#subsidence

Nearly half of China's major cities are suffering "moderate to severe" levels of subsidence, putting millions of people at risk of flooding especially as sea levels rise, according to a study of nationwide satellite data released on Friday. The authors of the paper, published by the journal Science, found 45 per cent of China's urban land was sinking faster than three millimeters per year, with 16 per cent at more than 10 mm per year, driven not only by declining water tables but also the sheer weight of the built environment. With China's urban population already in excess of 900 million people, "even a small portion of subsiding land in China could therefore translate into a substantial threat to urban life," said the team of researchers led by Ao Zurui of the South China Normal University.

Coastal flooding (no storm), shallow groundwater exposure and erosion (unimpeded model case) for one meter of sea-level rise and observed vertical land motion (VLM) across the Southeast Atlantic coast.

Excerpt from this report from the US Geological Survey:

A study led by USGS outlines a multifaceted climate-driven crisis facing communities along the Southeast Atlantic coast of the United States. As sea level rises, increased flooding, land subsidence, beach erosion, and rising groundwater levels threaten the safety, property, and infrastructure of millions.

While previous research has largely focused on flooding, the new study highlights additional threats such as groundwater hazards, land subsidence, and beach erosion. These hazards, often underappreciated in climate discussions, will be amplified by sea levels projected to rise by one meter over the next century. The study estimates that up to 70% of coastal residents and $1 trillion in property could face challenges from shallow and emerging groundwater. This risk is 15 times greater than the exposure to daily tidal flooding alone.

Storm activity, which is becoming more intense with climate change, adds another layer of complexity. The study projects that storm-driven flooding over the next century, including storm surge and wave-driven water levels, could expose roughly 50% of coastal residents and $770 billion in property to severe flooding, an increase by an order of magnitude compared to daily flood impacts.  

When volcanoes die

Once the heat from below that fed the magma chamber dies down, the volcano cools and its rocks get denser and contract, the entire structure begins to sink back into the underlying crust. When this happens to a volcanic island in the tropics, coral reefs begin to ring the sinking peak since it provides a perfect environment for growth in the middle of the deep ocean, as they require shallow illuminated seas. These phenomena are called atolls, and Darwin was the first to come up with this ingenious solution to their formation. Bora Bora in the Leewards Islands (part of French Polynesia) is a textbook example. Around the outside is a barrier reef, shielding the main island from storms and separating the pearly blue lagoon from the deep dark depths all around. The centre is the extinct peak of a volcano, that was at its most active some 3 to 3.5 million years ago, peaking at 750 metres. Now a major tourist spot, it was first settled some 1600 years ago, and the first Europeans arrived in 1722.

We also recently shared an agate that resembles this atoll seen from space at http://on.fb.me/1Kzdtog.

Loz

Indonesia: Alone in a sinking village, May 26, 2020

The village of Bedono, Central Java was once home to more than 200 families.

But now it’s now under water as the island is taken over by rising sea levels and only one family still lives there.

Researchers say Java, in Indonesia, is sinking because of intense groundwater extraction, the destruction of mangroves and rising sea levels due to climate change.

Produced by: Ayomi Amindoni  and Rebecca Henschke

Filmed by: Anindita Pradana

Edited by: Kevin Kim

En un MAR DE NUBES. #VanekitaNekita

A éste fenómeno natural se le denomina «mar de nubes». Éste es creado por los vientos alisios, que empujan a las nubes contra las laderas montañosas, reflejando una capa de nubosidad que se extiende horizontalmente por debajo de nuestro punto de observación. Las nubes que conforman dicha capa suelen pertenecer a los géneros Stratus y Stratocumulus.

Éste fenómeno puede ser observado en los Himalayas, Japón, España, México entre otros lugares. Necesitamos básicamente dos cosas para observar éste espectáculo: que existan las condiciones adecuadas para que se formen nubes a no demasiada altitud (vientos alisios, montañas, temperatura) y que “algo” las confine en las capas bajas de la atmósfera, que no les permita crecer verticalmente ni “escapar” hacia arriba (subsidencia). 

En la obra de 1818 del pintor romántico alemán Caspar David Friedrich, ya se apreciaba este espectacular evento meteorológico: “El viajero”, aparece representado en lo alto de una montaña y a sus pies el mar de nubes del que emergen varios picos de otras montañas que representan la Suiza sajona.