Former Vice President Al Gore praised Hillary Clinton’s credentials on climate change at a Florida rally Tuesday that brought the presidential campaign to the front lines of the fight against global warming in the U.S. and laid out a clear contrast with Donald Trump’s denial of the science.

The speeches from both Clinton and Gore in Miami delved into the science and policy of climate change in rare depth and nuance for a presidential campaign rally. The speakers took time to explain the science behind phenomena like sea-level rise, how climate change affects the spread of infectious diseases like Zika and how storm surge easily inundates cities with water during large storms.

That tenor of the argument departed sharply from the dramatic warning that Gore has adopted in the past, including in his global-warming documentary An Inconvenient Truth. That strategy may not appeal to the average voter unversed in the issue but could lend credibility to some activists skeptical of Clinton’s position on that issue. Her campaign said the rally was intended at least in part to energize millennials who care deeply about global warming.

“Hillary Clinton will make solving the climate crisis a top national priority,” Gore said. “Her opponent, based on the ideas he has presented, would take us toward a climate catastrophe.”

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Gore also devoted a significant portion of his speech to dismantling Trump’s position on man-made climate change. The GOP presidential nominee has said repeatedly that he does not believe the phenomenon exists, calling it merely “weather” and a “hoax” invented by China. Trump’s position has been debunked repeatedly by scientists, including a group of 375 leading scientists, including 30 Nobel laureates, who slammed the candidate in a recent letter.

The choice of Florida to hold a climate rally — one that echoes a similar move by President Obama last year — takes the issue to its U.S. heart. Scientists rank coastal Florida — particularly Miami and its environs — as the U.S. region most vulnerable to sea-level rise with more than $130 billion of real estate at stake. Images of Hurricane Matthew sweeping through the state just last week certainly contribute to that message. “Let’s really focus on what’s important in this election,” Clinton said. “At the rate we are going, 1 in 8 homes in Florida could be underwater by the end of the century.”

Florida is also home to a recalcitrant state government that reportedly denies the existence of climate change by the order of Governor Rick Scott. The lack of acknowledgement by state officials has created difficulties for local officials in need of funding and other assistance to address the issue.

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The rally represents perhaps the most focus the issue has received in this year’s long and winding presidential race. Trump devoted two speeches to energy and environmental issues, but in those he quickly dismissed climate change and focused instead on how he would repeal regulations. Beyond that, the issue has come up only briefly in presidential debates, including last Sunday’s.

The next President — whoever he or she may be — will enter office with a clear set of challenges on environmental issues. The U.S. has fallen behind on its commitment to cut greenhouse-gas emissions included in the Paris Agreement, and the Clean Power Plan — Obama’s signature measure to address global warming — remains wrapped up in litigation. A President Trump would struggle to reinvigorate a coal industry that has fallen behind due to market forces as he has repeatedly promised. He would also struggle to dismantle the Paris Agreement as he has promised after that deal took effect this year.

Gore emphasized that voters need to weigh in to stop Trump’s climate agenda, no matter how difficult some of the GOP candidate’s promises may be to achieve. “Please take it from me, every single vote counts,” Gore said in reference to the controversial Florida vote counting during the 2000 presidential election. “If you are not registered to vote, do so today.”

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Write to Justin Worland at justin.worland@time.com.