Climate change is being blamed for a whole host of unpleasant things, such as droughts, violent storms, and rising sea levels — but is it also to blame for a deadly bacteria that lurks in hot tubs and air conditioning units?

We recently reported on the Legionnaires’ outbreak, featuring new cases in New York, Illinois, and California. This is nothing new, Legionnaires’ outbreaks happen every year in the United States. But what is different, scientists have noticed, is that the number of cases have been steadily rising — and things may get worse before they get better, according to an NBC News report.

Legionnaires’ was first reported all the way back in 1976, and cases have been rising quite rapidly in recent years. About 1,110 cases of Legionnaires’ disease were reported in 2000 compared with 3,522 in 2009, an astonishing increase based on reports from the Centers for Disease Control and Prevention.

So what does this have to do with Global Warming? Legionnaires’ comes from the Legionella bacteria, which infects people through the air — it is not contagious and can’t be spread from human to human. This bacteria, which results in pneumonia that can kill children, the elderly, and people with compromised immune systems, likes to make its appearance in the summer and early fall, where it thrives in warm environments. It particularly likes warm water and may infect hot tubs, plumbing systems, or air conditioning cooling units.

The CDC suggested that improved testing may explain the increased numbers, but the facts about the Legionella bacteria and its preferred habitat has some scientists guessing that climate may be behind the rise in numbers. Dr. David Fishman, a professor at Dalla Lana School of Public Health at the University of Toronto, was quoted in the NBC News report as saying that while it’s tough to prove climate change is giving a helping hand to Legionnaire’s, it’s certainly a very possible scenario, especially since the bacteria likes warm temperatures and the wet and humid weather that comes with Global Warming is perfect for it. Unfortunately, if true, this means cases of Legionnaires’ may only get worse in the near future.