Dr. James Hansen has never been shy about standing up for his scientific principles. In 1988, speaking before Congress, Dr. Hansen laid out a blunt truth, “It is time to stop waffling so much and say that the evidence is pretty strong that the greenhouse effect is here.” The statement caused an eruption of controversy, but time has borne out the sad truth of these words. It is also quite typical of a visionary scientist who has become one of the clearest and most vocal advocates against climate change. The proud author of an incredibly detailed body of work, Hansen has written on black carbon, climate change models and the atmosphere, among other topics. He received the Carl-Gustaf Rosby medal and was featured on Time’s list of 100 Most Influential People for 2006.

On April 2, he announced his retirement from National Air and Space Administration’s Goddard Institute after 46 years. He plans to focus his energies on activism, taking the case for better climate protections to court at the state and federal levels.

Dr. Hansen testifies before Congress in 1988.  (NASA)

It is a role he is well-suited to, after years of fighting for action within NASA, even when this clashed with the White House itself. After he and several other employees were pressured to follow President Bush’s “vision” for the agency by a political appointee in NASA’s Office of Public Affairs, Hansen took the battle public and spoke with the New York Times. The resulting Inspector General’s investigation uncovered a pattern of attempts to politically influence the agency’s work, halting efforts to conceal the truth.

In recent years, Hansen has become more vocal and active in his quest for national solutions to climate change. Using his vacation days, he began traveling to rallies across the nation, pushing more progressive state bills, something he plans to continue. It has been a journey that brought him in conflict with the law multiple times. Starting with a coal protest in 2009, he was arrested for the first time along with other protestors. It does not look like this pattern will change any time soon, as he was arrested again in February along with Bill McKibben and others opposed to the Keystone XL Pipeline. As Hansen puts it,

At my age, I am not worried about having an arrest record.

While his departure from NASA leaves the federal government without a renowned and brilliant scientist, Hansen has felt a calling to help the growing movement protesting climate change. When his final papers are done at NASA, he will begin committing his time to this. Given how much Hansen has already accomplished in his spare time, it is exciting for those of us on the frontlines of the climate battle.