Data_Sheet_1_Increase in Arctic Oscillations explains most interannual variability in Russia’s wildfires.docx

Over the past two decades, the escalating emissions of greenhouse gases from boreal wildfires in the Northern Hemisphere have drawn significant attention, underscoring an unprecedented wildfire season in 2021. Our calculations indicate that between 2002 and 2020, wildfires in Russia released approximately 726 ± 280 Tg CO2eqv yr−1. This aligns closely with similar estimates derived from remote sensing data, far surpassing the earlier approximations found in the Russian National Inventory Report (NIR) by a factor of 2 to 3. Notably, in 2021 alone, Russia’s wildfires emitted an exceptionally high amount of 1,700 Tg CO2eqv, exceeding the carbon emissions from the country’s fossil fuel consumption. Consequently, this situation led to an almost complete counterbalance of carbon assimilation by Russian forests. Our analysis attributes over 50% of the variation in wildfire frequency between 2002 and 2021 to shifts in the Arctic Oscillation (AO). This suggests a potential for utilizing AO as a predictive variable for wildfires. It’s noteworthy that the AO itself is influenced by the sustained regression of Arctic sea-ice. From this, it can be inferred that in the foreseeable future, Russian forests might undergo a transition from their role as carbon sinks to the potential net contributors of carbon to the atmosphere.

在过去二十年中，北半球北极地区野火导致的温室气体排放量持续攀升，引起了广泛关注，尤其是在2021年，这一现象更是凸显了前所未有的野火季节。据我们的计算，在2002年至2020年间，俄罗斯野火释放了大约726±280 Tg CO2eqv yr−1的二氧化碳当量。这一数据与遥感数据得出的类似估计值非常接近，远远超过了先前在俄罗斯国家清单报告（NIR）中发现的早期近似值的2至3倍。值得注意的是，仅在2021年，俄罗斯野火就排放了异常高的1,700 Tg CO2eqv，超过了该国化石燃料消费所产生的碳排放量。因此，这一状况几乎完全抵消了俄罗斯森林的碳吸收作用。我们的分析认为，在2002年至2021年间，野火频率的变化超过50%归因于北极涛动（AO）的变化。这表明，AO可能作为预测野火的潜在变量。值得注意的是，AO本身受到北极海冰持续退缩的影响。据此推断，在可预见的未来，俄罗斯森林可能会从碳汇的角色转变为大气中碳的潜在净排放者。