This story was originally published by the Guardian and is reproduced here as part of the Climate Desk collaboration.

Amazon has threatened to fire employees for speaking publicly about the company’s role in the climate crisis, tech workers at the retail giant have revealed.

An email shared with the Guardian shows Amazon’s human resources department launched an “investigation” into one employee, Maren Costa, over comments made to the media that called for the company to do more to tackle the climate crisis.

In the email, Costa is told she will not face punishment at this point — but that any future comments unauthorized by Amazon “may result in formal corrective action, to and including termination of your employment with Amazon.”

A group of Amazon employees who banded together to call for stronger climate action by the company said several members have been questioned by legal and HR representatives about their public comments. Some received follow-up emails similar to Costa’s that threaten dismissal for speaking out in the future.

Costa said four employees have been questioned and two have been threatened with termination if they continue speaking up about Amazon’s role in the climate crisis without seeking approval.

Costa, a user experience principal designer, said: “It was scary to be called into a meeting like that, and then to be given a follow-up email saying that if I continued to speak up, I could be fired.

“But I spoke up because I’m terrified by the harm the climate crisis is already causing, and I fear for my children’s future. Any policy that says I can’t talk about something that is a threat to my children — all children — is a problem for me.”

According to Amazon, it started updating its external communications policy for staff in spring last year. It said it was not aimed at any particular group of employees.

A company spokesperson said: “Our policy regarding external communications is not new and, we believe, is similar to other large companies. We recently updated the policy and related approval process to make it easier for employees to participate in external activities such as speeches, media interviews, and use of the company’s logo.

“As with any company policy, employees may receive a notification from our HR team if we learn of an instance where a policy is not being followed.”

Amazon’s threats to Costa and other employees occurred after it announced a “climate pledge” in September. The plan commits Amazon to using 100 percent renewable energy by 2030, before becoming carbon neutral by 2040. To help achieve this, Amazon has ordered 100,000 fully electric delivery vehicles for its fleet.

Jeff Bezos, Amazon’s chief executive, said he was “done being in the middle of the herd” on climate policies at the policy’s unveiling, which took place just a day before 1,500 Amazon employees planned to walk out of work to join a wave of global climate strike rallies inspired by Swedish teenager Greta Thunberg.

Amazon’s shift on climate change represented a victory for its employee group, which is called Amazon Employees for Climate Justice. The group had previously pushed, unsuccessfully, a shareholder resolution to set a climate change plan.

A further 8,000 Amazon employees subsequently signed an open letter to Bezos calling for concrete climate goals, to cancel contracts with oil and gas companies, and to stop donations to politicians who deny the reality of the climate crisis.

Amazon employees said the company updated its policy on staff speaking to the press and on social media in early September, a day after the plan to join the climate walkout was announced. The new policy requires staff members to seek permission from Amazon prior to talking in a public forum while identified as an employee.

Victoria Liang, a software engineer at Amazon, said: “Amazon’s newly updated communications policy is having a chilling effect on workers who have the backbone to speak out and challenge Amazon to do better. This policy is aimed at silencing discussion around publicly available information. It has nothing to do with protecting confidential data, which is covered by a completely different set of policies.”

Bezos, the world’s richest person, has said he understands the concerns of employees and has promised to review Amazon’s political donations. He has rejected, however, calls to sever ties with oil and gas companies.

Amazon Employees for Climate Justice said it will continue to push the company to do more on climate, despite the threat of recriminations for speaking out publicly.

Justin Campbell, a data engineer at Amazon, said: “Amazon’s policy is not going to stop the momentum tech workers have built over the past year at Amazon. The climate crisis is the greatest challenge we face, and the only way we can find solutions is by protecting people’s right to speak freely and disrupting the status quo.”