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Investigadores de los Laboratorios Nacionales Sandia han ayudado a desentrañar un antiguo misterio de la astrofísica: ¿por qué el hierro se encuentra por todo el manto de la Tierra, en la región de más o menos 2,000 millas de espesor entre el núcleo de la Tierra y su corteza?

A primera vista, parecía más razonable que el hierro que llega de colisiones entre la Tierra y planetesimales (que van desde varios metros a cientos de kilómetros de diámetro), durante las últimas etapas de formación de la Tierra, debería haber sido impulsado como bala directamente al núcleo de la Tierra, donde el hierro ya existe en gran cantidad.

Arctic sea ice shrank to the lowest winter extent ever recorded, according to data released today by the US-based National Snow and Ice Data Center. The record-low ice level follows earlier news that 2014 was the warmest year since record keeping began.
 
An unusually warm February in parts of Alaska and Russia contributed to the record ice low. The winter reach of Arctic ice decreased 1.1 million square kilometres compared to the average maximum from 1981 to 2010. This represents an area more than twice the size of Sweden.
 
"This is not a record to be proud of. Low sea ice can create a series of reactions that further threaten the Arctic and the rest of the globe," said Alexander Shestakov, Director, WWF Global Arctic Programme.

Governments and donors must pay more attention to the environmental impact of road networks to limit their “devastating” effect on ecosystems, a study on global infrastructure expansion has warned. Road construction opens a “Pandora’s box” of negative impact, according to the authors of the paper, published this month in Current Biology. These include deforestation, animals hunted to extinction, land grabs by speculators betting on development, and wildfires. 

A study in this week’s Scientific Report by researchers at Michigan State University (MSU) and in China add more fuel to the already hot debate about whether electric vehicles are more environmentally friendly than conventional vehicles by uncovering two hidden benefits.

They show that the cool factor is real – in that electric vehicles emit significantly less heat.  That difference could mitigate the urban heat island effect, the phenomenon that helps turn big cities like Beijing into pressure cookers in warm months.

Water is our most precious natural resource.  Without clean water to drink human populations cannot exist.  But our water supplies are under constant assault from anthropogenic pollution.

When pollutants get into groundwater, they can stay there for decades. Cleanup efforts are difficult, expensive and not always successful. It would be better to protect groundwater from contamination in the first place, but risks to groundwater are moving targets. Although unchanging factors such as porous soil or shallow aquifer depth play a role, the greatest risk comes from the source of the pollutants: people. And people are always moving. A growing city, in particular, usually means a growing threat to groundwater quality. To lock on to the moving target of groundwater risk, planners worldwide need up-to-date information on how people are changing the land surface.