NOAA/WDS Paleoclimatology - King - Revelstoke Update - PIEN - ITRDB CAN725

Extreme summer temperatures are increasingly common across the Northern Hemisphere and inflict severe socioeconomic and biological consequences. In summer 2021, the Pacific Northwest region of North America (PNW) experienced a 2-week-long extreme heatwave, which contributed to record-breaking summer temperatures. Here, we use tree-ring records to show that summer temperatures in 2021, as well as the rate of summertime warming during the last several decades, are unprecedented within the context of the last millennium for the PNW. In the absence of committed efforts to curtail anthropogenic emissions below intermediate levels (SSP2–4.5), climate model projections indicate a rapidly increasing risk of the PNW regularly experiencing 2021-like extreme summer temperatures, with a 50% chance of yearly occurrence by 2050. The 2021 summer temperatures experienced across the PNW provide a benchmark and impetus for communities in historically temperate climates to account for extreme heat-related impacts in climate change adaptation strategies.

北半球夏季极端高温事件愈发频发，并带来严重的社会经济与生物生态后果。2021年夏季，北美太平洋西北地区（Pacific Northwest region of North America, PNW）遭遇了为期两周的极端热浪，致使当地夏季气温创下历史新高。本研究通过树木年轮记录分析证实，北美太平洋西北地区2021年的夏季气温，以及近数十年间的夏季升温速率，在近千年的气候背景下均属前所未有。若不采取切实举措将人为碳排放控制在中等排放情景（SSP2–4.5）的水平以下，气候模型的预测结果显示，该地区频繁遭遇类似2021年夏季极端高温事件的风险将快速攀升，到2050年时，此类事件的年发生概率将达到50%。北美太平洋西北地区2021年的夏季高温，为历来处于温带气候的社区在气候变化适应策略中纳入极端高温相关影响评估提供了基准参照与推动动力。