Yorkshire Philosophical Society

Event Information

Causes of mass extinctions

Professor Paul Wignall, Professor of Palaeoenvironments, University of Leeds

Mass extinctions are the major catastrophes that punctuate life’s history. They are marked by the loss of large numbers of species, up to 90% in some cases, from many environments in a short period of time. Just how short varies from extinction to extinction, although the wipeout of the dinosaurs was probably in a matter of weeks resulting from a giant meteorite impact. However, this event appears unique because all the other mass extinction coincide with giant-scale volcanism not impacts. The talk will look at this volcanism and the likely role that the voluminous emissions of gases play in the environmental changes that cause the extinctions. Latest research shows that the effects produce cascades of changes leading resulting in crises that have a different timing in the oceans and on land.

7pm in the Tempest Anderson Lecture Theatre in the Yorkshire Museum on Tuesday 12 May 2026.

YPS Members and students free, non members £5.

Member’s report:

Mass extinctions have been clear in the fossil record since the earliest days as identified by J. Phillips – Life on the Earth: its origin and succession, “the seventh period (Triassic) is everywhere marked by a zone of sterility, the local extinction of most classes”. A Mass Extinction is identified by an extinction rate elevated above background rates, occurring rapidly on a geological scale, affecting life globally in all habitats and commonly associated with a major decline in primary productivity in the oceans.

The most notable mass extinction was 66 million years ago, wiping out the dinosaurs and was caused by a meteorite striking the Gulf of Mexico near Chicxulub. This was so lethal because of its size (largest impact of the last billion years) and the fact that it hit limestone and gypsum. This caused acid rain, poisoning, molten droplets of rock resulting in widespread incineration and clouds of fine ash resulting in global darkness and starvation. The other main cause of mass extinctions is volcanic activity evidenced by giant lava fields of basalt known as Large Igneous Provinces(LIP) especially in the time of the continent Pangea. Rampino and Stothers identified that LIPs coincided with extinctions. These LIPs were the product of mantle plumes within the earth and generating massive volcanic activity and the best links are prior to 180 million years ago. These eruptions generated between 0.5 and 8 million cubic kilometres of basaltic extrusives and generated an interesting selection of gasses including CO2, halogens, sulphur dioxide and water. This was caused by the mantle plume erupting through previous sedimentary layers including coal which was effectively cooked by the eruption releasing the gasses.

Most extinction mechanisms are linked with global warming and changes in ocean circulation driven by greenhouse gas emissions from LIPs. These include on land – UV radiation, high temperatures, acid rain and aridity and in the oceans – widespread anoxia, ocean acidification, high temperatures, mercury and other toxic metal poisoning and ammonia poisoning. A further factor for the extinctions in the time of Pangea was the poor carbon burial of the planet at this time, carbon burial relies on forests, especially in swamps (for the last 380 million years) and plankton carbonate which has only existed for the past 160 million years and results in sediments on the ocean floor.

Jon Coulson