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There was a period during the last ice age when temperatures in the Northern Hemisphere went on a rollercoaster ride, plummeting and then rising again every 1,500 years or so. Those abrupt climate changes wreaked havoc on ecosystems, but their cause has been something of a mystery. New evidence published this week in the leading journal Science shows for the first time that the ocean's overturning circulation slowed during every one of those temperature plunges - at times almost stopping.

"People have long supposed this link between overturning circulation and these abrupt climate events. This evidence implicates the ocean," said L. Gene Henry, the lead author of the study and a graduate student at Columbia University's Lamont-Doherty Earth Observatory.

Most animal lovers wouldn’t dream of harming an animal for fashion. Fur? No, thank you. Leather? I don’t think so. Yet they might be unknowingly killing sharks — and highly endangered kinds on top of that — for their beauty routine.

Unbeknownst to most, one little ingredient in products like sunscreens, moisturizing lotions, lip balms, lipsticks and face creams is responsible for the death of over three million sharks annually.

Scientists at MIT and elsewhere have identified the "first fingerprints of healing" of the Antarctic ozone layer, published today in the journal Science.

The team found that the September ozone hole has shrunk by more than 4 million square kilometers -- about half the area of the contiguous United States -- since 2000, when ozone depletion was at its peak. The team also showed for the first time that this recovery has slowed somewhat at times, due to the effects of volcanic eruptions from year to year. Overall, however, the ozone hole appears to be on a healing path.

The authors used "fingerprints" of the ozone changes with season and altitude to attribute the ozone's recovery to the continuing decline of atmospheric chlorine originating from chlorofluorocarbons (CFCs). These chemical compounds were once emitted by dry cleaning processes, old refrigerators, and aerosols such as hairspray. In 1987, virtually every country in the world signed on to the Montreal Protocol in a concerted effort to ban the use of CFCs and repair the ozone hole.

Most animal lovers wouldn’t dream of harming an animal for fashion. Fur? No, thank you. Leather? I don’t think so. Yet they might be unknowingly killing sharks — and highly endangered kinds on top of that — for their beauty routine.

Unbeknownst to most, one little ingredient in products like sunscreens, moisturizing lotions, lip balms, lipsticks and face creams is responsible for the death of over three million sharks annually.

Killer ingredient

“Squalene is a naturally occurring compound found in large quantities in the liver of sharks,” explains the shark protection group Shark Trust. “A sharks’ large oily liver helps to control its position in the water column, however many cosmetics companies use the oil (and an associated compound called squalane) as a base for their moisturizing and skin care creams, lipstick and gloss, as it is non-greasy and softens skin.”

Los científicos pronostican que la zona muerta de este año en el Golfo de México, una zona de escaso o ningún oxígeno que puede matar a los peces y la vida marina, será de aproximadamente 5,898 millas cuadradas, más o menos del tamaño de Connecticut, el mismo tamaño que ha promediado en los últimos años.

La zona muerta en el Golfo de México afecta a nivel nacional importantes pescas comerciales y recreativas. Las zonas hipóxicas o zonas muertas son causadas ​​por altos niveles de nutrientes, principalmente de actividades como la agricultura industrializada y el tratamiento inadecuado de aguas residuales. 

Los bajos niveles de oxígeno no pueden soportar más la vida marina y los hábitats en aguas cercanas al fondo. Los organismos que pueden huir salen de la zona muerta, mientras que otros que no pueden están estresados ​​o mueren de asfixia. La reducción de nutrientes que fluyen hacia el Golfo ayudaría a la situación ya que, en condiciones normales, esta área contiene una diversidad de vida marina, los hábitats críticos, y una actividad pesquera clave.