The rate at which Earth is heating up due to the rise in greenhouse gasses is best described by what’s known as the Earth Energy Imbalance (EEI). This 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 James Hansen and a 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.
Unfortunately, data for the EEI does not date back very far. The best data I can find starts in March, 2000 and is current up to September, 2023. EEI data is available from CERES. The EEI is measured in units of Watts per square meter (W/m²). Because transient weather, especially clouds, can impact the EEI dramatically on a year-to-year basis, climate scientists prefer to work with a 36-month running mean (I’ve seen a 48-month running mean as well) for the EEI.
Here is a graph of the 36-month running mean for the EEI for all of the available data, from February 2003 through September, 2023. It shows that over the last 36 months, the rate of warming has been about 1.50 W/m². Moreover, this graph shows that there has been about a four-fold increase in the rate of heating over the course of the last 20 years.
There is another way of viewing this warming that gives a more intuitive perspective. In this article, I show how to convert from W/m² to another unit, namely, “Hiroshima bombs per Second” or HpS. The formula for the conversion is:
HpS = 8.12 × EEI
Using this formula and the latest value for the EEI, we find that the planet has been warming at an average rate of 8.12 x 1.50 = 12.2 HpS over the last 36 months. Multiplying everything out, this gives a total 36-month planetary heat gain equivalent to the total heat from 1.15 billion Hiroshima bombs.
This result calls for a new unit of planetary heating — the “Giga Hiroshima Bombs” unit, or GHB, representing the heating of Earth by one billion Hiroshima bombs. (Thanks to Twitter user @DSCHthan for suggesting this unit). With this unit in mind, we find that Earth has heated by 1.15 GHB since September, 2020. A deeper computation shows a total heating of 4.63 GHB since EEI data began being collected in March, 2000.
We need to take a momentary diversion to discuss carbon dioxide, CO₂. In case you don’t know what the Keeling curve is, it is the curve that shows the monthly total amount of CO₂ as sampled at the Mauna Loa observatory in Hawaii, in units of parts per million (ppm), since data began being collected there in 1958.
Like CO₂ and the Keeling curve, the EEI has a yearly cycle. This is due to the geographic differences between the Northern and Southern hemisphere. The South is dominated by oceans whereas the North is dominated by land masses. Because Oceans absorb incoming solar far more readily than land, during the months November-March (longer days in the Southern Hemisphere) the EEI is substantially positive, whereas during the months May-August (longer days in the Northern Hemisphere), the EEI is substantially negative.
Also like carbon dioxide which continues to accumulate over time, the EEI creates an ongoing aggregation of heating of the Earth system. The heating is long lasting and compounding. It follows that we should not be graphing the EEI according to its 36-month running mean (in units W/m² or HpS), but rather, the EEI should be plotted as “accumulated total heating.” And the best unit to measure this heat is the new unit GHB introduced above.
And so, I give you the “Keeling Curve” for the Earth Energy Imbalance:
Pretty cool, huh? Treating 1 GHB as equivalent to 1 unit of global planetary f&%kery, the curve above shows us exactly how f&%ked we are, to the actual f&%k. Right now we are just shy of five f&%ks in accumulated f&%kery since 2000.
It is worth noting that, just like CO₂ didn’t start accumulating in 1958, the EEI didn’t start accumulating in the year 2000. If you run the curve backwards using quadratic regression, the decade of the 1920’s shows up as the beginning of net positive EEI accumulation. Integrating under the curve shows that from the 1920’s through the time data collection began in 2000, about 0.4 GHB of additional heating took place, putting the planet at well over 5 GHB of total heating, and rising. I.e., F&%k F&%k F&%k F&%k F&%k. Of course, this is speculation, but it sounds about right.
NOTE ADDED: Nov. 25, 2023. I was just re-watching the recent James Hansen video on YouTube and saw the slide below, which is exactly what I have reproduced above. So this is not my own original work — somewhere I recalled this and reproduced it, thinking it was original. It is not. The only original contribution is converting this to GHB, and maybe the explainer is helpful as well.
So, the official name for this is “Planetary Heat Content Anomaly.”