More than 340 Amazon employees are protesting the company's external communications policy.

The employees signed onto a Medium post published Sunday by advocacy group Amazon Employees for Climate Justice. It includes signatures and quotes from Amazon employees, all of whom are named, across several divisions of the company.

By participating in the post, the employees are all defying Amazon's external communications policy, which forbids employees from speaking about the company's business without approval from management.

"Amazon participates in the global economy, where it has a substantial impact on many issues," Michael Sokolov, a principal engineer at Amazon, said in the post. "Expecting its employees to maintain silence on these issues, and Amazon's impact on them, is really a reprehensible overreach, and I am proud to take this opportunity to demonstrate my unwillingness to comply."

The protest was intended to show support for two Amazon employees who the company threatened to terminate for publicly criticizing its climate policies. Maren Costa, a user experience designer, and Jamie Kowalski, a software development engineer, were warned that doing so was in violation of Amazon's external communications policy.

Earlier this month, Costa and Emily Cunningham, another user experience designer, appeared in a video from Sen. Bernie Sanders, which took a swipe at CEO Jeff Bezos' stance on the climate.

The group also posted a video to Twitter on Tuesday that features Amazon employees saying they "won't be silenced" as a result of the company's external communications policy.

Tweet with video

Amazon said it encourages employees to engage with teams inside the company on issues like sustainability. Employees can also voice their opinions by submitting questions at Amazon's all-hands meetings or joining internal interest groups, as well as attending lunches and office hours held by Amazon executives, in which discussions are confidential, the company said.

"While all employees are welcome to engage constructively with any of the many teams inside Amazon that work on sustainability and other topics, we do enforce our external communications policy and will not allow employees to publicly disparage or misrepresent the company or the hard work of their colleagues who are developing solutions to these hard problems," Amazon spokesperson Jaci Anderson told CNBC in a statement.

Anderson added that "of course" Amazon is passionate about the issue of climate change.

Scott Ogle, a queue management analyst at Amazon, wrote in the post that the company's "role in the climate crisis is staggering and alarming." Ogle added that Amazon's public stance on the climate "does not add up" with its cloud-computing division, Amazon Web Services, or AWS, working with the oil and gas industries.

The employees aren't just protesting Amazon's stance on climate issues. Software development engineer Max Eliaser said Amazon should shut down Ring, the smart doorbell company it acquired in February 2018. Ring has faced pushback over the past year for its partnerships with law enforcement agencies and privacy concerns. Earlier this month, Ring acknowledged it fired four employees for abusing their access to customers' video feeds.

"The deployment of connected home security cameras that allow footage to be queried centrally are simply not compatible with a free society," Eliaser said in the post. "The privacy issues are not fixable with regulation and there is no balance that can be struck. Ring should be shut down immediately and not brought back."

Employees also called out AWS doing business with U.S. Immigration and Customs Enforcement, which has been routinely criticized for mistreatment of asylum-seekers and refugees. Others criticized the "brutal labor conditions" in Amazon's warehouses. It's an issue that has been highlighted repeatedly, including in a recent Reveal investigation, which found that serious injuries are much higher at Amazon facilities compared with national averages.

Amazon employees have increasingly pressured the company to address its environmental impact. At Amazon's annual shareholders meeting in May, thousands of employees submitted a proposal asking Bezos to develop a comprehensive climate change plan and reduce its carbon footprint, though it was ultimately rejected. The proposal was based on an employee letter published in April that accused Amazon of donating to climate-delaying legislators and urged the company to transition away from fossil fuels.

The employee group said in a release that Amazon's response to their demands has been "mixed." In September, Bezos announced that Amazon aims to rely on renewable energy entirely by 2030 and have net zero carbon emissions by 2040. The plans were largely viewed as a response to employees' demands.

The day after Bezos' announcement, more than 1,000 employees walked out as part of the Global Climate Strike and to protest Amazon's climate policies.

The employee group claims Amazon changed its external communications policy when it learned employees were planning to stage the walkout. However, Anderson, the Amazon spokesperson, previously told CNBC that the company's policy isn't new and that it was revised to make it easier for employees to submit requests to speak publicly.

Amazon isn't the only tech giant to face employee unrest. Google has seen internal tensions grow over the past several years, as employees have protested issues like the company's government partnerships and its handling of sexual misconduct allegations, among other things.

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