The message Tuesday morning to attendees of a Hawaii sustainability conference was powerful and straightforward: Climate change is real.

Not only is it a reality affecting the environment, but it also will get worse if naysayers don’t get on board with 97 percent of scientists, several major corporations, many lawmakers and a majority of the American public, U.S. Sen. Barbara Boxer warned.

"We do have a path forward, but the longer we wait, the harder and the costlier it will be," the longtime California Democrat said. "We know we have a horrific problem, and we know we’re getting the tools to solve it. All we need is the will."

Boxer, a champion for the environment and the first woman to lead the Senate’s Environment and Public Works Committee, delivered a keynote speech at the University of Hawaii’s "Ascent: Developing a New Social Contract for Public Investment in a Green Future" conference.

She spent much of her time calling attention to climate change "deniers," who she said stand in the way of creating a better future for the country and, ultimately, the world.

The University of Hawaii Sea Grant College Program worked with Hawaii’s U.S. Sen. Brian Schatz to convene the all-day conference that focused on ways to create a sustainable future in the isles and abroad.

The event culminated with a free lecture Tuesday evening delivered by former Vice President Al Gore.

"By claiming climate change doesn’t exist, deniers not only try to refute what scientists have been warning us about for years, they’re also going against the will of the American people," Boxer said. "According to a USA Today poll, an overwhelming majority of the American public recognizes that climate change is real, it’s happening now, and there is strong support to address this growing threat regardless of party affiliation."

Boxer praised Hawaii — calling it ground zero — for its early work on addressing climate change issues, including the state’s 1998 climate action plan, its requirement that new single-family homes have solar water heaters, and its nation-leading goal to have 70 percent of its energy generated from renewable sources by 2030.

"I really do want to congratulate you," she told the audience. "You have a lot of work to do — we all do — but it’s good to take a minute just to reflect on how far you have come and to build upon that progress. You love this state, this state is spectacular, it’s special, and we have to make sure it survives."

Schatz and Boxer serve together on the Senate Climate Action Task Force, which she formed earlier this year with Sen. Sheldon Whitehouse, D-R.I. Last month, the senators recruited more than 30 of their colleagues to take turns talking through the night on the Senate floor about climate change.

In introducing Boxer, Schatz credited her with co-authoring legislation that makes environmental and fiscal sense, such as a bill to tax the carbon content of fuels and return 60 percent of the profits to consumers.

"When something is doing such great harm, you’ve got to put a price on it; it’s just as easy as that," Boxer told the audience, later saying that "a healthy environment and a healthy economy go hand in hand."

Boxer compared climate change deniers to tobacco company supporters who, even in the 1990s, swore off scientific evidence showing that cigarettes were highly addictive and posed health concerns.

"But here’s the thing," she said. "The American people and elected officials eventually got on board … and agreed that nicotine and smoking cause cancer, and we took steps together — together — to encourage tobacco cessation. … When we agree to move, we can make a tremendous difference."

Boxer told the Honolulu Star-Advertiser after her address that she doesn’t think having to convince deniers of the reality of climate change detracts from the conversation about possible solutions. Instead, she said, it’s "an essential theme" of the discussion.

"Until we get people to put this issue front and center, we’re not going to make progress," Boxer said. "And one way to do it is to show them the connection between the tobacco deniers and the climate deniers.

"Because everybody knows now, looking back, how the health of the people was put at risk by the deniers and I believe once they get that anger at these deniers, we will see the kind of future that we need," she said.