Category Archives: Peer Reviewed Article Review

tipping points

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A new article from Proceedings of the National Academy of Sciences goes through eight climate change tipping points that have studied, and tries to assign an economic impact to each. I’ll list them here in order of highest to lowest impact according to this study (see Table 2). They use the change in social cost of carbon as their key metric.

Two tipping points have major potential impacts and represent over 80% of the total risk from the eight, according to this study:

  • ocean methane hydrates
  • permafrost carbon feedback

Four tipping points have relatively modest expected impacts, at least modest compared to the truly existential threats represented by the top two:

  • West Antarctic Ice Sheet
  • Greenland Ice Sheet disintegration
  • Indian Summer Monsoon
  • Amazon dieback

Finally, two actually have small positive impacts on the (human) economy according to these authors:

  • Atlantic Meridional Overturning Circulation slowdown (AMOC)
  • Arctic sea ice / Surface Albedo Feedback

They don’t include “nonmarket effects”, so if you just feel that the death of the Amazon forest is profoundly sad, that is not reflected here. The authors are explicit about this so I guess it is okay.

These results are mismatched with my impressions, which are most likely driven by the amount of media coverage given to tipping points. I have probably read the most about ice sheets, the AMOC, and the Amazon, and these somewhat surprisingly do not make the top of the list. I feel like I have some basic grasp of the scientific concepts on each of these other than the methane hydrates. I understand why releasing massive amounts of methane would raise temperatures. I just don’t yet understand the feedback loop that would cause it to happen, whereas with the permafrost thawing it is pretty clear. Are the methane hydrates just frozen and expected to melt? I suppose in that case they are very similar to methane under the permafrost, with the difference being land and water. So the release of vast amounts of trapped methane is by far the biggest impact identified by this paper. For the most part though, the solutions to address any of these tipping points are going to be the same – drastic greenhouse gas emissions reductions and/or drastic geoengineering. Nothing else is going to reduce the amount of heat and solar energy melting ice, thawing permafrost and undersea frozen methane hydrates, and affecting ocean currents across vast chunks of the planet.

early warning of Gulf Stream collapse?

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There has been plenty of hypothesizing that global warming could cause destabilization of key ocean currents that have determined the character of the world’s regional climates over the last few millennia or so, i.e. human history. This new paper is the first I am aware of (but I am not even close to an expert on this subject or oceanography more generally) to find empirical evidence that the the AMOC current (which I believe includes the Gulf Stream) could be nearing a tipping point.

Observation-based early-warning signals for a collapse of the Atlantic Meridional Overturning Circulation

The Atlantic Meridional Overturning Circulation (AMOC), a major ocean current system transporting warm surface waters toward the northern Atlantic, has been suggested to exhibit two distinct modes of operation. A collapse from the currently attained strong to the weak mode would have severe impacts on the global climate system and further multi-stable Earth system components. Observations and recently suggested fingerprints of AMOC variability indicate a gradual weakening during the last decades, but estimates of the critical transition point remain uncertain. Here, a robust and general early-warning indicator for forthcoming critical transitions is introduced. Significant early-warning signals are found in eight independent AMOC indices, based on observational sea-surface temperature and salinity data from across the Atlantic Ocean basin. These results reveal spatially consistent empirical evidence that, in the course of the last century, the AMOC may have evolved from relatively stable conditions to a point close to a critical transition.

Nature Climate Change

This would seem to have major consequences to (1) where and how much food we can grow in the world, and (2) the location of our actual physical coastlines and the coastal cities that house much of the world’s human population. Adjusting to gradual long-term changes in these things will be a challenge. A sudden, major shift might be something our civilization can’t adjust to. The consequences are unimaginably dire. The risk is unknown but this study suggests it is real. Logic and risk management principles suggest that we need to be cautious here and actually do what we can to avoid this. Let’s hope “a point close to a critical transition” is not really all that close in human terms, and we have time for our civilization, with its flawed geopolitical and economic systems, to come to its senses.

John Philip Grime

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Trends in Ecology and Evolution has an obituary on John Philip Grime, a giant in plant ecology. Not being well educated in plant ecology, I had not heard of him, but I like to learn.

Two seminal publications of the early 1970s would come to define Phil’s approach to finding universal patterns in the structure of vegetation. ‘Competitive exclusion in herbaceous vegetation’ [1.] introduced the ‘hump-backed’ model, which predicted that plant species richness peaks in communities that produce an aboveground biomass of about 600 g m–2 year–1. The model was one of the first to make specific recommendations about the management of local biodiversity. ‘Vegetation classification by reference to strategies’ [2.] introduced ‘competition-stress-disturbance’ (CSR) theory. CSR would become synonymous with Phil’s approach to studying vegetation; because he chose to present the concept as a triangle of three opposing selection pressures, many would come to refer to CSR theory as Grime’s triangle. Although not obvious from these papers, each was based on extensive vegetation datasets of the Sheffield region compiled by the UCPE team (particularly longtime associate John Hodgson). Although many would come to know Phil as a theorist and provocateur (a role he would assume often in the 1980s and 1990s), Phil would always argue that his insights were born of detailed field observations and a UCPE research team with expertise in both field botany and physiology.

Trends in Ecology and Evolution

what is green infrastructure

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Here’s a paper that goes into the many definitions of green infrastructure across different disciplines, along with related concepts. I’ve certainly seen narrow definitions used in my own discipline of water resources engineering. Defining clearly what you mean by a term and sticking to that definition is actually a good thing, because it takes the power out of the words in the definition itself, and you are now defining the actual structure and/or function of something, and you can now have a conversation with someone else once they understand the definition you are using. Using words without a clear definition, or not being aware of alternate definitions or broader perspectives that are out there, is a problem, and unfortunately not an uncommon one.

causes of death during the Covid-19 crisis

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CDC has a data table on excess deaths during the March-August 2020 period. Obviously, people died of Covid-19 itself, but they also died of other things indirectly caused by Covid-19.

  • 257,000 excess deaths compared to long-term average (I’m rounding numbers to the nearest thousand and nearest percent or so, although when I do math I will round after I do the math)
  • 174,000 due to Covid-19 disease itself – this is around 70% of the total, so 30% of the excess deaths were indirect (and/or random bad luck)
  • Drug overdoses were 13% higher than normal, but suicides were 6% lower than normal. These two things usually go together so there is a bit of a mystery here.
  • Homicides were 6% higher than normal. They don’t break down how much is domestic violence related versus street violence. I would imagine bar fights were down significantly.
  • “Unintentional injuries” were higher than normal. I imagine this is things like falls and drowning, but not motor vehicle crashes because those are separate. Maybe people hurt themselves doing things around the house. Unfortunately, we tend to take more risks doing similar activities around the house than if we were doing them at work.
  • Motor vehicle crashes were down slightly, but the drop was not statistically significant. Given the very significant drop in traffic last year, this suggests to me that deaths per mile traveled were high. I know pedestrian and bike deaths were disproportionately high last year. I would attribute a lot this to people driving faster and more recklessly on (perceived to be) empty streets and highways. This is unfortunate, but mostly human nature and needs to be solved by better street design. Solutions exist, we just need to reach out and grab them my fellow Americans!

So I think these data support the idea that street designs and a health care system that are at least average compared to modern developed countries would have saved U.S. lives during the pandemic, and would continue to save lives in the future. So can we have nice things or not?

Mandevillian Intelligence

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Mandevillian Intelligence is an idea where the (wise?) people in charge subtly manipulate incentives so that peoples’ individual dumb choices add up to the collective good.

Mandevillian intelligence is a specific form of collective intelligence in which individual cognitive vices (i.e., shortcomings, limitations, constraints and biases) are seen to play a positive functional role in yielding collective forms of cognitive success. The present paper introduces the concept of mandevillian intelligence and reviews a number of strands of empirical research that help to shed light on the phenomenon. The paper also attempts to highlight the value of the concept of mandevillian intelligence from a philosophical, scientific and engineering perspective. Inasmuch as we accept the notion of mandevillian intelligence, then it seems that the cognitive and epistemic value of a specific social or technological intervention will vary according to whether our attention is focused at the individual or collective level of analysis. This has a number of important implications for how we think about the design and evaluation of collective cognitive systems. For example, the notion of mandevillian intelligence forces us to take seriously the idea that the exploitation (or even the accentuation) of individual cognitive shortcomings could, in some situations, provide a productive route to collective forms of cognitive and epistemic success.

Synthese

I don’t have much faith in the wisdom of the average individual. But if there is one thing we should have learned in the last 20-odd years, we can’t have automatic faith in the wisdom of our leaders either. I’m probably naive, but I like to think system thinking education could help address this. It could make the average person much more wise in their conclusions and decisions about the world around them, and it could help them select wise leaders through a democratic process. I won’t go to that worn out Churchill quote, but I can’t think of any other system of identifying and choosing wise leaders that would reliably work better. The one that sometimes seems to work better is when existing wise leaders choose their successors and put rules in place making it hard for outsiders to break in. But the problem, of course, is that the wise rulers are self-proclaimed, and even if they are in fact wise, if unwise people manage to break in at some point they will be able to manipulate and abuse that same set of rules to keep themselves and their unwise cronies in power.

U.S. topsoil

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A study published in Nature says the U.S. “corn belt” has lost something like 35% of its topsoil. Sounds concerning, and I have heard dramatic claims like “the world only has 50 years of topsoil left. I also just find it sad to think that the topsoil was built up by the prairies over the millennia, and we have mined much of it into oblivion in a few short industrial generations. But this article also puts the loss in terms of crop yields at around 6%, which doesn’t sound so dramatic. This makes me think we are relying largely on agricultural chemicals rather than nutrients in the soil itself. Maybe it would actually make more sense to intensify industrial agricultural in some areas or even indoors, contain the impacts, and restore some of those prairies.

about 80% protection against Covid-19 reinfection in a Danish study

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When scientists are saying “we are not 100% sure” people who have had Covid-19 will have some immunity to reinfection, many smart people I know are hearing “people who have had Covid-19 have no immunity to infection”. Similarly, when scientists say they are not absolutely sure vaccinated people will not spread the virus (although they are quickly changing their tune on this one as they look at the evidence), people are hearing that vaccinated people are spreading the virus. Here is at least one study showing that when people who had a confirmed infection were tested again three months later, protection against reinfection was pretty good but not perfect at about 80%. It appears to have been lower in people over 65 at about 50%.

The CDC and others have also thrown out 3 months as a minimum amount of time they are confident people are protected against reinfection or protected by a vaccine. I think this is just a conservative estimate in the face of limited information, but again the public is hearing “no protection after 3 months”. In this study, they tested again after 6 months and found no decrease in the level of protection (still about 80%).

So my view is that logic suggests being infected would provide at least some protection against reinfection and being able to spread the virus, and the same for vaccination. I say this because this is how other diseases work. And now the data are backing that up. The science and public health policy communication are still pretty bad, and like a toxic spill, bad communication that takes a few hours can take years to clean up on the surface and there will still be puddles of toxic mess for decades whenever you turn over a rock.

Our planetary ecological support system is dying. Why aren’t we doing anything?

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That’s my summary (in my own words, not theirs) of this paper from Frontiers in Conservation Science.

Underestimating the Challenges of Avoiding a Ghastly Future

We report three major and confronting environmental issues that have received little attention and require urgent action. First, we review the evidence that future environmental conditions will be far more dangerous than currently believed. The scale of the threats to the biosphere and all its lifeforms—including humanity—is in fact so great that it is difficult to grasp for even well-informed experts. Second, we ask what political or economic system, or leadership, is prepared to handle the predicted disasters, or even capable of such action. Third, this dire situation places an extraordinary responsibility on scientists to speak out candidly and accurately when engaging with government, business, and the public. We especially draw attention to the lack of appreciation of the enormous challenges to creating a sustainable future. The added stresses to human health, wealth, and well-being will perversely diminish our political capacity to mitigate the erosion of ecosystem services on which society depends. The science underlying these issues is strong, but awareness is weak. Without fully appreciating and broadcasting the scale of the problems and the enormity of the solutions required, society will fail to achieve even modest sustainability goals.

This is not a paper about solutions. One thing they suggest is “for the scientific community to be more vocal”. I’m not sure. We need well-trained, well-funded scientists to do good science while talking amongst themselves, and then I think we need good science and risk communicators (some of whom might be scientists, but especially journalists and teachers and other types of people who write and speak in public, I think), along with engineers and technologists and economists and many other specialists (and generalists!) to help get through to our political and bureaucratic decision makers on the best courses of action. Facts and evidence don’t just speak for themselves, unfortunately. I certainly agree with the authors of this paper that we are failing to get through.

I’m always looking for that elevator pitch about why Uncle Lou (a fictional hard-headed relative, I don’t actually have an Uncle Lou) should care about biodiversity. Here is their attempt:

With such a rapid, catastrophic loss of biodiversity, the ecosystem services it provides have also declined. These include inter alia reduced carbon sequestration (Heath et al., 2005; Lal, 2008), reduced pollination (Potts et al., 2016), soil degradation (Lal, 2015), poorer water and air quality (Smith et al., 2013), more frequent and intense flooding (Bradshaw et al., 2007; Hinkel et al., 2014) and fires (Boer et al., 2020; Bowman et al., 2020), and compromised human health (Díaz et al., 2006; Bradshaw et al., 2019). As telling indicators of how much biomass humanity has transferred from natural ecosystems to our own use, of the estimated 0.17 Gt of living biomass of terrestrial vertebrates on Earth today, most is represented by livestock (59%) and human beings (36%)—only ~5% of this total biomass is made up by wild mammals, birds, reptiles, and amphibians (Bar-On et al., 2018). As of 2020, the overall material output of human endeavor exceeds the sum of all living biomass on Earth (Elhacham et al., 2020).

Frontiers in Conservation Science

I don’t think this paragraph will convince Uncle Lou. I think the message for the public is one where floods and fires threaten the value of their homes, and the future of the food supply we have taken for granted over the last century or so comes into doubt. The loss of natural ecosystems and animals is an epic tragedy to some, me included, but not to Uncle Lou down at the racetrack betting on the ponies (I’m not sure exactly who this character is I’ve just created, maybe we can interview him sometime and find out).

New Urbanism: Past, Present, and Future

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I basically agree with the principles of new urbanism (which were based on old urbanism). Communities where people can take most work, school, shopping, and entertainment trips by walking or biking are better for the planet and better for our physical and mental health. With good planning and design, there is plenty of room in the spaces we have already developed to accommodate whatever population growth we are expecting, without continuing to chew up land that could be left wild or used as farmland. The trick is to establish a virtuous cycle where gradually more people buy into the idea of life without private cars taking up half the space. And then some of that space saved has to be invested in good public infrastructure, access to recreation and nature to offset some of the negative effects of density. I think New Urban ideas have blunted suburban sprawl and car-dependency a little in the United States, but only a little unfortunately. There just aren’t that many walkable neighborhoods to choose from, and so people either aren’t familiar with them, and can’t imagine a non-car-dependent lifestyle, or else they assume people of average means can’t afford them, which is true in general of desirable things in short supply.

New Urbanism: Past, Present, and Future

The New Urbanism, initially conceived as an anti-sprawl reform movement, evolved into a new paradigm in urban design. Recently, however, some researchers have argued that the popular appeal of New Urbanism has eroded, the movement has lost its significance, and critical research on the broader theme has tapered off. In response, this article investigates whether the movement has lost its currency and explores the future of New Urbanism in the context of contemporary circumstances of development. The article begins with a brief description of the conceptualization of New Urbanism as an exception to the development trends of the time. Collaborative efforts of its protagonists that have contributed to the integration of New Urbanist concepts into other programs, policies, and development regulations are presented in the next section to describe its expansion, to clarify its mainstreaming, and to call attention to its broader impact. The concluding section presents contemporary circumstances of development and changes that are intensified by the COVID-19 pandemic, including those related to the nation’s demographics, climate change, technological advances, rapid growth of the digital economy, and acceleration of e-commerce to explore the significance of New Urbanism for future development.

Urban Planning open access journal