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Earth & Climate

“New Orleans’ Sinking City: $15 Billion Flood Defenses Under Threat from Land Subsidence”

Parts of New Orleans are sinking at alarming rates — including some of the very floodwalls built to protect it. A new satellite-based study finds that some areas are losing nearly two inches of elevation per year, threatening the effectiveness of the city’s storm defenses.

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New Orleans is facing an unprecedented threat from its own foundation. A recent study by Tulane University researchers has revealed that parts of the city are gradually sinking, while the $15 billion post-Katrina flood protection system may need regular upgrades to outpace long-term land subsidence.

The study, published in Science Advances, used satellite radar data to track subtle shifts in ground elevation across Greater New Orleans between 2002 and 2020. The findings show that some neighborhoods, wetlands, and even sections of floodwalls are sinking by more than an inch per year – with some areas experiencing up to 47 millimeters (nearly 2 inches) of elevation loss annually.

“In a city like New Orleans, where much of the land is already near sea level, even minor drops in elevation can increase flood risk,” said Simone Fiaschi, lead author of the study and a former researcher with Tulane’s Department of River-Coastal Science and Engineering. “The findings underscore how both natural and human-driven forces are reshaping the city’s landscape.”

Causes of the sinking – known as subsidence – include natural soil compaction, groundwater pumping, industrial development, and the legacy of wetland drainage for urban growth. The study used a remote sensing technique called InSAR (Interferometric Synthetic Aperture Radar), which detects millimeter-scale changes in land surface elevation by comparing satellite radar images taken over time.

Among the most troubling findings: some of the concrete floodwalls and levees built to protect the city after Katrina are themselves sinking. In a few cases, parts of the Hurricane and Storm Damage Risk Reduction System (HSDRRS) are losing elevation faster than sea levels are rising, reducing their capacity to block storm surges.

“These results are a wake-up call,” said co-author Prof. Mead Allison, also of Tulane. “We need ongoing monitoring and maintenance to ensure that our flood defenses don’t lose their level of protection beneath us.”

The study also found pockets of sinking around industrial sites, the airport, and newer residential developments – areas where soil compression and groundwater withdrawal are likely contributors. In contrast, some areas such as parts of Michoud showed modest land uplift, likely due to the halt of industrial groundwater pumping and recovery of the water table.

Wetlands east of the city, long known for their ecological importance, are also sinking rapidly in places. In some spots, the loss of elevation could transform marshes into open water within a decade if trends continue. This has implications not just for wildlife but also for storm protection, as wetlands help buffer storm surges.

New Orleans, much of which lies below sea level, relies on an elaborate system of levees, pumps, and drainage canals to keep water out. As sea levels rise and the ground sinks, the margin for error narrows.

Experts say that without sustained monitoring, including satellite data and ground-based measurements, it’s difficult to know where to reinforce levees or how to plan for future storms.

“This research shows that land movement isn’t uniform, and understanding these patterns is crucial for protecting lives and property in a city where inches truly matter,” Fiaschi said. “However, it’s crucial to remember that our results still require careful ground-truthing. This is especially true for critical areas like the floodwalls, where on-site verification was not possible during this project.”

The study highlights the potential of satellite monitoring to guide infrastructure maintenance and urban planning, not just in New Orleans but in coastal cities worldwide facing similar challenges.

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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Climate

Unraveling Chaotic Ant Wars to Save Coffee: The Complexities of Ecological Systems in Agriculture

In a Puerto Rican coffee farm, researchers uncovered a web of chaotic interactions between three ant species and a predator fly, revealing how shifting dominance patterns make pest management unpredictable. By combining theories of cyclic dominance and predator-mediated coexistence, they showed how ecological forces oscillate and intertwine, creating patterns too complex for simple forecasting. This deep dive into ant behavior underscores both the potential and the challenges of replacing pesticides with ecological methods, as nature’s own “rules” prove to be far from straightforward.

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As we strive to revolutionize agricultural practices without relying on harmful pesticides, researchers from the University of Michigan have made significant strides in understanding the intricacies of ecological systems on farmland. Led by professors John Vandermeer and Ivette Perfecto, their study published in the Proceedings of the National Academy of Sciences, sheds light on the complex interactions between three ant species and a recently introduced fly that preys upon one of them.

The researchers’ work on a coffee farm in Puerto Rico reveals that the interaction between these four insect species creates chaotic patterns – not just random fluctuations but intricate dynamics influenced by predator-prey relationships. This chaos is in the classical sense, where natural populations are subjected to fluctuations depending on the interactions of organisms within a system. The study’s findings show that any one of the four insect species could be dominant at any point in time.

For three decades, Vandermeer and Perfecto have been studying ant interactions in the coffee farm’s agricultural setting, seeking to help farmers use ants as biological control agents for pests like coffee leaf rust and scale insects. However, their research highlights that understanding which ants may be dominant over time is a challenging task due to the complex dynamics at play.

“We believe that the current international agricultural system with its use of pesticides and chemicals is not contributing to the welfare of anybody, especially farmers, and is actually contributing quite a bit to global climate change,” Vandermeer said. “We take the position that in order to incorporate the rules of ecology into the development of new forms of agriculture, we need to understand what those rules are and how those rules work.”

The researchers examined two types of ecological behavior: intransitive loop cyclic behavior and predator-mediated coexistence. Intransitive loop cyclic behavior means that if there’s a group of three ant species, Ant A might be dominant over Ant B, Ant B might dominate Ant C, but Ant C could dominate Ant A. When a predator is thrown into the mix, these dynamics become even more complicated.

The study’s findings have significant implications for agriculture. By understanding which ants may be dominant at different points in time, farmers can potentially use these ants as biological control agents to manage pests on their farms with fewer pesticides. However, the researchers acknowledge that the complex dynamics involved make it challenging to base agricultural practices solely on ecological principles.

“The good news is that the chaotic patterns of the insects are really very interesting from an inherent intellectual sense,” Vandermeer said. “The bad news is that it’s not really as simple as it might seem to base agricultural practices on ecological principles because the ecological principles themselves are way more complicated than simply finding a poison that kills the pests.”

Vandermeer and Perfecto’s work highlights the importance of understanding ecological systems in agriculture, acknowledging the complexities involved, and taking a holistic approach to developing new forms of agriculture. As researchers continue to unravel the intricacies of these complex interactions, we may find innovative solutions for more sustainable and pesticide-free agricultural practices – ultimately benefiting farmers, ecosystems, and society as a whole.

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Asteroids, Comets and Meteors

Unveiling Ancient Secrets on Mars: A Breakthrough Technique Reveals Hidden Clues

A curious red Martian rock nicknamed Sapphire Canyon has scientists excited, as its spotted appearance hints at possible organic origins. On Earth, researchers tested a powerful laser technique, O-PTIR, on a similar rock found by chance in Arizona, proving it can rapidly and precisely reveal a material’s chemical makeup. This high-resolution method could play a key role in analyzing Mars samples once they arrive, adding to its growing track record in NASA missions like Europa Clipper.

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The discovery of an unusual rock sample, named Sapphire Canyon, by NASA’s Mars rover Perseverance in 2024 has sent shockwaves of excitement through the scientific community. This enigmatic rock features striking white spots with black borders within a red mudstone, sparking hopes that it might hold clues about the presence of organic molecules on Mars.

To unlock the secrets hidden within Sapphire Canyon, researchers from the Jet Propulsion Laboratory and the California Institute of Technology employed an innovative technique called optical photothermal infrared spectroscopy (O-PTIR). This method uses two lasers to study a material’s chemical properties, creating its unique fingerprint by measuring thermal vibrations on its surface.

The team, led by Nicholas Heinz, put O-PTIR to the test on a basalt rock with dark inclusions of similar size to Sapphire Canyon’s. By chance, Heinz stumbled upon this visually similar rock while hiking in Arizona’s Sedona region. The results were astounding – O-PTIR proved to be an extremely effective tool for differentiating between the primary material and its dark inclusions.

One of the key advantages of O-PTIR is its enhanced spatial resolution, allowing scientists to pinpoint specific regions of interest within a sample. Additionally, this technique is remarkably rapid, with each spectrum collection taking mere minutes. This enables researchers to apply more sensitive techniques to study areas containing potential organics in greater detail.

Heinz expressed his hope that the capabilities of O-PTIR will be considered for future Martian samples, as well as those from asteroids and other planetary surfaces. The team’s expertise is currently the only one available at NASA’s Jet Propulsion Laboratory, having previously assisted with confirming the cleanliness of the Europa Clipper mission prior to its launch.

As the scientific community continues to unravel the mysteries hidden within Sapphire Canyon, Heinz and his team are working closely with NASA’s Mars science team to test O-PTIR on algal microfossils typically used as Mars analogs for the rovers. This breakthrough technique is poised to revolutionize our understanding of Martian geology and potentially uncover signs of ancient life on the Red Planet.

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