In 1990, the newly formed Intergovernmental Panel on Climate Change released its first assessment — the world’s first coordinated attempt to project what a warming planet would look like decades out. Computing power was a fraction of what we have today, and satellite records were thin. The scientists involved knew they’d eventually be graded on this by history.
Thirty-six years later, we can check their homework. The results are sobering — not because the science was wrong, but because it was largely right, and we didn’t act on it.
Carbon dioxide: It is the miss that matters most. In 1990, atmospheric CO2 stood at about 354 parts per million. The IPCC’s “business as usual” scenario — the pathway assuming no serious climate policy — projected roughly 410 ppm by the early 2020s. Today we’re at about 429 ppm. We didn’t just meet that line; recent years have added carbon faster than that scenario assumed, with the largest single-year jumps ever recorded. Pre-industrial CO2 was about 280 ppm, so we’ve now pushed concentrations more than 50 percent above the atmosphere our civilization was built in. This is the clearest evidence that the 1990 report’s blind spot wasn’t the science — it w...