Corals are likely to suffer as a result of the changes to our oceans

The health of the world’s oceans is deteriorating even faster than had previously been thought, a report says.

A review from the International Programme on the State of the Ocean (IPSO), warns that the oceans are facing multiple threats.

They are being heated by climate change, turned slowly less alkaline by absorbing CO2, and suffering from overfishing and pollution.

The report warns that dead zones formed by fertiliser run-off are a problem.

It says conditions are ripe for the sort of mass extinction event that has afflicted the oceans in the past.

It says: “We have been taking the ocean for granted. It has been shielding us from the worst effects of accelerating climate change by absorbing excess CO2 from the atmosphere.

“Whilst terrestrial temperature increases may be experiencing a pause, the ocean continues to warm regardless. For the most part, however, the public and policymakers are failing to recognise - or choosing to ignore - the severity of the situation.”

It says the cocktail of threats facing the ocean is more powerful than the individual problems themselves.

Coral reefs, for instance, are suffering from the higher temperatures and the effects of acidification whilst also being weakened by bad fishing practices, pollution, siltation and toxic algal blooms.

Climate change 'may shrink fish'

 

 
Fish body size is related to the water's temperature and oxygen levels, says the team
 

Fish species are expected to shrink

in size by up to 24% because of global warming, say scientists.

Researchers modelled the impact of rising temperatures on more than 600

species between 2001 and 2050.

Warmer waters could decrease ocean oxygen levels and significantly reduce

fish body weight.

The scientists argue that failure to control greenhouse gas emissions will

have a greater impact on marine ecosystems than previously thought.

Previous research has suggested that changing ocean temperatures would impact

both the distribution and the reproductive abilities of many species of fish.

This new work suggests that fish size would also be heavily impacted.

The researchers built a model to see how fish would react to lower levels of

oxygen in the water. They used data from one of the higher emissions

scenarios developed by the Intergovernmental Panel on Climate Change (IPCC).

Warming the fish

Although this data projects relatively small changes in temperatures at the

bottom of the oceans, the resulting impacts on fish body size are "unexpectedly

large" according to the paper.