Scientists are saying that climate change and El Niño, a climate pattern caused by the warming of the Pacific Ocean, are the culprits for the extreme weather that California is experiencing this winter. Here’s what USA Today reported:

Multiple weather phenomena are conspiring to make these storms particularly damaging. Warm water provides energy to storms, and record-high ocean water temperatures, likely from climate change, are being detected around the world.

Additionally, the Pacific Ocean is also seeing the effects of a more localized El Nino, where weakening trade winds reduce the upwelling of ocean waters and allow surface waters to bake in the sun and grow warmer still. And California, coming off years of drought and wildfires, is particularly vulnerable to mudslides and flooding.

“The atmospheric river firehose is aimed at Los Angeles,” tweeted Meteorologist Ryan Maue. “The onslaught has just begun from this treacherous bomb cyclone.”