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There is a new phenomenon growing in our oceans: areas of oxygen-depleted water that are killing off marine life. Between 1998 and 2007, 'ocean deserts' grew by 15%, encompassing a size larger than all of Asia. This disturbing trend has been reported recently by the National Oceanic and Atmospheric Administration (NOAA) and the University of Hawaii:

The research showed that the areas of low productivity in the Pacific Ocean are expanding from the center toward Hawaii. In the Atlantic Ocean, the least productive areas of the subtropical gyre are expanding at an even more rapid rate eastward across the Caribbean toward Africa. The low-productivity zones, likened to deserts, now cover an estimated 51 million square kilometers in the two oceans. The least productive area of the Indian Ocean shows the same trend, but there has been too much variability for it to be statistically significant.

This trend of declining amounts of oxygen is best explained this way:

Surface warming increases stratification, creating a barrier between the lighter warm water and denser cold water in the ocean. It's like putting maple syrup at the bottom of a container and lighter fluid at the top, explains Jack Sobel, a scientist at the nonprofit Ocean Conservancy. The two can't mix. "There's a stronger contrast in density between warm waters above and cool waters below," Johnson says.

Warmer water means less oxygen and serious threat to ocean species. The Hawaiian monk seal is in danger of starvation. This cap keeps oxygen-enriched surface waters from mixing with the colder water below and also decreases the likelihood of nutrient-rich, colder water making its way to the surface. The process, known as upwelling, is crucial to the productivity of marine life.

"The mixing of nutrients and oxygen is what drives an ocean's productivity," Sobel says. "Without this process, it's difficult for ocean wildlife to survive."

It's just another symptom of global warming to keep you up at night...

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