"Death By 1,000 Cuts" - Max Temperature Increase For Coral Reef Survival 1-1.5C, And We're Already Topping Out

The Kenyan marine ecologist David Obura is chair of a panel of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), the world’s leading natural scientists. For many decades, his speciality has been corals, but he has warned that the next generation may not see their glory because so many reefs are now “flickering out across the world”.

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Where is this most pronounced?
It is easier to say where it is not pronounced. The last major holdout is perhaps the “Coral Triangle” in the Indonesian-Philippine archipelagos. It shows some resilience, though even there some places are strongly impacted because of local threats or climate change. In almost every other region, you’re seeing declines in coral cover and diversity and a loss of abundance and diversity of fish and invertebrates. That weakens the general health of the reef systems, and makes them more vulnerable to diseases and microbial activity, which are very harmful to coral species. The most pronounced losses are probably in the Caribbean because it’s a smaller sea; a regional basin surrounded by land-based impacts. That’s also true of the Persian-Arabian Gulf, where there are many places that may no longer be called coral reefs. Whole regions are now vulnerable to ecosystem collapse and specific corals within them are increasingly endangered.

How close are coral reefs to a tipping point or has this already happened?
There’s a huge amount of discussion about that. Should we consider a tipping point at a small local scale, or at the level of an island or a coastline, or a region or the whole world? Certainly it is already evident at a local scale; many reefs across the world have passed a point of no return. At the regional scale, I think the Caribbean may have tipped as an integrated coral reef system, even though there are locations that are still very vibrant, like the Mesoamerican barrier reef and some of the islands. All the coral reef regions that have so far been assessed on the red list of ecosystems have been classed as threatened, which means there is a high risk they may collapse within a 50-year period – unless the right actions are taken.

How much global heating do scientists estimate coral reefs can withstand?
We have recently revised the temperature threshold. Up to 2022, the Intergovernmental Panel on Climate Change (IPCC) said the tipping point for coral reefs would occur when warming is between 1.5C and 2C above preindustrial levels. But in 2023, we revised that to between 1C and 1.5C. The world is already close to that upper limit and it will certainly come within the next 10 or 20 years as a result of committed climate change – which comes from cumulative emissions that have already gone into the atmosphere. So have we already gone past the tipping point for coral reefs in global terms? Perhaps.

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https://www.theguardian.com/environment/ng-interactive/2025/jun/25/tipping-points-coral-oceans-climate-crisis-marine-ecologist