Even with the 2016 election still more than a year away, television viewers are already seeing lots of issue ads paid for by 501(c)(4) nonprofit groups running in commercial breaks across the country.

These organizations — which aren’t required to disclose their donors — can participate in political activity so long as that activity accounts for less than half of their overall “social welfare” advocacy. No one knows exactly what that means, but some attorneys have speculated that anything less than 49 percent would be OK legally.

The rules established by the IRS are vague: If the ad doesn’t advocate for a specific candidate and is run outside the election cycle, many believe the IRS will consider it social welfare or issue advertising rather than political activity.

This could be why a lot of groups are running these “issue ads” in the off-year leading up to the presidential election. None of these ads explicitly advocate for a specific candidate; this way, the groups can say they were advertisements for a social welfare cause, not a political cause. So, if dark money groups take advantage of current events, they can leave themselves plenty of space under that 49 percent threshold to advocate politically for specific things during the presidential race.

This summer, groups seized this opportunity by running major ad campaigns around the Iran nuclear agreement. Just this week, issue ads have centered on climate change, with groups on both sides of the issue tying them to the visits from Pope Francis and Chinese President Xi Jinping.

Even before speaking about climate change at both his appearance at the White House and in his address to a joint meeting of Congress, Pope Francis had been very vocal in his belief that humans need to take action to address climate change. NextGen Climate, seizing on the Pope’s visit and perhaps hoping he would speak on the issue, bought $2 million in television, print and Facebook ads to capitalize on his message on climate change. The television ads ran in Iowa, Florida, New Hampshire, Ohio, Arizona, Kentucky and the District of Columbia. The group also ran another series of ads featuring Pope Francis earlier this summer.

NextGen Climate is funded by billionaire Tom Steyer. We’ve previously reported on his political activity here. 

Along with the Pope’s visit, Chinese President Xi Jinping is also visiting the U.S., arriving in Washington to meet with President Obama on Friday. Though they will likely discuss many issues, the two announced a deal in November for both countries to cut down on their carbon emissions.

Over the past two weeks, the National Association of Manufacturers launched this ad opposing stricter ozone emission standards, placing the blame for air pollution exclusively on China.

According to Political Ad Sleuth, the group has placed the ads in D.C., Indiana, New Mexico, Nevada, Ohio and Pennsylvania. On just a single ad buy, the group spent $213,000 purchasing spots on WRC-TV in Washington, D.C., between September 22-28, coinciding with both Pope Francis’ and President Jinping’s visit.

Due to the difference in the FEC definition, which regulates campaign finance groups like PACs, and the IRS definition, which regulates 501(c)(4) nonprofit organizations, these ads could be categorized as social welfare and not political advertising. These groups spent $145 million on advertising in the 2014 midterm, and that number is expected to rise dramatically this year.