Florida Republican Sen. Marco Rubio, who announced his presidential candidacy last week, told Bob Schieffer of CBS News on Sunday that he does not believe in manmade global warming. Instead, Rubio said he recognizes the climate is changing, but that scientists have not determined what percentage of such changes are due to human activities, such as burning coal, oil and gas for energy, compared to natural climate variability.

Unfortunately for Rubio, scientists have been quite clear that the majority of warming during the past few decades is due to manmade global warming.

In an appearance on CBS' Face the Nation, Rubio said that if the government implements policies such as a carbon tax or a cap-and-trade system to cut greenhouse gas emissions, it would be "devastating" for the economy, and scientists can't say precisely what the climate benefits would be.

None of the likely contenders for the Republican presidential nomination recognize mainstream climate-science findings, namely that the climate is warming largely due to human activities, which is having significant impacts. They include everything from sea level rise — a particular concern in Florida — to Arctic sea ice loss.

"I do not believe in climate change in the way that some of these people out there are trying to make us believe," Rubio said. "I believe the climate is changing because there's never been a moment where the climate is not changing."

"The question is what percentage of that, or what is due to human activity."

Implying that scientists, rather than political leaders and environmental groups, are advocating for specific policy measures to reign in global warming, he added, "Scientists can't tell us what impact [such policies would have] on reversing these changes."

Rubio also opposed an amendment in January that said humans "significantly" contribute to climate change. That amendment only garnered support from five Republican senators.

Rubio's comments are out of step with the scientific community, which is nearly unanimous in finding that the majority of recent climate change is largely due to manmade activities, and that if action is not taken soon to slow the pace of global warming, potentially devastating consequences may occur.

The senator's views also put him in opposition to the majority of voters in his home state, which is considered to be ground zero for sea level rise. A recent study from Yale University shows that 64% of Floridians believe global warming is occurring, and 50% think that climate change is mostly due to human activities.

In addition, the polling estimates show that a majority of Floridians are worried about global warming, and 75% favor regulating carbon dioxide, the main global warming gas, as a pollutant.

Polling estimates show public opinion regarding concern for global warming among Florida residents. Image: Yale University

Rubio is pitching himself as a candidate who can appeal to a broader cross-section of voters, given his Cuban heritage and fluency in Spanish. Interestingly, recent polling data indicates that Hispanic-Americans show higher levels of concern regarding global warming than many other segments of the population; this may present a conundrum for Rubio if he wants to win their votes, while maintaining a stance that critics are calling climate-change denial.

In contrast to Rubio's views and those of his fellow Republican candidates, U.S. President Barack Obama is planning to spotlight Florida's vulnerability to global warming in an Earth Day visit to the Everglades on Wednesday. Obama devoted his weekly radio address and video message this weekend to climate change. His view is the opposite of Rubio's.

"Climate change can no longer be denied or ignored," Obama said.

He added that sea level rise in particular is threatening the Everglades: "Rising sea levels are putting a national treasure –- and an economic engine for the South Florida tourism industry –- at risk."

Compared to Rubio's forecast of economic doom if climate policies are pursued, Obama said, "Our carbon pollution has fallen by 10% since 2007, even as we’ve grown our economy and seen the longest streak of private-sector job growth on record."

Sea level rise projections for the U.S. through 2100. Image: National Climate Assessment

The Obama administration is pursuing an ambitious agenda — which is bitterly opposed by Republicans — to reduce America's greenhouse gas emissions through the Environmental Protection Agency and others, by bypassing Congress, where lawmakers such as Rubio oppose taking action on global warming.

The U.S. has committed to cutting greenhouse gas emissions by 26% to 28% below 2005 levels by 2025, and secured a climate agreement with China, the world's largest emitter. The agreement would commit China to peaking its emissions by 2030 at the latest, and increasing the share of renewable energy it uses to about 20% by 2030.

It's unclear whether all the U.S. policies to reach climate goals can be implemented before or even shortly after Obama leaves office, considering that the EPA's rules around slashing emissions from coal-fired power plants are under legal assault from several states.