The Past Isn'€™t Dead: The Last 2 Million Years Can Help Biodiversity in the Next 100

Climate change, extinction, and other threats facing our ecosystems are nothing new under the sun – we have a number of examples in the recent fossil record to draw upon as analogs. Understanding how yesterday’s biodiversity responded to these “natural experiments” can help prepare us for the next century. In this talk, I’ll share several examples, asking: 1) What determines extinction risk, and 2) What are the consequences of ice age extinctions and climate change for present-day biodiversity? The Pleistocene ice ages are a particularly good model, because our biodiversity experienced repeated, dramatic, and often abrupt climate changes. Despite this, there appear to have been little extinction due to climate change alone, which begs several questions: Were species really that resilient? Are we overestimating future extinction risk? Or have we just underestimated how prevalent climate-driven extinctions have really been in the recent fossil record?

In contrast, the extinction of ice age megafauna has been extensively studied, but until recently, most research has focused on the causes of that extinction (largely focusing on humans versus climate). However, we know much less about the long-term ecological legacies of those extinctions. This leads to the question: if a mammoth dies in the forest, what happens to the trees? Quite a lot, it turns out; large herbivores appear to buffer the impact of climate change on plants, and their removal had large-scale consequences for modern ecosystems that are still playing out today. These lessons from the past can help inform cutting edge—but often controversial—conservation strategies, from managed relocation of species to de-extinction and rewilding.