This is not the kind of record one would hope to be setting at this point. Decades and decades into an era where we understand the problem, and closing in on seven decades since the best measurement record of atmospheric carbon dioxide began, 2024 offered a remarkably grim milestone: the increase in atmospheric CO2 last year was the largest in recorded history.
For context: Before the Industrial Revolution, the atmospheric CO2 level was around 278 ppm. When Charles David Keeling began his still-running measurements of CO2 at the Mauna Loa observatory in Hawai’i in 1958, the first measurement was 313 ppm. We breached 350 ppm, often considered a sort of uppermost bound for maintaining a “safe” climate in the 1980s. Next up was 400 ppm, already deemed largely catastrophic, in 2016. Right now, today, the number sits at 427.67 ppm, though the average for 2025 (there is well-understood seasonal variation in the measurement) will likely come in at 426.6, per the Met Office.
The record jump in 2024 has a few explanations, and it’s not entirely thanks to the record level of greenhouse gas emissions humans caused last year — but it’s mostly that. “El Niño conditions typically lead to a faster annual CO2 rise, due to an overall weakening of natural carbon sinks, largely driven by hotter, drier conditions in tropical land areas,” the Met Office wrote. La Niña conditions typically reverse that, which will explain much of the smaller jump forecast for 2025.
In general though, the overall trend is of increasing year-by-year jumps in CO2 concentration. In the 1960s the average yearly rise was less than one ppm; by the 1980s, it was 1.58 ppm, and by the 2010s it was 2.41 ppm. The current trends are, you will be shocked to learn, incompatible with the effort to keep warming below 1.5 degrees C, a target most scientists agree is all but dead at this point.
There are, it’s good to remember, climate-related records falling that are actually good — solar installations, battery power added to the grid, price drops for various clean tech. But the good, so far, is very much not keeping up with the bad.
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