Beyonce publicized the contest on Instagram, writing, "Click the link in my bio for a chance to win tickets to any JAY and/or my shows for life. #greenprintproject ." She shared a link to the Greenprint Project and declared her commitment to meatless Mondays and eating plant-based breakfasts.

The A-listers have teamed up with the Greenprint Project , a venture created by Beyonce's trainer Marco Borges, which encourages people to reduce their environmental impact by cutting back on animal products. The website focuses on the idea that even small changes can make a large impact.

On January 30, music power couple Beyonce and Jay-Z announced that one lucky fan could win a free concert ticket a year for the next 30 years — or, as Beyonce put it, "for life."

"We want to challenge you, as we challenge ourselves, to move toward plant-based foods," the Carters wrote in the introduction to Borges' book, "The Greenprint: Plant-Based Diet, Best Body, Better World," adding, "We all have a responsibility to stand up for our health and the health of the planet."

Science backs up the project's mission. What people eat directly affects climate change, a study published in Nature found. In order to keep global warming under 2 degrees Celsius, people around the world would need to eat a lot less meat. (Temperatures are already up 1 degree above pre-industrial levels and are on track to go up a disastrous 3 to 5 degrees if no changes are made.)

Greenhouse gas, or GHG, emissions "cannot be sufficiently mitigated without dietary changes towards more plant-based diets," the study says.

In other words, Beyonce is on to something: Changing what you consume could actually be the most important thing you do, researchers found, since "dietary change contributes the most to the reductions in GHG emissions."

Although the Greenprint website encourages contestants to adopt a plant-based diet, the sweepstakes itself seems to be based on the honor system. Your deadline to enter is April 22, and a winner will be chosen at random on May 22.

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