Alison Ballance's foray into the vaults finds a feature on ocean acidification, The Acid Test and adds a 2021 update.

Alison Ballance revisits a story about ocean acidification, which has been described as 'global warming's evil twin.'

She also catches up with NIWA marine biogeochemist Cliff Law to discover what we've learned in the past decade about the growing impact of carbon dioxide on the acidity of the world's seas.

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The Acid Test - a feature on ocean acidification, first played 2010.

Our Changing World has made a number of stories about climate change and its impact on the world's oceans:

Acid test for coastal seas

Winners or losers? Antarctic starfish and climate change

Go to this episode on rnz.co.nz for more details