U.K.-based Caroline Dennett took to social media following her resignation to outline why she had ended her 11-year relationship with the Anglo-Dutch oil firm.

In her resignation email—which was sent to 1,400 employees and contractors at Shell—she said despite warnings from the U.N. and the International Energy Agency that there was no safe level of new oil and gas extraction, Shell was planning to explore and extract “much more.”

“I can no longer work for a company that ignores all the alarms and dismisses the risks of climate change and ecological collapse,” Dennett said. “I want Shell execs and management to look in the mirror and ask themselves if they really believe their vision for more oil and gas extraction secures a safe future for humanity.”

Elaborating in a separate post on LinkedIn, the former Shell contractor said she felt she had “no other choice” but to call the company out.

“Shell’s disregard for climate change risks means they are completely failing on their Goal Zero safety ambition to ‘do no harm,’” Dennett said.

“Shell is fully aware that their continued oil and gas extraction and expansion projects are causing extreme harms, to our climate, environment, nature, and to people. Shell should be using all its capital, technical, and human power to lead this transition, but they have no plan to do this.”

Shell says it has invested billions of dollars in low-carbon energy, and expects its energy transition spend to reach 50% of total spending by 2050.

A spokesperson for the firm told Fortune in an email on Wednesday that the company is determined to deliver on its pledge to be a net-zero company by 2050.

“We have set targets for the short, medium, and long term, and have every intention of hitting them,” the rep said. “We’re already investing billions of dollars in low-carbon energy, although the world will still need oil and gas for decades to come in sectors that can’t be easily decarbonized.”