Explore the latest insights from top science journals in the Muser Press daily roundup, featuring impactful research on climate change challenges.
In brief:
The ozone hole is healing, thanks to global reduction of CFCs
Scientists including the MIT team have observed signs of ozone recovery in the past. But a new study is the first to show, with high statistical confidence, that this recovery is due primarily to the reduction of ozone-depleting substances, versus other influences such as natural weather variability or increased greenhouse gas emissions to the stratosphere.
“There’s been a lot of qualitative evidence showing that the Antarctic ozone hole is getting better. This is really the first study that has quantified confidence in the recovery of the ozone hole,” says study author Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies and Chemistry. “The conclusion is, with 95 percent confidence, it is recovering. Which is awesome. And it shows we can actually solve environmental problems.”
The new study is published in the journal Nature. Graduate student Peidong Wang from the Solomon group in the Department of Earth, Atmospheric and Planetary Sciences (EAPS) is the lead author. His co-authors include Solomon and EAPS Research Scientist Kane Stone, along with collaborators from multiple other institutions.
Roots of ozone recovery
Within the Earth’s stratosphere, ozone is a naturally occurring gas that acts as a sort of sunscreen, protecting the planet from the sun’s harmful ultraviolet radiation. In 1985, scientists discovered a “hole” in the ozone layer over Antarctica that opened up during the austral spring, between September and December. This seasonal ozone depletion was suddenly allowing UV rays to filter down to the surface, leading to skin cancer and other adverse health effects.
In 1986, Solomon, who was then working at the National Oceanic and Atmospheric Administration (NOAA), led expeditions to the Antarctic, where she and her colleagues gathered evidence that quickly confirmed the ozone hole’s cause: chlorofluorocarbons, or CFCs — chemicals that were then used in refrigeration, air conditioning, insulation, and aerosol propellants. When CFCs drift up into the stratosphere, they can break down ozone under certain seasonal conditions.
The following year, those relevations led to the drafting of the Montreal Protocol — an international treaty that aimed to phase out the production of CFCs and other ozone-depleting substances, in hopes of healing the ozone hole.
In 2016, Solomon led a study reporting key signs of ozone recovery. The ozone hole seemed to be shrinking with each year, especially in September, the time of year when it opens up. Still, these observations were qualitative. The study showed large uncertainties regarding how much of this recovery was due to concerted efforts to reduce ozone-depleting substances, or if the shrinking ozone hole was a result of other “forcings,” such as year-to-year weather variability from El Niño, La Niña, and the polar vortex.
“While detecting a statistically significant increase in ozone is relatively straightforward, attributing these changes to specific forcings is more challenging,” says Wang.
Anthropogenic healing
In their new study, the MIT team took a quantitative approach to identify the cause of Antarctic ozone recovery. The researchers borrowed a method from the climate change community, known as “fingerprinting,” which was pioneered by Klaus Hasselmann, who was awarded the Nobel Prize in Physics in 2021 for the technique. In the context of climate, fingerprinting refers to a method that isolates the influence of specific climate factors, apart from natural, meteorological noise. Hasselmann applied fingerprinting to identify, confirm, and quantify the anthropogenic fingerprint of climate change.
Solomon and Wang looked to apply the fingerprinting method to identify another anthropogenic signal: the effect of human reductions in ozone-depleting substances on the recovery of the ozone hole.
“The atmosphere has really chaotic variability within it,” Solomon says. “What we’re trying to detect is the emerging signal of ozone recovery against that kind of variability, which also occurs in the stratosphere.”
The researchers started with simulations of the Earth’s atmosphere and generated multiple “parallel worlds,” or simulations of the same global atmosphere, under different starting conditions. For instance, they ran simulations under conditions that assumed no increase in greenhouse gases or ozone-depleting substances. Under these conditions, any changes in ozone should be the result of natural weather variability. They also ran simulations with only increasing greenhouse gases, as well as only decreasing ozone-depleting substances.
They compared these simulations to observe how ozone in the Antarctic stratosphere changed, both with season, and across different altitudes, in response to different starting conditions. From these simulations, they mapped out the times and altitudes where ozone recovered from month to month, over several decades, and identified a key “fingerprint,” or pattern, of ozone recovery that was specifically due to conditions of declining ozone-depleting substances.
The team then looked for this fingerprint in actual satellite observations of the Antarctic ozone hole from 2005 to the present day. They found that, over time, the fingerprint that they identified in simulations became clearer and clearer in observations. In 2018, the fingerprint was at its strongest, and the team could say with 95 percent confidence that ozone recovery was due mainly to reductions in ozone-depleting substances.
“After 15 years of observational records, we see this signal to noise with 95 percent confidence, suggesting there’s only a very small chance that the observed pattern similarity can be explained by variability noise,” Wang says. “This gives us confidence in the fingerprint. It also gives us confidence that we can solve environmental problems. What we can learn from ozone studies is how different countries can swiftly follow these treaties to decrease emissions.”
If the trend continues, and the fingerprint of ozone recovery grows stronger, Solomon anticipates that soon there will be a year, here and there, when the ozone layer stays entirely intact. And eventually, the ozone hole should stay shut for good.
“By something like 2035, we might see a year when there’s no ozone hole depletion at all in the Antarctic. And that will be very exciting for me,” she says. “And some of you will see the ozone hole go away completely in your lifetimes. And people did that.”
***
This research was supported, in part, by the National Science Foundation and NASA.
Journal Reference:
Wang, P., Solomon, S., Santer, B.D. et al., ‘Fingerprinting the recovery of Antarctic ozone’, Nature (2025). DOI: 10.1038/s41586-025-08640-9
Article Source:
Press Release/Material by Jennifer Chu, MIT News | Massachusetts Institute of Technology (MIT)
The pot is already boiling for 2% of the world’s amphibians: new study
Scientists will be able to better identify what amphibian species and habitats will be most impacted by climate change, thanks to a new study by UNSW researchers.
Amphibians are the world’s most at-risk vertebrates, with more than 40% of species listed as threatened – and losing entire populations could have catastrophic flow-on effects.
Being ectothermic – regulating their body heat by external sources – amphibians are particularly vulnerable to temperature change in their habitats.
Despite this, the resilience of amphibians to rising temperatures has been poorly understood, with limited data for scientists to draw on.
But now, UNSW researchers have found out how to predict the heat tolerance of 60% of the world’s amphibian species – and they’ve shared their landmark findings in a study published in Nature.
Quantifying the resilience of biodiversity to a changing climate is one of the most pressing challenges for contemporary science, says Dr Patrice Pottier, UNSW post-doctoral researcher and lead author on the paper.
“We wanted to better understand the risk climate change poses to amphibians, and so put together the most comprehensive compilation of heat tolerance limits to date,” Dr Pottier says.
“Heat tolerance limits are the maximum temperature amphibians can tolerate before their physiological systems fail,” he explains.
The scientists used 2,661 heat tolerance limit estimates from 524 species to generate data for 5,203 species through data imputation – a statistical method that fills in missing information using patterns from existing data.
“In this case, it predicts heat tolerance limits for species we do not have data for by looking at how heat tolerance is linked to factors like habitat type, environmental temperature, and evolutionary history,” says Dr Pottier.
A novel approach to estimate vulnerability
To assess how vulnerable amphibians are to climate warming, the researchers first estimated the body temperatures amphibians would experience in different microhabitats – terrestrial, arboreal and aquatic.
“We assumed a best-case scenario, where they stay in the shade and keep their skin wet, which could help them survive extreme heat,” says Dr Pottier.
Since extreme heat events are the biggest threat to survival, the researchers then analysed daily temperature patterns over the past decade to see how often amphibians might face dangerously high temperatures.
Finally, they compared these temperatures to the amphibians’ known heat tolerance limits and projected how often these limits might be exceeded under different global warming scenarios (current, +2°C, +4°C) across their geographic range.
Study findings
“We found that 104 out of 5,203 species – 2 % – are already exposed to overheating in shaded terrestrial conditions. And a 4°C global temperature increase could push 7.5% of species beyond their physiological limits,” Dr Pottier says.
The study challenges the view of areas most at risk, which has previously been often based on a general latitude gradient to assess overheating risk.
“It has previously been often assumed that species closer to the equator are at greater risk from overheating due to climate change than those in temperate regions,” says Dr Pottier.
“However, our study found that tropical species in the Southern Hemisphere are the most impacted by overheating events, while non-tropical species are more impacted in the Northern Hemisphere.
“Assuming that all tropical species are more vulnerable than temperate species can be misleading. What matters is assessing if the area is going to experience extreme heat events relative to the species’ heat tolerance. This requires stepping away from general trends, and identifying specific areas and species at risk.”
Mapping the daily temperature fluctuations across regions gives a much clearer picture of how amphibians will be affected by higher temperatures, and highlights the escalating impacts of climate warming.
“Impacts escalate under different climate warming scenarios. There is an increase in impact between the current climate and +2C of warming; but impacts increase disproportionally under +4C of warming,” says Dr Pottier.
“This step-change impact severity shows that going above +2C of global warming can be a tipping point where we may see a lot of local extinctions,” he says.
Local extinctions can lead to ecological repercussions, such as reshuffling community compositions, eroding genetic diversity and impacts to the food chain and health of the ecosystem.
“Some amphibian populations may undergo range shifts to more hospitable habitats, but opportunities for this are likely limited due to low dispersal rates and reliance on water bodies,” says Dr Pottier.
“Amphibians are an important part of the ecosystem. For example, the loss of an amphibian population would likely lead to an increase in insect population with carry-over effects on plants and animals. They are prey for many animals and their loss would have knock-on effects on many other species,” says Dr Pottier.
“Beside ecosystem impacts, amphibians are deeply rooted in human cultures and it would be a shame to lose such beautiful and emblematic species.”
Next steps
Microhabitat selection is important for amphibians as some species live primarily on the ground, in vegetation, or in water; and some can move between those different habitats.
The study’s habitat specific predictions offer clear management priorities for conservation managers.
“Our analyses made it clear that vegetation and water bodies are critical in buffering amphibians during heat waves,” says Dr Pottier.
“We found that if you provide amphibians with enough water and enough shade, a lot of them can survive extreme heat events. We must protect and restore the environments that allow them to regulate their body temperature,” Dr Pottier says.
“We used very conservative estimates in this study assuming access to cool shaded environments. Therefore, the impacts of global warming will likely exceed our projections,” says Dr Pottier. “So all efforts to limit global warming are needed to protect the world’s amphibians.”
Journal Reference:
Pottier, P., Kearney, M.R., Wu, N.C. et al., ‘Vulnerability of amphibians to global warming’, Nature (2025). DOI: 10.1038/s41586-025-08665-0
Article Source:
Press Release/Material by Samantha Dunn | University of New South Wales
Putting vegetarian options higher up on hotel menus could reduce carbon emissions
Changing our dining habits in hotels could significantly reduce carbon emissions by simply arranging restaurant menus differently, which can lead to a dramatic increase in vegetarian orders, according to a new study from the University of Surrey.
By redesigning hotel menus to prioritise vegetarian and plant-based options, hotels can reduce their environmental impact. Implementing behavioural interventions, such as strategically framing vegetarian dishes as the first choice on menus, can guide guests toward more sustainable dining decisions. Such approaches not only align with the growing consumer demand for environmentally friendly options but also contribute to the reduction of greenhouse gas emissions associated with food choices.
The study, published in Journal of Sustainable Tourism, conducted a series of covert field experiments across two hotel restaurants, engaging 647 participants in various menu conditions. Participants were exposed to either the default menu or one of three intervention menus designed to encourage vegetarian choices. The interventions tested included cognitive nudges, based on the bandwagon effect, and behavioural nudges using framing and anchoring techniques that altered the presentation of menu options.
The results were clear: behavioural nudges were significantly more effective in increasing vegetarian orders compared to cognitive messaging.
Sofie Voss, lead author of the study and PhD researcher at the University of Surrey said: “By simply restructuring how hotels present food options, they can enable guests to make more sustainable choices. It’s not merely about reducing meat consumption; it’s about creating an environment where plant-based choices are the norm rather than the exception.”
Food consumption accounts for a staggering share of global greenhouse gas emissions, with high-emission foods such as meat contributing disproportionately to the problem. The study highlights the urgent need for the hospitality sector to rethink its menu strategies to combat these pressing environmental challenges. With nearly a third of global emissions attributed to food systems, the research suggests that hotels play a crucial role in shaping sustainable dining experiences.
Sofie Voss continued: “The hospitality sector stands at a crossroads, with an opportunity to lead the charge in sustainable dining practices. By reimagining menu designs and embracing behavioural nudges, hotels can significantly reduce their environmental impact and contribute to a more sustainable future.”
Journal Reference:
Voss, S., Andre, H., Kock, F., Karl, M., & Josiassen, A., ‘Guiding pro-environmental behaviour: examining the impact of cognitive and behavioural interventions on sustainable food choices in hospitality’, Journal of Sustainable Tourism, 1–21 (2024). DOI: 10.1080/09669582.2024.2439983
Article Source:
Press Release/Material by Georgie Gould | University of Surrey
Featured image credit: Gerd Altmann | Pixabay
