The collapse of tropical forests during Earth’s most catastrophic extinction event was the primary cause of the prolonged global warming that followed, according to new research.

The Permian-Triassic Mass Extinction – sometimes referred to as the “Great Dying,” happened around 252 million years ago, leading to the massive loss of marine species and significant declines in terrestrial plants and animals.

For decades, scientists have been unable to pinpoint why super-greenhouse conditions persisted for around five million years afterwards. Now a team of international researchers has gathered new data that supports the theory that the demise of tropical forests and their slow recovery limited carbon sequestration – a process where carbon dioxide is removed from the atmosphere and held in plants, soils, or minerals.

The researchers used a new type of analysis of fossil records as well as clues about past climate conditions found in certain rock formations to reconstruct maps of changes in plant productivity during the Permian-Triassic Mass Extinction. Their results show that vegetation loss during the event led to greatly reduced levels of carbon sequestration, resulting in a prolonged period with high levels of CO2.

The paper’s lead author, Dr. Zhen Xu from the University of Leeds, said: “The causes of such extreme warming during this event have been long discussed, as the level of warming is far beyond any other event.”

Critically, this is the only high-temperature event in Earth’s history where the tropical forest biosphere collapses, which drove our initial hypothesis. Now, after years of fieldwork, analysis, and simulations, we finally have the data that supports it.

The researchers believe their results reinforce the idea that thresholds or ‘tipping points’ exist in Earth’s climate-carbon system that, when reached, mean that warming can be amplified.

China is home to the most complete geological record of the Permian-Triassic mass Extinction and this work leverages an incredible archive of fossil data gathered over decades by three generations of Chinese geologists. The lead author Dr. Zhen Xu is the youngest of these and is continuing the work begun by Professor Hongfu Yin and Professor Jianxin Yu, who are also authors of the study.

Since 2016, Zhen and her colleagues have traveled throughout China from subtropical forests to deserts, visiting areas accessible only by boat or on horseback. Zhen came to the University of Leeds in 2020 to work with Professor Benjamin Mills on simulating the extinction event and assessing the climate impacts of the loss of tropical vegetation shown by the fossil record.

Their results confirm that the change in carbon sequestration suggested by the fossils is consistent with the amount of warming that occurred afterwards. Professor Mills added: “There is a warning here about the importance of Earth’s present-day tropical forests. If rapid warming causes them to collapse in a similar manner, then we should not expect our climate to cool to preindustrial levels even if we stop emitting CO2.”

Indeed, warming could continue to accelerate in this case even if we reach zero human emissions. We will have fundamentally changed the carbon cycle in a way that can take geological timescales to recover, which has happened in Earth’s past.

Reflecting on the study’s broader mission, Professor Hongfu Yin and Professor Jianxin Yu of the China University of Geosciences underscored the urgency of blending tradition with innovation: “Paleontology needs to embrace new techniques – from numerical modeling to interdisciplinary collaboration – to decode the past and safeguard the future,” explained Professor Yin.

Professor Yu added: “Let’s make sure our work transcends academia: it is a responsibility to all life on Earth, today and beyond. Earth’s story is still being written, and we all have a role in shaping its next chapter.”

The Hidden Dangers of Air Pollution: How It Quietly Damages Your Heart

A recent study published in Radiology has made a groundbreaking discovery about the impact of air pollution on our cardiovascular system. Researchers using cardiac MRI have found that even low levels of fine particulate matter in the air can lead to early signs of heart damage, including diffuse myocardial fibrosis – a form of scarring in the heart muscle.

Cardiovascular disease is the leading cause of death worldwide, and poor air quality has been linked to increased risk of cardiac disease. However, until now, the underlying changes in the heart resulting from air pollution exposure were unclear. This study sheds light on what drives this increased risk at the tissue level, providing valuable insights for healthcare providers and policymakers.

The researchers used cardiac MRI to quantify myocardial fibrosis and assess its association with long-term exposure to PM2.5 particles – small enough to enter the bloodstream through the lungs. They evaluated the effects of air pollution on both healthy individuals and those with heart disease, involving 201 healthy controls and 493 patients with dilated cardiomyopathy.

The study revealed that higher long-term exposure to fine particulate air pollution was linked with higher levels of myocardial fibrosis in both groups, suggesting that myocardial fibrosis may be an underlying mechanism by which air pollution leads to cardiovascular complications. Notably, the largest effects were seen in women, smokers, and patients with hypertension.

This research adds to growing evidence that air pollution is a cardiovascular risk factor, contributing to residual risk not accounted for by conventional clinical predictors such as smoking or hypertension. The study’s findings have significant implications for public health measures to reduce long-term air pollution exposure.

“We know that if you’re exposed to air pollution, you’re at higher risk of cardiac disease,” said senior author Kate Hanneman, M.D., M.P.H., from the Department of Medical Imaging at the Temerty Faculty of Medicine, University of Toronto and University Health Network in Toronto. “Our study suggests that air quality may play a significant role in changes to heart structure, potentially setting the stage for future cardiovascular disease.”

Knowing a patient’s long-term air pollution exposure history could help refine heart disease risk assessment and address the health inequities that air pollution contributes to both in level of exposure and effect. For instance, if an individual works outside in an area with poor air quality, healthcare providers could incorporate that exposure history into heart disease risk assessment.

The study reinforces that there are no safe exposure limits, emphasizing the need for public health measures to further reduce long-term air pollution exposure. While improvements have been made over the past decade in Canada and the United States, there is still a long way to go.

In conclusion, this study highlights the importance of medical imaging in research and clinical developments going forward, particularly in identifying and quantifying health effects of environmental exposures.

The use of chlorothalanol, a widely applied fungicide in American agriculture, has been linked to significant harm to beneficial insects critical for pollination and ecosystem health. Research from Macquarie University has found that even low levels of this chemical can severely impact the reproduction and survival of fruit flies (Drosophila melanogaster), which are essential for pollinating various crops.

The study, published in Royal Society Open Science, exposed fruit flies to chlorothalanol concentrations typically found on produce such as cranberries and wine grapes. The results showed a 37% drop in egg production among the exposed flies compared to those that were not treated with the fungicide. This significant decline was unexpected by the researchers, who had anticipated a more gradual effect.

Chlorothalanol is used on various crops in America, including cranberries, grapes, and other fruits and vegetables. Despite being banned in the European Union, this fungicide is extensively applied to Australian crops, often preventatively when no disease is present. The use of chlorothalanol has been linked to a decline in insect populations globally, with some regions reporting drops exceeding 75% in recent decades.

Associate Professor Fleur Ponton, supervising author of the study, emphasized that bees and flies are crucial for pollination, and the impact of chlorothalanol on these insects is a significant problem. The research highlights a critical knowledge gap in pesticide regulation, with fewer than 25 scientific papers examining the effects of chlorothalanol on insects despite its widespread use.

The findings recommend more sustainable practices, including reduced application frequency to allow insect population recovery between treatments. This approach would help mitigate the damage caused by chlorothalanol and promote a healthier ecosystem for pollinators.