Despite the overwhelming consensus of scientists who say climate change is occurring, Donald Trump on Sunday said that "nobody really knows" whether it is real.

"I'm still open-minded. Nobody really knows," Trump told Chris Wallace on "Fox News Sunday" in a wide-ranging interview. "Look, I'm somebody that gets it, and nobody really knows. It's not something that's so hard and fast. I do know this: Other countries are eating our lunch. You look at what's happening in Mexico where our people -- just our plants are being built. They don't wait 10 years to get an approval to build a plant, OK? They build it like the following day or the following week. We can't let all of these permits that take forever to get stop our jobs.”

Scientists point to rises in sea level and global temperature, shrinking ice sheets, warming oceans, glacial retreat, declining arctic sea ice, decreased snow cover, ocean acidification and extreme events such as the number of record high temperature events in the U.S. as evidence of global warming.

Trump said Sunday he was "studying" whether the U.S. should stick with the global warming agreement struck in Paris a year ago, signed by more than 100 countries to reduce carbon emissions.

"Paris, I'm studying. I do say this – I don't want that agreement to put us at a competitive disadvantage with other countries," he said. As you know, there are different times and different time limits on that agreement. I don't want that to give China or other countries signing agreements and advantage over us.”