The Guardian view on warming oceans: a rising toll

[nitpicker]

https://www.theguardian.com/commentisfree/2019/jan/16/the-guardian-view-on-warming-oceans-a-rising-toll

The Guardian view on warming oceans: a rising toll

Wed 16 Jan 2019 18.59 GMT Last modified on Thu 17 Jan 2019 05.01 GMT

We know remarkably little about the oceans that cover most of the Earth, provide half of our oxygen and help to regulate the climate. Maps of the ocean floor are less detailed than those of Mars or the moon. Marine biologists have discovered deeply weird and genuinely wonderful species: boxer crabs wielding anemones like weapons; the rope-like Praya dubia, up to 50 metres long; immortal jellyfish, which unlike any other known creature can revert from maturity to an earlier stage of development, akin to a butterfly becoming a caterpillar. But on one estimate we have identified less than a tenth of ocean-dwelling creatures.

What we can be certain about is that the extraordinary diversity of life in the oceans is under immense and growing threat. This week we learned that the last five years were the hottest on record. Global warming has heated the oceans by the equivalent of one atomic explosion per second for the last century and a half; in recent years the pace has accelerated to between three and six atomic bombs per second.

More than 90% of the heat trapped by greenhouse gas emissions has been absorbed by the seas. Billions of people living in coastal areas are under threat from rising sea levels, due both to the melting of ice – happening at a frightening and increasing rate – and the physical expansion of water as it warms. Climate change is making storms more powerful and disrupting the patterns of marine life on which communities depend.

But it is only the most comprehensive of the dangers. Carbon emissions are also causing ocean acidification. Intensive fishing, pollution and the exploitation of mineral resources are all taking their toll. Between a fifth and a quarter of marine species are already threatened with extinction; global marine populations have halved since 1970. Though only three humans have reached the deepest known point, the Mariana trench, our collective impact is felt there in the form of pollutants and plastics.
(snip)