Ecological response to environmental change in the Boreal Realm and the origins of three mass extinction events

Project Description

Since the Cambrian Explosion of life on Earth, about 540 million years ago (Ma), ecosystems have been suffered repeated mass extinctions. There have been at least five major extinctions since then, most recently the famous event 65Ma, that wiped out the dinosaurs. Life has shown itself to be remarkably resilient, and it follows that mass extinctions result from serious environmental stress. We live in a time of growing concern that Earth is about to see, or already is going through, a modern mass extinction to rival those of the geological past. In June 2011, the International Union for Conservation of Nature (IUCN) reported that a combination of environmental stresses on the oceans is creating the conditions associated with every previous mass extinction. The greatest threats are warming (mainly from greenhouse gases), marine oxygen depletion, ocean acidification, and eutrophication (a process that leads to blooms in life but can ultimately destabilise ecosystems). The difference between these threats in the past and present is that today they have a human origin. In the past they may have resulted from catastrophic volcanism, with widespread volcanic rocks (known as "large igneous provinces") associated with most extinctions. The underlying cause of change may be different between past and present, but there is concern that the effect (extinction) may be the same. We can learn much from Earth's past, and parallels can be drawn between future scenarios, and mass extinctions in the geological record. All of the aforementioned environmental stresses have been suggested as causes of the biggest crisis of all time, at the close of the Permian (251Ma), when 95% of species disappeared. Similar environmental changes have also been implicated in an earlier extinction in the Middle Permian (260Ma), and another at the end of the subsequent Triassic period (200Ma). This 60 million year interval witnessed some of the most important and remarkable events in the history of the planet, each extinction fundamentally shaping evolution and therefore our very existence. In this project I will study each of the three events between 260-200Ma, paying particular attention to Polar north oceans, an area known as the "Boreal Realm". Not only are past extinctions poorly understood in the Boreal Realm, this region has greatest uncertainty in the future. My investigations will start with geological fieldwork in Spitsbergen and Siberia, both regions that in the Permian and Triassic, as now, were located in the Arctic. I will sample the three extinction intervals, and my first objective will be to work out when, and how severe the extinctions were, and which species were most affected. I will do this using microscope slides of my samples. I will use several techniques to evaluate which environmental stresses were the likely causes of these crises. These techniques include geochemical analyses of molybdenum and strontium isotopes, looking at tiny pyrite blobs under a high-power microscope, and using an extremely powerful computer model, known as GENIE, all of which tell us about past oceans. A major challenge is to correlate rocks from the Polar regions with those from the tropics, in order to work out whether the Polar oceans suffered more, or less. I will produce a "chemical clock" based on carbon isotopes in the rocks, which will allow me to match sequences in Spitsbergen and Russia with those from elsewhere. The main goal of this project is to identify whether there is a latitudinal variation to extinction risk. This might influence the fate of Boreal communities in the future, and my study will inform future governance of the world's oceans, as we look to prevent a contemporary mass extinction. The results will not only be useful for geologists, but also to policy makers that extend through groups such as IUCN, right up to the United Nations, that is ultimately charged with protecting our oceans for future generations.