UN chief Antonio Guterres challenged AI firms on Tuesday to disclose their growing environmental footprint as part of a push for faster global action to curb climate change.

As Europe bakes under a second heatwave in as many months, Guterres delivered a speech in London that painted a stark picture of a planet that has just endured its 11 hottest years on record.

“Climate chaos is accelerating before our eyes,” Guterres said, while the energy crisis, fuelled by war in the Middle East, is “exposing the folly of a world hooked on hydrocarbons”.

“It is clear that our world is facing a Tale of Two Crises,” Guterres said.

“On the surface, these crises may seem separate. But they share the same destructive origin: Fossil fuels,” he said at London Climate Action Week, an annual gathering of policymakers, company executives and NGOs.

Guterres pushed for a rapid transition to renewable energy while announcing new initiatives to combat methane emissions and address concerns over the environmental impact of energy-hungry data centres.

The growing energy, water and land use of data centres -- vast server warehouses powering AI and other digital services -- is putting pressure on local communities and the environment.

“It is time to come clean,” Guterres said. “If AI is to help build a better future, it must be honest about what it costs us now.”

Guterres launched an AI Environmental Transparency Initiative, urging every major artificial intelligence company to measure and publicly disclose their environmental impact as well as commit to powering every data centre with renewable energy by 2030.

A UN study earlier this month found that the facilities consumed more electricity than all but 10 countries in 2025. By 2030, they could use more power than all but five countries, the study found.

About 30 percent of the electricity consumed by data centres comes from coal, followed by renewables at 27 percent, natural gas at 26 percent and nuclear at 15 percent, according to the International Energy Agency.

A coalition of dozens of cities announced Tuesday a “Global Urban Data Centres Pact” aiming to ensure that the facilities are built in a way that minimises their environmental impact.