Via The Guardian, discouraging news from the International Union for the Conservation of Nature: Soaring ocean temperature is 'greatest hidden challenge of our generation'. Excerpt:
The ocean has absorbed more than 90% of the extra heat created by human activity. If the same amount of heat that has been buried in the upper 2km of the ocean had gone into the atmosphere, the surface of the Earth would have warmed by a devastating 36C, rather than 1C, over the past century.
At some point, the report says, warming waters could unlock billions of tonnes of frozen methane, a powerful greenhouse gas, from the seabed and cook the surface of the planet. This could occur even if emissions are drastically cut, due to the lag time between emitting greenhouse gases and their visible consequences.
Warming is already causing fish, seabirds, sea turtles, jellyfish and other species to change their behaviour and habitat, it says. Species are fleeing to the cooler poles, away from the equator, at a rate that is up to five times faster than the shifts seen by species on land.
Even in the north Atlantic, fish will move northwards by nearly 30km per decade until 2050 in search of suitable temperatures, with shifts already documented for pilchard, anchovy, mackerel and herring.
The warming is having its greatest impact upon the building blocks of life in the seas, such as phytoplankton, zooplankton and krill. Changes in abundance and reproduction are, in turn, feeding their way up the food chain, with some fish pushed out of their preferred range and others diminished by invasive arrivals.
With more than 550 types of marine fishes and invertebrates already considered threatened, ocean warming will exacerbate the declines of some species, the report also found.
The movement of fish will create winners and losers among the 4.3 billion people in the world who rely heavily upon fish for sustenance. In south-east Asia, harvests from fisheries could drop by nearly a third by 2050 if emissions are not severely curtailed.
Global production from capture fisheries has already levelled off at 90m tonnes a year, mainly due to overfishing, at a time when millions more tonnes will need to be caught to feed a human population expected to grow to 9 billion by 2050.
Humans are also set to suffer from the spread of disease as the ocean continues to heat up. The IUCN report found there is growing evidence of vibrio bacterial disease, which can cause cholera, and harmful algal bloom species that can cause food poisoning. People are also being affected by more severe, if not more numerous, hurricanes due to the extra energy in the ocean and atmosphere.