Pacific Northwest ocean dead zone getting larger
Researchers believe global warming is behind a recurring low-oxygen “dead zone” in the Pacific Northwest ocean. Triggered by north winds, a process called upwelling encourages the growth of phytoplankton blooms; when the water calms, the phytoplankton die for lack of nutrients, sink to the bottom, and rot, using up oxygen in the water. Another round of upwelling then brings the low-oxygen water toward shore, killing fishies and crabs that aren’t quick enough to escape. “We are seeing wild swings from year to year in the timing and duration of the winds that are favorable for upwelling,” says marine specialist Jane Lubchenco. “This increased variability in the winds is consistent with what we would expect under climate change.” Not to be outdone, an agricultural-runoff-caused dead zone off the Louisiana coast is likely to be 40 percent larger than average this year, or about 6,700 square miles. Soon we’ll be looking around in vain for the live zones.