Earth is Heating at a Rate of Over One Million Hiroshima Bombs Every Day!

Our lasting legacy to the planet is unbearable heat

Back in March, 2012, James Hansen used the analogy of Hiroshima bomb explosions to make a point about how fast the planet is warming. In his now famous TED talk, Hansen said,

It's equivalent to exploding 400,000 Hiroshima atomic bombs per day 365 days per year. That's how much extra energy Earth is gaining each day.

James Hansen’s Ted Talk at the moment he says 400,000 Hiroshimas per day.

That’s 400,000 Hiroshimas per day (HpD), or about 146 million per year. Dividing by the number of seconds in a day, this comes out to 4.63 Hiroshimas per second (HpS). That was Hansen’s estimate back in 2012.

The oceans are estimated to absorb about 90% of the excess heat due to climate change, which means that the oceans were warming at a rate of about 360,000 HpD or about 4.17 HpS back when Hansen gave his talk.

Well, times have changed, and so has this number. Trying to keep up with what’s published in the media can make your head spin. Some sources have taken liberties, or educated guesses, or just made up a number. Others have been a bit more rigorous.

Here are a few examples that give reasonably accurate numbers:

• Four Hiroshima bombs a second: how we imagine climate change, August 13, 2013

• Earth is heating at a rate equivalent to 5 atomic bombs per second, February 20, 2020

• Oceans absorbed heat equivalent to seven Hiroshima nuclear explosions every second, expert says, January 11, 2022

• 12 Hiroshima bombs every second: Here’s how much Earth’s oceans warmed in 2025, January 9, 2026

And here are some wrong numbers:

• Global warming of oceans equivalent to an atomic bomb per second, January 7, 2019

• Energy of ‘25 billion atomic bombs’ trapped on Earth in just 50 years, all because of global warming, May 5, 2023

In this article, I’m going to show you how to do this computation. It all comes down to what’s known as the Earth Energy Imbalance (EEI). The EEI is the difference between the amount of incoming solar radiation that heats the planet and the outgoing radiation of all types that escapes back into space. As one group of scientists put it in a recent paper,

“The absolute value of EEI represents the most fundamental metric defining the status of global climate change, and will be more useful than using global surface temperature.”

Unlike weather, which changes wildly from year to year, the EEI is a direct measurement of the rate of heating of the planet. Heat in minus heat out. Couldn’t be any simpler than that. If you want to take a deeper dive, here is a good article on the topic.

The EEI is measured in units of Watts per square meter (W/m²). The most recent number for the EEI as published by NASA through their CERES (Clouds and the Earth’s Radiant Energy System) project, is a 12-month running average of 1.486 W/m², from February 2025 through January, 2026.

Let’s put this number into perspective. If you think of an old-fashion 100 Watt incandescent lightbulb and the heat that gives off (they got very hot), imagine gridding off the planet into (roughly) 27ft x 27ft squares and having one 100 Watt lightbulb in the center of that square all over the planet — including the oceans and poles. Imagine every single one of those lightbulbs was turned on and left on, every day, 365 days per year. That’s approximately the current rate of heating.

Okay, keeping the value EEI = 1.486 W/m² in mind, let’s do the math.

First question — how many square meters on planet Earth? If we assume the planet is a sphere with a radius of 6,371,000 meters, then by using the equation for the surface area of a sphere (A = 4πr²), we get a surface area of 5.100 × 10¹⁴ m². (I hope you are using Google to double check me). The correct answer is slightly larger than this, owing to geographic features that generate additional surface area — but we will ignore this slight additional surface area, so we can be sure that we are not overestimating the global EEI.

Multiplying, this leads to a global planetary energy imbalance of (1.486 Watts/m²) × (5.100 × 10¹⁴ m²) = 7.579 × 10¹⁴ Watts.

Now one Watt is the same as one Joule per second, where the physical unit “Joule” is the direct measurement of energy. So we get a global EEI of 7.579 × 10¹⁴ Joules per second. This is such a large number that physicists have come to the rescue by creating the “terajoule,” which is one trillion (10¹²) Joules. So, a simple division gives a global EEI of 757.9 terajoules per second.

And here is the easy part. How many terajoules in a Hiroshima bomb? You can Google that and find numbers quoted from 50 to 75. But we want to be precise here as a point of reference — the Hiroshima bomb was measured as being equivalent to 15 kilotons of TNT. Even though the actual explosion has never been pinned down, we can pin down 15 kilotons of TNT. Google it yourself: “terajoules in 15000 tons of TNT.” This number comes out to 62.76 terajoules.

Okay — one Hiroshima bomb = 62.76 terajoules. The global EEI is 757.9 terajoules per second. Converting EEI to Hiroshima bombs is now simple division. The global EEI, as of the end of January, 2026, is 757.9/62.76 = 12.08 HpS.

Multiplying 12.08 HpS by the number of seconds in a day (86,400), we get 1,043,712 Hiroshimas per day. Because there were only three significant figures in the original EEI data, we will round down to three significant figures, to get 1,040,000 Hiroshimas per day. Then multiplying that number by 365 gives a planetary heating of 380,000,000 (380 million) Hiroshimas over the 12-month period February, 2025 to January, 2026.

Now let’s do the oceans, which absorb about 90% of the excess heat. Multiplying the numbers above by 0.9 tells us that the oceans are warming at a rate of about 10.9 HpS or about 940,000 Hiroshimas per day, which comes out to 343,000,000 (343 million) over the 12-month period February, 2025 to January, 2026.

Summarizing for the headlines — feel free to use this CNN, MSNBC, FOX, ABC, CBS, NBC, NYTIMES, WAPO, TRUTH SOCIAL, ALEX JONES, ETC.:

“The planet is currently heating at the rate of over 12 Hiroshima nuclear bombs per second, or over 1,000,000 Hiroshima nuclear bombs per day.”

“The oceans are currently heating at the rate of nearly 11 Hiroshima nuclear bombs per second.”

Here is a graph that shows the 12-month running mean for the number of Hiroshimas per second, from February, 2001 through January, 2026. In particular, heating peaked in May, 2023, topping out at 2.00 W/m², or 16.24 HpS.

You may be wondering about the volatility shown in this graph. It turns out there are a number of contributing reasons:

• Natural oscillations like the El Niño-Southern Oscillation or Pacific Decadal Oscillation rearrange ocean heat uptake and alter cloud patterns.

• Reductions or changes in reflectivity of low-level clouds changes the amount of absorbed solar energy.

• Variations in atmospheric particles from pollution, wildfires, or volcanoes affect cloud brightness and sunlight reflection.

• Changes in sea ice extent and snow cover exposes darker surfaces that absorb more sunlight.

Because of this volatility, many climate scientists favor using a longer term average for the EEI than the simple 12-month running average I used above. Here is a graph showing the 36-month (3-year) running mean for the number of Hiroshimas per second, from February, 2003 through January, 2026:

Even with this longer term average, the current EEI is in excess of 11 Hiroshimas per second.

The EEI is changing all the time and is mostly getting larger. If you want to keep up on the latest numbers, here are the simple equations you can use for the next mainstream media article you write:

Hiroshima bombs per second = 8.12 × EEI

Hiroshima bombs per day = 701500 × EEI

Hiroshima bombs per second in the oceans = 7.31 × EEI

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Addendum

For those who object to the Hiroshima bomb comparison (for any number of valid reasons) here are some others.

• The current EEI is equivalent to 632,000,000,000 microwave ovens running on high (1200 Watts), full time, 24 hours a day. This is about 77 microwaves for every person on the planet.

• The current EEI is equivalent to each person on the planet (8.2 billion people) having 924 100-Watt lightbulbs burning full time, 24 hours a day.

• The current EEI is equivalent to 404,000,000,000 hand-held hair driers running on high (1875 Watts), full time, 24 hours a day. This is about 49 hair dryers for every person on the planet.