The Earth’s thermostat is broken. That is the stark conclusion from the UK Met Office, which today confirmed that global average temperatures for the past 12 months have exceeded 1.5°C above pre-industrial levels for the first time in recorded history. This is not a model projection. This is observed data. The planet is now operating outside the most ambitious guardrail set by the Paris Agreement, and the physics of the atmosphere will not negotiate with our intentions.
Dr. Helena Vance, Science & Climate Correspondent — The Met Office’s HadCRUT5 dataset, which combines measurements from over 10,000 land and ocean stations, shows that the period from February 2023 to January 2024 averaged 1.52°C above the 1850-1900 baseline. The margin of error is ±0.07°C, meaning we are safely above the line. This is not a one-month anomaly. It is a sustained breach. The previous record for a 12-month period was set in 2016, during a strong El Niño. That record now stands broken by 0.17°C.
Let us be clear about what this means. The Paris Agreement’s 1.5°C target is not a cliff edge beyond which all is lost. It is a threshold of increasing risk. Every tenth of a degree matters because the Earth system responds non-linearly. The extra energy retained by the atmosphere is equivalent to detonating four Hiroshima atomic bombs per second, every second, since the industrial revolution. That energy does not disappear. It melts ice, warms oceans, and intensifies weather.
We are already seeing the consequences. The Copernicus Climate Change Service reports that Arctic sea ice extent in January was the lowest on record for that month. Antarctic sea ice continues to hover at record lows, with the continent losing mass at an accelerating rate. The North Atlantic sea surface temperature in 2023 was the highest in at least 40,000 years — yes, that is a geological timescale. The implications for marine ecosystems and fisheries are profound.
The Met Office’s chief scientist, Professor Richard Allan, put it succinctly: “We are entering a new climate reality. The 1.5°C limit is de facto dead for this year, and likely for the coming years, given the inertia of the climate system and continued fossil fuel emissions.” The statement carries the calm urgency that science demands. There is no panic in the data. Only a quiet alarm.
Some may ask: is this the new normal? The answer is no. Normal is a moving baseline. If emissions continue at current rates, we will hit 2°C within two decades. At that point, extreme heatwaves that currently occur once in 50 years will become annual events. Coral reefs will functionally disappear. The Greenland ice sheet will pass a tipping point, committing sea levels to metres of rise. This is not speculation. This is physics.
What can be done? The solutions are known. Renewable energy is now cheaper than coal in most markets. Battery storage is scaling exponentially. Electric vehicle sales grew by 35% in 2023. But the pace is insufficient. We need to deploy these technologies at wartime speed, not peacetime convenience. The carbon budget for 1.5°C is effectively exhausted. Every tonne of CO2 we emit from now on is borrowed against our children’s future.
The data do not offer hope. They offer a choice. We can continue to treat the atmosphere as an open sewer, or we can treat it as the fragile envelope that sustains all life. The thermometers do not lie. The question is whether we will listen.
For now, the records fall like dominoes. Each one is a signal that the Earth is changing in ways that human civilisation has never experienced. We are living through the largest uncontrolled experiment in planetary history. And the results are coming in.
