The report compares two periods of summer-month water temperature: historic data from lighthouse keeper records from the late 1800s and three decades of recent temperature data.
One of the big concerns is how these higher temperatures will affect coral reefs, says Ilsa Kuffner, who co-authored the report.
Her research found that in the earlier data sets, August was the only month that saw the water hit dangerously high temperatures. Now, the averages for June, July and August are all within the dangerous range.
“The corals slow down their calcification rates so they’re growing less,” explains Kuffner. “They start to kick out algae that live inside the coral, [which] produce up to about 95 percent of the coral’s food source. So, when these get kicked out because of this high temperature, then the coral loses that food source… it starts to starve.”
That starvation can kill coral, an essential part of marine life food chains. Kuffner says it's yet to be seen if that will happen to coral around the Keys.