The Boston Red Sox on Wednesday are expected to announce that games at Fenway Park will be carbon neutral, a first for Major League Baseball, Axios has learned.

Why it matters: Sports venues like Fenway Park have large carbon footprints, particularly when attendee travel is taken into account.

Details: The team has signed an agreement with climate finance company Aspiration, whereby a portion of proceeds from each ticket sale will be used to purchase carbon offsets.

• The credits not only would cover the direct and indirect impacts of operating Fenway, such as its electricity and water usage, but also the so-called Scope 3 emissions attributed to attendees.
• This is the first deal struck with a Major League Baseball team by Aspiration, which recently agreed to go public at a $2.3 billion valuation. It does, however, have an arena-related deal with the NBA's Los Angeles Clippers.
• Aspiration's investors include actors Robert Downey Jr. and Leonardo DiCaprio, plus a slew of venture capital funds.

"What we've done is taken the tech we've built around measuring climate footprint, and worked with the Red Sox in assessing their emissions," explains Aspiration co-founder and CEO Andrei Cherny. "They have a lot of data, including about how people get to and from games."

• He adds that the per ticket contribution will be shouldered by the Red Sox, rather than by fans as a surcharge.
• A Red Sox spokesperson declined to disclose financial terms.

The bottom line: Expect to see more pro sports clubs follow suit.