Scientists have discovered a larger-than-normal seasonal “dead zone” in the Gulf of Mexico, a region where the water has so little oxygen it can’t support marine life, and are suggesting the climate crisis is partially to blame.
The dead zone comprises about 6,334 square miles, an area larger than the state of Connecticut, and is larger than the average seasonal dead patch over the last five years, which is usually around 5,380 square miles, according to the National Oceanic and Atmospheric Administration (NOAA), which supported a weeklong research cruise through the Gulf last week to collect data.
Dead zones, otherwise known as hypoxia, are caused by nutrients on land, usually from the over-application of fertilizer, running into the watershed then eventually the ocean. Nitrogen and other compounds encourage the growth of algae, which then dies, and the resulting decay consumes oxygen before it can sink deeper into the water.
This kills marine life and has caused an estimated $2.4bn in damages a year to fisheries and marine habitat.
"The low oxygen conditions were very close to shore, with many observations showing an almost complete lack of oxygen,” Louisiana State University researcher Nancy Rabalais, part of a consortium of scientists tracking the dead zone, said in a news release.
While farming practices are one major driver of the phenomenon, experts also said there’s a clear climate link.
“This year, we have seen again and again the profound effect that climate change has on our communities – from historic drought in the west to flooding events. Climate is directly linked to water, including the flow of nutrient pollution into the Gulf of Mexico,” EPA Assistant Administrator for Water Radhika Fox said in a statement. “As we work to address the Gulf of Mexico hypoxic zone, we must consider climate change and we must strengthen our collaboration and partnerships to make needed progress.”
In addition to the size of the zone being larger than normal this year, it’s well above the 1900 square mile target set by a federal task force.
The US Department of Agriculture has spent more than $50m in recent years trying to strengthen the Mississippi River watershed to prevent further hypoxia in the Gulf of Mexico.