Special Climate Envoy John Kerry indicated that the U.S. will support “largely” phasing out fossil fuels amid climate negotiations during a global summit in Dubai.

“The science says we have to reduce the emissions,” Kerry told reporters during a press conference on Wednesday. “We believe that that means if you’re going to reduce the emissions and you’re actually going to hit the target of net-zero by 2050, you have to do some phasing out.” 

“We said very clearly that you [have got to]  have … largely a phase out of fossil fuels in our energy systems by 2050,” he said. 

Kerry’s comments come amid a heated debate at the climate summit about whether countries should call for a “phaseout” or a less intense “phasedown”of fossil fuels, which are the main driver of global warming. 

In his remarks, the former secretary of state also said that technology that captures carbon emissions to prevent them from going into the atmosphere and warming the planet should be focused on the “hardest-to-abate sectors,” including the making of steel, cement, aluminum and concrete. 

Kerry also defended the economics of the energy transition, saying, “We’re convinced that the other side of this transition is an upside for people.”

“Our economy is growing and the jobs of renewable energy are actually growing a lot faster in America than the jobs of fossil fuel,” he said, also pointing to a projection from the International Energy Agency that fossil fuel demand will peak this decade.