FADING REEFS

Warm-water corals are the first major ecosystem to collapse in a rapidly warming planet. Scientists are racing to save them using cutting-edge technologies, from preserving spawn to breeding hardier varieties, but admit their efforts may fall short unless global temperature rises are limited to below 1.5°C.

- A report by DAKSHIANI PALICHA AND HIMANSHU NITNAWARE

THE EARTH has reached its first catastrophic tipping point, with widespread bleaching and death of coral reefs.

Surging global temperatures have pushed these sensitive yet vital ecosystems towards irreversible decline, warns the “Global Tipping Points Report 2025”. Prepared by 160 scientists from 23 countries, the report states that warm-water coral reefs, or shallow coral reefs in tropical and subtropical regions, are crossing their thermal tipping point and undergoing unprecedented die-off. This collapse threatens the livelihoods of nearly one billion people who depend on reefs for food, income and coastal protection. The report was released ahead of the 30th UN climate summit (COP30), where countries are expected to set out their goals for bringing down emissions over the next decade.

The report also warns that the world is “on the brink” of reaching other tipping points, including the dieback of the Amazon rainforests and Eurasian boreal forests, collapse of major ocean currents such as the Atlantic Meridional Overturning Circulation (AMOC) and the sub-polar gyre (SPG) and melting of ice sheets, including land permafrost and mountain glaciers (see ‘Escalated risks’, p38). “We're in a new climate reality,” says Tim Lenton, founding director at Global Systems Institute at the University of Exeter, UK, who led the report. “We have crossed a tipping point in the climate system, and we're now sure we're going to carry on through 1.5°C of global warming above the prior industrial level, and that’s going to put us in the danger zone for crossing more climate tipping points.”

According to the Intergovernmental Panel on Climate Change (IPCC), tipping points are “critical thresholds” that, when exceeded, can lead to significant changes in the state of the system. This change, which is often irreversible, is propelled by self-perpetuating feedback loops, even if what was driving the change in the system stops.