Scientists are seeing an expansion of the regions of the ocean that support the least ocean life.
These are regions of warm water at the centers of the world’s oceans. Scientists often refer to them as the ocean’s biological deserts.
Jeff Polovina of the U.S. National Marine Fisheries Service studies a measure of phytoplankton – ocean plant life – estimated from a satellite. Polovina has seen these biological deserts in the oceans expand by 15% – or 6.6 million square kilometers – over the past 9 years.
Jeff Polovina: To see a similar and persistent expansion of the regions that have the least productivity was quite surprising.
These regions in the ocean – places lacking in ocean life – happen naturally. They occur when nutrients from the bottom of the sea are not mixed up towards the surface. It’s thought that warming ocean surface temperatures, or changes in wind patterns, could keep nutrients in nearby waters from mixing. If so, that could explain why these ocean deserts are expanding.
Jeff Polovina: It’s consistent with what we know about global warming, that as the oceans warm, we would expect this phenomena to happen. It’s happening at a little faster rate than we thought.
If the expansion of these ocean ‘deserts’ is linked to climate change…
Jeff Polovina: Then we’re looking at changes that will persist and increase over time, that will result in large areas of the ocean declining in productivity.
The major impact of this phenomenon is that it reduces the ocean’s ability to support large animals and fish. It may also affect fisheries, which are double-stressed from overfishing top predators, and loss of production from the bottom.
Jeff Polovina: If it were part of natural fluctuation, you might see it fluctuating in one direction in one ocean, and another direction in another ocean, the way a lot of natural variability does occur. But what we’re seeing is the same trend over all four of our ocean basins.
Our thanks today to NASA: explore, discover, understand.
Our thanks to:
U.S. National Marine Fisheries Service
Learning to love science. As a producer for EarthSky, Lindsay Patterson interviews some of the world's most fascinating scientists. Through EarthSky, her work content is syndicated on some of the world's top media websites, including USAToday.com and Reuters.com. Patterson is also charged with helping to stay in steady communication with the thousands of scientists who contribute to EarthSky's work of making the voice of science heard in a noisy world. She graduated from Colorado College with a degree in creative writing, and a keen interest in all forms of journalism and media.