India has logged a record 47 degrees Celsius in the shade, a temperature so extreme that it is erasing the thermal distinction between day and night. Local meteorologists report that the diurnal temperature range has collapsed to less than 5 degrees in some regions, meaning mornings and nights as defined by cool respite no longer exist. This is not a weather event. It is a phase shift in the planet’s energy balance.
The Indian Meteorological Department confirmed that the reading, taken at a standard Stevenson screen in the northern plains, exceeds the previous high by 0.6 degrees. The heatwave, now in its third week, has killed at least 90 people, with many more hospitalised for heatstroke and dehydration. The real death toll is likely higher: India does not routinely count excess mortality from heat.
The UK Met Office has issued an unusual warning, stating that the Indian heatwave is not an isolated anomaly but a preview of conditions that could affect mid-latitude regions within decades. Their latest climate models show that under current emissions trajectories, parts of southern Europe, the US Midwest and even southern Britain could experience 40C days by 2050. The warning carries a tone of calm urgency: the physics is not in dispute.
The mechanism is straightforward. As greenhouse gases accumulate, they trap more outgoing longwave radiation. That extra energy does not disappear. It goes into the ocean, the atmosphere and the land. In the Indian subcontinent, the combination of high solar insolation, reduced soil moisture and a stalled monsoon jet has created a positive feedback loop. Dry ground heats faster. That heat dries the ground further. The temperature climbs until the human body can no longer shed heat through sweating. Wet bulb globe temperatures in the region have exceeded 32C, the limit for survival of healthy adults at rest.
The ‘vanishings’ of mornings and nights is a direct consequence of the urban heat island effect compounded by the background warming trend. Cities like Delhi, built from concrete and asphalt, absorb solar energy all day and release it slowly at night. Normally, the night provides a window for cooling. But with daytime temperatures so high, the urban fabric never fully sheds its heat. Minimum temperatures have stayed above 35C for several nights running. For the millions without air conditioning, there is no escape.
This is not a problem that can be solved by adaptation alone. The UK’s warning is a reminder that the atmosphere is a single, coupled system. What happens in India affects the jet stream, which affects European weather. The recent heatwave in the UK, which closed schools and buckled railway lines, was directly linked to a stalled high pressure system that originated over North Africa. The chain of causation is global.
Technological solutions exist. Heat pumps, passive cooling design, white roofs and tree cover can reduce urban temperatures by several degrees. But they are not deployed at scale. The financial flows are still going into fossil fuel infrastructure. The International Energy Agency reported this week that global energy investment in renewables exceeded fossil fuels for the first time, but the absolute amount of fossil investment is still rising. We are pouring more energy into the warming engine while trying to build a cooling shelter.
The biosphere is already responding. Coral reefs are bleaching, forests are burning, and the Arctic sea ice is in terminal decline. The Indian heatwave is another data point on a curve that is not yet bending. The question is no longer whether the climate is changing, but whether we can change fast enough to prevent the loss of the climatic conditions under which civilisation developed.
The record in India will likely be broken again next year. That is not alarmism. It is the physics of a planet out of balance.
