by Many experts believe that we may soon face a mass extinction event, with a high percentage of Earth’s species dying. Projections indicate that the climate will continue to change for centuries to come, and this is a significant threat to biodiversity that has already affected many species.
Despite the threat that climate change poses to biodiversity, we still do not fully understand how it drives animals out of existence. In our new paper, published in Science, we used the fossil record to make more precise estimates.
The geological rock record provides critical insight into past extinctions caused by various climate change events. Fossils therefore provide a rare opportunity to understand the mechanisms of extinction and to investigate how climate change occurred in the past. Understanding why species became extinct under pre-human natural conditions is critical, since human-caused extinction drivers are accumulating over time.
By identifying traits linked to extinction, we can use this information to identify species at risk to prioritize in conservation efforts.
In our latest research article, we analyzed a dataset that included over 290,000 marine invertebrate fossils, covering the last 485 million years of Earth’s history. We looked directly at the traits most critical to survival in the geological past.
Previous studies have emphasized small body size and limited geographic range (the amount of space occupied by a species) as key predictors of extinction risk throughout geologic history.
We recreated the climate for 81 geological periods throughout the Phanerozoic (the current geological era, starting 541 million years ago). And we used climate models to determine the temperature range each species can tolerate.
These factors were then compared with geographic range, size and body size to assess their relative importance. We then estimated an external factor that could influence extinction risk: the degree of climate change experienced by each species.
We assessed how intrinsic traits, such as temperature tolerance and body size, compared to climate change in terms of influencing species extinction risk. Our study is the first to directly compare traits and external factors to determine what causes attrition.
Our results indicated that species that lived in climatic extremes, such as polar or equatorial regions, were particularly at risk of extinction. Species with a narrow thermal tolerance of about 15°C less than that had a much higher risk. We also found that small species are more likely to go extinct due to climate and other changes.
However, size of geographic range was the most important predictor of extinction risk. Species with smaller ranges, which were in geographically restricted areas, had a higher probability.
A conversation is needed
Alarmingly, for the first time, our research has identified climate change as a significant predictor of extinction, along with other species traits.
We observed that species subject to local climate changes of 7°C or more were significantly more likely to disappear across geological stages. This suggests that exceeding this climate change threshold increases the likelihood of a species becoming extinct, regardless of its other characteristics.
That said, the research shows that these variables have a cumulative effect on extinction risk. This highlights the importance of considering a broad spectrum of factors when assessing vulnerability to extinction.
For example, a species living in polar regions, characterized by a small geographic range and body size, and subject to significant climate change, would have a higher risk of extinction than might be understood if only its geographical range were considered. This holistic approach reveals the interplay of various biological and environmental factors to determine species survival over geological timescales.
Our research highlights the urgent challenge that climate change poses to global biodiversity. But it also emphasizes the need for continued research.
Many uncertainties remain regarding extinction risk, particularly regarding why certain traits confer extinction resistance and how traits interact to exert extinction risk. This additional research is necessary to fully leverage the implications of our study for conservation strategies.
Without immediate and targeted conservation efforts, based on a deeper understanding, we risk heading towards a sixth mass extinction event. Our work therefore provides a vital call to action. We should mitigate climate change, but also do more research to strengthen our understanding of the impacts on vulnerable species.
This article from The Conversation is republished under a Creative Commons license. Read the original article.
Erin Saupe receives funding from a Leverhulme Prize and NERC grant NE/V011405/1.
Cooper Malanoski does not work for any company or organization that would benefit from this article, does not consult with, shares in a company or organization that would benefit from this article, and has not disclosed any material relationships beyond their appointment academic.
