Global climate change produces many effects – warming air energizes the atmosphere and intensifies storms; warmer water expands and raises sea level; storage of more carbon dioxide in the oceans is acidifying large realms. Now it is becoming clear that another, profound result of human activities is underway: lower oxygen levels in our oceans.

The world’s oceans, coastal seas, estuaries, and many rivers and lakes are experiencing declines in dissolved oxygen. Long known as an issue associated with sewage discharges and fertilizer runoff, the problem now is exacerbated by climate change, often independent of nutrient loads, and is global in scale.

If left unchecked, this decline will result in losses of fisheries and biodiversity, poorer water quality, and knock-on effects ranging from falling tourism to reduced marine ecosystem services.

In 2015, scientists from around the world formed an IOC (Intergovernmental Oceanographic Commission)-UNESCO working group called the Global Ocean Oxygen Network or GO2NE, of which I am a member. Our goals are to raise awareness about this problem, called deoxygenation, and stimulate research and policy to understand and mitigate it.