An extended heatwave has pushed electricity demand to record levels across parts of Europe, Asia and North America, straining power grids built for cooler average conditions.
Several countries have issued conservation appeals asking residents to limit air conditioning use during peak afternoon hours.
Grid operators say aging infrastructure, not just demand, is a key factor behind the strain, with some regions reporting rolling outages.
Climate scientists say the frequency of such heatwaves is consistent with long-term warming trends and is likely to keep testing grid capacity in coming summers.