The Holocene: 11,700 years of 'wholly new' time, and the epoch geologists refused to replace
Everything humans have ever written happened inside one geological epoch, the Holocene, which began around 11,700 years ago as the last ice sheets retreated. In March 2024, after 15 years of argument, stratigraphers voted down a proposal to declare it over and start an Anthropocene.
The Holocene is the current epoch and, together with the Pleistocene before it, makes up the Quaternary period. Its name joins the Greek words for whole and new, and the same kainos root supplies the -cene ending of every epoch in the Cenozoic Era. Officially it starts about 11,700 years before 2000 CE, or roughly 9,700 BCE. It is an interglacial, a warm pause within ongoing ice-age cycles, and older texts sometimes call it the Flandrian. In July 2018 the International Union of Geological Sciences divided it into three ages: the warming Greenlandian, the Northgrippian, marked by cooling when meltwater disrupted ocean circulation 8,200 years ago, and the Meghalayan, which opened 4,200 years ago with a drought lasting about two centuries.
The landscape changed dramatically even though continents barely moved. Melting ice raised sea levels about 35 metres early in the epoch and another 30 later. Land north of about 40 degrees latitude, once pressed down by glaciers, has sprung back by as much as 180 metres and is still rising, which is why the Baltic Sea is shrinking and why weak earthquakes still rattle northern Europe. Temporary seas once reached so far inland that marine fossils from this epoch turn up in Vermont and Michigan.
Climate was never as steady as Greenland's ice cores first suggested. North Atlantic records show rhythms of roughly 2,500, 1,500 and 1,000 years, and collapsing Laurentide ice made conditions erratic between 8,500 and 6,700 years ago. After the Holocene Climatic Optimum came slow cooling, interrupted by the Mediaeval Warm Period of the 10th to 14th centuries and then the Little Ice Age, the coldest stretch of the past two thousand years. Researchers find a one-degree warming now happens 5 to 40 times more often than in mediaeval times, driven by greenhouse gases rather than the sun.
Human land use since the Mesolithic may explain why this interglacial never slid into significant cooling. Paul Crutzen and Eugene Stoermer coined Anthropocene in 2000, and a working group voted in May 2019 to formalize it with a mid-twentieth-century base. The subcommission rejected the idea by a wide margin, citing its shallow sediments and very recent start.
Source: Holocene
