Juneau - An Alaska scientist whose observations of drowned polar bears helped galvanise the global warming movement has retired as part of a settlement with a federal agency he says tried to silence him to protect its political goals.Charles Monnett was briefly suspended in 2011 during an inspector general's investigation into a polar bear research contract he managed while working with what is now known as the US Bureau of Ocean Energy Management, or Boem. An Interior Department employee had alleged Monnett wrongfully released government records and that he and another scientist intentionally omitted or used false data in an article on polar bears.In 2004, during an aerial survey of bowhead whales, Monnett and another researcher saw four dead polar bears floating in the water after a storm, observations that were later detailed in a peer-reviewed article. They said they were reporting, to the best of their knowledge, the first observations of the bears floating dead and presumed drowned while apparently swimming long distances. They said their findings suggested drowning-related deaths of polar bears may increase in the future if the regression of pack ice or periods of longer open water continues. The observations helped make the polar bear a symbol for the climate change movement.‘Chilling message’Following the investigation, Boem ultimately found no evidence of scientific misconduct. But Monnett was reprimanded for improper release of emails that were later used by an appeals court to strike down an Arctic oil and gas exploration plan approved by Boem.Monnett returned to work, but his prior research work focusing on Arctic issues had been reassigned, said Jeff Ruch, executive director of the watchdog group Public Employees for Environmental Responsibility, which helped Monnett with his case and a complaint filed last year.Under the settlement, signed in October but released on Wednesday by Public Employees for Environmental Responsibility, Monnett will receive $100 000 but cannot seek Interior Department work for five years. His retirement was effective on 15 November, at which point the agency agreed to withdraw the letter of reprimand and give Monnett a certificate for his work on the tracking project.The settlement does not constitute any admission of liability, including any admission that federal employees "treated Monnett in a discriminatory or retaliatory manner". Boem spokesperson Connie Gillette said by email she could not comment on personnel matters but said sound science is the foundation of Boem's decision-making, and the agency takes the integrity of it scientists and reliability of their work very seriously.Monnett, in a release, said the agency tried to silence and discredit him "and send a chilling message to other scientists at a key time when permits for oil and gas exploration in the Arctic were being considered. They failed on the first two goals, but I believe that what they did to me did make others afraid to speak up, even internally".He said he could not, in good conscience, "work for an agency that promotes dishonesty, punishes those who actually stand up for scientific integrity, and that cannot tolerate scientific work not pre-shaped to serve its agenda”."I am a very strong believer in transparency in the scientific process," he said in a phone interview. "And I think it's very hard, certainly in the Department of Interior, to pursue science in that fashion."Ruch said Monnett, aged 65, is exploring his future options. He said he left his federal job with a fully vested pension.