. This is how violence escalates, I believe, and it goes hand in hand with development of a culture that tolerates and even celebrates violence, in a never-ending feedback loop.

The puzzling part comes when they try to drill down and look at explanatory factors at a very fine spatial scale. They found a correlation between crime and mixed use zoning, which appears to contradict the idea that eyes on the street around the clock will help to deter crime. And they found more crime around businesses like cafes, restaurants, bars and retail shops. They found that longer open hours seemed to have some deterrent effect on crime relative to shorter open hours.

I think they have made an excellent effort to do this, and I am not sure it can be done a lot better, but I will point out one idea I have. They talk about some limitations and nuances of their data, but one they do not mention is the idea that they are looking at reported crimes, most likely police reports or 911 calls. It could be that business owners, staff and patrons are much more likely to call 911 and report a crime than are residential neighbors. The business staff and patrons may see this as being in the economic interest, increasing the safety of their families, and the (alleged) criminals they are reporting are generally strangers. In quieter all-residential neighborhoods, people may not observe as many of the crimes that do occur (fewer “eyes on the street”), they may prefer not to report crimes either through a sense of loyalty to one’s neighbors, minding one’s own business, quid pro quo, or in some cases a fear of retaliation. There is also the factor of some demographic groups trusting the police more than others, although the authors’ statistical attempts to control for demographics may tend to factor this out.