Nearly 1,000 Amazon employees have pledged to walk out in protest of what they say is their company’s inaction on climate change.

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.

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For example, the group wants Amazon to stop donating to politicians and lobbyists who deny climate change. It also wants Amazon to stop awarding contracts to fossil fuel companies. And the group wants the company to test electric vehicles in cities that are most affected by the company’s environmental impact. The group said it was “critical” for Amazon to emit zero emissions by 2030.

“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.”

In a response to the Amazon Employees for Climate Justice, the company told CNN Business that reducing human-made climate change is an “important commitment.” Amazon said it has sustainability teams working on initiatives to reduce its environmental impact.

Earlier this year, it launched Shipment Zero, which aims to produce net zero carbon emissions by 2030 for half of its shipments. The company also maintains that e-commerce and cloud computing inherently emit less carbon than personal shopping trips and on-premises data centers.

“Over the past decade through our sustainable packaging programs, we’ve eliminated more than 244,000 tons of packaging materials and avoided 500 million shipping boxes,” a statement said. It has an 85-person team devoted to improving its packaging.

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Amazon and its employees have butted heads over climate change before. During an investor meeting in May, more than 7,600 employees signed a letter asking the company for a plan to respond to climate change.

CEO Jeff Bezos said at the time that climate change is a concern. “It’s hard to find an issue that is more important than climate change,” he said. “There are a lot of initiatives underway, and we’re not done. We’ll think of more, we’re very inventive.”