Claim: Climate Change Threatens Sharks

Guest essay by Eric Worrall

Sharks survived the dinosaur killer, the Cretaceous-Paleogene extinction event which wiped out 80% of Earth’s species, but apparently our gentle 0.1C / decade global warming is a grave threat to their continued survival.

How will sharks respond to climate change? It might depend on where they grew up

November 27, 2020 6.01am AEDT
Culum Brown Professor, Macquarie University
Connor Gervais Connor Gervais

They may have been around for hundreds of millions of years — long before trees — but today sharks and rays are are among the most threatened animals in the world, largely because of overfishing and habitat loss. 

Climate change adds another overarching stressor to the mix. So how will sharks cope as the ocean heats up?

An existential threat

In Australia, the grim reality of climate change is already upon us: we’re seeing intense marine heat waves and coral bleaching events, the disappearance of entire kelp forestsmangrove forest dieback and the continent-wide shifting of marine life

The southeast of Australia is a global change hotspot, with water temperatures rising at three to four times the global average. In addition to rising water temperatures, oceans are becoming more acidic and the amount of oxygen is declining. 

Any one of these factors is cause for concern, but all three may also be acting together.

One may argue sharks have been around for millions of years and survived multiple climate catastrophes, including several global mass extinctions events

To that, we say life in the anthropocene is characterised by changes in temperature and levels of carbon dioxide on a scale not seen for more than three million years.

Read more: https://theconversation.com/how-will-sharks-respond-to-climate-change-it-might-depend-on-where-they-grew-up-150460

The study is available here.

I think most Australians if asked would suggest there are too many sharks.

I swim in Australia’s coastal waters a lot less than I used to, and never venture out too deep. The beloved politicians who run our country have cut back on shark culling near popular beaches, because you know, if you venture into their territory you should accept a little risk. Something to think about when our borders re-open, if you are thinking of visiting Australia for a New Year beach holiday.

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November 28, 2020 at 08:28PM

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