24th July 2026
The Threat
Greenhouse gases (GHG) now trap 14.8 Hiroshima Bomb’s worth of energy in our atmosphere every single second, 12 in our oceans alone. This had already driven atmospheric temperatures up by 1.63oC by 2023. This may rapidly worsen as we face massive dumping of heat from the Pacific Ocean in the strongest El Nino event in a century.
Meanwhile, emissions are still rising: last year, they totalled nearly 60Gt of CO2e.
Whilst they may soon plateau, GHG concentrations are rising faster than emissions as CO2 sinks are failing, and as multiple positive feedback loops now drive GHG emissions from land and oceans. Methane is being released from melting clathrates/ hydrates from land and undersea, and from fermenting wetlands. It’s atmospheric half-life is extending with the loss of trees (bark microbiome breaks down methane), and as carbon monoxide from wildfires destroys (methane-degrading) hydroxyl radicals. Black soot is being released from wildfires, as is CO2 (11 billion tonnes in 2025 alone). Warming tundra is now respiring and releasing CO2 and rainforests (such as that in Australia) have become net CO2 emitters. Heat is evaporating water from rivers, lakes an oceans and water vapour at high altitude acts as a GHG.
But worse still, heating is rising faster than GHG concentrations as surface albedo is lost (less light reflected back into space (as we lose tree cover, snow and ice and low altitude cloud – here and here).
But if this is bad, we have grossly and consistently underestimated the hazards associated with any temperature rise. A recent Nature paper states that for societal extreme weather impacts, “… 2 °C of global warming may turn out to be much more extreme than model-averaged projections at 3 °C or 4 °C warming” And we have passed/ will soon pass irreversible tipping points: coral reefs will be lost; the major northern hemispheric ocean circulation is already failing; Amazon loss may soon be triggered. Our very civilisation, and with it our health and survival, is under immediate threat.
Our very civilisation, and with it our health and survival, is under immediate threat.
- The food industry warns that that our food supply can no longer be relied upon
- The UK Joint Intelligence Committee review (2026) stated that: “The UK’s national security is under severe threat from the climate crisis “ with, “food shortages and economic disaster potentially just years away”.
- DEFRA state that it was “almost certain” that “by 2030…Britain’s food and water supply and international trade networks are at strategic risk of catastrophic failure”.
- Actuaries warn “Without immediate transformative change, our economy may not exist at all”.
Remember that even were GHG concentrations static and heating at that static concentration not rising, it would take 100 years for temperatures to reach 60% of the resultant peak, and 300 years to get to 80%. 1kg of CO2 emitted today takes 400,000 years to fully clear, so colling doesn’t happen for geological timescales.
Can we adapt?
In London, on 22nd June, the Hammersmith and City lines and the Circle line were shut. There was (ironically) no rail connection between 2 Heathrow terminals. For national rail, heat causes overhead power cables to sag, and transformers to fail. Steel rails in the sun are 20°C hotter than air temperature. Network Rail typically enforces speed restrictions when track temperatures reach 46°C (roughly equivalent to an air temperature of 30°C- we will be at 38°C this week). Thermal expansion causes buckling. The Rail network asked that people make only essential journeys. Tarmac temperatures can be 20°C above air temp (65°C if air is 40°C), and standard tarmac (asphalt) road surfaces begin to soften and bleed bitumen when ground temperatures reach roughly 50-55°C. Think of the cost of adaptation for just transport, to the temperatures we are seeing this week.
The London Ambulance Service saw its highest number of 999 calls ever seen. Hospitals faced collapse of IT systems, and failing operating theatre cooling. Critical Incidents were declared. Operations cancelled.
Meanwhile, schools were shut, impacting the economy as parents took time off for childcare. Heatwaves also bring mounting wildfires. Electrical transformer life is shortened by raised temperatures, and very high temperatures can cause acute failure. Power lines sag too. Can we afford to adapt our road and rail network, health service, school buildings, power grid, and fire service? Can we adapt to the effects of sustained reductions in rainfall? Clay is already desiccating in London, meaning that 30% of London properties will be affected by subsidence by 2030. Can we cope when the rest of the globe- upon which we depend- is likewise affected? When nuclear power stations were switched off in France for a lack of cool water? When (as now) barges on the Rhine are limited to 49% capacity (doubling transport costs) as water levels fall?
But the problem is that we also have to adapt to other extreme weather events. Recent years have seen huge storm damage at coasts, and power lines felled across Scotland. Spring 2025 saw the driest period in 132 years. Eight months later, parts of the UK saw 40 days of continuous rain, with massive floods- likely to have cost the agricultural sector close to £1bn. Then we had a drought for 5 months, with rainfall in the SE of England at only 12% of normal. Then a heatwave in May. Then a cold snap, when some put central heating back on. Then the June heatwave with an associated massive thunderstorm, bringing floods and fires. Now another.
The Response
We must focus on mitigation- reducing emissions. Maths, physics and chemistry – and related climate science- are apolitical. Climate impacts strike those of every political belief. The threat humanity faces is immediate, and may soon be irrevocable. Now is the time for cross-party consensus to immediately transform our power generation and grid, agriculture and food supply systems, building regulations and transport network. The first focus should be on the ‘no regret’ actions which also help us adapt. Food systems account for nearly 38% of greenhouse gas emissions, and legislating and incentivising for healthy plant-based diet brings wins for jobs, UK farmers, food security, the nation’s health and wealth (more in employment, fewer costs for benefits and healthcare) and for our food security. Restorative agriculture also helps prevent flooding and river pollution, and increases biodiversity and soil carbon sequestration. Transforming our power system brings jobs and, whilst expensive in coming years, is good for infrastructure security (distributed grids are less vulnerable), protects from price-shocks, and soon yields substantial financial returns. Refreshed infrastructure can also be made to be resilient in the face of increasingly extreme weather.
Now is the time for action.
There is now time left for delay.
If you need reminding, look out of your window.
Prof Hugh Montgomery OBE FMedSci
Professor of Intensive Care Medicine, UCL; Co-chair Lancet Countdown on Health and Climate Change; Co-chair, UK Health Alliance on Climate Change.