The Heat Doesn’t Stop at the Waterline
This week London is full of rooms where good people are working out how to fight a warming world. Some of those who should be in them are stuck at home in the heat.
It’s Tuesday evening, and this afternoon I had to collect my son from nursery early, because it had got too hot for him and he’d had enough of it. We came home, filled the paddling pool, and cracked open a box of ice lollies.
The hard part is still ahead. Tomorrow and Thursday, the Met Office expects at least 39°C across much of England, under a red warning, and the June record set back in 1976 is likely to fall before the week is out.
This is also the week of London Climate Action Week. Thousands of people, room after room across the city, handed over to a single question: a warming world, and what we intend to do about it. I was meant to be there on Friday. I’m no longer sure I’ll make it.
I’m not the only one. Over the past couple of days, I’ve spoken to a few people who should be in those rooms and won’t be, kept home by the very thing the week exists to fight. Their children’s schools have closed, hundreds have across the south. Nurseries have rung them, the way my son’s rang me. Rail companies are telling people not to travel on the hottest days unless they must. People who have given their working lives to this are spending this week of all weeks at home, filling paddling pools and refreshing the forecast, shut out of the conversation about the fight by the fight itself.
It’s a small thing, in the scheme of it. A few missed panels. A larger absence sits inside it. For all the attention the heat is getting this week, the maps, the records, the warnings, the thing absorbing almost all of it gets the least attention of all.
Go down to the coast over the next few days to cool off and the sea won’t have got the memo. It will be cold, properly cold, cold enough that the RNLI is warning about cold water shock, the gasp that can drown a strong swimmer in the first minute. Record heat in the air, water cold enough to be dangerous, both true on the same beach.
That cold surface fools you. While the top metre stays cool, the same still, sunlit weather that’s about to roast the land will be pouring heat into the sea beneath it. High pressure, no wind, hour after hour of sun is exactly how you cook an ocean from above. In 2023, this set-up pushed sea temperatures around the UK and Ireland to extreme levels, as much as 5°C above normal off the west of Ireland, where NOAA rated the marine heatwave beyond extreme, the top of its five-point scale. Heat that feels survivable on a beach doesn’t go anywhere. It sinks, and the sea keeps it. The ocean has taken up more than 90 percent of all the extra heat we have ever trapped. Most of global warming isn’t in the sky we keep looking at. It’s in the water we don’t.
There is life down there with a stake in all this, too. Take the white-beaked dolphin, one of ours, a stocky character with a short white beak that has worked the cool seas around Britain since the ice left, tens of thousands of them in the North Sea. It’s a cold-water specialist, which is the trouble. It avoids warm water, and as our seas have warmed, it has been backing north, edging off the bottom of its own range, while its warm-water cousin, the common dolphin, moves up into the space it leaves. Off Scotland, researchers have watched the swap since the 1980s. It can swim away from a hot summer, which is more than a kelp forest can manage, but only while there is colder water to swim to, and for the dolphins in the southern North Sea, the map eventually runs out.
The odd thing is how little we watch any of it. For human heat we have built something serious: graded warnings, alerts to every hospital and care home, schools and nurseries deciding it’s too hot for children, all of it working hard this week and rightly so. For the sea, almost none of that. It is only fair to say why. Heat kills people fast, and a system that protects them first has its head screwed on right. The sea is harder to watch, and newer to the science. The gap is startling all the same. It took a recent piece of work at the National Oceanography Centre to give us the first proper map of where marine heatwaves are likeliest in British waters. We are an island, and we drew that map about five minutes ago.
The dolphins, for their part, have been filing a report nobody commissioned. UK researchers have taken to calling cetaceans sentinels, animals whose comings and goings reveal what a warming sea is doing to the life in it, in a way no instrument can. Where the white-beaked dolphin stops turning up, the water has crossed a line it couldn’t hold. It is as clear a voice on a warming world as anything you’ll hear in London this week, and it isn’t in the room either.
This evening, my son has been sun-pink and delighted, sticky with melted ice lolly, cooled by a hose and the people who love him. The sea gets no such care, and hardly anyone is looking.
When the marine heatwave data for this week is in, Ocean Rising will publish what the sea actually did while the country watched the sky.