Are the oceans doomed?

The latest UN report says it is horribly likely.

Traversing the Pacific during a world cruise this year, it was apparent that wildlife has largely left the ocean.  Where flocks of flying fish used to accompany the ship, there were only one or two to be seen.  I know that ships don't throw tempting garbage overboard these days, but there must be another reason why the ship was never followed by an albatross, or was flocked with seabirds close to the shore.  In the Baltic we saw many birds, and in the Atlantic dolphins often frolicked, and whales made an occasional appearance, but in the open Pacific? Nothing to be seen.

The difference from previous voyages was alarming, and the UN report tells us why.

From the NYT - Story by Brad Plumer

WASHINGTON — Earth’s oceans are under severe strain from climate change, a major new United Nations report warns, which threatens everything from the ability to harvest seafood to the well-being of hundreds of millions of people living along the coasts.

Rising temperatures are contributing to a drop in fish populations in many regions, and oxygen levels in the ocean are declining while acidity levels are on the rise, posing risks to important marine ecosystems, according to the report issued Wednesday by the Intergovernmental Panel on Climate Change, a group of scientists convened by the United Nations to guide world leaders in policymaking.

In addition, warmer ocean waters, when combined with rising sea levels, threaten to fuel ever more powerful tropical cyclones and floods, the report said, further imperiling coastal regions and worsening a phenomenon that is already contributing to storms like Hurricane Harvey, which devastated Houston two years ago.

“The oceans are sending us so many warning signals that we need to get emissions under control,” said Hans-Otto Pörtner, a marine biologist at the Alfred Wegener Institute in Germany and a lead author of the report. “Ecosystems are changing, food webs are changing, fish stocks are changing, and this turmoil is affecting humans.”

For decades, the oceans have served as a crucial buffer against global warming, soaking up roughly a quarter of the carbon dioxide that humans emit from power plants, factories and cars, and absorbing more than 90 percent of the excess heat trapped on Earth by carbon dioxide and other greenhouse gases. Without that protection, the land would be heating much more rapidly.

But the oceans themselves are becoming hotter and less oxygen-rich as a result, according to the report. If humans keep pumping greenhouse gases into the atmosphere at an increasing rate, the risks to human food security and coastal communities will increase sharply, particularly since marine ecosystems are already facing threats from plastic pollution, unsustainable fishing practices and other man-made stresses.

“We are an ocean world, run and regulated by a single ocean, and we are pushing that life support system to its very limits through heating, deoxygenation and acidification,” said Dan Laffoley of the International Union for Conservation of Nature, a leading environmental group that tracks the status of plant and animal species, in response to the report.

The report, which was written by more than 100 international experts and is based on more than 7,000 studies, represents the most extensive look to date at the effects of climate change on oceans, ice sheets, mountain snowpack and permafrost.