Scientists at Utah State University studying the ongoing drought in California say that manmade global warming is the likely cause, according to the Associated Press. They made the connection after analyzing weather factors that contribute to the El Niño effect.
El Niño pushes warm ocean water and air to the west, which affect weather patterns across the continental United States. Researchers say colder waters off the coast of China appear to be a precursor to El Niño itself and are a result of greenhouse gases in the atmosphere.
The El Niño effect also played a role in the 2013 polar vortex that affected states in the Midwest. This too can be linked to concentrations of greenhouse gases, scientists say.