HOUSTON — Anyone scoring the debate over hydraulic fracturing would notice that critics of the controversial oil and natural gas extraction process have lately put a few points on the board.

In hydraulic fracturing, millions of gallons of water, sand and chemicals are injected into a well at high pressure to create multiple fractures in the rock and free trapped gas or oil.

In April, a paper by scientists at Cornell University argued that shale gas, touted as a cleaner alternative to coal, could actually be a worse contributor to climate change because of methane that leaks into the air during fracturing.

The latter recalled hotly debated scenes from the Oscar-nominated documentary Gasland, which showed homeowners in Colorado and Wyoming igniting tap water they said contained natural gas that seeped into aquifers after hydraulic fracturing.