More than two decades ago, my coauthors, Raymond Bradley and Malcolm Hughes, and I published the now iconic “hockey stick” curve. It was a simple graph, derived from large-scale networks of diverse climate proxy (“multiproxy”) data such as tree rings, ice cores, corals, and lake sediments, that captured the unprecedented nature of the warming taking place today. It became a focal point in the debate over human-caused climate change and what to do about it. Yet, the apparent simplicity of the hockey stick curve betrays the dynamicism and complexity of the climate history of past centuries and how it can inform our understanding of human-caused climate change and its impacts. In this article, I discuss the lessons we can learn from studying paleoclimate records and climate model simulations of the “Common Era,” the period of the past two millennia during which the “signal” of human-caused warming has risen dramatically from the background of natural variability.

二十多年前，我和我的合著者 Raymond Bradley 和 Malcolm Hughes 发表了现在标志性的“曲棍球棒”曲线。这是一个简单的图表，源自各种气候代理（“multiproxy”）数据的大规模网络，例如树木年轮、冰芯、珊瑚和湖泊沉积物，捕捉了当今发生的前所未有的变暖性质。它成为关于人为气候变化及其应对措施的辩论的焦点。然而，曲棍球棒曲线的明显简单性暴露了过去几个世纪气候历史的动态性和复杂性，以及它如何帮助我们了解人为气候变化及其影响。在本文中，我将讨论我们可以从研究“共同时代、