The Expansion of Ocean "Deserts"
A new study by NOAA and the University of Hawaii states the least biologically productive areas of the oceans are expanding much faster than predicted.
Between 1998-2007, ocean deserts (expanses of saltwater with low surface plant life in the Pacific and Atlantic) grew by 15% or 6.6 million sq/km.The study notes that this is happening at the same time that sea-surface temperatures are warming about 1% or 0.02-0.04 degrees celsius a year.
Global ocean temperature anomalies (purple lines) since 1880, courtesy of NASA GISS.
This warming, according to the study published in the Geophysical Research Papers, increases stratification of the ocean waters, preventing deep ocean nutrients from rising to the surface and creating plantlife.
"The fact that we are seeing an expansion of the ocean’s least productive areas as the subtropical gyres warm is consistent with our understanding of the impact of global warming. But with a nine-year time series, it is difficult to rule out decadal variation," said Jeffrey J. Polovina, lead author of the study.
Using a sensor on a spacecraft, the research showed that the areas of low productivity in the Pacific are expanding from the center toward Hawaii. In the Atlantic, the least productive areas of the subtropical gyre are expanding at a more rapid rate eastward across the Caribbean toward Africa.
The black areas are the least productive.
