In recent years, climate change has been at the forefront of global concerns, and one of the most critical regions affected by this phenomenon is Antarctica. Researchers from the University of Copenhagen have made a groundbreaking discovery that sheds new light on the mechanisms behind the collapse of Antarctic ice shelves, which are crucial for predicting sea level rise in the Northern Hemisphere.

On November 28, 1966, an American aeroplane flew over the Antarctic Peninsula, capturing an aerial photo of the Wordie Ice Shelf. This image, taken just south of the southernmost tip of Chile, marked the beginning of a unique dataset that would provide unparalleled insights into the collapse of ice shelves. The researcher’s analysis of historical aerial photos and satellite data has revealed that melting under the ice where the sea and ice meet is the primary driver of Wordie’s collapse.

The study’s findings have already altered the foundation of scientists’ knowledge about ice shelf collapse, suggesting that these events may be slower than previously thought. However, this longer process will make it even harder to reverse the trend once it has started, highlighting the urgent need to prioritize halting greenhouse gas emissions now rather than sometime in the future.

The consequences of ice shelf collapse are far-reaching and have significant implications for global sea level rise. As the glaciers lose their support, they can begin to float and melt more rapidly, contributing to rising ocean levels. Although Antarctica is far away, areas like Denmark are being affected significantly by sea level rise caused by gravitational forces.

In conclusion, the study’s findings mark a new era of climate adaptation, emphasizing the need for urgent action to address the consequences of ice shelf collapse. By prioritizing halting greenhouse gas emissions now rather than sometime in the future, we can reduce the risk of violent sea level rise and mitigate its impact on global communities.

A new study has challenged the long-held notion that a massive ice shelf once sealed the Arctic Ocean during the coldest periods of the last 750,000 years. Researchers from the European Research Council Synergy Grant project Into the Blue — i2B have found no evidence for the presence of a giant ~1km thick ice shelf, instead discovering that seasonal sea ice dominated the region.

The study, published in Science Advances, used sediment cores collected from the seafloor of the central Nordic Seas and Yermak Plateau, north of Svalbard. These cores hold tiny chemical fingerprints from algae that lived in the ocean long ago. Some of these algae only grow in open water, while others thrive under seasonal sea ice.

“Our sediment cores show that marine life was active even during the coldest times,” said Jochen Knies, lead author of the study, based at UiT The Arctic University of Norway and co-lead of the Into The Blue — i2B project. “That tells us there must have been light and open water at the surface. You wouldn’t see that if the entire Arctic was locked under a kilometre-thick slab of ice.”

One of the key indicators the team looked for was a molecule called IP25, which is produced by algae that live in seasonal sea ice. Its regular appearance in the sediments shows that sea ice came and went with the seasons, rather than staying frozen solid all year round.

To test their findings, the research team used the AWI Earth System Model to simulate Arctic conditions during two especially cold periods: the Last Glacial Maximum around 21,000 years ago, and a deeper freeze about 140,000 years ago when large ice sheets covered a lot of the Arctic. The models supported what was found in the sediments – even during these extreme glaciations, warm Atlantic water still flowed into the Arctic gateway.

The study not only reshapes our view of past Arctic climates but also has implications for future climate predictions. Understanding how sea ice and ocean circulation responded to past climate extremes can improve models that project future changes in a warming world.

“These reconstructions help us understand what’s possible — and what’s not — when it comes to ice cover and ocean dynamics,” said Gerrit Lohmann, co-author of this study, based at Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and co-lead of Into The Blue — i2B. “That matters when trying to anticipate how ice sheets and sea ice might behave in the future.”

The full paper, “Seasonal sea ice characterized the glacial Arctic-Atlantic gateway over the past 750,000 years,” is available in Science Advances. This research is part of the European Research Council Synergy Grant project Into the Blue — i2B and the Research Council of Norway Centre of Excellence, iC3: Centre for ice, Cryosphere, Carbon, and Climate.

Antarctica’s Ocean Flip: Satellites Reveal Sudden Salt Surge Melting Ice from Below

In a shocking discovery, researchers have found that the Southern Ocean surrounding Antarctica has undergone a dramatic and unexpected shift. Since 2015, the region has lost an astonishing amount of sea ice, equivalent in size to Greenland – the largest environmental change witnessed anywhere on Earth in recent decades.

The ocean’s surface salinity has been rising, while the sea ice is rapidly declining. This sudden turn of events has significant implications for the planet. The findings were published in a study led by the University of Southampton, using European satellite data to reveal the unexpected changes in the Southern Ocean.

For decades, the ocean’s surface had freshened (becoming less salty), helping sea ice grow and thrive. However, this trend has sharply reversed, with scientists detecting a sudden rise in surface salinity south of 50° latitude. This shift has coincided with the dramatic loss of sea ice around Antarctica and the re-emergence of the Maud Rise polynya – a massive hole in the sea ice nearly four times the size of Wales.

The findings were published on June 30 in the Proceedings of the National Academy of Sciences. Dr. Alessandro Silvano, who led the research, warned that this new state could have permanent consequences for the Southern Ocean and the planet as a whole. The effects are already global: stronger storms, warmer oceans, and shrinking habitats for penguins and other iconic Antarctic wildlife.

The research team has attributed the sudden rise in surface salinity to a weakening of stratification between water layers. In the winter, cold, fresh surface water overlays warmer, saltier waters from the deep. As the surface cools and sea ice forms, the density difference weakens, allowing heat to be transported upward, melting the sea ice from below.

The early 1980s saw a strengthening of stratification, trapping heat below and sustaining more sea ice coverage. However, this trend has reversed, with new satellite technology and data from floating robotic devices revealing that surface salinity is increasing, stratification is weakening, and sea ice has reached multiple record lows – with large openings of open ocean in the sea ice (polynyas) returning.

This groundbreaking study highlights the urgent need for continuous satellite and in-situ monitoring to better understand the drivers of recent and future shifts in the ice-ocean system. The project was supported by the European Space Agency, and the paper “Rising surface salinity and declining sea ice: a new Southern Ocean state revealed by satellites” is available online.