The study, published in Proceedings of the National Academy of Sciences (PNAS), used sedimentary ancient DNA to uncover evidence of temperate trees such as oak, elm, and hazel more than 16,000 years ago. Researchers also detected DNA from a tree genus thought to have disappeared from the region around 400,000 years ago. In addition, the results suggest that parts of Doggerland persisted through major flooding events, including the Storegga tsunami about 8,150 years ago, with some areas remaining above water until roughly 7,000 years ago.

Professor Robin Allaby at University of Warwick and lead author of this study says: “By analyzing sedaDNA from Southern Doggerland at a scale not seen before, we have reconstructed the environment of this lost land from the end of the last Ice Age until the North Sea arrived. We unexpectedly found trees thousands of years earlier than anyone expected — and evidence that the North Sea fully formed later than previously thought.

“From a human perspective, this is the best evidence that Doggerland’s wooded environment could have supported early Mesolithic communities prior to flooding and may help explain why relatively little early Mesolithic evidence survives on mainland Britain today.”

Reconstructing the Lost Landscape of Doggerland

Doggerland once formed a land bridge connecting Britain to mainland Europe before rising sea levels submerged it, creating the modern North Sea. While scientists have long known the region was eventually forested, the timing of when trees first took hold and how suitable the environment was for early humans has remained uncertain.

To investigate, researchers analyzed sedimentary ancient DNA from 252 samples taken from 41 marine cores along the prehistoric Southern River (chosen for its well-preserved sediments and potential to reveal past habitats). This approach allowed them to trace the ecological history of Doggerland from about 16,000 years ago until it disappeared beneath the sea.

Their findings show that temperate woodland species, including oak, elm, and hazel, were present much earlier than suggested by pollen records from Britain. Lime (Tilia), a tree that prefers warmer conditions, also appeared around 2,000 years earlier than previously recorded in mainland Britain, indicating that parts of Doggerland may have acted as a northern refuge during the last Ice Age.

In another unexpected result, the team identified DNA from Pterocarya, a relative of walnut believed to have vanished from north-western Europe about 400,000 years ago. This suggests the species survived in the region far longer than previously thought.

New Insights Into Ice Age Europe and Early Humans

The findings add to growing evidence that small, protected areas known as “microrefugia” allowed temperate plant species to survive harsh Ice Age conditions in northern Europe. These refuges may help explain Reid’s Paradox — how forests were able to spread so quickly across the region after the last Ice Age ended.

The presence of woodland ecosystems in southern Doggerland 16,000 years ago also suggests the area could have supported abundant wildlife and provided valuable resources for humans, including animals such as boars. This would place a rich environment in the region thousands of years before the appearance of early groups like the Maglemosian culture around 10,300 years ago.

Co-author, Professor Vincent Gaffney at University of Bradford says, “For many years, Doggerland was often described as a land bridge – only significant as a route for prehistoric settlement of the British Isles. Today, we understand that Doggerland was not only a heartland of early human settlement, but also that the presence of the land mass may have provided a refuge for plants and animals and acted as a fulcrum for how prehistoric communities settled and resettled northern Europe over millennia.”

An international team of scientists led by the University of Portsmouth has completed a large global study of these so-called surging glaciers. The research looks at the risks they pose and how climate change is reshaping when and where these sudden events occur.

What Causes Glacier Surges

A glacier surge happens when ice that normally moves slowly suddenly speeds up. During these periods, large amounts of ice are pushed quickly toward the glacier’s front, often causing it to advance. These surges can last for several years, and many glaciers go through repeated cycles, with long quiet periods in between.

The study, published in Nature Reviews Earth and Environment, brought together data on more than 3,100 glaciers that have experienced surges. Instead of being evenly spread around the globe, they are concentrated in specific regions, including the Arctic, High Mountain Asia, and the Andes.

Researchers analyzed how these glaciers work, what conditions lead to surges, and where they are most likely to occur. The study also maps their global distribution and explains why they cluster in certain climates.

“Surge-type glaciers are very unusual and can be troublesome,” said lead author Dr. Harold Lovell, Senior Lecturer and glaciologist from the University of Portsmouth’s School of the Environment and Life Sciences. “As a friend and fellow glaciologist once put it, they save up ice like a savings account and then spend it all very quickly like a Black Friday event. But while they only represent 1 per cent of all glaciers worldwide, they affect just under one-fifth of global glacier area, and their behavior can result in serious and sometimes catastrophic natural disasters that affect thousands of people.”

Why Surging Glaciers Are Vulnerable

The findings show that these glaciers are not protected from climate change. In fact, surging activity can make them more sensitive. During surges, they can lose large amounts of ice, contributing significantly to ice loss in some regions.

Six Major Hazards Linked to Glacier Surges

The study highlights six main dangers that surging glaciers can create for nearby communities, especially in mountainous areas:

• Glacier advance — ice can move over buildings, roads, and farmland
• River blockages — glaciers can dam rivers, forming unstable lakes that may burst and cause severe flooding
• Meltwater outbursts from beneath the glacier — sudden releases of water can also trigger destructive floods
• Sudden detachments of glaciers — these events can produce large avalanches of ice and rock
• Widespread crevassing — fast-moving ice creates deep cracks, making travel extremely dangerous where glaciers are used as routes between settlements or for tourism and climbing
• Iceberg hazards — when glaciers surge into the ocean, they can release many icebergs quickly, posing risks to ships and marine tourism

Using this information, scientists identified 81 glaciers that present the greatest threat when they surge. Many of these are located in the Karakoram Mountains in High Mountain Asia, where populated valleys and key infrastructure sit directly below them. These glaciers tend to be large, close to people, and prone to repeated surging.

Climate Change Is Increasing Uncertainty

One of the most concerning conclusions is that warming temperatures are changing how glacier surges behave, making them harder to predict at a time when accurate forecasts are critical.

“By drawing on previous studies, we have been able to piece together the growing body of evidence that shows how climate change is affecting glacier surges, including where and how often they happen,” Dr. Lovell said. “This includes instances of extreme weather such as heavy rainfall events or very warm summers triggering earlier than expected surges, suggesting an increasing unpredictability in their behavior.”

The overall picture is complex and varies by region. In some places, surges are happening more often than in the past. In others, they are becoming less frequent. Some glaciers have thinned so much that they may no longer be able to build up enough ice to surge again.

Shifting Patterns Around the World

Surging glaciers are currently concentrated in the Arctic and sub-Arctic (48 percent) and High Mountain Asia (50 percent), where climate conditions support this behavior. However, continued warming could change where surges occur.

In regions like Iceland, where glaciers are shrinking quickly, surges may largely disappear. In contrast, parts of High Mountain Asia and the Canadian and Russian Arctic could see more frequent surges due to warmer conditions and increased meltwater. There is even the possibility that surging glaciers could emerge in new areas, such as the Antarctic Peninsula.

Co-author Professor Gwenn Flowers, from Simon Fraser University in Canada, said: “The challenge we face is that just as we’re starting to develop a more comprehensive understanding of the mechanisms behind glacier surges, climate change is rewriting the rules. Extreme weather events that might have been rare even 50 years ago could become triggers for unexpected surges. Given that surges cause hazards in some settings, this makes protecting vulnerable communities much more difficult.”

The Need for Better Monitoring and Forecasting

Dr. Lovell added: “This research is extremely important because understanding which regions have concentrations of surging glaciers helps us plan monitoring efforts and understand future behavior. Knowing which specific glaciers pose the greatest risks can help protect communities, especially those most at risk. But the increasing unpredictability means we need much better surveillance and forecasting capabilities.”

The researchers stress that ongoing satellite monitoring, more field observations during surges, improved modeling, and better projections are essential. These efforts will help scientists understand how surging glaciers will respond to continued climate warming and how to reduce the risks they pose to communities around the world.

Key Points

• Scientists have identified more than 3,100 surging glaciers worldwide, with most grouped in key regions such as the Arctic, High Mountain Asia, and the Andes
• Researchers pinpointed 81 glaciers as especially dangerous, many in the Karakoram Mountains where surges could directly impact nearby communities and critical infrastructure
• Climate change is making these surges harder to predict, with extreme weather events like heavy rain and unusually warm periods now capable of triggering earlier and more unexpected activity

The author stresses that there is no simple solution for losing weight and keeping it off. Regular exercise and a balanced, healthy diet remain essential. In addition, the long term effects of consuming large amounts of carbonated water are still unclear.

Sparkling water is often seen as a helpful tool because it can create a feeling of fullness, which may reduce hunger. It has also been suggested that it could speed up digestion and help lower blood glucose levels, leading some to view it as a potential aid for weight loss.

Unclear Mechanisms Behind Blood Sugar Effects

Despite these claims, the exact way carbonated water might lower blood glucose is not well understood. It is also unclear how any such effect would translate into meaningful weight management benefits.

To explore this further, the author compared drinking fizzy water to hemodialysis, a medical process in which blood is filtered (dialyzed) to remove waste and excess fluid when the kidneys can no longer perform this function. This comparison draws on findings from earlier research.

What Hemodialysis Reveals About Glucose Use

During hemodialysis, the blood becomes more alkaline, mainly due to the production of carbon dioxide (CO₂). In a similar way, the CO₂ in carbonated water is absorbed through the stomach lining and quickly converted into bicarbonate (HCO₃) within red blood cells. This shift toward alkalinity may activate certain enzymes that increase how quickly glucose is absorbed and used by the body.

Observations from clinical settings show that blood glucose levels drop as blood moves through the dialyzer, even when the starting glucose level in the dialysate solution is higher.

Why the Real World Impact Is Small

Although these findings suggest that fizzy water could slightly improve how the body uses glucose, the overall impact is very limited. Context is important, the author notes.

In a standard 4 hour hemodialysis session, about 48000 ml of blood passes through the dialyzer. This process results in roughly 9.5 g of glucose being used.

“Given this minimal glucose reduction, the impact of CO₂ in carbonated water is not a standalone solution for weight loss. A balanced diet and regular physical activity remain crucial components of sustainable weight management,” he insists.

Possible Digestive Side Effects

The author also points out that carbonated water can affect the digestive system, especially in people with sensitive stomachs or existing gastrointestinal issues.

“Also, drinking carbonated water can have some effects on the digestive system, particularly for individuals with sensitive stomachs or pre-existing gastrointestinal conditions. The primary concerns include bloating, gas and, in some cases, exacerbation of certain symptoms associated with digestive disorders, such as irritable bowel syndrome or gastro-oesophageal reflux disease,” he explains.

“Moderation is key to avoiding discomfort while still enjoying the possible metabolic benefits of carbonated water,” he says.

Experts Urge Caution

Professor Sumantra Ray, Executive Director of the NNEdPro Global Institute for Food, Nutrition and Health, which co-owns the journal, emphasized that the findings are still preliminary.

“While there is a hypothetical link between carbonated water and glucose metabolism this has yet to be tested in well designed human intervention studies.

“And although this study adds to the evidence base, it doesn’t provide sufficient evidence on which to make recommendations for the preventive or therapeutic use of carbonated water. Additionally, any potential benefits must be weighed up against the potential harms of carbonated drinks which may contain sodium, glucose, or other additives.”