Most of that speed-up comes from Earth getting darker and reflecting less sunlight. It’s a risk we need to start taking seriously.
Earth is gaining heat faster than scientists expected.
Most of the speed-up shows up somewhere few people look.
About 30% bounces back to space, off clouds, snow, ice and haze.
The rest is soaked up by land and sea, and turns into heat.
Greenhouse gases trap some of it, as you’ve heard.
When energy in matches energy out, temperatures hold steady.
Right now, more comes in than goes out.
That gap has roughly doubled in about 20 years.
Greenhouse gases are still the root cause.
But most of that growth comes from the sunlight side.
Earth is getting darker. It reflects less sunlight than it used to.
Less ice and snow. Fewer bright clouds. Cleaner air.
Scientists are still working out the mix.
It’s rising faster than climate models expected.
Some of it may be warming feeding on itself.
If so, the climate is more sensitive to our emissions than the most hopeful forecasts assume.
Earth is losing its brightness.
It’s a risk we need to start taking seriously.
1.78 W/m²
Average for July 2025 to June 2026. NASA CERES data as of June 2026.
Across the whole planet, that’s about 50 times all the energy humanity uses, which is a lot of heat for a number that sounds so small.14 It’s only about 0.5% of the sunlight arriving, but it never switches off, so the heat keeps piling up, mostly in the ocean.1,2
Why is Earth darker?
Less ice and snow
Fewer bright clouds
Cleaner air
Natural swings?Satellites measure the sunlight coming in and the energy going back out to space, while thousands of floats across the oceans measure the heat piling up below the surface. The two records are independent of each other, and they agree on how fast the gap has grown.2
Most of that growth is on the sunlight side. Earth is soaking up more of the sunlight that reaches it because it reflects less than it used to, and the Sun’s own output has barely changed.1,3
Some of the change is ice and snow, since shrinking sea ice and snow cover expose darker ocean and land that take in more sunlight. More of it is clouds, with fewer of the bright low clouds that bounce sunlight back to space.1,2 One study finds the world’s belts of stormy cloud narrowing by 1.5 to 3% a decade, and calls that the main reason Earth absorbs more sunlight.4 Much of the cloud change looks like a response to warming, which would mean warming is feeding on itself.1
Cleaner air plays a part too. Sulfur pollution from power plants, factories and ships forms a thin haze and makes clouds brighter, and both reflect sunlight. As China, the US and Europe cut that pollution, the haze over them thinned, even as it grew over India.2,5
Ships are only a small part of the total, but they’re the clearest example. In 2020 a global rule cut the sulfur allowed in ship fuel from 3.5% to 0.5% to clean up air pollution, and researchers had estimated it would reduce ship-related premature deaths by about a third.8 The air along shipping lanes got cleaner, and the bright trails of cloud that satellites used to see behind ships dropped to their lowest level in decades (the pandemic slowdown in shipping helped too).6,7 How much warming that added is still debated, and one study puts it, together with two other short-term factors, at under 0.1 °C for 2023.9
Natural swings matter from year to year, since ocean cycles like El Niño move heat around and change cloud cover, which is why single years jump around. But a rise this steady over two decades is very unlikely to come from natural variation alone.10
As of September 2026, two big questions are still open. One is how much of the cloud change is a response to warming, and how much comes from cleaner air or natural cycles. The other is why climate models fall short of the rise, where one team lists ocean temperature patterns and pollution as suspects, “or something else.”3
Cutting emissions is the foundation, because it stops the gap from growing and, over time, slows the darkening too.1 But it closes the gap slowly, because the ocean keeps absorbing heat for decades after emissions stop.11 That slowness is one reason scientists are studying ways to reflect more sunlight, which would act fast but comes with big unknowns,12 while adapting protects people in the meantime.
What it does
Stops the cause from growing.
Every five years of high emissions adds about 0.1 °C to how hot it eventually gets.11
How fast
Stops the rise at net zero.
Temperatures stop rising once carbon dioxide emissions reach net zero, and the gap itself closes slowly after that.11
How long it lasts
Permanently.
Carbon left in the ground stays out of the air.
Open questions
How fast the world does it.
What it does
Pulls carbon back out.
Methods include forests and soils, biochar, bio-oil burial, bioenergy with carbon capture, rock weathering, direct air capture and ocean alkalinity.16
How fast
Very slow at today’s scale.
Forests and soils remove about 2 billion tonnes a year, and newer methods about 2 million, growing around 40% a year.16
How long it lasts
From decades to millennia.
Forests and soils can lose it again to fire or land-use change, while rock and deep geological storage last thousands of years.16
What it does
Offsets some warming.
It sends a little more sunlight back to space without touching the greenhouse gases.12,13
How fast
Quickly, once in place.
It’s the only one of the four that works directly on the sunlight side.13
How long it lasts
Only while it’s kept up.
Stopping suddenly after years of use could bring the hidden warming back fast.12
What it does
Protects people.
Heat plans for cities and defenses for coasts protect against the warming that’s already here, but they don’t change the energy gap itself.11
How fast
Can start now.
It happens place by place.
How long it lasts
While it’s kept up, to a point.
Past some limits, no amount of adapting can avoid the harm.11
Open questions
Who pays, and where the limits are.
Reflecting sunlight is often called solar geoengineering or solar radiation modification. Global ideas, such as adding reflective particles high in the atmosphere, would cool the whole planet, while regional ideas, such as brightening clouds over a particular stretch of ocean, aim at one place.12 It’s mostly still at the research stage, and whether and how to use it is actively debated.13
About 90% of the extra energy goes into the ocean,2 and the rest warms the land, melts ice and heats the air. That means the warming we actually feel in the air is only a small part of what Earth is taking in.
Seawater expands as it warms, and the deep ocean keeps taking up heat long after the surface settles. Add slowly melting ice sheets, and seas will keep rising for centuries, even once warming stops.11
Some of the darkening may be warming feeding on itself, because a warmer planet with less ice and fewer bright clouds soaks up more sunlight and warms further.1 If that’s what is happening, the climate is more sensitive to our emissions than the most hopeful estimates assume. One recent study found that climate models with low sensitivity can’t reproduce the rise that satellites measured.15 That doesn’t settle how sensitive the climate is, but it makes the gentlest outcomes look less likely.9
The gap is also growing faster than climate models expected. Since 2020 the measurements have moved outside the range that the models’ natural ups and downs can explain.3 In 2023 the gap reached about 1.8 W/m², roughly twice what models predicted for that year, before falling back in 2024. One year on its own proves little, and it’s the steady rise over two decades that worries scientists.
The measurement record is also at risk, because within a decade one new satellite instrument, Libera, will be the only one measuring this from space. There are no formal plans to continue the record after it, which the researchers who flagged this call “a single point of failure.”3