As 20 Democratic candidates arrive in Miami this week for the first round of presidential debates, the region of tide-swollen floods, hurricane-battered communities and toxic-algae infestations is providing a vivid backdrop for an issue that has emerged as a top priority for many voters: climate change.

Recent polls show that the issue is a litmus test for many Democratic voters, and the party’s candidates have responded with more detailed and aggressive proposals than were imagined even four years ago.

Washington Gov. Jay Inslee has made climate change the center of his campaign and released two packages of proposals that include shutting down all coal plants by 2030 and investing $3 trillion in emissions-efficient transportation, infrastructure and housing. Former Texas Rep. Beto O’Rourke has used his climate proposal to bring renewed attention to his faltering campaign.

And Massachusetts Sen. Elizabeth Warren, Vermont Sen. Bernie Sanders, former Vice President Joe Biden, New York Sen. Kirsten Gillibrand and New York Mayor Bill de Blasio have all embraced the Green New Deal, the aspirational attempt to move to a low-carbon economy put forward by Rep. Alexandria Ocasio-Cortez of New York.

For an issue that received fewer than six minutes of total attention in the 2016 debates between Hillary Clinton and Donald Trump, climate change has now become an election-year centerpiece and serves to bring into focus a sharp contrast between Democrats and Trump, who has tweeted that global warming was a “hoax” and perpetrated by the Chinese.

Democratic pollsters say that in surveys and focus groups, climate change often matches healthcare in importance for voters. The Center for American Progress Action Fund’s poll of likely Democratic voters in the first four primary states ranked climate change as the top priority — tied with healthcare.

A poll released Friday for the Florida League of Conservation Voters by Public Policy Polling found that 57 percent of all Florida voters think the environment and climate issues are important and 58 percent support a clean energy economy by 2050. And in April, a CNN poll found that 82 percent of registered voters who identified as Democrats or Democratic-leaning independents listed climate change as “very important.”

“The urgency to defeat this emerging catastrophe is now apparent to people where it was not in years past,’’ Inslee said last week in an interview. He recalled that as a congressman from Washington in 1999, he warned his fellow representatives about “insidious” greenhouse gases overheating the planet.

“Back then, it was an intellectual exercise. A line on a graph,’’ he said. “It is now a visceral punch in the gut when you’ve seen a town of 25,000 burn to the ground, the Midwest facing unprecedented floods, Miami Beach having to spend taxpayer money to raise roads, red tide on the coast, and homes and farms destroyed.”

Slow rising crisis

For Democrats, the focus on energy and climate is not totally new. President Jimmy Carter talked about solar panels in 1976, but it’s taken more than 40 years for the issue to emerge as a moral imperative, spurred in part by a generation of millennial voters with progressive stands on global warming.

Because any path to the White House leads through Florida, state Democrats say that the primary field would be wise to address the issue aggressively with specifics.

U.S. Rep. Kathy Castor, a Tampa Democrat who chairs the newly created House Select Committee on the Climate Crisis, said that unlike other states that developed statewide clean energy goals, Florida “lost a decade” because former Gov. Rick Scott and the Republican-led Legislature never made addressing sea level rise a priority.

“Florida is behind, so this is a perfect opportunity for the presidential candidates to speak to this,’’ Castor said during a call with reporters Friday. “What is their plan? We’re going to be listening very closely.”

State Sen. Jose Javier Rodriquez, a Miami Democrat, said that the candidates need to come prepared to show Floridians “a track record that they have been aggressive in pushing for clean energy, or talking about our climate issues holistically as a human problem.”

While there is no disagreement among Democrats that the next president must address climate change as a priority, the degree to which candidates have detailed their strategies differs greatly.

Nearly all of them say they would rejoin the Paris climate accords, a landmark international agreement designed to accelerate investments needed for a sustainable low carbon future. President Trump has withdrawn from the agreement because, he said, it will have a “draconian” impact on the U.S. economy.

By contrast, the Democrats say they will use climate change to spark investment, innovation and create new jobs for a “green” economy.

Candidates thinking green

Warren proposes a “green manufacturing plan” that would spend $2 trillion over 10 years for environmentally sustainable research, manufacturing and exports, intended to help “achieve the ambitious targets of the Green New Deal.”

O’Rourke, the former Texas congressman, would spend $5 trillion over 10 years on green investments. Inslee, the Washington governor, proposes spending $3 trillion, and Biden has proposed $1.7 trillion in climate spending.

As with any debate, the odds of candidates overproducing promises while coming up short on the details are high. Inslee, Biden, Warren and O’Rourke appear to have the most detailed plans to date.

Biden and Inslee want Congress to pass a law by 2025 to establish some form of price or tax on carbon dioxide pollution, an approach most economists say is the most effective way to fight climate change. But the idea has been unpopular with voters — with ballot initiatives in Inslee’s own state failing twice.

When Barack Obama was president he proposed a carbon tax in 2010 and, even though Democrats controlled both the House and Senate, the idea was scuttled amid Republican claims that it would impose a national energy tax on consumers.

Biden’s plan calls for rolling back Trump’s tax breaks on corporations and using it to finance clean energy and other initiatives over 10 years.

Warren also supports massive investment in clean and renewable energy initiatives, calling for the creation of a National Institutes of Clean Energy.

O’Rourke calls for net zero greenhouse gas emissions by 2050, with a goal of reaching the halfway mark by 2030. He said he wants all federal procurement to reflect the costs of climate change and pollution, and he would pay farmers to plant cover crops to pull more carbon out of the air and sequester carbon.

Former U.S. Rep John Delaney of Maryland also supports passage of a carbon tax, but he would give the money back to taxpayers in the form of a dividend and use another $5 billion in in tax credits to put into negative emissions technology that takes carbon out of the atmosphere. Delaney also calls for a fivefold increase in the Department of Energy research budget.

Warren and O’Rourke favor a moratorium on new federal fossil fuel leases on public lands, even though oil and natural-gas drilling remains the mainstay of the economy in O’Rourke’s home state.

California U.S. Rep. Eric Swalwell proposes hosting a global climate summit to prepare an international plan to invest in “greening the grid” through solar, wind, fusion, alternative fuel cells and storage.

New York Mayor Bill de Blasio touts his record of moving his city fleet to electric cars, putting up electric charging stations, mandating all buildings be energy efficient and divesting $5 billion of its investments from fossil fuels and into renewable energy investments.

Florida state Rep. Anna Eskamani, an Orlando Democrat, said she will be watching where the Democratic candidates get their campaign contributions, noting that major donors such as “investor-owned utilities across the nation and across the state” have resisted progress on clean energy standards and want to impede a president’s “flexibility on the issue.”

Rodriguez, the state senator from Miami, added he doesn’t want to see the debates get “caught up in infrastructure spending and seawalls.” Instead, he hopes candidates take a broader approach and acknowledge that in Florida the issue is already affecting public health, and leading to economic inequalities as wealthier residents move inland and displace others.

“We no longer have a debate on the science,’’ Rodriguez said. “It’s now about what should we do and how quickly.”