Collapse

Editor’s summary

The mid-Pleistocene transition (MPT), approximately 1.25 to 0.85 million years ago, was a period during which the glacial cycle changed from 41,000 years to 100,000 years in duration. It is widely believed that the cause of the MPT was a slowdown of deep ocean circulation punctuated by a collapse at about 0.90 million years ago. Hines et al. found no evidence of a dramatic change in deep ocean circulation over the MPT, only modest ocean circulation adjustments. Their data also illustrate how the deep ocean is able to sequester carbon dioxide without substantial changes in circulation geometry. —Jesse Smith

Abstract

The mid-Pleistocene transition (MPT) [~1.25 to 0.85 million years ago (Ma)] marks a shift in the character of glacial-interglacial climate (1, 2). One prevailing hypothesis for the origin of the MPT is that glacial deep ocean circulation fundamentally changed, marked by a circulation “crisis” at ~0.90 Ma (marine isotope stages 24 to 22) (3). Using high-resolution paired neodymium, carbon, and oxygen isotope data from the South Atlantic Ocean (Cape Basin) across the MPT, we find no evidence of a substantial change in deep ocean circulation. Before and during the early MPT (~1.30 to 1.12 Ma), the glacial deep ocean variability closely resembled that of the most recent glacial cycle. The carbon storage facilitated by developing deep ocean stratification across the MPT required only modest circulation adjustments.

Abstract

Microplastics (MP) are ubiquitous in the environment; their atmospheric relevance is being increasingly recognized. Because of their atmospheric concentrations, there is the question of whether MP can act as ice nucleating particles in the atmosphere. This study investigates the immersion freezing activity of lab-prepared MP of four different compositions─low density polyethylene (LDPE), polypropylene (PP), poly(vinyl chloride) (PVC), and poly(ethylene terephthalate) (PET)─using droplet freezing assays. The MP are also exposed to ultraviolet light, ozone, sulfuric acid, and ammonium sulfate to mimic environmental aging of the plastics to elucidate the role that these processes play in the ice nucleating activity of MP. Results show that all studied MP act as immersion nuclei, and aging processes can modify this ice nucleating activity, leading, primarily, to decreases in ice nucleating activity for LDPE, PP, and PET. The ice nucleating activity of PVC generally increased following aging, which we attribute to a cleaning of chemical defects present on the surface of the stock material. Chemical changes were monitored with infrared spectroscopy (ATR-FTIR), and the growth of a peak at 1650–1800 cm–1 was associated with a decrease in ice nucleating activity while loss of an existing peak in that region was associated with an increase in ice nucleating activity. The studied MP have ice nucleating activities sufficient to be a non-negligible source of ice nucleating particles in the atmosphere if present in sufficiently high concentrations.

Highlights

Acute exposure to phthalates affects fundamental aspects of adult brain function.

The effects are massive both with DEHP and its substitute DINP.

Both plasticizers affect neuronal signaling and central information processing.

Both offset the balance between excitation and inhibition.

Both cause a massive decline in conduction speed and potentially impact neuroglia.

Abstract

Phthalates are key additives in many plastic products and among the most frequently used plasticizers. The release of some of them into the environment has been shown to have serious effects on development and reproduction. Based on such effects, diisononyl phthalate (DINP) has been advocated as a safer alternative to di-2-ethylhexyl phthalate (DEHP). Recently, it has been suggested that DEHP may affect the vertebrate blood-brain barrier. This could have serious consequences not only for the developing, but also for the adult brain. Here we tested for such impact on neuronal function and demonstrate acute exposure effects of both plasticizers on fundamental aspects of brain function in an adult vertebrate. We used the Mauthner neuron in the hindbrain of fish and its diverse inputs from various sensory systems as a model. After exposing intact goldfish to environmentally relevant plasticizer concentration (either 100 µg L–1, or 10 µg L–1), we show from in vivo intracellular recording that one month of environmental exposure to DEHP or DINP affected the sensory input to this central neuron, offset the balance between excitation and inhibition, and reduced its conduction speed by 20 %. The effects of both plasticizers were strong even at the concentration of 10 µg L–1. In an adult vertebrate, our findings thus demonstrate a previously neglected high sensitivity of various crucial brain functions to the acute exposure to phthalates.

[...]

For days, the city of 14 million people has been enveloped by smog, a mix of fog and pollutants caused by low-grade diesel fumes, smoke from seasonal agricultural burning and winter cooling.

The air quality index, which measures a range of pollutants, exceeded 1,000 on Saturday—well above the level of 300 considered "dangerous"—according to data from IQAir. The Punjab government also recorded peaks of over 1,000 on Sunday, which it considered "unprecedented".

"Weather forecast for the next six days shows that wind patterns will remain the same. Therefore we are closing all government and private primary schools in Lahore for a week," Jahangir Anwar, a senior environmental protection official in Lahore told AFP.

[...]

"This smog is very harmful for children. Masks should be mandatory in schools. We are keeping an eye on the health of children in senior classes," Punjab senior minister Marriyum Aurangzeb told a news conference Sunday.

Smog counters have been established in hospitals, she added.

Breathing the toxic air has catastrophic health consequences, with the WHO saying strokes, heart disease, lung cancer and respiratory diseases can be triggered by prolonged exposure.

[...]

Government offices and private companies will have half their staff work from home starting Monday.

Children are particularly vulnerable because they have less developed lungs and breathe more rapidly, taking in more air relative to their size than adults.

Last month, authorities banned schoolchildren from outdoor exercise until January and adjusted school hours to prevent children from traveling when the pollution is most punishing.

Pollution in excess of levels deemed safe by the WHO shortens the life expectancy of Lahore residents by an average of 7.5 years, according to the University of Chicago's Energy Policy Institute.

According to UNICEF, nearly 600 million children in South Asia are exposed to high levels of air pollution and half of childhood pneumonia deaths are associated with air pollution.

Signs that progress was lacking were clear from the outset of the meeting, with nearly all countries missing a deadline to submit official plans on how they will achieve the ambitious biodiversity targets set two years ago at COP15, including protecting 30 per cent of the planet’s land and oceans by 2030. A few more of these plans trickled in during the two weeks of the summit, including those from large countries like India and Argentina, but most countries’ strategies are still missing.

Going into COP16, it was clear the world is not on track to hit those targets. Since 2020, the area of the planet’s land and oceans under formal protections has increased just 0.5 per cent, according to a UN report released during the summit. That is a rate far too slow to protect 30 per cent of the planet by the end of the decade.

[...]

Many lower-income countries said their failure to develop and submit plans by the deadline, let alone to begin carrying them out, was due to a dearth of financial resources. COP16 did see higher-income countries make pledges – totalling about $400 million – to help these efforts, but funds remain billions short of the $20 billion annual goal promised by 2025.

[...]

Although COP16’s failure to move the needle on finance disappointed observers, the meeting did manage one key agreement: a deal on how to collect revenue from products developed using the planet’s genetic data. Before the meeting was suspended, countries agreed to urge pharmaceutical and other biotech companies that use such “digital sequence information” to contribute 0.1 per cent of revenue or 1 per cent of profits to a “Cali Fund”. This fund will be used to protect the biodiversity that is the source of such genetic data.

Submitter's note: It seems this voluntary tax is expected to support primarily indigenous populations. But without funding for biodiversity protection plans, habitat destruction will continue largely unabated. The voluntary tax itself would be woefully insufficient for empowering local populations to protect their ecosystems or their traditional lifestyles.

[...] UN estimates suggest the fund could raise up to a billion dollars a year for biodiversity. “It might raise some, but at nowhere near the scale or speed required,” says Pierre du Plessis, a long-time negotiator for the African Union.

[...]

[T]he overall mood was dour. “A real shame of COP16 is that [debates on] digital sequence information sucked up the last drops of energy and time,” says Amber Scholz at the Leibniz Institute DSMZ in Germany.

One reason for the apparent lack of urgency is that the world treats climate change and biodiversity loss as two separate issues. The annual global climate summits are better attended and receive far more attention than the biodiversity negotiation – only six heads of state attended COP16, compared with the 154 who went to last year’s climate summit in Dubai, United Arab Emirates. That is a problem when the two issues are intertwined: climate change is one of the main threats to biodiversity, and the most biodiverse ecosystems are often also the best at storing carbon.

Abstract

Unabated 21st-century climate change will accelerate Arctic-Subarctic permafrost thaw which can intensify microbial degradation of carbon-rich soils, methane emissions, and global warming. The impact of permafrost thaw on future Arctic-Subarctic wildfires and the associated release of greenhouse gases and aerosols is less well understood. Here we present a comprehensive analysis of the effect of future permafrost thaw on land surface processes in the Arctic-Subarctic region using the CESM2 large ensemble forced by the SSP3-7.0 greenhouse gas emission scenario. Analyzing 50 greenhouse warming simulations, which capture the coupling between permafrost, hydrology, and atmosphere, we find that projected rapid permafrost thaw leads to massive soil drying, surface warming, and reduction of relative humidity over the Arctic-Subarctic region. These combined processes lead to nonlinear late-21st-century regime shifts in the coupled soil-hydrology system and rapid intensification of wildfires in western Siberia and Canada.

Abstract

The growth rate of the atmospheric abundance of methane (CH4) reached a record high of 15.4 ppb yr−1 between 2020 and 2022, but the mechanisms driving the accelerated CH4 growth have so far been unclear. In this work, we use measurements of the 13C:12C ratio of CH4 (expressed as δ13CCH4) from NOAA’s Global Greenhouse Gas Reference Network and a box model to investigate potential drivers for the rapid CH4 growth. These measurements show that the record-high CH4 growth in 2020–2022 was accompanied by a sharp decline in δ13CCH4, indicating that the increase in CH4 abundance was mainly driven by increased emissions from microbial sources such as wetlands, waste, and agriculture. We use our box model to reject increasing fossil fuel emissions or decreasing hydroxyl radical sink as the dominant driver for increasing global methane abundance.

Abstract

Under the Paris Agreement, signatory nations aim to keep global warming well below 2 °C above pre-industrial levels and preferably below 1.5 °C. This implicitly requires achieving net-zero or net-negative greenhouse gas emissions to ensure long-term global temperature stabilisation or reduction. Despite this requirement, there have been few analyses of stabilised climates, and there is a lack of model experiments to address our need for understanding the implications of the Paris Agreement. Here, we describe a new set of experiments using the Australian Community Climate and Earth System Simulator Earth system model (ACCESS-ESM-1.5) that enables the analysis of climate evolution under net-zero emissions, and we present initial results. Seven 1000-year-long simulations were run with global temperatures stabilising at levels in line with the Paris Agreement and at a range of higher global warming levels (GWLs). We provide an overview of the experimental design and use these simulations to demonstrate the consequences of delayed attainment of global net-zero carbon dioxide emissions. We show that there are substantial differences between transient and stabilising climate states and differences in stabilisation between GWLs. As the climate stabilises under net-zero emissions, we identify significant and robust changes in temperature and precipitation patterns including continued Southern Ocean warming and changes in regional precipitation trends. Changes under net-zero emissions differ greatly between regions, including contrasting trajectories of sea ice extent between the Arctic and Antarctic. We also examine the El Niño–Southern Oscillation (ENSO) and find evidence of reduced amplitude and frequency of ENSO events under climate stabilisation relative to projections under transient warming. An analysis at specific GWLs shows that significant regional changes continue for centuries after emission cessation and that these changes are stronger at higher GWLs. Our findings suggest substantial long-term climate changes are possible even under net-zero emission pathways. These simulations are available for use in the community and will hopefully motivate further experiments and analyses based on other Earth system models.

Sustainable planet for all, for very small values thereof.