As we reported recently, the fish and sea life in the ocean are suffocating to death as oxygen levels plunge. But what are we doing to cause this? The answer is surprising, if only because it reveals just how many indirect effects due to climate change there are as well as the direct ones we all know about.

The new report finds that atmospheric pollution is heating up the Earth at an extremely rapid rate, which in turn is causing oxygen levels to dip in the ocean. Bottom-dwelling sea life that depends on this oxygen is slowly suffocating. And with ocean warming expected to continue, those oxygen levels will only continue to decline, according to a National Science Foundation statement.

Most people are aware that climate change and global warming can result in violent storms, severe droughts, rising flood waters, and other serious problems. But the pollution we pump into our atmosphere also has indirect effects, as this study shows, heating the ocean and causing problems for other creatures far beyond what we can see. It’s an example that not only will we be made uncomfortable by the changing climate, but the increasing global temperatures is hammering the fragile ecosystem in even the deepest depths of the Earth.

“Thanks to natural warming and cooling, oxygen concentrations at the sea’s surface change constantly — and deeper in the ocean, those changes can linger for years or decades,” the statement notes. “For example, an exceptionally cold winter in the North Pacific would allow the ocean surface to soak up a large amount of oxygen. Thanks to the natural circulation pattern, that oxygen would then be carried deeper into the ocean, where it might still be detectable years later as it travels along its flow path.

“The climate change pattern also became evident in the model runs around 2030, adding confidence to the conclusion that widespread deoxygenation due to climate change will become detectable around that time,” it continued. “The maps could also be useful resources for deciding where to place instruments to monitor ocean oxygen levels in the future to get the best picture of climate change effects. Currently, ocean oxygen measurements are relatively sparse.”