Scientists have discovered that the number of “dead zones” in the sea have quadrupled, and they believe it is due to global warming and other human activities. It’s an alarming discovery that could lead to the collapse of ecosystems if something isn’t done to reverse the trend, scientists warn.

Scientists call areas of the ocean that are starved of oxygen as dead zones, as plants and animals suffocate and either die or leave the area. This tremendous expansion in the number of dead zones world wide indicate that the problem of climate change is advancing and having a big effect in areas of the world that we aren’t immediately cognizant of, according to the study, which was published in the journal Science.

But although we don’t see these effects, they will have a tremendous impact on us, scientists say. These dead zones could result in ecosystem collapse, which have a negative effect on humans when it comes to economics and societal harm.

“Oxygen is fundamental to life in the oceans,” said Denise Breitburg, lead author and marine ecologist with the Smithsonian Environmental Research Center. “The decline in ocean oxygen ranks among the most serious effects of human activities on the Earth’s environment.”

“It’s a tremendous loss to all the support services that rely on recreation and tourism, hotels and restaurants and taxi drivers and everything else,” said Lisa Levin, a biological oceanographer at Scripps Institution of Oceanography at the University of California San Diego. “The reverberations of unhealthy ecosystems in the ocean can be extensive.”