Planetary Health Research Digest
Authors: Sam Hinsley
Journal: The Lancet Planetary Health (2022)

Chemical pollutants resulting from human activities, including plastic waste, pose a serious risk to earth system processes, and are collectively known as novel entities. Although these novel entities are recognised as forming one of the planetary boundaries that should not be exceeded in a sustainable world, defining a quantifiable boundary for them has proved difficult. Linn Persson (Stockholm Environment Institute, Sweden) and colleagues propose approaches to quantifying this boundary by defining possible control variables that could indicate exceedance. Judging these variables according to their feasibility, relevance, and comprehensiveness, the authors conclude that a combination of variables will be necessary to correctly characterise this boundary. Based on the weight of available evidence on their variables, the authors argue that humanity is already operating above the boundary for novel entities, particularly given increases in their rate of introduction, production, and release, which far outstrip any society's ability to monitor and assess their safety. Marine aquaculture, or mariculture, has been proposed as a sustainable solution to the overexploitation of wild catch fisheries. The widespread adoption of mariculture could, however, be threatened by climate change. Muhammed Oyinlola (University of British Columbia, Canada) and colleagues investigated the extent to which climate change could affect global mariculture production by creating a model that takes into account not just effects on species distributions, but also future socioeconomic variables and availability of fish meal and fish oil used as feed. While they predict that production will expand by the mid-21st century, it declines again by the end of the century in their high emissions scenario. Introducing alternative feeds instead of fish meal and fish oil was shown to be a potential adaptation measure to reduce the impacts of climate change, although less effect was seen for regions that were predicted to lose substantial areas suitable for mariculture. The future development of mariculture will depend on strong climate change mitigation pathways as well as adaptation, the authors conclude. Political polarisation hinders the widespread cooperation needed to tackle the world's greatest threats like climate change and the COVID-19 pandemic. Despite these challenges existing across the world, relatively little work has been done to investigate polarisation across countries. Alexandra Flores (University of Colorado Boulder, USA) and colleagues designed a survey experiment to study how support for COVID-19 control policies differed among individuals depending on their political alignment and those of the policy proponent. Across Brazil, Israel, Italy, South Korea, Sweden, the UK, and the USA respondents acted similarly; they were more likely to support policies from political elites within their political ingroup and less likely to support those from outside their group, suggesting that politicians have a polarising effect. Policies from bipartisan coalitions and non-partisan experts were more likely to be supported than those from outside individuals’ political ingroups, potentially undoing some polarisation. The authors suggest that polarisation over such policies could be reduced if public messaging focuses more on non-partisan experts and bipartisan coalitions, and less on politicians. More isolated Indigenous groups live in the Brazilian Amazon than any other part of the world. However, their ability to continue living in isolation as a way to preserve their lives and culture is under threat from legislation proposed by the Brazilian government that would legalise mining within Indigenous lands. To quantify the extent of this threat, Sara Villén-Pérez (Universidad de Alcalá, Spain) and colleagues cross referenced official mining requests with information on uncontacted Indigenous groups in the Brazilian Amazon. They found 3645 requests on Indigenous lands inhabited by 43 isolated groups. 96·7% of these requests were on the lands inhabited by 21 Indigenous groups, suggesting a serious threat to their continued isolation. The number of requests on Indigenous lands was, however, negatively associated with knowledge about the isolated groups on these lands as corporations are more likely to worry about reputational issues or licensing challenges when working on the lands of well known isolated groups. As such, the authors call for greater efforts to study less well known groups to confirm their presence and dissuade corporations from mining on their lands.