The collective known as “Amazon Employees for Climate Justice” posted a letter online Monday declaring that Amazon should lead on the issue because it’s “one of the largest and most powerful companies in the world.”

The walkout is scheduled for September 20, prior to the Global Climate Strike, a week-long international event that encourages employees to walk out from their workplaces to raise awareness.

Amazon employs around 600,000 people globally, so the group is small. However, it’s making big demands.

“Amazon is one of the world’s most innovative companies,” the group said. “We pride ourselves on being a leader. But in the face of the climate crisis, a true leader is one who reaches zero emissions first, not one who slides in at the last possible moment.”