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Charles Darwin

Southern Ocean Cooling: A Surprising Response to Global Warming

Researchers found increased meltwater and rain explain 60% of a decades-long mismatch between predicted and observed temperatures in the ocean around Antarctica.

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The article “Southern Ocean Cooling: A Surprising Response to Global Warming” reveals that the Southern Ocean has been cooling over most of the past four decades, contradicting climate models’ predictions. Scientists have now found that this discrepancy comes down mainly to missing meltwater and underestimated rainfall.

The study’s lead author, Earle Wilson, an assistant professor of Earth system science at Stanford University, explains that rising temperatures melt Antarctica’s ice sheet, causing more precipitation in the Southern Ocean’s upper layer. This freshening creates a lid that limits the exchange of cool surface waters with warmer waters below, making it harder to mix warm water up.

However, this freshening is not fully represented in state-of-the-art climate models, which is a major source of uncertainty in projections of future sea level rise. The study’s findings suggest that missing freshwater explains up to 60% of the mismatch between observed and predicted Southern Ocean surface temperatures between 1990 and 2021.

The researchers used a collection of simulations from the recently launched Southern Ocean Freshwater Input from Antarctica (SOFIA) Initiative, as well as an older set of models simulating ocean density and circulation changes. They analyzed how much simulated sea surface temperatures changed in response to the actual freshwater inputs between 1990 and 2021.

The study’s results provide new evidence that meltwater trends are already altering ocean dynamics and possibly the global climate. The researchers highlight the importance of reconciling global discrepancies, such as the mismatch between observed and simulated sea surface temperatures around Antarctica, to improve our understanding of climate impacts.

As a result, this research has significant implications for predicting future sea level rise, ocean heat uptake, and carbon sequestration.

Charles Darwin

The 10,000-mile March Through Fire: How Dinosaurs Evolved to Thrive

Despite Earth’s most devastating mass extinction wiping out over 80% of marine life and half of land species, a group of early reptiles called archosauromorphs not only survived but thrived, venturing across the supposedly lifeless tropics to eventually evolve into the dinosaurs and crocodiles we know today. Armed with a groundbreaking model dubbed TARDIS, researchers have reconstructed their ancient dispersal routes, revealing how these resilient reptiles conquered a hostile, post-apocalyptic Earth.

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The 10,000-mile march through fire that made dinosaurs possible is a remarkable story of survival and evolution. New research suggests that the forerunners of dinosaurs and crocodiles in the Triassic period were able to migrate across areas deemed completely inhospitable to life, paving the way for the rise of these iconic creatures.

A team of researchers from the University of Birmingham and University of Bristol has used a new method of geographical analysis to infer how these ancestral reptiles, known as archosauromorphs, dispersed following one of the most impactful climate events in Earth’s history – the end-Permian mass extinction. This event saw more than half of land-based animals and 81% of marine life die.

The first archosauromorphs were previously believed to only survive in certain parts of the globe due to extreme heat across the tropics, viewed by many paleontologists as a dead zone. However, by developing a new modelling technique based on landscape reconstructions and evolutionary trees, the team has discovered clues about how these reptiles moved around the world during the Triassic period.

The archosauromorphs that survived the extinction event rose to prominence in Earth’s ecosystems in the Triassic, leading to the evolution of dinosaurs. The team now suggests that their later success was in part due to their ability to migrate up to 10,000 miles across the tropical dead zone to access new ecosystems.

Dr Joseph Flannery-Sutherland from the University of Birmingham and corresponding author of the study said: “Amid the worst climatic event in Earth’s history, where more species died than at any period since, life still survived. We know that archosauromorphs as a group managed to come out of this event and over the Triassic period became one of the main players in shaping life thereafter.”

The researchers’ findings have significant implications for our understanding of how life on Earth evolved and adapted to changing environments. As Professor Michael Benton from the University of Bristol, senior author of the study, notes: “The evolution of life has been controlled at times by the environment, but it is difficult to integrate our limited and uncertain knowledge about the ancient landscape with our limited and uncertain knowledge about the ecology of extinct organisms.”

By combining fossils with reconstructed maps of the ancient world in the context of evolutionary trees, the researchers have provided a way of overcoming these challenges. Their work offers a new perspective on the remarkable story of how dinosaurs evolved to thrive in a world previously thought to be inhospitable to life.

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Ancient DNA

Chemists Recreate a Crucial Step in the Origin of Life

Chemists have demonstrated how RNA (ribonucleic acid) might have replicated itself on early Earth — a key process in the origin of life.

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The origin of life is one of humanity’s greatest mysteries. For centuries, scientists have sought to understand how the complex systems that govern our world emerged from the simple chemistry of the early Earth. A crucial step in this process is the replication of genetic material, which would have been carried by RNA (ribonucleic acid) molecules before DNA and proteins later took over.

Chemists at UCL and the MRC Laboratory of Molecular Biology have made a groundbreaking discovery that brings us closer to understanding how life began. They’ve successfully recreated the conditions under which RNA might have replicated itself on early Earth, a key process in the origin of life.

The researchers used three-letter “triplet” RNA building blocks in water and added acid and heat, which separated the double helix structure that normally prevents RNA strands from replicating. By neutralizing and freezing the solution, they created liquid gaps between the ice crystals where the triplet building blocks could coat the RNA strands and prevent them from zipping back together, allowing replication to occur.

By repeating this cycle of changes in pH and temperature, which could plausibly occur in nature, the researchers were able to replicate RNA over and over again. This process produced RNA strands long enough to have a biological function and play a role in the origin of life.

The study’s lead author, Dr James Attwater, emphasized that replication is fundamental to biology. “In one sense, it is why we are here,” he said. “But there’s no trace in biology of the first replicator.”

The researchers believe that early life was run by RNA molecules, and their findings provide a possible explanation for how this process could have occurred before life began several billion years ago.

While the study focuses solely on the chemistry, the conditions they created could plausibly mimic those in freshwater ponds or lakes, especially in geothermal environments where heat from inside the Earth has reached the surface. However, this replication of RNA could not occur in freezing and thawing saltwater, as the presence of salt interferes with the freezing process and prevents RNA building blocks from reaching the concentration required to replicate RNA strands.

The origin of life is likely to have emerged out of a combination of RNA, peptides, enzymes, and barrier-forming lipids that can protect these ingredients from their environment. The researchers are uncovering clues about how life began, and their findings bring us closer to understanding this fundamental mystery.
In recent years, teams led by Dr John Sutherland and Professor Matthew Powner have demonstrated how chemistry could create many of the key molecules of life’s origin, including nucleotides, amino acids and peptides, simple lipids and precursors to some of the vitamins, from simple molecular building blocks likely abundant on the early Earth.

The latest study was supported by the Medical Research Council (MRC), part of UK Research and Innovation (UKRI), as well as the Royal Society and the Volkswagen Foundation.

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Biotechnology

“Uncovering Ancient Roots: A Gene’s Journey Through Evolution”

A gene that regulates the development of roots in vascular plants is also involved in the organ development of liverworts — land plants so old they don’t even have proper roots. The discovery highlights the fundamental evolutionary dynamic of co-opting, evolving a mechanism first and adopting it for a different purpose later.

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The discovery of a root development gene older than root development itself is a fascinating find in the realm of plant biology. A recent study by Kobe University researchers has shed light on this phenomenon, providing insights into the fundamental evolutionary dynamic of co-opting and adapting mechanisms for new purposes.

The gene in question, called RLF, was previously found to be essential for lateral root development in Arabidopsis thaliana, a model plant commonly used in scientific research. However, it was surprising to discover that the equivalent gene in other plants, specifically liverworts (Marchantia polymorpha), is also involved in organ development.

Liverworts are ancient land plants that lack proper roots, but they do have their own version of the RLF gene. The Kobe University researchers studied this gene’s function and compared it to its Arabidopsis counterpart. They found that liverworts lacking RLF exhibit severe deformations in various organs, demonstrating the gene’s crucial role in organ development.

Furthermore, the study showed that the Arabidopsis gene can perform its function in liverwort cells, and vice versa. This functional interchangeability between the two genes highlights their shared evolutionary history and significance in plant development.

The RLF gene produces a protein that belongs to the heme-binding proteins group, which may bind a molecule called “heme” involved in energy transfer within the cell. The discovery of this mechanism is significant, as it was previously unknown to be involved in organ development in plants.

This research has implications for our understanding of plant evolution and development. By studying how the RLF protein interacts with others, scientists can gain more insights into the evolution of plant organ development. As Kobe University researcher Hidehiro Fukaki notes, “The fact that RLF plays an important role in organ development since at least the dawn of land plants is an example of how evolution often co-opts existing mechanisms for new functions.”

This research was funded by various Japanese institutions and conducted in collaboration with researchers from several universities. The findings have been published in the journal New Phytologist, providing a valuable contribution to our understanding of plant biology and evolution.

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