Over the first half of 2020, Siberia experienced the warmest period from January to June since records began and on the 20th of June the weather station at Verkhoyansk reported 38 °C, the highest daily maximum temperature recorded north of the Arctic Circle. We present a multi-model, multi-method analysis on how anthropogenic climate change affected the probability of these events occurring using both observational datasets and a large collection of climate models, including state-of-the-art higher-resolution simulations designed for attribution and many from the latest generation of coupled ocean-atmosphere models, CMIP6. Conscious that the impacts of heatwaves can span large differences in spatial and temporal scales, we focus on two measures of the extreme Siberian heat of 2020: January to June mean temperatures over a large Siberian region and maximum daily temperatures in the vicinity of the town of Verkhoyansk. We show that human-induced climate change has dramatically increased the probability of occurrence and magnitude of extremes in both of these (with lower confidence for the probability for Verkhoyansk) and that without human influence the temperatures widely experienced in Siberia in the first half of 2020 would have been practically impossible.

在 2020 年上半年，西伯利亚经历了自有记录以来从 1 月到 6 月的最热时期，6 月 20 日，维尔霍扬斯克的气象站报告了 38°C，这是北极圈以北记录的最高日最高温度。我们使用观测数据集和大量气候模型，包括为归因而设计的最先进的高分辨率模拟，对人为气候变化如何影响这些事件发生的概率进行了多模型、多方法分析许多来自最新一代的海洋-大气耦合模型 CMIP6。意识到热浪的影响可以跨越空间和时间尺度的巨大差异，我们专注于 2020 年极端西伯利亚高温的两项措施：1 月至 6 月的平均气温是西伯利亚大片地区的平均气温，以及 Verkhoyansk 镇附近的最高日气温。我们表明，人为引起的气候变化显着增加了这两种极端事件的发生概率和幅度（对 Verkhoyansk 概率的置信度较低），并且在没有人为影响的情况下，2020 年上半年西伯利亚广泛经历的温度实际上是不可能的。