Ocean heat waves

A study in the journal Nature Climate Change found that heat waves were destroying the framework of many ocean ecosystems. The waves affect fishing and fish farming, or aquaculture. They found that from 1925 to 2016, marine heat waves became, on average, 34 percent more frequent and 17 percent longer. Over all, there were 54 percent more days per year with marine heat waves globally.

Scientists estimate that the oceans have absorbed more than 90 percent of the heat trapped by excess greenhouse gases since mid-century. Humans have added these gases to the atmosphere largely by burning fossil fuels, like coal and natural gas, for energy.

There has been a significant loss of what biologists call foundational species, like coral reefs, sea grasses and kelp forests. They support the diversity of aquatic life by providing shelter from predators, moderating temperatures and acting as food sources. When they disappear, the entire ecosystem disappears along with them.