Climate Change And Species Extinction
As the climate changes, so do the dynamics of species, ecosystems, and the relationships between and among them. At Faunalytics, we’ve covered these relationships whenever we find solid studies that help us to understand just how interlinked these dynamics are.
The focus of this study was specifically to better understand the cause and effect relationship between climate change and species extinction. Climate-related variables that were considered included changes in mean temperature, precipitation, climate variability, and the rate of change in temperature over time. Species-related variables of interest included species dispersion (to higher elevations or latitudes) and the ability to adapt to a modified climate.
Historical time-series survey data on species and climate variables were obtained from 10 studies encompassing data for 538 species across 581 sites. The time-series nature of the data allowed for comparisons over time and calculations of rates of change. Species extinctions were examined in two ways: (1) a binary variable indicating the absence or presence of extinctions, and (2) the count of extinctions within a given location. Two separate statistical analyses were done based on the two metrics of species extinction.
The results revealed that the most significant factor associated with local extinctions was the maximum annual temperature in terms of total amount of change and the rates of change. For example, local extinctions were more likely to be found at sites where the maximum temperature increased by approximately 300% with a rate of change at about 300% as well. In other words, locations where temperatures were three times higher than they had been previously, and where the rate of change in temperature was three times faster than other locations, were most likely to have experienced local extinctions.
Although maximum temperature absolute changes and rates of change were associated with species extinction, mean annual temperatures changes were not. Specifically, in temperate locations, the increase in the mean annual temperature was smaller in locations with extinctions when compared to those without. For tropical locations, the mean increase in annual temperature was about the same for locations with extinctions and those without. While not as significant as temperature, precipitation was also found to be a significant variable: locations with decreasing precipitation over time were associated with local extinctions.
While climate-related variables are critically important to understanding past extinctions, predicting future extinctions requires the combination of both projected climate changes and a species’ anticipated need to disperse to a new location in order to survive. If a species can’t adapt to the new climate, it will need to disperse to survive. As such, a third critically important variable to estimate is the species’ ability to disperse fast enough to avoid extinction if it cannot adapt to the warmer climate. Based on statistical models, the researchers estimated that between 16% and 30% of the 538 species studied will likely go extinct by 2070.
Based on the results of this study, climate change as evidenced by extremes in maximum annual temperatures and decreasing precipitation, appears to be a causal driver in species extinction. These findings indicate that it is not the gradual or more consistent change in temperature over time, but the extreme fluctuations within a given time period that impact extinction rates most. Furthermore, many species will not be able to tolerate the warmer climates or disperse fast enough to locations with tolerable climates. As such, extinction will result as a consequence of climate change.