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Earth & Climate

Winter Sea Ice Plays a Crucial Role in Regulating Southern Ocean’s CO2 Uptake

A breakthrough study has uncovered that the Southern Ocean’s power to pull carbon dioxide from the atmosphere fluctuates dramatically depending on winter sea ice. When sea ice lingers longer into winter, the ocean absorbs up to 20% more CO2, thanks to a protective effect that blocks turbulent winds from stirring up deeper, carbon-loaded waters. This subtle seasonal shield plays a vital role in buffering our planet against climate change. But here s the twist: winter data from the Southern Ocean is notoriously scarce due to its brutal conditions, meaning we might be missing a key piece of Earth s climate puzzle.

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The Southern Ocean is one of the most critical regions when it comes to absorbing carbon dioxide from the atmosphere. However, new research has revealed that the presence or absence of sea ice in winter plays a significant role in determining how much CO2 this region can absorb from the atmosphere.

In years where sea ice lasts longer into the winter months, the ocean absorbs about 20% more CO2 than in years when it forms late or disappears early. This is because sea ice acts as a protective barrier against strong winter winds that drive mixing between the surface of the ocean and its deeper, carbon-rich layers. As a result, less CO2 is released from the ocean into the atmosphere.

The study, led by scientists at the University of East Anglia in collaboration with other research institutions, used data collected along the west Antarctic Peninsula to investigate this phenomenon. The findings suggest that what happens during winter is crucial in explaining the year-to-year variability of CO2 uptake in this region.

“The global ocean takes up about a quarter of all CO2 humans emit into the atmosphere,” said Dr. Elise Droste, lead author of the study. “The Southern Ocean is responsible for about 40% of this, and we’ve been trying to understand why its atmospheric CO2 uptake varies so much from year to year.

“Our picture of the Southern Ocean’s carbon cycle is incomplete, and so we cannot predict whether its atmospheric CO2 uptake – and therefore its contribution to climate change mitigation – will increase, decrease, or remain the same in the future,” added Dr. Droste.

The study suggests that to improve predictions, researchers need to look at how sea ice affects the exchange of carbon between the deep and shallow parts of the ocean. This requires more wintertime observations in the Southern Ocean.

In a normal year, the Southern Ocean absorbs large amounts of atmospheric CO2 during the spring and summer months when phytoplankton growth and melt water lead to low CO2 concentrations at the ocean surface. However, as sea ice forms in winter, the ocean underneath mixes with deeper waters that contain lots of ‘natural’ carbon that has been in the ocean for centuries. This can cause CO2 at the ocean surface to increase to the point where it can be released into the atmosphere.

Sea ice blocks a large amount of this CO2 ‘outgassing’. However, some CO2 does escape the ocean as part of the natural seasonal cycle. The total amount of CO2 absorbed by the Southern Ocean within one year often depends on how much CO2 is absorbed in summer and how much is released in winter.

“We don’t have a good grasp on what’s driving this year-to-year variability, which is making it difficult to fully understand the system and improve predictability,” said Dr. Droste.

The study highlights the importance of collecting data in the wintertime, particularly in the Southern Ocean, where harsh weather conditions make sampling challenging.

“A series of ocean scientists have wintered at Rothera on the Antarctic Peninsula to collect these and other samples, from either a small boat or a sea ice sledge, to build a unique time series of year-round oceanographic conditions for the last 25 years,” said Dr. Hugh Venables, from the British Antarctic Survey.

“This important result shows the importance of this winter sampling and will hopefully lead to more year-round sampling in the Southern Ocean, both by humans and autonomous technology.”

Prof Dorothee Bakker, Professor in Marine Biogeochemistry at the University of East Anglia, added that the study “will help us better understand how the rest of the Southern Ocean works”.

The study was supported by funding from the UK’s Natural Environment Research Council and European Union’s Horizon 2020 research and innovation program.

Air Quality

Greenland’s Glacial Runoff Fuels Explosive Growth in Ocean Life

NASA-backed simulations reveal that meltwater from Greenland’s Jakobshavn Glacier lifts deep-ocean nutrients to the surface, sparking large summer blooms of phytoplankton that feed the Arctic food web.

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Greenland’s glacial runoff is fueling an explosion in ocean life, according to a recent study supported by NASA. As the ice sheet melts, it releases massive amounts of freshwater into the sea, which then interacts with the surrounding saltwater and nutrients from the depths.

The researchers used a state-of-the-art computer model called Estimating the Circulation and Climate of the Ocean-Darwin (ECCO-Darwin) to simulate the complex interactions between biology, chemistry, and physics in one pocket along Greenland’s coastline. The study revealed that glacial runoff delivers nutrients like iron and nitrate, essential for phytoplankton growth, to the surface waters.

Phytoplankton are tiny plant-like organisms that form the base of the ocean food web. They take up carbon dioxide and produce oxygen as byproducts of photosynthesis. In Arctic waters, their growth rate has surged 57% between 1998 and 2018 alone. The study found that glacial runoff boosts summertime phytoplankton growth by 15 to 40% in the study area.

Increased phytoplankton blooms can have a positive impact on Greenland’s marine animals and fisheries. However, untangling the impacts of climate change on the ecosystem will take time and further research. The team plans to extend their simulations to the whole Greenland coast and beyond.

The study also highlights the interconnectedness of the ocean ecosystem, with phytoplankton blooms influencing the carbon cycle both positively and negatively. While glacial runoff makes seawater less able to dissolve carbon dioxide, the bigger blooms of phytoplankton take up more carbon dioxide from the air as they photosynthesize, offsetting this loss.

The researchers emphasize that their approach is applicable to any region, making it a powerful tool for studying ocean ecosystems worldwide. As climate change continues to reshape our planet, understanding these complex interactions will be essential for predicting and mitigating its impacts on marine life and ecosystems.

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Atmosphere

NASA’s SWOT Satellite Captures Kamchatka Megaquake Tsunami in Stunning Detail

When a massive 8.8 magnitude earthquake struck off Russia’s Kamchatka Peninsula, NASA and CNES’s SWOT satellite captured a rare and detailed picture of the tsunami that followed. Recorded just over an hour after the quake, the satellite revealed the wave’s height, shape, and path, offering scientists an unprecedented multidimensional view from space.

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The recent megaquake that struck off the coast of Russia’s Kamchatka Peninsula has been captured in striking detail by NASA’s SWOT satellite. Launched jointly with the French space agency CNES, the SWOT satellite is equipped with a unique radar system that can measure ocean topography and water levels across vast areas.

On July 30, at around 11:25 a.m. local time, an 8.8 magnitude earthquake struck off the coast of Kamchatka, generating a massive tsunami wave. The SWOT satellite captured the leading edge of this tsunami just 70 minutes after the quake hit. This remarkable footage has provided scientists with crucial data to improve tsunami forecast models.

The data collected by the SWOT satellite included measurements of the wave height exceeding 1.5 feet (45 centimeters), as well as a detailed look at the shape and direction of travel of the leading edge of the tsunami. These observations have been plotted against a forecast model produced by the U.S. National Oceanic and Atmospheric Administration (NOAA) Center for Tsunami Research.

Comparing these observations to the model helps forecasters validate their predictions, ensuring that they can provide accurate early warnings to coastal communities in the event of a tsunami. As Nadya Vinogradova Shiffer, NASA Earth lead and SWOT program scientist at NASA Headquarters, explained, “The power of SWOT’s broad, paintbrush-like strokes over the ocean is in providing crucial real-world validation, unlocking new physics, and marking a leap towards more accurate early warnings and safer futures.”

Ben Hamlington, an oceanographer at NASA’s Jet Propulsion Laboratory, highlighted the significance of the 1.5-foot-tall wave captured by SWOT, saying that what might seem like a small wave in open waters can become a massive 30-foot wave in shallower coastal areas.

The data collected by the SWOT satellite has already helped scientists improve their tsunami forecast models at NOAA’s Center for Tsunami Research. This is a crucial step towards enhancing operational tsunami forecasts and saving lives. As Josh Willis, a JPL oceanographer, noted, “The satellite observations help researchers to better reverse engineer the cause of a tsunami, and in this case, they also showed us that NOAA’s tsunami forecast was right on the money.”

This breakthrough has significant implications for coastal communities around the world. By providing more accurate early warnings, SWOT data can save lives and reduce damage caused by tsunamis. As Vasily Titov, the center’s chief scientist in Seattle, emphasized, “It suggests SWOT data could significantly enhance operational tsunami forecasts — a capability sought since the 2004 Sumatra event.” The devastating tsunami generated by that quake killed thousands of people and caused widespread destruction in Indonesia.

The SWOT satellite was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. NASA JPL leads the U.S. component of the project, providing a Ka-band radar interferometer instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations.

This groundbreaking technology has opened up new possibilities for scientists to better understand ocean dynamics and improve tsunami forecasting models. As SWOT continues to capture stunning images of our oceans, it will undoubtedly play a vital role in enhancing operational tsunami forecasts and saving lives around the world.

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Climate

The Ocean’s Fragile Fortresses: Uncovering the Impact of Climate Change on Bryozoans

Mediterranean bryozoans, including the “false coral,” are showing alarming changes in structure and microbiomes under acidification and warming. Field studies at volcanic CO₂ vents reveal that these stressors combined sharply reduce survival, posing risks to marine ecosystems.

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The Ocean’s Fragile Fortresses: Uncovering the Impact of Climate Change on Bryozoans

Bryozoans, small colonial invertebrates, play a vital role in forming marine habitats. However, their response to environmental changes has long been overlooked. A recent study published in Communications Biology sheds light on how ocean acidification and warming can affect bryozoan colonies, with crucial implications for marine conservation.

The researchers from the Institut de Ciències del Mar (ICM-CSIC) used a natural laboratory on the island of Ischia, Italy, to simulate the conditions projected for the end of the century. They analyzed the morphology, skeleton mineralogy, and microbiome of two bryozoan species exposed to these conditions. The findings revealed that the species exhibit some acclimation capacity, modifying their skeletal mineralogy to become more resistant.

However, a loss in functional microbial diversity was observed, with a decline in genera potentially involved in key processes such as nutrition, defense, or resistance to environmental stress. This suggests that even if colonies look externally healthy, changes in the microbiome could serve as early bioindicators of environmental stress.

The study also considered the effects of rising temperatures, another key factor in climate change. The models used indicate that the combination of these two stressors intensifies the effects observed, significantly reducing the coverage of the encrusting bryozoan and increasing mortality.

These findings have important implications for marine conservation. Habitat-forming species like bryozoans are not only vulnerable but their disappearance could trigger cascading effects on many other species that rely on them for shelter or food. The characterization of the microbiome and preliminary identification of potentially beneficial microorganisms open new research avenues to enhance the resilience of holobionts (host and its associated microbiome) through nature-based approaches.

The complexity of this issue demands integrated analyses, highlighting the importance of interdisciplinary approaches in anticipating future scenarios and protecting marine ecosystems.

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