# Is the Younger Dryas associated with an extinction event?

It's often said that, while warming and cooling have happened before, what is unusual about the current anthropogenic warming is that it's happening so fast, relative to previous warming phases$^1$. This is considered to be likely to contribute to mass species extinction, as some species will not be able to migrate or adapt fast enough.

However, the warming at the end of the Younger Dryas seems to have also happened quite fast. Is this period associated with any known extinction event?

$^1$: "It is thus clear that the current rate of global climate change is much more rapid and very unusual in the context of past changes." - IPCC AR4 FAQ 6.2

Some authors thinks that the extinction of the Pleistocene megafauna (large mammals such as mammoths, etc.) was contemporaneous with the Younger Dryas (Firestone et al. 2007; Faith & Surovell 2009), while some thinks that it predates it by a couple thousand years (Gill et al. 2009).

Whether or not it was contemporaneous with the Younger Dryas, it constitutes a rather modest extinction event compared to the Big Five (i. e. the five bigger mass extinctions of the Phanerozoic: End Ordovician, Late Devonian, Permian/Triassic boundary, Triassic/Jurassic boundary and Cretaceous/Paleogene boundary, see this previous answer of mine for more details on that), with nonetheless a noteworthy impact (e. g. Johnson 2009) on the remaining ecosystem. The current/future mass extinction is however often considered to be at a comparable scale with these previous five (see for instance Barnovsky et al. 2011), but climate change is not the only one to blame: active destruction of ecosystems, mainly through anthropization, is one major factor as well.

References:
Barnovsky et al., 2011. Has the Earth’s sixth mass extinction already arrived? Nature, 471: 51-57.
Faith & Surovell, 2009. Synchronous extinction of North America’s Pleistocene mammals. PNAS, 106(49): 20641-20645.
Firestone et al., 2007. Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. PNAS, 104(41): 16016-16021.
Gill et al., 2009. Pleistocene Megafaunal Collapse, Novel Plant Communities, and Enhanced Fire Regimes in North America. Science, 326: 1100-1104.
Johnson, 2009. Ecological consequences of Late Quaternary extinctions of megafauna Proc. Roy. Soc. B, 276 (1667): 2509-2519.

• If there's an error of a couple of thousand years, then there's no real way of saying whether such an extinction event is due to the extreme rate of change at the end of the Younger Dryas (which only lasted about a thousand years) or if it's just due to the over-all warming during the change from ice-age to the current state, right? – naught101 Oct 23 '14 at 3:03
• Indeed, hence the debate on whether the extinction of the megafauna has anything to do with the Younger Dryas. Other theories on why this extinction occurred is the over-hunting by early humans (which would explained with this extinction only affected large mammals). – plannapus Oct 23 '14 at 6:35
• Would it also be true to say that since it's not long enough ago to have a fossil record, we don't really have any idea of how many smaller species might have become extinct? – naught101 Oct 23 '14 at 7:08
• On the contrary, the fact that it was not so long ago, make the fossil record of that period far more complete. – plannapus Oct 23 '14 at 7:34