Today's Image of the Day from the <a href="https://www.esa.int/" target="_blank" rel="noreferrer noopener">European Space Agency </a>features the barred spiral galaxy NGC 3783, which is located about 130 million light-years away in the constellation Centaurus. NGC 3783 is also the most prominent of a galaxy group (by the same name) that contains 47 <a href="https://www.earth.com/news/james-webb-captures-galaxies-that-are-too-old-to-exist/" target="_blank" rel="noreferrer noopener">galaxies</a>. 



<h2 class="wp-block-heading" id="h-galaxy-groups">Galaxy groups</h2>



“Like galaxy clusters, galaxy groups are aggregates of gravitationally bound galaxies. Galaxy groups, however, are less massive and contain fewer members than <a href="https://www.earth.com/news/titanic-galaxy-cluster-collision-defies-all-current-understanding-of-the-universe/" target="_blank" rel="noreferrer noopener">galaxy clusters</a> do: where galaxy clusters can contain hundreds or even thousands of constituent galaxies, galaxy groups do not typically include more than 50,” noted ESA.



“The Milky Way is actually part of a galaxy group, known as the Local Group, which contains two other large galaxies (Andromeda and the Triangulum galaxy), as well as several dozen satellite and dwarf galaxies.”



<h2 class="wp-block-heading" id="h-hd-101274-a-blue-giant-star">HD 101274: A blue giant star</h2>



The bright object that appears to the right of the galaxy is the star HD 101274. “The perspective in this image makes the star and the galaxy look like close companions, but this is an illusion. HD 101274 lies only about 1,530 light-years from Earth, meaning it is about 85 thousand times closer than NGC 3783,” explained ESA.&nbsp;



HD 101274 is part of the NGC 3766 cluster, which is sometimes referred to as the Pearl Cluster, an open cluster known for its richness in bright stars and its relatively young age.



HD 101274 is categorized as a blue giant star, characterized by its high temperature and luminosity. Blue giants are massive stars that have left the main sequence phase of stellar evolution and are burning helium or heavier elements in their cores. These stars are known for their short lifespans relative to smaller stars due to their rapid consumption of nuclear fuel.



<a href="https://www.earth.com/news/dark-stars-scientists-discover-a-new-type-of-star-powered-by-dark-matter/" target="_blank" rel="noreferrer noopener">Stars</a> like HD 101274 are important for astronomers because they help in studying the properties of stellar populations in clusters and the dynamics of stellar evolution in different environments. The spectral and photometric observations of such stars can provide valuable insights into the characteristics of their atmospheres, internal structures, and the processes occurring within and around them.



<h2 class="wp-block-heading" id="h-bright-central-region-of-ngc-3783">Bright central region of NGC 3783</h2>



One of the most interesting aspects of NGC 3783 is that it harbors an active galactic nucleus, meaning its central region is exceptionally luminous, likely due to the presence of a supermassive black hole. This black hole is actively accreting material, which emits a substantial amount of radiation as it spirals inward and heats up.



This galaxy is particularly known for its bright central region and has been studied extensively in the ultraviolet and X-ray light spectra to understand better the properties of the accretion disk around the black hole and the complex dynamics of the material surrounding it. These studies are crucial for understanding the physics of active galactic nuclei and the role they play in <a href="https://www.earth.com/news/galaxies-like-our-own-milky-way-are-not-unique/" target="_blank" rel="noreferrer noopener">galaxy evolution</a>.



According to ESA, NGC 3783 is a Type I Seyfert galaxy. “In this image it is recorded by Hubble in incredible detail, from its glowing central bar to its narrow, winding arms and the dust threaded through them, thanks to five separate images taken in different wavelengths of light," noted ESA.



“In fact, the galactic center is bright enough to Hubble that it exhibits diffraction spikes, normally only seen on stars such as HD 101274.”



<h2 class="wp-block-heading" id="h-more-about-the-ngc-3783-galaxy-group">More about the NGC 3783 galaxy group</h2>



The NGC 3783 group is part of the larger Hydra-Centaurus Supercluster, which itself is a massive collection of galaxies and galaxy clusters located primarily in the constellations of Hydra and Centaurus.



The NGC 3783 group consists of several galaxies that are gravitationally bound and interact with each other. These interactions can influence the galaxies' evolution through mechanisms like tidal forces and merger events, which can trigger star formation, fuel central black holes, and reshape the galaxies' structures.



Studying groups like the NGC 3783 group helps astronomers understand how <a href="https://www.earth.com/news/ceers-2112-ancient-galaxy-looks-strikingly-similar-to-ours/" target="_blank" rel="noreferrer noopener">galaxies</a> evolve together in a common gravitational environment, offering insights into the dynamics and evolution of structures on cosmic scales. This is especially relevant in understanding how galaxies influence each other through gravitational interactions and the environmental effects on galaxy evolution.



Image Credit: ESA/Hubble &amp; NASA



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The luminous galaxy NGC 3783 and a blue giant star

Today's Image of the Day from the European Space Agency...

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features sediment swirling in the Gulf of Alaska on December 29, 2023.



"After an unusually snowy start to winter, southern Alaska’s coastline remained under a blanket of white in late December," said NASA.



"Meanwhile, greens and tans swirled in the dark blue water offshore. The dullness of the hues near shore suggests that the water is mostly colored by sediment. It is likely that phytoplankton - microscopic plant-like organisms - contributed to some of the hues farther from the coast."



According to NASA, much of the sediment in this region comes from “glacial flour” carried into the gulf by the Copper River.&nbsp;



"Glacial flour forms as glaciers move over bedrock and grind it into a fine silt. When suspended in water, glacial flour can make the water appear an opaque turquoise color - similar to phytoplankton blooms. The sediment carries iron and other nutrients that can spur the growth of these tiny marine organisms," explained NASA.



Aimee Neeley, a biological oceanographer at NASA’s Goddard Space Flight Center, noted that there are always phytoplankton in the water, but usually at lower levels in the wintertime at these latitudes.



The Gulf of Alaska is a vast and biologically rich body of water that lies at the northernmost part of the Pacific Ocean, encircled by Alaska.&nbsp;



The gulf extends approximately 1,500 miles from the Alaska Peninsula and the Aleutian Islands in the west to the Alexander Archipelago in the east.



Characterized by a subarctic climate, it's known for heavy rain and <a href="https://www.earth.com/news/sea-ice-loss-increases-snowfall-over-west-antarctica/">snowfall</a>. The region is also prone to frequent storms and is a significant pathway for colder northern weather patterns moving into the United States.



The Gulf of Alaska is home to a diverse marine ecosystem. It supports many species of fish, such as salmon and halibut, and is also a habitat for marine mammals like whales, sea lions, and seals.



The image was captured by the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua satellite.



Image Credit: NASA Earth Observatory&nbsp;



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Sediment swirling in the Gulf of Alaska

Today's Image of the Day from NASA Earth Observatory features...

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features an astronaut view of the Aladaghlar Mountains in northwestern Iran. These mountains are known for their strikingly colorful landscapes, which make them stand out among other mountain ranges.



"Ridges cast shadows in the valleys and other low elevation areas, creating a three-dimensional appearance. Human alterations to the landscape are most evident in riverbeds, where the even topography is easier to build on and navigate," said NASA.



"Natural processes over millions of years have folded rock layers of various compositions and colors into the curved patterns seen here. These folds are produced by tectonic forces operating along the convergent plate boundary of the Arabia and Eurasia plates. The convergence of these tectonic plates causes uplift, folding, and deformation of the colorful rock layers, and subsequent erosion exposes them."



One of the most remarkable features of the Aladaghlar Mountains is the vivid coloration of their slopes. The name "Aladaghlar" translates to "Colorful Mountains," which is a testament to their unique appearance. 



The Aladaghlar Mountains are part of a larger ecosystem that includes forests, meadows, and rivers, contributing to a rich biodiversity. The region supports a variety of wildlife, including several species that are unique to the area. The diverse wildlife add to the natural beauty and ecological importance of these <a href="https://www.earth.com/news/how-and-why-do-mountains-form-new-theories-for-an-age-old-mystery/">mountains</a>.



In addition to their natural appeal, the Aladaghlar Mountains hold cultural significance. The region has a rich history, with evidence of ancient civilizations and historical sites. Local communities have their unique cultures and traditions, which have been influenced by the natural environment of the mountains.



Image Credit: NASA Earth Observatory&nbsp;



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The Aladaghlar Mountains of northwestern Iran

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features a large sediment plume from the Yangtze River that extends hundreds of kilometers off the coast of China.



"Brown, sediment-laden water is visible along this shallow, turbid stretch of coast year-round, but a vast plume like the one visible here is a characteristic feature of winter. Scientists have proposed several causes of this seasonal phenomenon," said NASA.



"The ebb and flow of tides contain enough energy to stir up sediments from the seafloor, a 2017 study found. While there are also tides in the summer, the models used in the study showed that sediment only rises to the surface in the winter. That’s when temperatures and salinities at the sea surface and bottom are similar, allowing for vertical mixing to occur and for sediment to churn higher into the water column."



Additional studies have suggested that the summer monsoon’s influence on currents impedes the eastward flow of sediment out of the estuaries, noted NASA.



"Despite what looks like a glut of suspended sediment in the water, the overall amount of it flowing from the Yangtze River has declined steadily over the past several decades. The construction of dams, including the Three Gorges Dam, has been the primary driver of this trend."



It is important for scientists to track the movement of suspended sediment. This material can cause direct harm to marine life, as well as indirect harm by blocking sunlight.



The Yangtze River, also known as the Chang Jiang in Chinese, is the longest river in Asia and the third-longest in the world, following the Nile and the <a href="https://www.earth.com/news/amazon-river-dolphins-are-at-great-risk-of-extinction-due-to-human-activities/">Amazon</a>. It flows for over 6,300 kilometers (about 3,917 miles) from the glaciers of the Qinghai-Tibet Plateau in western China to the East China Sea at Shanghai.&nbsp;



The Yangtze River basin is a key region for China's agriculture, industry, and hydroelectric power production. The river's waters are used for irrigation, navigation, and as a source of freshwater. The basin is home to diverse wildlife, including the critically endangered Yangtze river dolphin or Baiji, which may now be extinct.



The image was captured on February 12, 2024 by the Visible Infrared Imaging Radiometer Suite sensor on the NOAA-20 satellite.



Image Credit: NASA Earth Observatory



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Sediment flows offshore from the Yangtze River 

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features the Ruki River in the Democratic Republic of the Congo (DRC). It is a tributary of the Congo River, one of the largest <a href="https://www.earth.com/news/warmer-rivers-keep-antimicrobial-resistant-genes-at-bay/">rivers</a> in the world by discharge and depth. 



The Ruki River, previously known as the Busira, merges with the Momboyo River near the town of Basankusu to become the Lulonga River, which eventually flows into the Congo River at the town of Lisala.



"If the appearance of the muddy Amazon River evokes a coffee cut with cream, the Ruki River, coursing gently through the Congo Basin, is like a dark tea," said NASA.



"On its slow path through mostly untouched lowland rainforest in the Democratic Republic of Congo (DRC), the water leaches organic material from vegetation, prompting some researchers to think it is one of the darkest blackwater rivers on Earth. The dissolved material in this distinctive water, scientists are finding, offers clues into the carbon cycle of tropical forests."



In a recent study, researchers measured the chemical composition and flow of the Ruki for the first time.&nbsp;



"The study reported that, as the water color suggests, the Ruki is rich in dissolved organic carbon compounds. It contains four times as much organic carbon as the Congo River and 1.5 times as much as the Rio Negro, the world’s largest blackwater river and a major tributary of the Amazon," said NASA.



Due to this heavy carbon load, the researchers concluded that “tropical forests like those around the Ruki might not accumulate quite as much carbon as we once thought.”



The region around the Ruki River is rich in biodiversity, hosting various species of flora and fauna. It is part of the Congo Basin, the second-largest tropical rainforest area in the world, which is a critical habitat for endangered species and a significant carbon sink.



The river is vital for the livelihoods of local communities. Fishing is a crucial activity, with many people depending on it for sustenance and income. The river also supports agriculture along its banks, where communities grow crops.



In many parts of the DRC, rivers like the Ruki are crucial transportation corridors due to the challenging and often nonexistent road infrastructure. The river enables the movement of people and goods, facilitating trade and access to markets, health care, and education.



The region faces several challenges, including deforestation, overfishing, and environmental degradation, which threaten its ecological balance and the livelihoods of people who depend on it. Efforts to manage and conserve the river's resources are vital for sustainable development.



Understanding and protecting the Ruki River and its surroundings are crucial for the DRC's environmental sustainability, economic development, and the well-being of its communities.



The image was captured by the OLI (Operational Land Imager) on Landsat 8.



Image Credit: NASA Earth Observatory&nbsp;



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The Ruki River in the Democratic Republic of the Congo

In the U.S., the wave of <a href="https://www.earth.com/news/cannabis-legalization-reduces-designer-drug-poisonings/" target="_blank" rel="noreferrer noopener">cannabis</a> legalization sparks debates about its impact on young people. A new study from <a href="https://www.bc.edu" target="_blank" rel="noreferrer noopener">Boston College</a> sheds light on these concerns, providing evidence that increasing legal access does not necessarily increase substance abuse among adolescents.



<h2 class="wp-block-heading" id="h-cannabis-legalization">Cannabis legalization</h2>



As of 2021, a total of 24 states and Washington, D.C., have passed laws that legalize the recreational use of <a href="https://www.earth.com/news/recreational-cannabis-use-protects-against-cognitive-decline/" target="_blank" rel="noreferrer noopener">cannabis</a>. In these locations, adults legally possess and use marijuana for personal enjoyment, not just for medical purposes.



This represents a major shift in U.S. drug policy. It shows increasing public acceptance of cannabis. There are also growing legislative efforts to regulate and tax cannabis. These efforts are similar to those for alcohol.



Additionally, of those 24 states, 18 have also set up systems that allow for the legal sale of cannabis. This includes regulations for retail dispensaries where consumers can purchase cannabis legally. 



<h2 class="wp-block-heading" id="h-regulations-due-to-cannabis-legalization">Regulations due to cannabis legalization</h2>



In states where <a href="https://www.earth.com/news/chemical-found-in-cannabis-plants-can-actually-reduce-cannabis-induced-anxiety/" target="_blank" rel="noreferrer noopener">cannabis</a> has been legalized, the government sets comprehensive regulations covering all aspects of the cannabis industry. These regulations encompass not just the use and possession of cannabis but extend to its production, distribution, and commercial sale. 



One of the main goals of regulatory oversight is to dismantle illegal markets. States provide a legal, regulated alternative that is safer and more reliable than unregulated sources. By regulating the cannabis industry, states ensure product safety for consumers. This reduces risks linked to contamination or overly potent products.



This legislative trend is part of a broader movement toward cannabis legalization observed nationwide and globally, prompted by arguments for criminal justice reform, economic benefits, and emerging evidence suggesting controlled legalization might not increase substance abuse rates - especially among youth.



<h2 class="wp-block-heading" id="h-cannabis-legalization-impact-on-teens">Cannabis legalization impact on teens</h2>



The primary goal of the study was to assess the impact of cannabis accessibility. Researchers explored if legalization and normalization through legal channels increased substance use. They specifically looked at <a href="https://www.earth.com/news/why-cannabis-use-disorder-risk-varies-among-young-adults/" target="_blank" rel="noreferrer noopener">cannabis</a> use rates among teenagers.



The researchers collected data from nearly 900,000 high school students. These students were from 47 states. The data spanned from 2011 to 2021. This period includes years before and after the enactment of cannabis legalization laws in many states.



<h2 class="wp-block-heading" id="h-cannabis-legalization-and-substance-abuse">Cannabis legalization and substance abuse</h2>



The extensive analysis revealed key findings. Instead of increasing, substance use among teenagers showed modest decreases. This included the use of <a href="https://www.earth.com/news/cannabis-use-strongly-linked-to-mental-disorders-in-a-new-study/" target="_blank" rel="noreferrer noopener">cannabis</a>, alcohol, and e-cigarettes. 



These findings suggest that cannabis legalization and regulation may be reducing substance use among adolescents. The researchers hypothesized that several factors could be at play in these results:



<h3 class="wp-block-heading" id="h-regulation-reduces-illegal-cannabis-access">Regulation reduces illegal cannabis access </h3>



In legal cannabis markets, strict regulatory frameworks are put in place to control who can legally purchase and possess cannabis. The regulations typically include measures such as requiring proof of age via government-issued identification, much like the systems used for alcohol sales. 



This requirement mandates that buyers must meet the minimum age, usually 21 years, in the United States. Only those who meet this age can purchase cannabis from legal dispensaries.



In unregulated or illegal markets, there are no such controls or checks on purchasers. Illegal dealers typically do not require any form of ID verification, which makes it easier for underage individuals to access cannabis. 



These dealers operate outside the law, with the primary goal of selling their product regardless of the buyer's age, thereby increasing the risk of adolescent access and use.



Furthermore, legal dispensaries also contribute to reducing access for minors through the implementation of stringent security measures and strict adherence to local and state laws. 



Staff members receive training to comply with these regulations. They refuse sales to individuals who cannot provide proper identification or appear to be purchasing for underage users.



<h3 class="wp-block-heading" id="h-normalization-reduces-appeal">Normalization reduces appeal</h3>



The concept of the "forbidden fruit" appeal refers to the phenomenon where prohibited items or behaviors become more attractive simply because they are off-limits. This psychological effect is often observed among adolescents. 



Breaking rules or engaging in taboo activities can be seen as a form of rebellion or a way to assert independence. When a substance like <a href="https://www.earth.com/news/after-centuries-of-speculation-heres-what-really-causes-the-munchies/" target="_blank" rel="noreferrer noopener">cannabis</a> is illegal, it might be perceived by some teenagers as a daring, rebellious act to use it, enhancing its allure.



However, with the legalization of cannabis, this dynamic begins to shift. Legalization demystifies cannabis by integrating it into regular, legal commerce and subjecting it to everyday regulatory scrutiny like any other commodity. 



This change can alter the perception of cannabis among young people. When cannabis is legally available and regulated, and when its use is normalized within society, it loses some of its rebellious allure. Instead of being a symbol of defiance against authority, it becomes just another regulated substance, akin to alcohol or tobacco.



A reduction in the "forbidden fruit" appeal can lead to lower rates of use among adolescents. They might no longer associate cannabis use with rebellion or see it as an attractive way to challenge societal norms. 



Moreover, the discussions around cannabis use tend to become more focused on health and safety rather than legality. This can further deter adolescents from using it as a statement against authority.



<h3 class="wp-block-heading" id="h-public-health-initiatives">Public health initiatives</h3>



When cannabis is legalized, the regulatory framework that accompanies this shift often includes provisions for using some of the revenue generated through taxes and fees for public health initiatives. 



The funding is frequently directed toward educational programs and public health campaigns designed to inform the public about the safe and responsible use of cannabis. These programs are crucial, especially for teenagers, who are at a formative stage and susceptible to influences regarding substance use.



The focus of these educational initiatives is typically comprehensive, covering the potential risks and health implications of cannabis use. They aim to debunk myths and provide factual information that can help teenagers make informed decisions. 



By increasing awareness of the consequences of misuse and the legal stipulations surrounding cannabis consumption, these educational efforts serve as a preventive measure against substance abuse.



Moreover, public health campaigns can effectively leverage multiple media platforms that are popular among teenagers, such as social media, videos, and interactive websites, to ensure that the message is conveyed in an engaging and accessible manner. 



This broad reach is vital in countering the often-glamorized portrayals of substance use prevalent in various media and peer groups.



<h2 class="wp-block-heading" id="h-cannabis-legalization-and-our-youth">Cannabis legalization and our youth</h2>



While the findings provide encouraging insights into the effects of cannabis legalization on adolescent substance use, it is important to recognize that these results represent just one piece of a larger, ongoing investigation. 



The study alleviates some initial fears that legalization would directly lead to increased substance use among teenagers. However, this does not mean that the issue is fully resolved or that the potential risks have vanished entirely.



Longitudinal studies are research methods that observe the same individuals repeatedly over a prolonged period. These studies are highly effective for understanding changes and long-term outcomes in a population. In the context of cannabis legalization, longitudinal studies can offer valuable insights. 



“Although studies of early-enacting states and Canada reported few effects of recreational cannabis legislation on adolescent substance abuse, experts have highlighted the need to further assess policy outcomes in youth as legislation and retail availability spread, and other policies targeting youth substance use shift,” noted the researchers. 



“We found limited associations between recreational cannabis legalization and retail sales with adolescent substance use, extending previous findings.”



<h2 class="wp-block-heading" id="h-future-directions">Future directions</h2>



As we move forward, sustained research efforts are necessary. These should not only continue to track usage rates among adolescents but also examine deeper impacts, such as the effects on mental health, academic performance, and social behavior. 



Longitudinal studies, which follow the same individuals over many years, will be particularly valuable in painting a clearer picture of how cannabis legalization influences youth over significant periods.



Moreover, it’s crucial that as more data becomes available, policymakers use it to refine and adjust regulations and public health strategies. Sensible regulation - balancing control with accessibility, and enforcement with education - might prove to be a key strategy in preventing cannabis misuse among teenagers while also addressing other public health concerns.



<h2 class="wp-block-heading" id="h-more-about-cannabis-and-its-legalization">More about cannabis and its legalization</h2>



<a href="https://www.earth.com/news/smoking-cannabis-significantly-increases-the-risk-of-heart-attack/" target="_blank" rel="noreferrer noopener">Cannabis</a>, also known as marijuana, has a complex and evolving status globally, with a wide range of uses, effects, and legal standings. Here are some key aspects to consider about cannabis apart from the study previously discussed:



<h3 class="wp-block-heading" id="h-medical-uses">Medical uses</h3>



Cannabis is recognized for its medicinal properties and is used to treat a variety of conditions. It can alleviate chronic pain, reduce nausea during chemotherapy, manage seizures in conditions like epilepsy, and help with sleep disorders. Medical cannabis is legal in many countries and U.S. states, where it is prescribed by doctors under specific conditions.



<h3 class="wp-block-heading" id="h-recreational-use">Recreational use</h3>



Beyond medical use, recreational cannabis is consumed for its psychoactive effects. THC (tetrahydrocannabinol) is the main psychoactive component that provides the "high" associated with its use. Recreational use is increasingly being legalized in various states and countries, with regulations focusing on controlling distribution and consumption among adults.



<h3 class="wp-block-heading" id="h-economic-impact">Economic impact</h3>



The legalization of cannabis has significant economic implications. It creates jobs in cultivation, distribution, and retail. Legal cannabis markets also generate substantial tax revenue that often supports public services such as education and law enforcement.



<h3 class="wp-block-heading" id="h-social-issues">Social issues</h3>



Cannabis legalization is also linked to social justice issues. For decades, marijuana laws disproportionately affected minority communities, leading to high rates of incarceration. Legalization efforts often include measures to address these past injustices, such as expunging criminal records and promoting equity in the cannabis industry.



<h3 class="wp-block-heading" id="h-regulation-and-safety">Regulation and safety</h3>



Legal markets are regulated to ensure product safety and quality. This includes testing for pesticides, molds, and other contaminants, as well as regulating the potency of products to ensure consumer safety. Regulations also aim to prevent underage use and address concerns related to impaired driving.



<h3 class="wp-block-heading" id="h-cultural-shifts">Cultural shifts</h3>



As cannabis becomes more mainstream, its cultural perception is shifting. What was once considered a dangerous drug is now increasingly viewed as a safe and acceptable form of relaxation or social activity, similar to alcohol.



<h3 class="wp-block-heading" id="h-global-trends">Global trends</h3>



Internationally, the stance on cannabis varies widely. Countries like Canada and Uruguay have legalized cannabis nationwide, while others maintain strict prohibitions. International bodies like the United Nations are also reevaluating cannabis under global drug treaties.



Understanding these multifaceted aspects of cannabis helps to frame the broader context of its role in society, beyond the specific impacts of legalization on adolescent substance use.



The study is published in the journal <a href="https://jamanetwork.com/journals/jamapediatrics/article-abstract/2817566" target="_blank" rel="noreferrer noopener">JAMA Pediatrics</a>.



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Cannabis legalization does not increase youth substance abuse

In the U.S., the wave of cannabis legalization sparks debates...

Deep beneath the icy waters of <a href="https://www.earth.com/news/east-antarctica-once-thought-to-be-stable-is-on-the-verge-of-collapse/" target="_blank" rel="noreferrer noopener">Antarctica</a>, a silent crisis is brewing. As the Antarctic deep sea warms, it sets off a chain reaction that reaches the far-off waters of the North Atlantic, causing sea levels to rise. 



This alarming phenomenon threatens not just marine life but also the millions of people living in coastal areas. This scenario connects distant corners of our planet in ways we are only beginning to understand.



<h2 class="wp-block-heading" id="h-amoc-earth-s-ocean-conveyor-belt">AMOC: Earth's ocean 'conveyor belt'</h2>



At the heart of this story is the AMOC (Atlantic Meridional Overturning Circulation). This is a complex system of currents within the Atlantic Ocean, acting to transport heat, essential nutrients, and carbon dioxide from the tropics to the higher latitudes. 



The AMOC plays a vital role in regulating Earth's climate on a global scale. It functions much like the various branches of a river system, with different components contributing to its overall flow and direction.



Scientists have been meticulously studying a specific part of the AMOC: the "abyssal limb." This refers to a current residing thousands of meters below the ocean's surface, fueled by the formation of Antarctic Bottom Water (ABW). 



ABW is an extremely cold and dense water mass that forms around <a href="https://www.earth.com/news/mysterious-force-moves-ross-ice-shelf-antarctica-every-day/" target="_blank" rel="noreferrer noopener">Antarctica</a> under specific conditions. Due to its density, ABW sinks to the ocean floor and flows northwards. It becomes a primary driver of the AMOC's abyssal limb.



<h2 class="wp-block-heading" id="h-slowdown-in-crucial-ocean-current">Slowdown in crucial ocean current</h2>



Scientists at University of Miami <a href="https://www.earth.miami.edu" target="_blank" rel="noreferrer noopener">Rosenstiel School of Marine, Atmospheric, and Earth Science</a>, and the National Oceanic and Atmospheric Administration’s <a href="https://www.aoml.noaa.gov" target="_blank" rel="noreferrer noopener">Atlantic Oceanographic and Meteorological Laboratory</a> have dedicated over twenty years to meticulously tracking this deep, Antarctic-sourced water.



The experts used specialized instruments moored thousands of meters below the surface. The findings are truly chilling: the abyssal limb of the AMOC is weakening. The measured slowdown, approximately 12%, might seem small at first glance. However, it's crucial to grasp the sheer scale of the AMOC and this deep-ocean flow.



We're talking about a current system that spans the entire Atlantic basin, moving a volume of water greater than all the world's rivers combined. A slowdown of even a small percent translates to a massive change in the transport of cold water from the Antarctic towards the North Atlantic.



<h2 class="wp-block-heading" id="h-antarctic-dynamics-and-warming">Antarctic dynamics and warming</h2>



During the Antarctic winter, the formation of sea ice plays a vital role. As seawater freezes, the ice structure itself excludes salt, which is concentrated into the surrounding liquid water. This increases both the salinity and density of the unfrozen water, making it significantly heavier.



This newly-formed, extremely dense water, ABW, sinks towards the ocean floor. Driven by its density, ABW becomes the primary fuel for the abyssal limb of the AMOC, initiating a vast northward flow within the Atlantic Ocean basin.



A weaker abyssal limb indicates that less ABW is being formed and transported towards the North Atlantic. This leads to a reduced influx of cold, dense water in those regions, resulting in the gradual warming of the deep North Atlantic.



Thermal expansion is a fundamental physical property of water. As the deep North Atlantic warms, even slightly, the affected water molecules occupy a greater volume. 



“The areas affected by this warming spans thousands of miles in the north-south and east-west directions between 4,000- and 6,000-meters of depth,” said&nbsp;William Johns, a co-author and professor of ocean sciences at the Rosenstiel School. “As a result, there is a significant increase in the abyssal ocean heat content, contributing to local sea level rise due to the thermal expansion of the water.”



<h2 class="wp-block-heading" id="h-impact-of-antarctic-warming">Impact of Antarctic warming</h2>



The threat of <a href="https://www.earth.com/news/global-sea-levels-spiked-dramatically-in-2023/">rising sea levels</a> is most evident for coastal cities, where flooding and erosion pose an increasing risk to infrastructure and communities. However, the weakening of the AMOC's abyssal limb has far-reaching consequences that extend well beyond coastal regions.



<h3 class="wp-block-heading" id="h-stronger-storms">Stronger storms</h3>



The amount of heat stored in the ocean has a direct link to the intensity of tropical storms and hurricanes. Warmer oceans evaporate more readily, providing additional moisture that fuels these powerful weather systems. 



The warming of the deep North Atlantic contributes to an overall increase in the ocean's heat content, which ultimately intensifies these destructive storms.



<h3 class="wp-block-heading" id="h-shifting-ecosystems">Shifting ecosystems</h3>



Marine organisms have evolved to thrive within specific temperature ranges. Disruptions to these temperature patterns, even in the deep ocean, have cascading effects on marine food webs. 



Changes in temperature can impact the distribution of plankton, disrupting the base of the food chain, and impact the migration patterns and reproductive cycles of larger marine species.



<h3 class="wp-block-heading" id="h-the-unexpected-connection">The unexpected connection</h3>



Changes in the abyssal regions of the ocean might feel far removed from everyday life for many people. However, these changes in <a href="https://www.earth.com/news/antarcticas-protective-ice-barriers-are-melting-at-double-the-pace/" target="_blank" rel="noreferrer noopener">Antarctica</a> and the Atlantic highlight a core concept of Earth's climate system: our planet is an intricately interconnected web. Actions or changes occurring in one region can have far-reaching consequences on a global scale.



<h2 class="wp-block-heading" id="h-tips-to-control-antarctic-warming">Tips to control Antarctic warming</h2>



The primary factor driving the changes observed in the Antarctic and the weakening of the AMOC is human-caused climate change. 



Greenhouse gas emissions, primarily from burning fossil fuels, trap excess heat within Earth's atmosphere. This excess heat is absorbed by the oceans, leading to warming trends even in the most remote regions, such as the <a href="https://www.earth.com/news/antarctica-is-experiencing-rapid-plant-growth-concerning-scientists/" target="_blank" rel="noreferrer noopener">Antarctic</a>.



Here's how the responsibility, and power, shift towards personal decisions and collective action:



<h3 class="wp-block-heading" id="h-be-aware">Be aware</h3>



Building a strong knowledge base is essential. Climate change is a complex issue, but reliable sources such as <a href="https://climate.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Global Climate Change</a> provide accurate, science-based information about causes, impacts, and potential solutions. Staying informed empowers individuals to make better choices and advocate for informed policy decisions.



<h3 class="wp-block-heading" id="h-change-your-habits">Change your habits</h3>



Reducing your carbon footprint has multiple benefits. Energy-efficient homes conserve resources and lower bills. Opting for greener transportation methods, such as cycling, public transit, or electric vehicles, directly reduces greenhouse gas emissions. Supporting businesses with sustainable practices sends a clear message that consumers prioritize environmental responsibility.



<h3 class="wp-block-heading" id="h-vote-with-your-voice">Vote with your voice</h3>



Elected officials are tasked with representing their constituents. Communicating with local, state, and national representatives demonstrates that climate action matters to voters. Supporting candidates whose platforms clearly address climate solutions is crucial.



<h3 class="wp-block-heading" id="h-spread-the-word-on-antarctic-warming">Spread the word on Antarctic warming</h3>



Open dialogue and information sharing within your social circles can have a ripple effect. Discussing climate change, its impacts, and actionable solutions with friends, family, and your broader community builds awareness and encourages collective engagement for climate-conscious decisions.



The story of the AMOC's abyssal slowdown underscores the web of our planet's climate systems. It highlights how individual choices, multiplied across billions of people, truly shape the future health of our oceans and the wellbeing of those who rely on them. 



The study is published in the journal <a href="https://www.nature.com/articles/s41561-024-01422-4" target="_blank" rel="noreferrer noopener">Nature Geoscience</a>.



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Antarctic warming triggers rising North Atlantic sea levels

Deep beneath the icy waters of Antarctica, a silent crisis...

Soil <a href="https://www.earth.com/news/secrets-of-soil-microbes-could-revolutionize-climate-predictions/" target="_blank" rel="noreferrer noopener">microbes</a> face extreme challenges for survival in desert environments, which are characterized by prolonged drought and scarce rainfall. Despite these harsh conditions, an invisible world thrives below the surface. 



The microbes reside in the desert's biocrust - the uppermost layer of soil. They play a crucial role in enriching the <a href="https://www.earth.com/news/how-dormant-soil-microbes-survive-in-a-60-year-old-fire/" target="_blank" rel="noreferrer noopener">soil</a> with essential nutrients like carbon and nitrogen. 



Additionally, they help prevent erosion and retain moisture, contributing significantly to ecosystem health. Yet, the survival strategies of soil microbes in such a punishing environment have long baffled scientists.



<h2 class="wp-block-heading" id="h-from-dormancy-to-dynamism">From dormancy to dynamism</h2>



A recent study has shed light on how these resilient microorganisms manage to survive and even thrive under extreme conditions. Dagmar Woebken and her team in the Centre for Microbiology and Environmental Systems Science at the <a href="https://www.univie.ac.at/" target="_blank" rel="noreferrer noopener">University of Vienna</a> published their findings in the journal <a href="https://www.nature.com/articles/s41467-024-46920-6" target="_blank" rel="noreferrer noopener">Nature Communications</a>.



The experts found that <a href="https://www.earth.com/news/desert-microbes-release-greenhouse-gases/" target="_blank" rel="noreferrer noopener">desert soil</a> microbes are uniquely adapted to swiftly respond to the infrequent moisture provided by rainfall. The bacteria enter a dormant state during dry periods, springing to life almost immediately following a rainfall event. This fascinating phenomenon was closely studied in the biocrusts of the Negev Desert, Israel. 



The researchers discovered that within a very short time frame after rain - sometimes as little as 15 to 30 minutes - nearly all of the diverse <a href="https://www.earth.com/news/microbial-life-soil-planet-warming-global-carbon-cycle/" target="_blank" rel="noreferrer noopener">microbial life</a> present in the soil transitions from dormancy. They quickly reach full activity. This rapid shift is not commonly seen in other soil types, where bacteria reactivation takes significantly longer.



<h2 class="wp-block-heading" id="h-a-closer-look-at-desert-soil-microbes">A closer look at desert soil microbes </h2>



The researchers used advanced techniques involving stable isotope-labeled water, which contains a form of heavy hydrogen, to simulate rainfall events. By using NanoSIMS, a sophisticated imaging technology, they were able to observe how individual cells responded to simulated rainfall.



The method allowed the researchers to identify which cells were reactivating and assess their growth potential during these brief periods of moisture.



Interestingly, while almost all of the biocrust cells reactivated quickly, only a minority were capable of cell division. This occurred within the short span of rain, typically lasting just one to two days. The majority of cells focused on regeneration, preparing themselves for the next dry spell rather than dividing.



"These data help us understand how biocrust bacteria make optimal use of the short activity windows they experience in deserts. They are ideally adapted to withstand short-term changes in soil water content, a very stressful situation for the cells. This allows them to survive the sudden increase in water content during rain, as well as the subsequent drying out,” noted Dagmar Woebken, principal investigator of the study.



“Additionally, the diverse microbial community is capable of immediate reactivation, which is of great benefit when it must return to a dormant state within a few hours to days.”



<h2 class="wp-block-heading" id="h-broader-ecological-insights">Broader ecological insights</h2>



The insights gained deepen our understanding of desert microbial life and have broader ecosystem implications. 



Furthermore, as global droughts become more frequent and intense due to <a href="https://www.earth.com/news/can-soil-microbes-survive-climate-change/" target="_blank" rel="noreferrer noopener">climate change</a>, understanding microorganism responses to water scarcity is crucial. 



The desert-adapted strategies of soil microbes showcase resilience and adaptability, providing valuable lessons for managing soil health in other vulnerable areas.



<h2 class="wp-block-heading">Why are desert soil microbes important?</h2>



Desert soil microbes play a vital role in decomposing organic matter, which is scarce in deserts. This decomposition releases nutrients back into the soil, making them available to plants. Microbes such as bacteria and fungi are particularly crucial in the nitrogen cycle, converting atmospheric nitrogen into forms that plants can absorb and use.



Microbes also help to maintain and improve soil structure. Their activity helps bind soil particles together, which improves soil's ability to retain water and resist erosion, a critical function in arid environments where water is limited and soil erosion can be a severe problem.



Many desert plants rely on symbiotic relationships with microbes to survive in such extreme conditions. For example, <a href="https://www.earth.com/news/plants-distribute-enormous-amounts-of-co2-to-mycorrhizal-fungi/" target="_blank" rel="noreferrer noopener">mycorrhizal fungi</a> colonize plant roots and extend far into the soil, increasing a plant’s reach for water and essential nutrients, which is particularly important in nutrient-poor desert soils.



Furthermore, desert microbes sequester carbon in the soil, contributing to the mitigation of climate change. Their ability to survive in extreme conditions also provides insights into resilience strategies that could be useful in managing ecological responses to climate change.



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Soil microbes survive the desert by 'sleeping' through the dry spells

Soil microbes face extreme challenges for survival in desert environments,...

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Today’s Video of the Day from the <a href="https://www.esa.int/">European Space Agency</a> features the Gulf of Morbihan, a natural harbor with numerous islands and islets in northwest France. 



In this region, Brittany is an important cultural center that is divided into four departments: Ille-et-Vilaine, Côtes d&#8217;Armor, Finistère, and Morbihan.



According to ESA, Brittany is known for its rich and varied agriculture including meats and dairy products and a variety of high quality fruit and vegetables.&nbsp;&nbsp;



The Gulf of Morbihan opens onto the Bay of Quiberon by a narrow passage between Locmariaquer and Port-Navalo.



Morbihan is known for its Alignements de Carnac, which consists of around 3,000 standing stones and megalithic tombs. The stones were erected during the Neolithic period, around 4500 BC.&nbsp;&nbsp; 



The towns and villages around the edges of the Morbihan Gulf are a popular destination with visitors and the bay itself contains numerous small islands, some of which can be visited, and is a haven for wildlife, especially birds. 



The most important towns around the coast of the Morbihan Gulf are Vannes to the north-east and Auray to the north-west. The Morbihan Gulf is an area of sea that extends 20 kilometres inland from the Bay of Quiberon.



Video Credit: ESA&nbsp;



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By <a href="mailto:csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Editor



Check us out on <a href="https://www.earth.com/earthsnap/">EarthSnap</a>, a free app brought to you by Eric Ralls and Earth.com.

The Gulf of Morbihan in northwest France