Death Valley Stopped Cooling Down at Night. Why.
Everybody argues over the daytime record. The real story — almost everywhere on Earth — is what's happening after dark.
[Everybody argues over the daytime record. The real story — almost everywhere on Earth — is what's happening after dark]
Just as well it isn’t snowing outside. Imagine trying to shovel snow in this heat.
Anyway. It could be worse.
We could be in Death Valley — where the trouble was never shovelling the snow. It’s that nothing stays solid long enough to need shovelling. At 113°F the snow wouldn’t reach the ground. It’d surrender mid-air.
And here’s the thing about that place. It used to cool down at night.
That was the arrangement. Furnace Creek would throw everything it had at us by mid-afternoon — 120, 125, whatever the air could carry — and then, come dark, it would relent. The heat lifted. We could breathe. Humans and desert called a truce till morning.
It doesn’t relent like it used to.
The famous number
We know the headline. Death Valley: hottest air on Earth. It’s the line we reach for when a British summer turns nasty — well, at least we’re not in Death Valley. The gospel figure. The one that makes the news.
Now. Here’s what’s holding the thermometer that tells all.
Like me, you probably didn’t know of a white box on a post, out in the open, in the cruellest afternoon sun on the planet — and it doesn’t breathe the way it should.
Vegetation’s crept up to the south of it over the years and cut the wind that used to flush it through. The sensor sits near metal bars and a solar panel that drink the heat and hold it.
On a still, bright afternoon the whole contraption runs a degree or two hot on its own, before the air’s done a thing.
And the people who spotted it? Sceptics. The very crowd we’d expect to talk the heat down turned round and said the daytime record’s inflated, the box is cooking itself. And they may well be right. Good of them.
It’s just that being right about the thermometer doesn’t lower the temperature of anything except the headline.
Okay. So, here’s the number nobody’s arguing about
Because while everyone stood arguing over the afternoon figure, nobody was watching the nights. And the nights don’t have the excuse. That drift the sceptics found is a sunshine problem — a shield baking in still afternoon air — and it has nothing whatever to say after dark.
Across the 1990s, the average Death Valley night sat around 61°F. Across the 2010s it sat around 65°F — better than two degrees Celsius, at night, in the two decades between.
The days barely moved. And the freezing nights, the ones cold enough to drop to 32°F, halved: fifteen a year in the nineties, six a year by the 2010s.
The day record is contested. The night floor just quietly came up.
Now, fair’s fair — it’s the same station, and a station with vegetation and buildings closing in around it will run its nights warm too. That’s the old urban-heat-island trick, and it’s strongest after dark.
So don’t take Furnace Creek’s word for it. You don’t have to.
The night-time rise doesn’t rest on this one box at all: the same pattern turns up across thousands of stations worldwide with no solar panel pressed against them. Death Valley isn’t the proof. It’s just the place you can feel it.
The desert used to throw the blanket off at sundown. Now it sleeps in it.
And before we file this under well, it’s a desert, deserts are mad — this is the part that matters. It isn’t Death Valley being strange. It’s Death Valley being honest.
The nights are warming faster than the days more or less everywhere on Earth. The National Oceanic and Atmospheric Administration — NOAA, the US government’s climate and weather agency — has been saying it for years: overnight temperatures are climbing quicker than the afternoon ones.
A study out this month put a number on the sharp end: the hottest nights of the year warming at 0.32°C a decade, the hottest days at 0.27.
For scale, the planet as a whole is warming at about 0.2°C a decade — and it’s the nights, near enough everywhere, carrying more than their share of it.
The whole world is slowly losing its night-time relief. Death Valley’s just the one place hot enough that we’d notice the lights staying on.
So if we want to know which number to trust, trust the quiet one. The daytime record is the showy figure with a solar panel pressed against its ear — contested, and the people contesting it have a point.
The night-time rise is the duller figure, and the duller figure has the better alibi: it shows up everywhere, on instruments with nothing to blame. It’s the cleaner signal precisely because it’s the boring one.
(Same rule as any council meeting worth sitting through — the number to read is the dull one in the appendix, never the proud one on the press release. I’ve made that case about Bristol’s own Green administration before.)
Though — and I’ll mention it only once, because it’s the sort of thought that stays where it’s put down — there is the money.
Last year the world spent $3.3 trillion on energy, $2.2 trillion of it badged clean, $450 billion on solar alone.
And the people who count it, the International Energy Agency, note almost in passing that the surge was driven “not only by climate policies” but by industrial strategy and energy security — by who comes to own the supply chains, and who can’t be left at the mercy of a rival’s gas tap.
Which leaves a small question lying about, doesn’t it. Not whether the warming is real; it is. But supposing it weren’t. Supposing the nights were cooling as they always had.
Would a single one of those trillions move any differently — would the fund managers waive the fee, would China hand back its third, would one panel go unbuilt?
Or is the heat simply the story we tell about the money: the cover, the permission, the thing that gets the cheque signed.
No matter. Just a thought.
And the likely shape of it, on the road we’re on, is more nights that never cool, in more places that always used to.
Which brings us back to our shovel.
There’ll be no snow to clear in Death Valley. There never was. The joke was always that we’d be daft to want any. But the desert’s quietly stopped keeping the older bargain — the one where the night gave the heat back.
It used to cool down at night.
It doesn’t relent like it used to.
Now. If all that wasn’t food for thought. Let’s add an additional item to the menu. Lunar Panels.
It’s the anti-solar panel — sometimes called a night panel or thermoradiative cell.
A normal solar panel catches sunlight on its way out from a hot sun to cold space, skimming a little off the flow as it passes. Flip the idea over.
At night the ground is still warmish and the sky above it is bitterly cold — space is near enough absolute zero. Heat pours upward off a panel into that cold sky, and you can rig a cell to harvest power from heat leaving rather than light arriving.
Researchers have built them. They produce a fraction of what a solar panel does — tens of milliwatts a square metre against hundreds of watts — but they produce it in the dark, which solar never will.
And here’s the bit we’ll appreciate. That night panel runs on one thing: the night sky being cold. The colder the night, the more power it makes.
Which means the very trend the article’s about — nights warming faster than days, the desert no longer cooling down — is quietly eating the fuel of the only panel that ever worked in the dark.
And that’s no coincidence. The thing warming the nights and the thing starving the panel are one and the same: a sky throwing more of its own heat back down instead of letting it escape.
Warmer nights and a fading chill aren’t two problems. They’re one problem, wearing two coats.
So the answer to “how about lunar panels” is: the moon was never the point. The cold was. And we’re losing the cold.
Losing it. Not harvesting it.
The Almighty Gob is an independent Bristol publication. No party. No press pass. No proprietor leaning on the desk. Just the three questions asked of everything — is it practical, is it logical, what’s the likely outcome — and a flat refusal to be recruited by anyone’s side of it. Since 2010.
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Sources & verification.
Death Valley decade temperatures (night and day averages, freezing nights). Decadal averages for Furnace Creek / Death Valley National Park, drawn from the NOAA National Centers for Environmental Information Global Summary of the Year (station GHCND:USC00042319), as compiled by Current Results: Death Valley Temperature Averages by Decade. 1990s mean nightly low 60.9°F; 2010s 65.1°F (+2.3°C). Freezing nights: 15/yr in the 1990s, 6/yr in the 2010s. Figures are decade averages ending in 2019 — the most recent decade the dataset covers, not a 2026 reading.
Nights warming faster than days — global signal. Rebecca Emerton et al., “Global heat stress intensification and its expanding footprint on the human population,” Nature Climate Change, 22 June 2026 (open access). The hottest nights of the year warming at 0.32 ± 0.05°C per decade against 0.27 ± 0.05°C for the hottest days, since the 1970s (feels-like / Universal Thermal Climate Index; global land average). The paper also notes nighttime minima have risen almost everywhere, with a few documented exceptions — hence “almost everywhere,” not “everywhere.”
Nights outpacing days — longer-run confirmation. NOAA Climate.gov: “Climate change rule of thumb: cold ‘things’ warming faster than warm things.”
Global rate of warming for scale. NOAA Climate.gov: “Climate Change: Global Temperature“ — roughly 0.20°C per decade since 1982.
The daytime instrument-bias claim. This is presented in the piece as the sceptics’ own argument, and is sourced to a non-peer-reviewed analysis associated with climatologists Roy Spencer and John Christy: Highest Temperature Reports in Death Valley (a degree or two of warm drift from a non-aspirated radiation shield in still, bright afternoon conditions). It is engaged and conceded deliberately — the argument stands whether or not the daytime bias is real, because the case rests on the nights and the global record, not on the contested daytime figure.
Anti-solar / thermoradiative panels. Tristan Deppe and Jeremy Munday, “Nighttime Photovoltaic Cells: Electrical Power Generation by Optically Coupling with Deep Space,” ACS Photonics (2020) — the primary peer-reviewed “anti-solar” paper. Output figures from Stanford (Prof. Shanhui Fan’s group): roughly 50 milliwatts per square metre at night against ~200 watts per square metre by day. The mechanism described — radiative heat loss to a cold sky, weakening as greenhouse downwelling infrared increases — is standard radiative physics.
The money. International Energy Agency, World Energy Investment 2025: global energy investment ~$3.3 trillion in 2025, ~$2.2 trillion of it clean, ~$450 billion into solar (the single largest line item); China’s share of clean-energy spending risen from roughly a quarter to a third. The IEA states the recent surge was driven “not only by climate policies” but by industrial strategy and energy-security considerations.