This result says nothing*. Carbon-poor soils will not release more CO2 under warming, since they are carbon-poor. But there are ~1670 petagrams of carbon under the Arctic permafrost (and a little more in Tibet), which could absolutely cause a runaway scenario. For comparison, the atmosphere has about 900 Pg of carbon.

* Okay, that’s too harsh. I’m sure this study will help refine the current equations, and could be useful in making local policies.

The lead is misleading. Warming alone will absolutely increase CO2 emission if the soil has a lot of stored carbon. In this experiment, they used carbon-poor soil.

This is important because the concern is that warming will increase emissions in the taiga and tundra, not in the subtropics. It’s like saying the Titanic’s deck wasn’t damaged by the iceberg - technically true, but meaningless.