Films such as A Plastic Ocean, and the huge success of Blue Planet II, have brought ocean plastic pollution firmly into the popular domain. Plastic has become ubiquitous through the world’s oceans, with fragments found in deep ocean trenches and the Arctic ice sheets. Furthermore, pictures of charismatic animals such as whales and turtles consuming or entangled in plastic provide powerful imagery of the problem to the public.
There is no doubt plastic is a big issue. A study in the journal Marine Policy suggests plastic pollution might be reaching a planetary boundary, a term used to describe safe operational environmental limits within which the world can continue to function safely.
Yet, for all the attention given to ocean plastic, it is not the biggest threat to the marine environment. Both climate change and biodiversity loss (much of which is caused by the impacts of overfishing of our oceans) were shown to have exceeded their respective planetary boundaries when the term was first introduced, in 2009. More recent studies also flag climate change and biodiversity as the two core planetary boundaries. Excessively exceeding these for a prolonged period could cause rapid and major changes, such as runaway temperature rises or the collapse of important ecosystem functions.
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