Monday, July 26, 2021

Changes in Atlantic major hurricane frequency since the late-19th century

Changes in Atlantic major hurricane frequency since the late-19th century. Gabriel A. Vecchi, Christopher Landsea, Wei Zhang, Gabriele Villarini & Thomas Knutson. Nature Communications volume 12, Article number: 4054. Jul 19 2021.

Abstract: Atlantic hurricanes are a major hazard to life and property, and a topic of intense scientific interest. Historical changes in observing practices limit the utility of century-scale records of Atlantic major hurricane frequency. To evaluate past changes in frequency, we have here developed a homogenization method for Atlantic hurricane and major hurricane frequency over 1851–2019. We find that recorded century-scale increases in Atlantic hurricane and major hurricane frequency, and associated decrease in USA hurricanes strike fraction, are consistent with changes in observing practices and not likely a true climate trend. After homogenization, increases in basin-wide hurricane and major hurricane activity since the 1970s are not part of a century-scale increase, but a recovery from a deep minimum in the 1960s–1980s. We suggest internal (e.g., Atlantic multidecadal) climate variability and aerosol-induced mid-to-late-20th century major hurricane frequency reductions have probably masked century-scale greenhouse-gas warming contributions to North Atlantic major hurricane frequency.


One of the most consistent expectations from projected future global warming is that there should be an increase in TC intensity, such that the fraction of MH to HU increases6,20,21,22,25,26,27,28,29,30,31. This issue has become more pressing with the recent finding of a global increase in this metric since 1979 using homogenized satellite-based data14—a finding to which Atlantic HU contribute. We here build on the methods of refs. 9,10 to build a homogenized record of Atlantic MH frequency and MH/HU ratio since the 19th century. We find here that, once we include a correction for undercounts in the pre-satellite era basin-wide NA HU and MH frequency, there are no significant increases in either basin-wide HU or MH frequency, or in the MH/HU ratio for the Atlantic basin between 1878 and 2019 (when the U.S. Signal Corps started tracking NA HUs35). We suggest that the modestly significant 1851–2019 increase in basin-wide MH frequency and MH/HU ratio that remains after including the HU and MH adjustment reflects data inhomogeneity that our adjustment is unable to correct—rather than an actual increase in these quantities. The homogenized basin-wide HU and MH record does not show strong evidence of a century-scale increase in either MH frequency or MH/HU ratio associated with the century-scale, greenhouse-gas-induced warming of the planet. For example, the temporal evolution of the global mean temperature is not closely reflected in the temporal evolution of adjusted MH/HU ratio shown in Fig. 4.

Does this work provide evidence against the hypothesis that greenhouse-gas-induced warming may lead to an intensification of North Atlantic HUs? Not necessarily. Substantial multi-decadal variability may obscure trends computed over the past century16,17,18,20,21, and recent studies suggest the possibility for an aerosol-driven reduction in NA HU and MH activity over the 1960s–1980s (refs. 19,20,21,22,23,24), which may have obscured any greenhouse induced NA HU and MH intensification over the 20th century. For example, a statistical downscaling of global climate models (GCMs) that were part of the Coupled Model Intercomparison Project Phase 5 (CMIP5) shows a robust and significant projection for a greenhouse gas-induced 21st century NA hurricane intensification; yet applying that same method to historical simulations the greenhouse-induced intensification over the late-19th and 20th century is masked by the late-20th century aerosol-induced weakening20. Historical simulations show that aerosol forcing may have masked the 19th-20th century greenhouse-gas-induced increase in potential intensity, the theoretical upper bound on tropical cyclone intensity, even though climate models show increases in potential intensity in tropical cyclone regions in response to projected future warming24,25,26. The homogenized MH and HU data developed in the present study serve as a target for century-scale historical simulations with high-resolution dynamical and statistical models that are used for 21st century projections.

The adjusted NA basin-wide MH frequency and MH/HU ratio show substantial multi-decadal variability (Figs. 24), and the adjusted basin-wide MH frequency shows its lowest values over the 1960s–1980s (Fig. 2). These features show at least qualitative consistency with the notion of a strong influence of either internal multi-decadal climate variability and/or late-20th century aerosol-induced weakening of NA HU intensity during that period. Our homogenized records also correspond with document- and proxy-based reconstructions of Antilles and Atlantic HUs, which indicate that substantial variability in HU frequency has been present in the Atlantic, and the inactive period in the late 20th century may have been the most inactive period in recent centuries42,43.

The homogenized hurricane records suggest a consistent and marginally statistically significant decrease in the ratio of basin-wide hurricanes striking the USA as hurricanes (Table 2, row 3). Some models project an eastward shift in the location of NA TCs in response to increasing greenhouse gases (e.g., refs. 27,28), so this observed change may reflect the emerging impact of greenhouse warming on NA TC tracks. However, although there is a nominal decrease in the ratio of basin-wide MH striking the USA as MH (Table 2, row 4), the trends are not significant for any of the time periods explored.

Caution should be taken in connecting recent changes in Atlantic hurricane activity to the century-scale warming of our planet. The adjusted records presented here provide a century-scale context with which to interpret recent studies indicating a significant recent increase in NA MH/HU ratio over 1980–2017 (ref. 14), or in the fraction of NA tropical storms that rapidly intensified over 1982–2009 (ref. 15). Our results indicate that the recent increase in NA basin-wide MH/HU ratio or MH frequency is not part of a century-scale increase. Rather it is a rebound from a deep local minimum in the 1960s–1980s. We hypothesize that these recent increases contain a substantial, even dominant, contribution from internal climate variability16,17,18,20,21, and/or late-20th century aerosol increases and subsequent decreases19,20,21,22,23,24, in addition to any contributions from recent greenhouse gas-induced warming20,22,24,44. It has been hypothesized, for example, that aerosol-induced reductions in surface insolation over the tropical Atlantic since between the mid-20th century and the 1980s may have resulted in an inhibition of tropical cyclone activity19,20,21,22,23,24; the relative contributions of anthropogenic sulfate aerosols, dust, and volcanic aerosols to this signal (each of which would carry distinct implications for future hurricane evolution)—along with the magnitude and impact of aerosol-mediated cloud changes—remain a vigorous topic of scientific inquiry. It has also been suggested that multi-decadal climate variations connected to changes in meridional ocean overturning may have resulted in a minimum in northward heat transport in the Atlantic and a resulting reduction in Atlantic hurricane activity16,17,18,20,21. Given the uncertainties that presently exist in understanding multi-decadal climate variability, the climate response to aerosols and impact of greenhouse gas warming on NA TC activity, care must be exercised in not over-interpreting the implications of, and causes behind, these recent NA MH increases. Disentangling the relative impact of multiple climate drivers on NA MH activity is crucial to building a more confident assessment of the likely course of future HU activity in a world where the effects of greenhouse gas changes are expected to become increasingly important.

Children shared more treats when there was gossiping, regardless of whether the gossip receiver could identify them; this suggests that 4- and 8-year-old children attempt to manage their reputation when they could be a target of gossip

Children manage their reputation by caring about gossip. Asami Shinohara, Yasuhiro Kanakogi, Yuko Okumura, Tessei Kobayashi. Social Development, July 20 2021.

Abstract: Individuals engage in reputation management by adjusting their behaviour in front of others. As gossip plays an important role in human society, individuals need to concern themselves with not only a present observer's evaluations but also non-present people's impressions. In this study, we investigated whether 4- and 8-year-old children (N = 144) would adjust their sharing behaviours when presented with the possibility of an observer's gossiping. We manipulated whether the receiver of gossip could identify the child being gossiped about by using real-life group boundaries. The children shared their treats with an anonymous peer in front of an observer under three conditions. In the same-group gossip condition, the observer told the children that she would report their behaviour to their friends. In the different-group gossip condition, the children's behaviours were to be reported to an unknown peer (from a different kindergarten or elementary school). In the no-gossip condition, the observer would not gossip. Children from both age groups shared more treats in the two gossip conditions than in the no-gossip circumstance, regardless of whether the gossip receiver could identify them. These findings suggest that 4- and 8-year-old children attempt to manage their reputation when they could be a target of gossip.

White sclerae in primates are associated with increased cooperative behaviors (determining a conspecifics likely intentions from their gaze direction), & dark sclerae are associated with increased intra-specific lethal aggression

The evolutionary origins of primate scleral coloration. Alex S. Mearing, Judith M. Burkart, Jacob Dunn, Sally E. Street, Kathelijne Koops. bioRxiv Jul 25 2021.

Abstract: Primate gaze following behaviors are of great interest to evolutionary scientists studying social cognition. The ability of an organism to determine a conspecifics likely intentions from their gaze direction may confer an advantage to individuals in a social group. This advantage could be cooperative and/or competitive. Humans are unusual in possessing depigmented sclerae whereas most other extant primates, including the closely related chimpanzee, possess dark scleral pigment. The origins of divergent scleral morphologies are currently unclear, though human white sclerae are often assumed to underlie our hyper-cooperative behaviors. Here, we use phylogenetic generalized least squares (PGLS) analyses with previously generated species-level scores of proactive prosociality, social tolerance (both n=15 primate species), and conspecific lethal aggression (n=108 primate species) to provide the first quantitative, comparative test of three complementary hypotheses. The cooperative eye and self-domestication explanations predict white sclerae to be associated with cooperative, rather than competitive, environments. The gaze camouflage hypothesis predicts that dark scleral pigment functions as gaze direction camouflage in competitive social environments. We show that white sclerae in primates are associated with increased cooperative behaviors whereas dark sclerae are associated with reduced cooperative behaviors and increased intra-specific lethal aggression. Our results lend support to all three hypotheses of scleral evolution, suggesting that primate scleral morphologies evolve in relation to variation in social environment.

From 2009... Good-death Beliefs and Cognition in Himalayan Hinduist Pilgrimage

Good-death Beliefs and Cognition in Himalayan Pilgrimage. Andreas Nordin. Method and Theory in the Study of Religion 21 (2009) 402-436.

Abstract: This article discusses the notions of a good death associated with Hindu pilgrimages in the Nepalese and Tibetan Himalayas. Using theories and concepts from the cognitive anthropology of religion and from the cognitive science of religion—particularly the cultural epidemiological method—my objective is to explain why certain systems of thought and behaviour are favoured over others in cultural transmission. My thesis is that the apprehension of contagion and/or contamination, combined with prevailing cultural representations, exerts selective pressure on the formation of beliefs about good death. Pilgrimage sites are associated with intuitions about contagious and contaminating contact, avert the pollution of death, and provide links to supernatural agents.

Keywords: Hindu pilgrimage, cognition, death, good-death beliefs

We can't handle the truth... From the paper, pp 427-8:

In a summary of pilgrimage sites in the Hindu textual tradition Saraswati refers to such scriptures as the Dharmashastra, in which suicide at pilgrimage sites such as Prayag, Gangasagr och Kashi was morally sanctioned under certain condition (1983: 24). Saraswati’s presentation of the dharmashastra prescribes various forms of sanctioned and meritorious pilgrim suicides for soteriological purposes:

Following are the meritorious modes of suicides: (1) starving; (2) covering oneself with dry cowdung cakes and setting it on fire and consuming oneself therein; (3) burying oneself in snow; (4) to plunge into the water at the sangam, enumerate one’s sins and pray till alligators come and devour the man; (5) hanging with the head down in the stream and feet up and drinking the waters of Ganga; (6) cut one’s own throat, or cutting off one’s flesh and giving it as food to birds; (7) by falling head-long from a cliff, at Amarkantaka, for instance (1983: 24).

Clearly, several sources confi rm that religious suicide at pilgrimage sites has been sanctioned.

This, however, was denied by most of the pilgrims interviewed in this study. Theological norms that sanctioned ritual suicide were rejected by most of the pilgrims who were travelling to Muktinath, Pasupatunath and Mt. Kailash and Manasarovar. The pilgrims’ aversion to suicide in a context that was otherwise declared to be positive may exemplify a “theological correctness-effect” (Barrett 1999) or, more aptly, the tendency towards theological incorrectness (Slone 2004). That is, this aversion may be strengthened by fast, “online-reasoning” (Barrett 1999) associated with social exchange intuitions, rather than a slow matching of theological reflection with religious sources.

Quotations from the dharmashastra were shown to some pilgrims as an example of a scripture that did sanction suicide at pilgrimage sites. But the pilgrims generally had a strong antipathy for suicide and rarely hesitated to condemn it. Some of the pilgrims who saw the excerpts from the dharmashastra claimed they were false even though they were specially trained in the theology of their tradition.

Across cultures, males dominate reputation in most areas, like Cultural group unity, Dominance, Social and material success, & Supernatural healing; women excel in Sexuality (less infidelity)

Garfield, Zachary H., Ryan Schacht, Emily R. Post, Dominique Ingram, Andrea Uehling, and Shane Macfarlan. 2021. “The Content and Structure of Reputation Domains Across Human Societies: A View from the Evolutionary Social Sciences.” OSF Preprints. July 2. doi:10.31219/

Abstract: Reputations are an essential feature of human sociality, critical for the evolution of cooperation and group living. Much scholarship has focused on reputations, yet typically on a narrow range of domains (e.g., prosociality, aggressiveness), usually in isolation. Humans can develop reputations, however, from any collective information. We conducted exploratory analyses on the content, distribution, and structure of reputation domain diversity across cultures, using the Human Relations Area Files ethnographic database. After coding ethnographic texts on reputations from 153 cultures, we used hierarchical modelling, cluster analysis, and text analysis to provide an empirical view of reputation domains across societies. Findings suggest: 1) reputational domains vary cross-culturally, yet reputations for cultural conformity, prosociality, social status, and neural capital are widespread; 2) reputation domains are more variable for males than females; and 3) particular reputation domains are strongly interrelated, demonstrating a structure consistent with dimensions of human uniqueness. We label these reputational features: Cultural group unity, Dominance, Sexuality, Social and material success, and Supernatural healing. Ultimately, through this work, we highlight the need for future research on the evolution of cooperation and human sociality to consider a wider range of reputation domains, as well as their patterning by social, ecological, and gender-specific pressures.