Peatlands have acted as net CO₂ sinks over millennia, exerting a global climate cooling effect. Rapid warming at northern latitudes, where peatlands are abundant, can disturb their CO₂ sink function. Here we show that sensitivity of peatland net CO₂ exchange to warming changes in sign and magnitude across seasons, resulting in complex net CO₂ sink responses. We use multiannual net CO₂ exchange observations from 20 northern peatlands to show that warmer early summers are linked to increased net CO₂ uptake, while warmer late summers lead to decreased net CO₂ uptake. Thus, net CO₂ sinks of peatlands in regions experiencing early summer warming, such as central Siberia, are more likely to persist under warmer climate conditions than are those in other regions. Our results will be useful to improve the design of future warming experiments and to better interpret large-scale trends in peatland net CO₂ uptake over the coming few decades.

数千年来，泥炭地一直是 CO ₂净汇，发挥着全球气候变冷效应。在泥炭地丰富的北纬地区，快速变暖会扰乱它们的 CO ₂汇功能。在这里，我们表明泥炭地净 CO ₂交换对不同季节变暖的符号和幅度变化的敏感性，导致复杂的净 CO ₂汇响应。我们使用来自 20 个北部泥炭地的多年期净 CO ₂交换观测结果表明，初夏较暖与 CO ₂净吸收增加有关，而夏末较暖会导致 CO ₂净吸收减少。因此，净 CO ₂在经历初夏变暖的地区，如西伯利亚中部，泥炭地的下沉比其他地区更可能在温暖的气候条件下持续存在。我们的结果将有助于改进未来变暖实验的设计，并更好地解释未来几十年泥炭地净 CO ₂吸收的大规模趋势。