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Editor’s summary

Only a few of the many volcanism-driven hyperthermals during the Phanerozoic caused mass extinctions, and none of them approached the level of global species loss seen at the end of the Permian. Why was the end-Permian so different? Sun et al. found that a combination of extreme El Niño events and mean state warming led to deforestation, reef demise, and a plankton crisis, all of which resulted in a positive feedback cycle that led to an even warmer mean climate and still stronger El Niño events. —Jesse Smith

Abstract

The ultimate driver of the end-Permian mass extinction is a topic of much debate. Here, we used a multiproxy and paleoclimate modeling approach to establish a unifying theory elucidating the heightened susceptibility of the Pangean world to the prolonged and intensified El Niño events leading to an extinction state. As atmospheric partial pressure of carbon dioxide doubled from about 410 to about 860 ppm (parts per million) in the latest Permian, the meridional overturning circulation collapsed, the Hadley cell contracted, and El Niños intensified. The resultant deforestation, reef demise, and plankton crisis marked the start of a cascading environmental disaster. Reduced carbon sequestration initiated positive feedback, producing a warmer hothouse and, consequently, stronger El Niños. The compounding effects of elevated climate variability and mean state warming led to catastrophic but diachronous terrestrial and marine losses.

Abstract

Extensive research highlights global and within-country inequality in personal carbon footprints. However, the extent to which people are aware of these inequalities remains unclear. Here we use an online survey distributed across four diverse countries: Denmark, India, Nigeria and the USA, to show widespread underestimation of carbon footprint inequality, irrespective of participants’ country and income segment. Of the 4,003 participants, within each country, 50% of participants were sampled from the top 10% income group. Our results show links between carbon footprint inequality perceptions and climate policy support, but with significant variations observed across the four countries and with participants’ income segments. Furthermore, there are links to the perceived fairness of actual carbon footprint inequality, highlighting the need to raise awareness about carbon footprint inequality and further unpack its implications for climate justice and policy.

"All of humanity could share a prosperous, equitable future but the space for development is rapidly shrinking under pressure from a wealthy minority of ultra-consumers, a groundbreaking study has shown.

Growing environmental degradation and climate instability have pushed the Earth beyond a series of safe planetary boundaries, say the authors from the Earth Commission, but it still remains possible to carve out a “safe and just space” that would enable everyone to thrive.

That utopian outcome would depend on a radical transformation of global politics, economics and society to ensure a fairer distribution of resources, a rapid phase-out of fossil fuels and the widespread adoption of low-carbon, sustainable technologies and lifestyles, it said.

This would probably mean that limits have to be placed on excess consumption and that taxes have to be used to address inequality and raise revenue for investment in technology and infrastructure.

The scale of the required change will alarm many governments, acknowledged one of the lead authors. “It won’t be immediately welcomed. To some extent, it is frightening, but it shows that there is still a space for people and other species,” said Joyeeta Gupta, a former co-chair of the Earth Commission and a professor of environment and development in the global south at the University of Amsterdam..."

cross-posted from: https://lemmy.world/post/19669541

We’re all doomed, says freshwater ecologist Dr Mike Joy

Earth will only remain able to provide even a basic standard of living for everyone in the future if economic systems and technologies are dramatically transformed and critical resources are more fairly used, managed and shared

Seems like we're doing the opposite with wider support by voters for the orthdoxy of destruction. Even then I remain sceptical.

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Abstract

The 2023 Canadian forest fires have been extreme in scale and intensity with more than seven times the average annual area burned compared to the previous four decades1. Here, we quantify the carbon emissions from these fires from May to September 2023 on the basis of inverse modelling of satellite carbon monoxide observations. We find that the magnitude of the carbon emissions is 647 TgC (570–727 TgC), comparable to the annual fossil fuel emissions of large nations, with only India, China and the USA releasing more carbon per year2. We find that widespread hot–dry weather was a principal driver of fire spread, with 2023 being the warmest and driest year since at least 19803. Although temperatures were extreme relative to the historical record, climate projections indicate that these temperatures are likely to be typical during the 2050s, even under a moderate climate mitigation scenario (shared socioeconomic pathway, SSP 2–4.5)4. Such conditions are likely to drive increased fire activity and suppress carbon uptake by Canadian forests, adding to concerns about the long-term durability of these forests as a carbon sink5,6,7,8.

Summary

Background

Inadequate micronutrient intakes and related deficiencies are a major challenge to global public health. Analyses over the past 10 years have assessed global micronutrient deficiencies and inadequate nutrient supplies, but there have been no global estimates of inadequate micronutrient intakes. We aimed to estimate the global prevalence of inadequate micronutrient intakes for 15 essential micronutrients and to identify dietary nutrient gaps in specific demographic groups and countries.

Methods

In this modelling analysis, we adopted a novel approach to estimating micronutrient intake, which accounts for the shape of a population's nutrient intake distribution and is based on dietary intake data from 31 countries. Using a globally harmonised set of age-specific and sex-specific nutrient requirements, we then applied these distributions to publicly available data from the Global Dietary Database on modelled median intakes of 15 micronutrients for 34 age–sex groups from 185 countries, to estimate the prevalence of inadequate nutrient intakes for 99·3% of the global population.

Findings

On the basis of estimates of nutrient intake from food (excluding fortification and supplementation), more than 5 billion people do not consume enough iodine (68% of the global population), vitamin E (67%), and calcium (66%). More than 4 billion people do not consume enough iron (65%), riboflavin (55%), folate (54%), and vitamin C (53%). Within the same country and age groups, estimated inadequate intakes were higher for women than for men for iodine, vitamin B12, iron, and selenium and higher for men than for women for magnesium, vitamin B6, zinc, vitamin C, vitamin A, thiamin, and niacin.

Abstract

Global climate change disrupts key ecological processes and biotic interactions. The recent increase in heatwave frequency and severity prompts the evaluation of physiological processes that ensure the maintenance of vital ecosystem services such as pollination. We used experimental heatwaves to determine how high temperatures affect the bumblebees’ ability to detect floral scents. Heatwaves induced strong reductions in antennal responses to floral scents in both tested bumblebee species (Bombus terrestris and Bombus pascuorum). These reductions were generally stronger in workers than in males. Bumblebees showed no consistent pattern of recovery 24 h after heat events. Our results suggest that the projected increased frequency and severity of heatwaves may jeopardize bumblebee-mediated pollination services by disrupting the chemical communication between plants and pollinators. The reduced chemosensitivity can decrease the bumblebees’ abilities to locate food sources and lead to declines in colonies and populations.