Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/">NASA Earth Observatory</a> shows the Afsluitdijk, a 20-mile dam that separates the Wadden Sea from the freshwater Lake Ijssel in the Netherlands.&nbsp;

According to NASA, without Afsluitdijk and the rest of the dams and dykes of the Zuiderzee Works, an inland sea would flood large patches of land around Lake Ijssel. To cope with sea level rise, the Dutch are currently making extensive upgrades to Afsluitdijk.

Sea level rise will impact nearly every coastline on the planet, but it will impact some places - including river deltas and island atolls - more than others.&nbsp;

“One of the reasons it is difficult to offer definitive assessments about how much sea levels will lead to impacts in certain areas is that governments could respond and influence which areas will flood and which will not by building infrastructure,” said Ben Hamlington of the Jet Propulsion Laboratory and current leader of NASA's sea level team.&nbsp;

“In places like The Netherlands or the Sacramento-San Joaquin Delta, countering strategies have either already been implemented. Or it’s a good bet that dykes and other infrastructure will be built to prevent inland seas from forming where they otherwise might.”

“If you add in the isostatic rebound in formerly glaciated parts of Europe and North America, the issue becomes even more complex,” said paleoclimatologist Anders Carlson of the Oregon Glaciers Institute.&nbsp;

“Throw in competing gravitational effects from the Greenland Ice Sheet, and you can start to see how we’re dealing with ‘known unknowns’ when we're making regional sea level rise projections.”

Image Credit: NASA Earth Observatory&nbsp;

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

Predicting sea level rise involves many unknowns

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

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/">NASA Earth Observatory</a> features the Canterbury region of New Zealand’s South Island, where the landscape is remarkably diverse.&nbsp;



On the east coast of the island, the topography shifts dramatically on Banks Peninsula, which was an active volcanic complex until about 6 million years ago.



According to NASA, water from the sea and from streams have since cut away at the rock, helping to shape the peninsula’s valleys, bays, and coastal cliffs



Image Credit: NASA Earth Observatory&nbsp;



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

Banks Peninsula on New Zealand’s South Island

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

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/">NASA Earth Observatory</a> features tidal currents in the western Sea of Okhotsk in the Russian Far East. The Shantar Islands and Uda Bay are also visible in the natural-color photo.



According to NASA, the currents around the Shantar Islands are heavily influenced by the strong tides and by freshwater discharge from rivers draining into Uda Bay.&nbsp;



Some of the highest diurnal tides in the world have been recorded in the Sea of Okhotsk. In the Russian Far East, narrow bays funnel and amplify the incoming tides, making it a prime location for tidal power generation, reports NASA.



The image was captured on September 24, 2021, by the Operational Land Imager (OLI) on Landsat 8.



Image Credit: NASA Earth Observatory&nbsp;



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

Colorful currents in the Sea of Okhotsk

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/">NASA Earth Observatory</a> features a natural-color photograph of north-central Kyushu, the southernmost of Japan’s four largest islands.&nbsp;



While the Northern Hemisphere had lost most of its fall color by late November, some parts of Japan were still hitting their autumn peak. In the image, colorful vegetation is still visible across the mountainous landscape of Aso-Kuju National Park.



According to NASA, it is not possible to know the exact sources of the color based on this satellite image alone, but it is likely a combination of evergreens, deciduous trees, grasses, shrubs, and agricultural fields.&nbsp;



The photograph of Kyushu was captured on November 29, 2021 by the Operational Land Imager (OLI) on Landsat 8.



Image Credit: NASA Earth Observatory&nbsp;



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

Fall colors persist in Kyushu, Japan

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/">NASA Earth Observatory</a> features Frederikshåb Isblink, a glacier in southwest Greenland that flows downward from the Greenland Ice Sheet. After winding through a series of valleys, the glacier flattens out on a delta along the coast.&nbsp;



In this image xaotured by the Operational Land Imager (OLI) on Landsat 8, meltwater draining from Frederikshåb is mixing with the darker waters of the Labrador Sea.



According to ESA, Greenland’s glaciers function like bulldozers, grinding away and pulverizing rocks along the land surface. This produces a powder called glacial flour, made up of silt and clay, that builds up in the water around the glaciers.



Image Credit: NASA Earth Observatory&nbsp;



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

Frederikshåb Isblink meltwater colors the Labrador Sea

A new study published in the journal <a href="https://cgejournal.biomedcentral.com/articles/10.1186/s40575-021-00111-4">Canine Medicine and Genetics</a> has found that most dog breeds are highly inbred, with an average inbreeding level of over 25 percent. These extremely high levels of inbreeding have been associated with the increased prevalence of a large variety of complex <a href="https://www.earth.com/news/study-confirms-plastics-contribute-to-heart-disease/">diseases</a> and conditions.



Dog breeds are often recognized by their distinctive traits, such as the wrinkled face of a pug, the spotted coat of a Dalmatian, or the short legs of a dachshund. Unfortunately, these traits are frequently the result of inbreeding.



A team of researchers led by the <a href="https://www.ucdavis.edu/">University of California, Davis</a> together with <a href="https://www.wisdompanel.com/en-us">Wisdom Health Genetics</a>, a company owning the world’s largest dog DNA database, has collected and analyzed data from 49,378 dogs across 227 breeds.&nbsp;



The analysis revealed that the average inbreeding across this cohort was 25 percent, or the equivalent of sharing the full same genetic material with a full sibling.&nbsp;



According to the researchers, dogs are inbred by humans in order to select for traits such as their looks. However, such methods pose quite significant dangers to dogs’ health, increasing the risk of different diseases, many of which are lethal.



“It’s amazing how inbreeding seems to matter to health,” said study lead author Dannika Bannasch, a veterinary geneticist at UC Davis. “While previous studies have shown that small dogs live longer than large dogs, no one had previously reported on morbidity, or the presence of disease.&nbsp;This study revealed that if dogs are of smaller size and not inbred, they are much healthier than larger&nbsp;dogs with high inbreeding.”



"Data from other species, combined with strong breed predispositions to complex diseases like cancer and autoimmune diseases, highlight the relevance of high inbreeding in dogs to their health."



In order to preserve the genetic diversity and health of a breed, several measures should be taken, including the careful management of breeding populations in order to avoid additional loss of existing genetic diversity. This can be achieved through breeder education and close monitoring of inbreeding levels, which is now enabled by direct genotyping technologies.&nbsp;



Moreover, in the few breeds with low inbreeding levels, such as the Danish-Swedish farm dog, every effort should be made to maintain the genetic diversity that is already present.&nbsp;



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Dogs have a high risk of disease due to inbreeding

A new study published in the journal Canine Medicine and...

A set of footprints found in 1976 in Laetoli, Tanzania - just next door to the oldest known human tracks - were initially dismissed as belonging to <a href="https://www.earth.com/news/loss-of-genetic-diversity-in-polar-bears-linked-to-climate-change/">bears</a>. Now, a study from <a href="https://home.dartmouth.edu/">Dartmouth</a> takes a new look at the prints and concludes that they were ancient human tracks.&nbsp;



“Given the increasing evidence for locomotor and species diversity in the hominin fossil record over the past 30 years, these unusual prints deserved another look,” explained study lead author Professor Ellison McNutt.



Professor McNutt is a specialist in locomotion, especially upright locomotion and has looked at comparative anatomy in bears and other animals to gain a better understanding of bipedalism. Bears do occasionally walk upright, but Professor McNutt was fascinated by the footprints in Tanzania because of their possibility.&nbsp;



To get to the truth of the matter, researchers led by co-author Charles Musiba visited Laetoli to gather evidence from the footprints. The prints were measured, photographed and 3D scanned to collect evidence of their origins.&nbsp;



The footprints were then compared to those of black bears, humans and chimpanzees. Young bears from the Kilham Bear Center, a rehabilitation facility were lured to walk on their hind legs across mud for treats. Over 50 hours of bear videos were also used. During the video footage, bears only walked on hind legs one percent of the time.



“As bears walk, they take very wide steps, wobbling back and forth," said Professor Jeremy DeSilva. "They are unable to walk with a gait similar to that of the Site A footprints, as their hip musculature and knee shape does not permit that kind of motion and balance.”&nbsp;



The shape of the footprints being more squared off like a human and less fan shaped like a bear also lends evidence of an early relative making these prints. One strange detail, however, is that the prints seem to show "cross stepping" where one foot crosses over the other, an unusual way of walking for humans.&nbsp;



&nbsp;“Although humans don’t typically cross-step, this motion can occur when one is trying to reestablish their balance," explained Professor McNutt. "The Site A footprints may have been the result of a hominin walking across an area that was an unlevel surface.”



Chimpanzee footprints also don’t quite match the shape of the Laetoli prints, as chimpanzees generally have wider heels. Although the prints are different from those nearby that were already conclusively human, the scientists feel comfortable with the assessment that both are human prints.&nbsp;



“Through this research, we now have conclusive evidence from the Site A footprints that there were different hominin species walking bipedally on this landscape but in different ways on different feet,” said Professor DeSilva.



The study is published in the journal <a href="https://www.nature.com/">Nature</a>.



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By <a href="mailto:zachfitzner@yahoo.com">Zach Fitzner</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Ancient bear footprints turned out to be human

A set of footprints found in 1976 in Laetoli, Tanzania...

The western honey bee (Apis mellifera) is the most common of the 7–12 different species of honey bees worldwide. It is commercially important as a <a href="https://www.earth.com/news/one-third-of-plants-are-completely-reliant-on-animal-pollinators/">pollinator</a> of crops and a producer of honey. The geographic origin of the western honey bee has been hotly debated over decades. Some believing in an African origin, while others think it first evolved in Asia. 



In new research, led by scientists from <a href="https://www.yorku.ca/">York University</a> the genomes of 251 honey bees, from 18 different subspecies, collected in their native ranges, have been sequenced in order to determine the probable geographic origin and pattern of dispersal of honey bees.&nbsp;



The results indicate that an Asian origin – most likely western Asia – is strongly supported by the genetic data. According to this data, the probability of the bees originating within western Asia is 64 to 71 percent. In comparison, the genetic analysis indicates only a six percent chance that western honey bees originated in Africa and a three to six percent chance that they came initially from Europe.



“As one of the world’s most important pollinators, it’s essential to know the origin of the western honey bee to understand its evolution, genetics and how it adapted as it spread,” said study co-author Professor&nbsp;<a href="https://news.yorku.ca/experts/?name_or_keyword=amro+zayed&amp;research_area=&amp;submit=Search+the+Guide&amp;search=Y">Amro Zayed</a>.



The research also indicates that western honey bees underwent three separate expansion events during their evolution. They expanded into Africa in one event, and also experienced two separate expansions into Europe. This led to the existence of seven geographically and genetically distinct evolutionary lineages traceable back to Western Asia. The adaptive radiation of the honey bees after these expansions has led to the development of the approximately 27 different subspecies of honey bees that are found in the world.



Today, western honey bees inhabit every continent except Antarctica and show a remarkable capacity for surviving in vastly different environments – from tropical rainforests, to near deserts and to temperate regions with cold winters. The researchers were interested in identifying the genes and genetic variation that are associated with honey bee adaptation to these different environments.&nbsp;



They found that the bee genome has several “hotspots” that allowed honey bees to adapt to new environmental conditions. While the bee genome has more than 12,000 genes, only 145 of them had repeated signatures of adaptation associated with the formation of all major honey bee lineages found today. In particular, many of the genes involved in adaptation related to changes in the behavior of worker bees, and the analysis showed that these genes have been under positive selective pressure in the past.&nbsp;



“Our research suggests that a core-set of genes allowed the honey bee to adapt to a diverse set of environmental conditions across its native range by regulating worker and colony behavior,” said York University PhD student Kathleen Dogantzis of the Faculty of Science, who led the research.



“It’s important to understand how locally adapted subspecies and colony-level selection on worker bees, contributes to the fitness and diversity of managed colonies."



The sequencing of these bee genomes also led to the discovery of two distinct lineages, one in Egypt and another in Madagascar.



The researchers hope their study will finally resolve the debate about the ancestral origins of the western honey bee so that future research can focus on exploring how they adapted to different climates and geographic areas.



The study is published in the journal <a href="https://www.science.org/journal/sciadv">Science Advances</a>.



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Mysterious origins of western honey bees revealed

The western honey bee (Apis mellifera) is the most common of...

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What causes glaciers to melt from below? Today&#8217;s Video of the Day from <a href="https://earthobservatory.nasa.gov/">NASA Earth Observatory</a> explains why many of Greenland&#8217;s glaciers are melting from below.
Scientists with the Oceans Melting Greenland (OMG) mission have been surveying more than 200 glaciers over the past five years. 
The researchers found that glaciers in deep fjords come into contact with more warm water, which causes undercutting. During this process, warm seawater melts the base of the glacier and causes the ice to break apart.  A glacier is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years. Also  Glaciers slowly form and flow under stresses induced by their weight, creating crevasses, seracs, and other distinguishing features. They also abrade rock and debris from their substrate to create landforms such as cirques, moraines, or fjords. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that forms on the surface of bodies of water. So you ask What causes glaciers to melt from below? Its from the climate and warm weather.
Video Credit: NASA Earth Observatory 
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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer