"Today the synergistic effects of human impacts are laying the groundwork for a comparably great Anthropocene mass extinction in the oceans, with unknown ecological and evolutionary consequences," Jeremy Jackson of the Scripps Institution of Oceanography at the University of California, San Diego, wrote in a 2008 article published in the journal Proceedings of the National Academy of Sciences.
When it comes to the oceans, research shows a parallel to the Permian-Triassic extinction — also known as the Great Dying — which eradicated 95 percent of marine species when the oceans lost their oxygen about 250 million years ago.
The same phenomenon is taking place in many areas of today's oceans. The entry of fertilizers into rivers and subsequently oceans is eating up the oceans' oxygen — that runoff is the primary source of the Gulf of Mexico's 3,000-square-mile (7,770-square-kilometer) dead zone. Around the world, the number of dead zones, some of which are naturally occurring, increased from 149 in 2003 to more than 200 in 2006, according to a 2008 report by the United Nations Environmental Program.
What's more, the ocean surface is warming, driven by the emission of carbon dioxide and other greenhouse gases. This keeps the deeper waters, which are rich in nutrients but low in oxygen, from mixing with the oxygenated surface. According to a 2007 report from the International Panel on Climate Change (IPCC), global surface temperatures increased by 1.1 degrees Fahrenheit (0.6 degrees Celsius) throughout the 21st century, and, according to the National Oceanic and Atmospheric Administration (NOAA), this decade is the warmest since record-keeping began in 1880.