Exxon, Shell, BP and five other big oil and natural gas companies have announced that they are joining forces to work on ways to cut emissions of methane, a potent greenhouse gas, from natural gas production, according to Wall Street Journal.

Why it matters: There has been growing pressure from government and consumers on the energy industry to find more environmentally-friendly energy sources and production methods, and Exxon's participation leaves Chevron as the only major U.S. oil company not part of the group. These companies have already made significant investments in fossil fuels, which they believe will be an important source of energy stability even as renewables gain popularity, and natural gas is the cleanest compared to oil and coal.