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Tracing the worst coral bleaching event in recorded history \u2013 video<\/p>\nThe earth has reached its first catastrophic tipping point linked to greenhouse gas emissions, with warm water coral reefs now facing a long-term decline and risking the livelihoods of hundreds of millions of people, according to a new report.<\/p>\n
The report from scientists and conservationists warns the world is also \u201con the brink\u201d of reaching other tipping points, including the dieback of the Amazon, the collapse of major ocean currents and the loss of ice sheets.<\/p>\n
But some experts have questioned the report\u2019s claims about the fate of coral reefs, with one saying while they are in decline there is evidence they could remain viable at higher temperatures than suggested.<\/p>\n
Tracing the worst coral bleaching event in recorded history \u2013 video<\/p>\n
Tipping points are recognised by scientists as moments when a major ecosystem reaches a point where severe degradation is inevitable.<\/p>\n
The world\u2019s coral reefs are home to about a quarter of all marine species but are considered one of the most vulnerable systems to global heating.<\/p>\n
\u201cUnless we return to global mean surface temperatures of 1.2C (and eventually to at least 1C) as fast as possible, we will not retain warm-water reefs on our planet at any meaningful scale,\u201d the report says.<\/p>\n
Reefs at tipping point<\/p>\n
Coral reefs have been in the midst of a global bleaching event since January 2023 \u2013 the fourth and worst on record \u2013 with more than 80% of reefs in more than 80 countries affected by extreme ocean temperatures. Scientists say the event<\/a> has pushed reefs into \u201cuncharted territory\u201d.<\/p>\n The Global Tipping Points report, led by the University of Exeter and financed by the fund of the Amazon owner, Jeff Bezos, includes contributions from 160 scientists from 87 institutions in 23 countries.<\/p>\n It estimates that coral reefs hit a tipping point when global temperatures reach between 1C and 1.5C above where they were in the latter half of the 19th century, with a central estimate of 1.2C. Global heating is now at about 1.4C.<\/p>\n Without rapid and unlikely cuts to greenhouse gases, the upper threshold of 1.5C would be hit in the next 10 years, the report says.<\/p>\n \u201cWe can no longer talk about tipping points as a future risk,\u201d said Prof Tim Lenton at the University of Exeter\u2019s Global Systems Institute. \u201cThe first tipping of widespread dieback of warm water coral reefs is already under way.\u201d<\/p>\n He said this was already impacting hundreds of millions of people who depend on reefs. The report points to reefs in the Caribbean, where marine heatwaves, low diversity and disease outbreaks have pushed reefs \u201ctowards collapse\u201d.<\/p>\n Experts agree that coral reefs need \u2018aggressive\u2019 action on climate change and improved local management. Photograph: Glenn Nicholls\/AFP\/Getty Images<\/p>\n However, Prof Peter Mumby, a leading coral reef scientist at the University of Queensland in Australia, said he accepted reefs were in decline but there was emerging evidence corals could adapt with some reefs remaining viable even at 2C of global heating.<\/p>\n He said coral reefs needed \u201caggressive\u201d action on climate change and improved local management, but he was concerned some would interpret the report as saying coral reef habitats were heading for collapse, which was a position he did not support.<\/p>\n He said he was worried society would \u201cgive up on coral reefs\u201d if people think they can no longer be saved.<\/p>\n skip past newsletter promotion<\/a><\/p>\n Sign up to Clear Air Australia<\/p>\n Adam Morton brings you incisive analysis about the politics and impact of the climate crisis<\/p>\n Privacy Notice: Newsletters may contain information about charities, online ads, and content funded by outside parties. If you do not have an account, we will create a guest account for you on theguardian.com<\/a> to send you this newsletter. You can complete full registration at any time. For more information about how we use your data see our Privacy Policy<\/a>. We use Google reCaptcha to protect our website and the Google Privacy Policy<\/a> and Terms of Service<\/a> apply.<\/p>\n after newsletter promotion<\/p>\n Dr Mike Barrett, the chief scientific adviser at WWF-UK and co-author of the report, said it \u201cdemonstrates that conservation of reefs is now more critical than ever. The game has changed and the response has to be really urgent.\u201d<\/p>\n He said there were some coral reefs that were known as refugia \u2013 places where climate impacts were not as pronounced \u2013 and protecting these places was paramount.<\/p>\n \u201cWe have to make sure we have the seeds of recovery for a future world where we have managed to stabilise the climate,\u201d he said.<\/p>\n