Roman-era deforestation around Rotsee in Switzerland, approximately 2,000 years ago, increased the rate of organic carbon burial in lake sediments. De Jonge, Dubois, and colleagues measured this using a 12-meter sediment core spanning 13,000 years, with XRF, carbon/nitrogen isotopes, organic macromolecule analysis, and ancient DNA.

The increase in sedimentary carbon accumulation during the Roman deforestation exceeded the increase caused by the Holocene Thermal Maximum (9,800-8,800 years ago) — a natural climate event that warmed the region significantly.

The mechanism: deforestation exposes soil, which washes nutrients into the lake. The nutrient pulse boosts aquatic productivity — algae, cyanobacteria, aquatic plants. The increased biological production rains organic matter to the lake floor, where anoxic conditions preserve it as sedimentary carbon.

The carbon didn’t disappear when the trees were cut. It relocated — from forest biomass (standing carbon) to lake sediment (buried carbon). The form changed, the location changed, but the carbon budget includes a transfer, not just a loss.

This doesn’t mean deforestation is good for carbon storage — the total terrestrial carbon pool still decreases. But it means the accounting is more complex than “trees removed, carbon released.” Some of the released nutrients feed aquatic systems that bury carbon efficiently.

The through-claim: when an ecosystem is disrupted, carbon doesn’t simply leave the system. It finds alternative sinks. The accounting that treats one pool (forest biomass) as the whole story misses the transfers to other pools (lake sediments) that partially compensate — not enough to offset the loss, but enough to change the arithmetic.