These are hard numbers and observed facts even the most delusional climate change denialists can't dispute. Our oceans have warmed by more than 1C from the pre-industrial era. Over the same period, our oceans have become 30% more acidic. We have been rapaciously fishing down the food chain. From overfishing to pollution to ocean warming and acidification, we have lost half of all marine life - fish, mammal and sea bird - over the past four decades. Around the world, surviving species are migrating poleward. These trends are showing no sign of slowing anytime soon.
It should come as no surprise then that a new study finds the marine food chains are in danger of collapse if we don't sharply reduce our ways and soon.
A study of 632 published experiments of the world’s oceans, from tropical to arctic waters, spanning coral reefs and the open seas, found that climate change is whittling away the diversity and abundance of marine species.
The acidification of the ocean, where the pH of water drops as it absorbs carbon dioxide, will make it hard for creatures such as coral, oysters and mussels to form the shells and structures that sustain them. Meanwhile, warming waters are changing the behaviour and habitat range of fish.
The overarching analysis of these changes, led by the University of Adelaide, found that the amount of plankton will increase with warming water but this abundance of food will not translate to improved results higher up the food chain.
“There is more food for small herbivores, such as fish, sea snails and shrimps, but because the warming has driven up metabolism rates the growth rate of these animals is decreasing,” said associate professor Ivan Nagelkerken of Adelaide University. “As there is less prey available, that means fewer opportunities for carnivores. There’s a cascading effect up the food chain.
“Overall, we found there’s a decrease in species diversity and abundance irrespective of what ecosystem we are looking at. These are broad scale impacts, made worse when you combine the effect of warming with acidification.
“We are seeing an increase in hypoxia, which decreases the oxygen content in water, and also added stressors such as overfishing and direct pollution. These added pressures are taking away the opportunity for species to adapt to climate change.”
Given that, for the poorest and most vulnerable people in the world, seafood represents about 70% of their protein intake maybe we should be debating the justification for Canada's future as a petro-state in the context of what that means for not just our atmosphere but also our oceans.