Climate threats?

In my last lecture on Holocene climate variations, what particularly caught my attention was that small changes in forcing can lead to instability. Hmmm..

Whilst doing some further reading, I found this article by Crowley and North that discussed climate variations and its relation to extinction. Instead of posing obvious connections between climate change and extinction, they mentioned that the magnitude of Late Permian extinction seemed to be too great for the area of land to be affected by glaciation. Also, there was no major extinction event during the Late Carboniferous (330 Ma) glaciations, but a significant reduction in some faunal groups. Certainly, some evidence for the three of five extinction events shows connection to the evolution of Cenozoic climate at about 2.4 to 3.0 Ma.

An interesting fact - climate change does have an impact on extinction. Many extinctions occurred at the early stages of cooling millions years ago, with each cooling event removing the most vulnerable species. As species that are more adaptive remained, the effect of climate change on extinction has been smaller since then. 

At least, one of the mass extinctions - the Mid-Jurassic, was argued to be triggered by massive climate change, a mega monsoon. Dr Ruben Cuneo explained the possibility on BBC.

Fuelled by my personal interest on animals, I spent some time to look up some endangered species on WWF's website.

Although there are many other deadly threats that centre around endangered species (some poses connections to the possibility of next extinction), climate change is certainly regarded as one of the major causes. Under changing climate, the proportion of female and male turtle hatchling leads to unstable population.  Poloczanska, Limpus and Hays stated in the past 100 million years, turtles had to move to tropics to establish nesting grounds during glacial periods. Ambient surface air temperatures were naturally higher as global temperatures rose, which consequently reduced the likelihood of male hatchlings. Small changes in temperature close to the pivotal level (29°C) have proved to have great impact in distorting the sex ratios of turtle hatchlings. 

Worryingly, these marine turtles are only the tip of the iceberg of endangered species in the world..

So, back to the question - Does climate change lead to a mass extinction? Perhaps so, to the extent that it is gradually forcing some species to the edge of a wipeout, but certainly not sudden mass extinction events.