Almost one third of a bat population in eastern Australia was killed over the course of just two days of November of 2018, when a heat wave in eastern Australia devastated the Queensland region and temperatures were as high as 108 degrees Fahrenheit. Climate change makes heat waves like this one disproportionately more likely.

An estimated 23,000 to 30,000 spectacled flying fox bats perished during the heat wave, which lasted from November 26 to 27, according to the BBC. Some media reports alleged that once the temperatures exceeded 104 degrees Fahrenheit, bats literally started falling out of trees. David White, a wildlife rescuer from Australia, told the BBC that the event was "totally depressing.”

Justin Welbergen from Australia’s Hawkesbury Institute for the Environment told Australian outlet ABC.net that the event was likely the second-largest mass die-off for the species, which have been listed as “vulnerable” in the country since 1999. In 2014, as many as 100,000 spectacled flying fox bats died, also during a heat wave.

The late-November Australian heat wave also caused more than 80 intense brush fires, and coincided with a series of dust storms that swept across the Queensland region. It’s worth noting that desertification—the process of places becoming more dusty, dry, and desert-like over time—is exacerbated by climate change.

Climate change makes monster heat waves like this one disproportionately more likely. When the air gets hotter, it’s able to hold more water, and humid air makes heat waves more likely. Australia specifically, which is already prone to heat waves, is vulnerable to "more frequent, hotter, and longer" heat waves.

Heat waves also pose a major threat to human lives.It’s difficult to account for the number of human deaths during a heat wave, since experiencing extreme heat can exacerbate pre-existing medical problems in vulnerable populations and contribute to death. For instance, a study found that many of the human deaths associated with the 2009 Australian heat wave occurred in people with heart disease that also lived alone.