Even after Hurricane Sandy and other extreme weather, New Jersey is not doing nearly enough to sharply reduce greenhouse gas emissions to prevent future storm damage, according to clean energy advocates and environmentalists.

With a new report suggesting the effects of global warming are already apparent, they argued that it is time for the Legislature to take the lead in devising strategies to cope with those changes, which a law passed seven years ago directed the state to do.

The Christie administration, they said, is failing to aggressively push efforts to reduce greenhouse gas emissions by not effectively promoting offshore wind farms or encouraging new fossil fuel plants to be built — and by diverting funds earmarked for clean energy projects.

The result? Not only will storms like Hurricane Sandy be more frequent, they will likely be more intense as a result of global warming, which, among other things, is raising the sea level, the Assembly Telecommunications and Utilities Committee was told yesterday.

In a coastal state with a 127-mile long shoreline, those storms are likely to cause enormous economic damage if policymakers fail to act, virtually all of those who spoke before the panel agreed.

“What climate change is doing is making it easier for weaker storms [than Hurricane Sandy] to cause that kind of damage from flooding,’’ said Anthony Broccoli, professor of atmosphere science in the Department of Environmental Science at Rutgers University and a codirector of the Rutgers Climate Institute. He attributed the problem to rising sea levels, among other factors.

Broccoli did not offer any policy prescriptions, but offered plenty of details about how climate change is affecting New Jersey. “We already are experiencing climate change,’’ Broccoli said, adding there is high confidence among scientists that flooding will become more frequent in the state.

The hearing, which Christie administration officials declined to attend, comes at a time when scientists are declaring with ever more certainty that global climate change is real. Recently, an international intergovernmental panel on climate change noted with 95 percent certainty that humans are causing it. The past three decades have been the hottest on record since 1850, the panel noted.

The failure of Christie administration officials to show up at the hearing led several speakers to say it demonstrates its failure to take climate change seriously.

“The administration’s absence speaks volumes,’’ said Doug O’Malley, interim director of Environment New Jersey. He noted that Atlantic County has been hit by severe storms resulting in federal weather-related disaster declarations nine times in the past six years. “If we do stick our heads in the sand, we’re going to see much more economic damage, he said.’’

Jeff Tittel, director of the New Jersey Sierra Club, agreed, arguing the Legislature needs to come up with a plan to move forward on global warming. One relatively easy step that the state could take is to upgrade building codes to reduce energy usage, he said.

Other signs of global climate change also have surfaced in New Jersey. Nine of the 10 warmest years on record in the state have been recorded since 1998, Broccoli noted.

While the evidence of climate change is mounting, environmentalists and clean energy advocates argued that the state, once a leader in recognizing the dangers of global warming, is failing to follow up on its commitments to deal with the issue.

In 2007, with bipartisan support, a law aimed at reducing greenhouse gas emissions by 80 percent by 2050 was approved, but key elements of the plan to achieve that goal have been discarded or are yet to be implemented. Those policies included participating in a regional initiative to reduce greenhouse gas emissions from power plants, a newly revamped state Energy Master Plan, and plans to reduce pollution contributing to global warming from cars.

Gov. Chris Christie pulled out of the 10-state effort to reduce power plant emissions, dubbed the Regional Greenhouse Gas Initiative (RGGI), a step repeatedly criticized at the hearing. Many aspects of the state’s Energy Master Plan have yet to implemented. And progress has been slow in reducing greenhouse gas emissions for vehicles, which account for roughly 40 percent of pollution.

It is a prescription for failure, according to some.

“There’s no policy framework and there is no plan that can get us there,’’ commented Lyle Rawlings, a vice president of the Mid-Atlantic Solar Energy Industries Association, and owner of a solar firm long active in New Jersey.

Assemblyman Upendra Chivukula (D-Somerset), the chairman of the committee, agreed, saying more action is needed. “We can shy away from it. We can deny it, but it is real. We want to see how do we move forward and how we address climate change.’’

Others, however, suggested New Jersey continues to be a leader in reducing harmful emissions from power plants. Sara Bluhm, a vice president of the New Jersey Business & Industry Association, noted that all of the power plants in the state are already complying with a new draft federal standard that would limit carbon dioxide emissions — a contributor to global warming.

“We’re doing the right thing,’’ Bluhm said. “We are cutting our emissions.’’