She saw it as a good career for someone who wanted to make a difference, and help protect species and their habitats.

Much of her work, including enforcing environment protection laws, lived up to those early hopes.

"It was a really powerful feeling, as someone in my early 20s, to really feel like I was participating in public life. I really felt like I was doing something that people cared about," she said.

Years later, it had become a workplace that troubled rather than rewarded her.

Ms Schoo was asked to carry out tasks she believed were overtly political or not in the public interest.

She also felt embarrassed to work under the previous government, as it resisted more decisive climate measures needed to protect species from extinction.

"That's where the waters get muddy for public servants, because we have an obligation to give frank and fearless advice," she said.

"We have an obligation to be apolitical and impartial. And when you're working with a government that has politicised the science, it's impossible to perform both duties.

"Because simply stating the science becomes a political action. And there are some really inconvenient scientific truths in the extinction and climate crisis."

She began to feel the public service wasn't the right place for her to work, if she wanted to defend the environment. It kept her up at night.

"I would ask myself, 'why is this happening? What would you need to change?'," she said.

"I do think that I did everything I could while I was working in the public service. But it still wasn't enough for me."

Ms Schoo left the department, unable to reconcile her own values with her public service workplace, and joined an environmental advocacy group.

However, writing in The Canberra Times today, she argues other public servants don't have to reach the same decision about their careers.

She also says they can help the environment by staying in the public service.

"Now, more than ever, we need frank and fearless advice from the public service. We need policy guided by independent and robust science," Ms Schoo writes.

Polly Hemming believed in the public service as an institution. She joined it wanting to make a difference, and having seen the impact of good policy informed by lived experiences, expert opinion and unbiased data.

The public service's code of conduct - including its requirements to give frank, honest, and informed advice, and to act with integrity - was part of the attraction.

"If you are idealistic, or driven by some sense of purpose, those are quite compelling reasons to be there," she said.

"I think they've been completely subverted. But that was my belief when I started."

Ms Hemming grew uneasy while working in the then-Environment and Energy Department as the previous government pursued policies supporting the expansion of fossil fuels despite warnings from climate science.

The tipping point arrived when she was trapped with her children on the NSW South Coast in the Black Summer bushfires. Before, her understanding of climate change had been something more abstract and removed.

"Having the red sky and the water bombers overhead, and just the wide-eyed fear of my kids and my nieces, really made it all so incredibly real," Ms Hemming said.

"I don't know how much more real it has to get, to be honest, for us to actually start taking it seriously as a policy issue as opposed to paying lip service to it."

Returning to her work while Canberra was blanketed in suffocating smoke, and seeing the business-as-usual of the then-government's climate policy, felt crushing afterwards.

"To me, working inside that system became intolerable and untenable," she said.

"Being under the broader auspices of government inaction to me felt ... I felt complicit, I suppose."

READ MORE:

She left the public service, and now works for The Australia Institute where she monitors whether carbon markets are reducing emissions, and investigates greenwashing efforts by companies and governments.

"Ultimately, the irony is that I feel like I'm doing more of a public service outside of the public service, especially when it comes to climate change."

Ms Hemming still believes in the public service as an institution, but says it has become politicised, too reliant on consultants, and needs to return to the values summarised in its code of conduct.

"It should be what it says on paper. It should serve the public. It's all there, nothing needs to change, it just needs to return to what it was for," she said.

Whistleblowers also needed to be supported in speaking out about wrongdoing, she said.

A spokesperson at the newly-formed Department of Climate Change, Energy, the Environment and Water said recent staff survey results showed high levels of job satisfaction and pride among employees.

"Public servants are bound by the APS Code of Conduct and Values, and any integrity related issues are taken seriously by the department," the spokesperson said.

Soon after becoming environment minister after Labor's election victory, Tanya Plibersek promised a new era for public servants working in the portfolio.

In a letter to staff, she signalled she would work closely and co-operatively with her department.

"But I would also like something more from you. I welcome constructive criticism. I welcome creativity. Challenge me. Give me bad news directly. But once a decision is made, I want you all in. Our work is too important to be pursued half-heartedly," she wrote.

It was a sign of a shift in relations between government and the public service under Labor, after years of job cuts and competition with consultants to deliver advice under the Coalition government.

Both Ms Schoo and Ms Hemming see positive signs in the new government's message for public servants - but both acknowledge its true level of commitment remains to be seen.

Ms Schoo says her role as an environmental investigator at the Australian Conservation Foundation, where she exposes environmental harm and maladministration, frequently shows her the important work of public servants.

"I ask the question, how did this bad thing happen? And because of good public servants, who are taking notes, appropriately keeping records, responding to FOIs adequately, I'm able to answer that question. And my colleagues in campaigns are able to campaign for something better," she said.

"We're all a part of one big ecosystem."

Ms Schoo said the public service now needed people with ambition, who cared and had good ideas, flocking to the environmental policy area.

"We have a new government that's willing to do new things. And we need a public service with the capacity to deliver.

"And those who've been sitting on good ideas for a decade to start thinking about them," she said.

"There's plenty of folks still in government who care and have been waiting for their moment."

Ms Schoo said public servants who couldn't square their views with the government's environment policy should leave, as she did.

But those who remain could help the environment simply by doing their jobs as public servants well - by keeping notes, making records, giving frank and fearless advice, and responding adequately to freedom of information requests.

"I would urge people right now with this government in the public service to just do their jobs," she said.

"Be the public servant that you imagined you would be when you applied for your first gig. Because now's the time."