Google’s Maps app will start directing drivers along routes estimated to generate the lowest carbon emissions based on traffic, slopes and other factors, the company said on Tuesday.

Google, an Alphabet Inc unit, announced that the feature would launch later this year in the United States and eventually reach other countries as part of its commitment to help combat climate change through its services.

Unless users opt out, the default route will be the “eco-friendly” one if comparable options take about the same time, Google said. When alternatives are significantly faster, Google will offer choices and let users compare estimated emissions.

“What we are seeing is for around half of routes, we are able to find an option more eco-friendly with minimal or no time-cost tradeoff,” Russell Dicker, a director of product at Google, told reporters on Monday.

Google said it derives emissions relative estimates by testing across various types of cars and road types, drawing on insights from the U.S. government’s National Renewable Energy Lab (NREL). Road grade data comes from its Street View vehicles as well as satellite and aerial imagery.

The possible effect on emissions from the feature is unclear. But in a study of 20 people at California State University, Long Beach, university researchers last year found participants were more inclined to consider carbon emissions in route selection after testing an app that showed estimates.

Google’s announcement included more climate-focused changes. From June, it will start warning drivers about to travel through low emissions zones where some vehicles are restricted in France, Germany, the Netherlands, the U.K., and Spain.

In the next months, Maps app users will be able to compare car, biking, public transit and other travel options in one place instead of toggling between various sections.