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.

Climate change is happening at an unprecedented rate, leaving forests behind in its wake. For decades, ecologists have been concerned that forest ecosystems will not be able to keep pace with this rapid warming, ultimately becoming unhealthy and unproductive.

In reality, tree populations in the Northern Hemisphere had adapted to colder and warmer periods over thousands of years before the current climate crisis. During Ice Ages, trees would migrate south to find warmer conditions as global temperatures cooled. However, when the climate warmed again, these same species would adapt by migrating northward to more suitable areas.

Mature trees are long-lived, but their populations cannot migrate quickly enough to keep up with today’s accelerated climate change. The study recently published in Science reveals that forests have a significant lag time of one to two centuries to shift tree populations in response to climate changes.

Lead researcher David Fastovich from Syracuse University’s Paleoclimate Dynamics Lab explains that this research aimed to map the timescales at which tree populations respond to climate change by examining pollen data from lake sediment cores spanning up to 600,000 years ago. The team used spectral analysis – a statistical technique common in fields like physics and engineering – to study long-term ecological data.

Spectral analysis allowed researchers to compare the relationship between tree populations and climate over various timescales, from decades to millennia. This method provided insights into how closely tree population migrations, tree mortality, and forest disturbances match climate changes over time.

The findings indicate that at timescales of years and decades, forests tend to change slowly. However, after about eight centuries, larger changes in the forest become more pronounced, tied to natural climate variability.

Fastovich emphasizes that this new technique can help us understand ecological processes on any timescale and how they are connected. It also highlights the need for nuanced, long-term management strategies to assist forests in adapting to climate change.

One such strategy is assisted migration – the practice of planting warmer-climate trees in traditionally colder locations to help woodlands adapt and flourish despite habitat warming from climate change. Fastovich notes that this approach will be crucial in helping cherished forests thrive in a rapidly changing world.

In conclusion, while forests have a natural lag time in responding to climate change, assisted migration and other human interventions can play a vital role in keeping these ecosystems healthy and productive for longer.