The Sun provides the principal energy input into the Earth system and solar variability represents a significant external climate forcing. Although observations of solar activity (sunspots) cover only the last about 400 years, radionuclides produced by cosmic rays and stored in tree rings or ice cores serve as proxies for solar activity extending back thousands of years. However, the presence of weather-induced noise or low temporal resolution of long, precisely dated records hampers cosmogenic nuclide-based studies of short-term solar variability such as the 11-yr Schwabe cycle. Here we present a continuous, annually resolved atmospheric ¹⁴C concentration (fractionation-corrected ratio of ¹⁴CO₂ to CO₂) record reconstructed from absolutely dated tree rings covering nearly all of the last millennium (ad 969–1933). The high-resolution and precision ¹⁴C record reveals the presence of the Schwabe cycle over the entire time range. The record confirms the ad 993 solar energetic particle event and reveals two new candidates (ad 1052 and ad 1279), indicating that strong solar events that might be harmful to modern electronic systems probably occur more frequently than previously thought. In addition to showing decadal-scale solar variability over the last millennium, the high-temporal-resolution record of atmospheric radiocarbon also provides a useful benchmark for making radiocarbon dating more accurate over this interval.

太阳为地球系统提供了主要的能量输入，太阳变率代表了一个重要的外部气候强迫。尽管对太阳活动（太阳黑子）的观测只涵盖了过去大约 400 年，但由宇宙射线产生并储存在树木年轮或冰芯中的放射性核素可以作为太阳活动的代名词，可以追溯到数千年前。然而，天气引起的噪声或长期精确记录的低时间分辨率的存在阻碍了基于宇宙成因核素的短期太阳变率研究，例如 11 年施瓦贝循环。在这里，我们展示了一个连续的、每年解析的大气¹⁴ C 浓度（¹⁴ CO ₂与 CO _{2的分馏校正比率}) 记录从绝对年代的树木年轮中重建，几乎涵盖了上个千年的所有时间（公元969-1933年）。高分辨率和精确的¹⁴ C 记录揭示了 Schwabe 循环在整个时间范围内的存在。该记录证实了公元993年的太阳高能粒子事件并揭示了两个新的候选者（公元1052年和公元1279），表明可能对现代电子系统有害的强烈太阳事件可能比以前认为的更频繁地发生。除了显示上个千年的年代际尺度太阳变率外，大气放射性碳的高时间分辨率记录还提供了一个有用的基准，可以使放射性碳测年在这个间隔内更加准确。