Former New York mayor Michael Bloomberg said Republicans must acknowledge the reality of climate change. The politically independent Bloomberg now acts as the U.N. Secretary-General's Special Envoy for Cities and Climate Change.

"Even the right-wing crazies no longer say climate change isn't real," said Bloomberg, according to CNN. "They say it's natural, it's not business, not man-made.

"Why do they say that? Because in every one of their towns and villages and states and counties, they now have floods where they had droughts, they have droughts where they had floods, they have storms, they have tornadoes."

Bloomberg said that cities are now leading fight against climate change.

"Cities are leading the charge against climate change, and one of the reasons is that they share so much in common -- what works for one city usually holds valuable lessons for many others," said Bloomberg in a statement, according to the U.S. State Department. "The more we help city leaders collaborate and share their wisdom, the faster they can make progress."

Bloomberg also criticized Republicans like Sen. Ted Cruz who is a climate change denier.

"You've got a guy like Ted Cruz, who I think (prominent American lawyer Alan) Dershowitz said was the smartest law student he ever had, and he says some of the stupidest things I've ever heard, " said Bloomberg, according to CNN. "The only explanation - the only explanation - is he doesn't believe it, he's just saying it. Ted Cruz is a smart guy and you can't say what he says in an intelligent way."

Rick Tyler, a Cruz spokesman, responded to Bloomberg's statements. "The myopic Mr. Bloomberg should look past his armed guards and beyond his cloistered circumstances and take in a big gulp of reality'', said Tyler, according to Business Insider. "Most of what Ted Cruz says is simple common sense. Most of what Mr. Bloomberg says defies logic."