After 46 years at the Goddard Institute for Space Studies, one of climate change's most vocal scientists, James E. Hansen, is quitting.
Quitting, yes. But not retiring.
The 72-year-old climate scientist said he is leaving his job so that he pursue the fight in ways he couldn't while working for the Institute.
"As a government employee, you can't testify against the government," he said in an interview with The New York Times.
Despite this restriction, Hansen was known to use vacation time from his NASA job to make appearances at protests that often led to his arrest, something not everyone in Washington appears to have been thrilled about.
"It was becoming clear that there were people in NASA who would be much happier if the 'sideshow' would exit," he wrote the Times in an e-mail.
The decision, Hansen said, was one he felt morally obliged to make.
"If we burn even a substantial fraction of the fossil fuels, we guarantee there's going to be unstoppable change," he said. "We're going to leave a situation for young people and future generations that they may have no way to deal with."
As Hansen explained to the newspaper, he plans to use his new-found freedom to lobby European leaders to impose a tax on oil derived from tar sands, a process that creates more greenhouse emissions than the one used in extracting conventional oil.
Hansen's acheivements over the past half-century include being one of the first to identify how the planet would respond to rising temperatures and how those effects would compound each other in a way that made the sinking of many of the world's cities due to rising sea levels a very real and tangible possibility.
It was Hansen that stood before Congress in 1988 and announced that human-induced global warming had begun.
As climate activist Bill McKibben told The New York Times, "He's done the most important science on the most important question that there ever was."