Hillary Clinton said gas from shale is the bridge to a cleaner future, though rival Bernie Sanders said embracing fossil fuels was the wrong policy move.

CNN hosted the debate between the former Secretary of State Clinton and Vermont Sen. Sanders in Brooklyn ahead of the state primary. Sanders has called for a ban on hydraulic fracturing, known also as fracking, as part of a push to advance a low-carbon economy. Pressured on the potential loss of jobs, the senator said the consequences of oil and gas weren't the fault of industry workers.

"It is not their fault that fossil fuels are destroying our climate," he said. "But we have got to stand up and say right now, as we would if we were attacked by some military force, we have got to move urgency -- urgently and boldly."

Vermont was the first state to ban fracking. New York has also moved in opposition to the drilling practice.

Fracking involves the injection of high-pressure water, a trace amount of chemicals and solid particles to coax oil and natural gas out of shale bed formations, giving drillers access to reserves previously out of reach. Environmental groups have expressed concern about the potential environmental and health impacts of hydraulic fracturing fluids. More recently, the U.S. Geological Survey has said the disposal of wastewater associated with hydraulic fracturing may be triggering small-scale seismic events.

Both New York and Vermont have potential shale reserves, with New York hosting a portion of the Marcellus gas basin. Clinton, a former New York senator, has unveiled conditions ranging from public support to the disclosure of chemicals used in hydraulic fracturing fluid before she'd support the drilling practice as a U.S. president. Natural gas, she said, should be viewed as a bridge to a low-carbon economy.

"We want to cross that bridge as quickly as possible, because in order to deal with climate change, we have got to move as rapidly as we can," she said.

According to campaign finance watchdog OpenSecrets.org, the oil and gas industry to date has contributed more than $330,000 to Clinton's campaign, compared with $53,700 for Sanders.