Data_Sheet_2_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.

在过去的二十年间，北半球北极森林野火所排放的温室气体量逐年攀升，引起了广泛关注，尤其是在2021年经历的空前野火季节尤为显著。据我们的计算，2002年至2020年间，俄罗斯野火排放了大约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相似估计值相吻合，远超过早期在俄罗斯国家清单报告（NIR）中发现的估计值的两至三倍。值得注意的是，仅在2021年，俄罗斯野火就排放了高达1,700 Tg CO2eqv的二氧化碳当量，超过了该国化石燃料消费所产生的碳排放量。因此，这一状况导致了俄罗斯森林碳吸收能力的几乎完全抵消。我们的分析表明，2002年至2021年间野火频率变化的超过50%可以归因于北极振荡（AO）的变化。这表明利用AO作为野火预测变量的可能性。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，俄罗斯森林可能从碳汇的角色转变为大气中碳的潜在净排放源。