The level at which Earth is instrumented, observed, and modelled has radically advanced our knowledge of recent and ongoing climate change, but this knowledge lends a false sense of sophistication to our understanding of Earth system behaviour. The geological record has revealed repeated examples of seemingly unimaginable climate scenarios — times when Earth’s climate evolved in surprising ways (for example, complete ice sheet coverage, no ice sheet coverage, equable climate in polar and equatorial regions). The data tell us that extreme states occurred — but fundamental questions about the forcings, feedbacks, and tipping points that led to these alternative Earth-system states remain unresolved.

Earth’s continental sedimentary archives can be used to develop proxy records to test hypotheses and further elucidate past climate states at local to global scales. Scientific drilling, which provides more pristine and continuous sediment records than surface sampling, enables investigation of alternative Earth-system states. This includes past warm periods, spanning the relatively warm interglacial intervals between glaciations over the last few hundred thousand years to the extreme greenhouse climate of the Palaeocene–Eocene Thermal Maximum (around 55.7 million years ago). Additionally, continental records capture times when plate configurations were quite different from those of today, including the Eocene–Oligocene transition (around 33.4 million years ago), when a reconfiguration of ocean gateways led to the growth of Antarctic ice, and earlier in the Mesozoic and Palaeozoic, when the assembly and disintegration of Pangea had drastic impacts on continental climate.

地球的仪器、观测和建模水平从根本上提高了我们对最近和正在进行的气候变化的了解，但这些知识给我们对地球系统行为的理解带来了一种虚假的复杂感。地质记录揭示了看似难以想象的气候情景的重复例子——地球气候以令人惊讶的方式演变（例如，完全覆盖冰盖、没有冰盖覆盖、极地和赤道地区的气候相等）。数据告诉我们，极端状态发生了——但关于导致这些替代地球系统状态的强迫、反馈和临界点的基本问题仍未解决。

地球的大陆沉积档案可用于开发代理记录，以检验假设并进一步阐明从局部到全球尺度的过去气候状态。与地表采样相比，科学钻探提供了更多原始和连续的沉积物记录，使研究地球系统的其他状态成为可能。这包括过去的温暖时期，跨越过去几十万年冰期之间相对温暖的间冰期间隔，一直到古新世-始新世热盛期（约 5570 万年前）的极端温室气候。此外，大陆记录捕捉了板块配置与今天完全不同的时间，包括始新世-渐新世过渡期（约 3340 万年前），当时海洋门户的重新配置导致南极冰的生长，以及中生代和古生代早期，当盘古大陆的组装和解体对大陆气候产生巨大影响时。