by Arjen Luijendijk et al., April, 27, 2018 in Nature (Open Access)
Coastal zones constitute one of the most heavily populated and developed land zones in the world. Despite the utility and economic benefits that coasts provide, there is no reliable global-scale assessment of historical shoreline change trends. Here, via the use of freely available optical satellite images captured since 1984, in conjunction with sophisticated image interrogation and analysis methods, we present a global-scale assessment of the occurrence of sandy beaches and rates of shoreline change therein. Applying pixel-based supervised classification, we found that 31% of the world’s ice-free shoreline are sandy. The application of an automated shoreline detection method to the sandy shorelines thus identified resulted in a global dataset of shoreline change rates for the 33 year period 1984–2016. Analysis of the satellite derived shoreline data indicates that 24% of the world’s sandy beaches are eroding at rates exceeding 0.5 m/yr, while 28% are accreting and 48% are stable. The majority of the sandy shorelines in marine protected areas are eroding, raising cause for serious concern.
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by Tim Ball, July 21, 2018 in WUWT
I know there are many articles on this website about sea level, none better than the recent one by David Middleton that speaks about “More nonsense about sea level rise.” I thought his article would make the continuance of this article unnecessary. It doesn’t because it is written for the WUWT readers. Unfortunately, too many of them like most of the public, scientists, and media don’t know what is involved in creating the net result that is sea level. I think because they don’t know, that it is time for something more basic as a citizen’s template for fighting city hall. Citizens of Honolulu are the most recent victims of this as the Mayor of Honolulu directs the City to prepare for a 3-foot sea level rise in some undetermined time period. It was reinforced during a recent radio interview when a caller asked about it because his city was planning to spend millions on structures to anticipate sea level rise. I provided a few facts about changes in sea level, scientifically called eustasy, and all the other mechanisms that could explain that change.
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by Samuel Furfari, 22 juillet 2018, in ScienceClimatEnergie
L’hydrogène est un sujet captivant, mais une terrible illusion si on pense à lui comme combustible alternatif. Le public et le monde politique semblent fascinés par cette molécule perçue comme une panacée pour la politique énergétique. Est-ce parce qu’ils ont appris à l’école que c’est le premier élément du tableau de Mendeleïev ? Est-ce parce que ça sonne plus « scientifique » que le charbon ou le pétrole ? Est-ce parce qu’il y a tellement longtemps qu’on en parle qu’ils pensent qu’il faudra bien un jour qu’il perce ? Toujours est-il que cette « énergie alternative » suscite un tel engouement que tout le monde en parle et qu’il convient donc de revenir aux fondamentaux.
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by McGill University, July 18, 2018 in ScienceDaily
The findings, published in the journal Nature, represent the oldest measurement of atmospheric oxygen isotopes by nearly a billion years. The results support previous research suggesting that oxygen levels in the air during this time in Earth history were a tiny fraction of what they are today due to a much less productive biosphere.
“It has been suggested for many decades now that the composition of the atmosphere has significantly varied through time,” says Peter Crockford, who led the study as a PhD student at McGill University. “We provide unambiguous evidence that it was indeed much different 1.4 billion years ago.”
The study provides the oldest gauge yet of what earth scientists refer to as “primary production,” in which micro-organisms at the base of the food chain — algae, cyanobacteria, and the like — produce organic matter from carbon dioxide and pour oxygen into the air.
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La géologie, une science plus que passionnante … et diverse
