A group of the world’s largest oil companies agreed to lower methane emissions from their operations over the coming years. The Oil and Gas Climate Initiative (OGCI) calls for a reduction of methane emissions by a fifth by 2025.

ExxonMobil (NYSE: XOM) and Chevron (NYSE: CVX) recently joined the initiative and said they would limit methane emissions to 0.25 percent of total production, compared to 0.32 percent in 2017.

The OGCI pledge calls for a reduction to 0.20 percent. The OGCI consists of companies accounting for a third of global oil and gas production, and includes BP (NYSE: BP), Royal Dutch Shell (NYSE: RDS.A), Total (NYSE: TOT) and national oil companies in China, Mexico, Brazil and Saudi Arabia.