Category Archives: Peer Reviewed Article Review

climate change threatens barley yields

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A new study says climate change is likely to threaten barley yields, leading to high beer prices later in the century. I’m hoping this is wrong and we can grow hops and barley in the formerly frozen tundra of Canada and Siberia. Of course the bigger picture is about grain yields overall, and that is not just about average temperature but about extreme heat and drought.

Decreases in global beer supply due to extreme drought and heat

Beer is the most popular alcoholic beverage in the world by volume consumed, and yields of its main ingredient, barley, decline sharply in periods of extreme drought and heat. Although the frequency and severity of drought and heat extremes increase substantially in range of future climate scenarios by five Earth System Models, the vulnerability of beer supply to such extremes has never been assessed. We couple a process-based crop model (decision support system for agrotechnology transfer) and a global economic model (Global Trade Analysis Project model) to evaluate the effects of concurrent drought and heat extremes projected under a range of future climate scenarios. We find that these extreme events may cause substantial decreases in barley yields worldwide. Average yield losses range from 3% to 17% depending on the severity of the conditions. Decreases in the global supply of barley lead to proportionally larger decreases in barley used to make beer and ultimately result in dramatic regional decreases in beer consumption (for example, −32% in Argentina) and increases in beer prices (for example, +193% in Ireland). Although not the most concerning impact of future climate change, climate-related weather extremes may threaten the availability and economic accessibility of beer.

statistical analysis of the Supreme Court

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A statistical analysis of the U.S. Supreme Court suggests that it is not all that partisan after all. Okay, I admit it, I am really just pretending to understand half the words in the abstract below. It’s always kind of fun when physicists dabble in fields outside their usual boundaries, like economics or politics.

Partisan Intuition Belies Strong, Institutional Consensus and Wide Zipf’s Law for Voting Blocs in US Supreme Court

The US Supreme Court throughout the twentieth century has been characterized as being divided between liberals and conservatives, suggesting that ideologically similar justices would have voted similarly had they overlapped in tenure. What if they had? I build a minimal, pairwise maximum entropy model to infer how 36 justices from 1946–2016 would have all voted on a Super Court. The model is strikingly consistent with a standard voting model from political science, W-Nominate, despite using 105 less parameters and fitting the observed statistics better. I find that consensus dominates the Super Court and strong correlations in voting span nearly 100 years, defining an emergent institutional timescale that surpasses the tenure of any single justice. Thus, the collective behavior of the Court over time reveals a stable institution insulated from the seemingly rapid pace of political change. Beyond consensus, I discover a rich structure of dissenting blocs with a heavy-tailed, scale-free distribution consistent with data from the Second Rehnquist Court. Consequently, a low-dimensional description of voting with a fixed number of ideological modes is inherently misleading because even votes that defy such a description are probable. Instead of assuming that strong higher order correlations like voting blocs are induced by features of the cases, the institution, and the justices, I show that such complexity can be expressed in a minimal model relying only on pairwise correlations in voting.

IPCC terminology

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I find some of the IPCC terminology interesting. Alternatives analysis and communication of uncertainty are professional interests of mine. I am afraid I am not all that good at them, but when I see the state of the art in scientific communication from the experts sometimes I feel a little better.

Here is a footnote in the Summary for Policy Makers on the terminology they use to try to communicate uncertainty.

A level of confidence is expressed using five qualifiers: very low, low, medium, high and very high, and typeset in italics, for example, medium confidence. The following terms have been used to indicate the assessed likelihood of an outcome or a result: virtually certain 99–100% probability, very likely 90–100%, likely 66 100%, about as likely as not 33–66%, unlikely 0–33%, very unlikely 0–10%, exceptionally unlikely 0–1%. Additional terms (extremely likely 95–100%, more likely than not >50–100%, more unlikely than likely 0–<50%, extremely unlikely 0–5%) may also be used when appropriate. Assessed likelihood is typeset in italics, for example, very likely.

Here are some definitions of scenarios and pathways in Chapter 1 of Global Warming of 1.5 °C.

A ‘scenario’ is an internally consistent, plausible, and integrated description of a possible future of the human–environment system, including a narrative with qualitative trends and quantitative projections (IPCC, 2000). Climate change scenarios provide a framework for developing and integrating emissions, climate change and climate impact projections, including an assessment of their inherent uncertainties. The long-term and multi–faceted nature of climate change requires climate scenarios to describe how assumptions about inherently uncertain socio-economic trends in the 21st century could influence future energy and land use, resulting in emissions, and climate change as well as human vulnerability and exposure to climate change. Such driving forces include population, GDP, technological innovation, governance, and lifestyles. Climate change scenarios are used for analysing and contrasting climate policy choices.

The notion of a ‘pathway’ can have multiple meanings in the climate literature. It is often used to describe the temporal evolution of a set of scenario features, such as GHG emissions and socioeconomic development. As such, it can describe individual scenario components or sometimes be used interchangeably with the word ‘scenario’. For example, the RCPs describe GHG concentration trajectories (van Vuuren et al., 2011) and the SSPs are a set of narratives of societal futures augmented by quantitative projections of socio-economic determinants such as population, GDP, and urbanization (Kriegler et al., 2012; O’Neill et al., 2014). Socio-economic driving forces consistent with any of the SSPs can be combined with a set of climate policy assumptions (Kriegler et al., 2014) that together would lead to emissions and concentration outcomes consistent with the RCPs (Riahi et al., 2017). This is at the core of the scenario framework for climate change research that aims to facilitate creating scenarios integrating emissions and development pathways dimensions (Ebi et al., 2014; van Vuuren et al., 2014).

fair vs. unfair inequality

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This interesting article in Vox talks about academic ideas on how to distinguish and measure a difference between fair and unfair inequality. The premise is that there is no moral justification for leaving anyone below the poverty line, even if they are there due to bad choices of their own making. But once out of poverty, there is a need for incentives for people to make effort, make good choices and take the kind of good risks that sometimes pay off for society. There is also a difference between people who are less well off because of bad luck (often the luck of who their parents are) and people who are less well off because they have made less effort or bad choices. Of course, people who are better off because of luck or breeding will tend to rationalize their success relative to others as being due to superior effort and good choices, when in fact they may not be the case. So having an objective way to measure this is an interesting idea. It suggests you could have policies that kick in automatically when some measure of “unfair inequality” gets to a certain level. I don’t quite understand the measure itself, but this is a blog post referring to an academic paper, and I didn’t dig into the academic paper itself.

do kids do better in private school than public?

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The answer, at least in this study, is a clear no. Kids in private school are doing better than kids in public school, but it can be entirely explained by family income.

Does Attendance in Private Schools Predict Student Outcomes at Age 15? Evidence From a Longitudinal Study

By tracking longitudinally a sample of American children (n = 1,097), this study examined the extent to which enrollment in private schools between kindergarten and ninth grade was related to students’ academic, social, psychological, and attainment outcomes at age 15. Results from this investigation revealed that in unadjusted models, children with a history of enrollment in private schools performed better on nearly all outcomes assessed in adolescence. However, by simply controlling for the sociodemographic characteristics that selected children and families into these schools, all of the advantages of private school education were eliminated. There was also no evidence to suggest that low-income children or children enrolled in urban schools benefited more from private school enrollment.

virtual reality and philosophy

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That’s right, this article is about virtual reality and philosophy.

Why Is Virtual Reality Interesting for Philosophers?

This article explores promising points of contact between philosophy and the expanding field of virtual reality research. Aiming at an interdisciplinary audience, it proposes a series of new research targets by presenting a range of concrete examples characterized by high theoretical relevance and heuristic fecundity. Among these examples are conscious experience itself, “Bayesian” and social VR, amnestic re-embodiment, merging human-controlled avatars and virtual agents, virtual ego-dissolution, controlling the reality/virtuality continuum, the confluence of VR and artificial intelligence (AI) as well as of VR and functional magnetic resonance imaging (fMRI), VR-based social hallucinations and the emergence of a virtual Lebenswelt, religious faith and practical phenomenology. Hopefully, these examples can serve as first proposals for intensified future interaction and mark out some potential new directions for research.

The main thing I got from this article is that it is really…long. It starts with a glossary of terms you need to learn before you read the rest of the paper, then gets longer from there.

half the world’s power from the Sahara

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There’s a big idea to provide half the world’s energy from solar panels in the Sahara desert, using the actual desert sand as a raw material to manufacture the panels. An interesting article in Science says that wind and solar farms on such a large scale could actually change the local weather drastically by altering wind and surface temperatures, ultimately increasing rainfall and allowing more vegetation in the desert.

In this study, we used a climate model with dynamic vegetation to show that large-scale installations of wind and solar farms covering the Sahara lead to a local temperature increase and more than a twofold precipitation increase, especially in the Sahel, through increased surface friction and reduced albedo. The resulting increase in vegetation further enhances precipitation, creating a positive albedo–precipitation–vegetation feedback that contributes ~80% of the precipitation increase for wind farms. This local enhancement is scale dependent and is particular to the Sahara, with small impacts in other deserts.

Could this work on Mars? I guess not, because you don’t have the water vapor in the atmosphere to begin with. Unless you get that alien ice breaker thing from Total Recall (the 1990 version, again, I don’t recognize the 2012 version’s right to exist) – why do I keep coming back to this movie?

non use values

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This paper mentions the importance of including non-use values in ecosystem services valuation.

Evidence of a Shared Value for Nature

Ecosystem service analysis aims to expand the accounting of human values for nature, yet frequently ignores or obfuscates a category of human values with potentially large magnitude, namely nonuse or passive use values. These values represent the satisfaction derived from the protection or restoration of species, habitats and wilderness areas, even if people never use them in any tangible way. The shunting of nonuse values to the background of ecosystem service analysis appears, in part, to be an attempt to avoid the perceived elitism of environmental values. To examine whether such values are the purview of the elite, we explore three types of evidence of who holds nonuse values. We find that when people are asked to 1) commit money via stated preference instruments, 2) respond to tweets, or 3) express opinions via surveys they demonstrate a significant willingness to protect and restore natural resources, regardless of their own use of those resources. Such values are represented in all socio-demographic groups that encompass race, ethnicity, immigration status, income, political affiliation, geographic location, age or gender, although the magnitude can vary among groups. The implications are that omitting nonuse values in ecosystem service analysis will tend to underestimate values, particularly for remote sites with limited use, and fail to represent important tradeoffs.

directed technological change

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If I follow the general idea in this paper, it is that some government policy intervention, whether through taxes or direct R&D spending, is necessary to get green technological improvement to a rate that would be best for society.

Directed Technological Change in a Post-Keynesian Ecological Macromodel

Abstract: This paper presents a post-Keynesian ecological macromodel, which is stock-flow consistent, and incorporates directed technological change. Private and public R&D spending across three competing, yet complementary inputs – Labor, Capital, and Resources – follow a portfolio allocation decision, where inputs with relatively higher growth in costs, see higher R&D investment and productivity gains. Two policy experiments are reported; a market-based Resource tax increase, and a centralized green policy, where public R&D budget is shifted towards Resource-saving technologies. We highlight that in the presence of labor market institutions, which give rise to hysteresis, and limited R&D budgets, a policy of continuous Resource tax growth is needed to induce Resource-saving technological change to achieve a greener economy. This needs to be coupled with planned government spending adjustment to spur demand and boost investment. The findings also suggest that a mix of market-based and centralized policies may be optimal.

I had to look up the term “post-Keynesian”, and I’m still confused after reading the Wikipedia entry. Basically, these are people trying to carry on and build on Keynes’s original work. They emphasize the importance of long term aggregate demand on growth and employment, and the importance of money and interest rates in this system.