Do we like James Hansen?
Our score: 8 out of 10. A long record of risking his job and his freedom for the climate, with a couple of contested calls on science and strategy.
Jim Hansen started out as a maths student at the University of Iowa and ended up with all three of his degrees there. His doctoral research used data from Venus, under the space scientist James Van Allen. He remembers being “a very shy student, and very unconfident”, which is a funny start for the bloke who became the face of climate alarm.
He then spent nearly 50 years at NASA's Goddard Institute for Space Studies. In 2013 he stepped down, telling reporters he wanted more time for his campaign to cut carbon emissions and to take a bigger role in lawsuits against governments and in efforts to stop Canadian tar sands development. That's a scientist swapping a comfy post for the barricades.
The barricades were literal. In August 2011 he was among 140 people arrested in the Keystone XL pipeline sit-in outside the White House, and he was released the same day after paying a $100 fine. At the rally beforehand he said: “If the tar sands pipeline is approved, we will be back and we will grow.”
On the harm check, we found nothing from him on LGBTQ+ people, women, migrants or race, so that box is honestly thin rather than clean-sheet confirmed. What we did find is a man fighting fossil fuels. He proposes a carbon fee with the money returned to the public, saying a carbon price “will favor nuclear power” among low-carbon options, and in 2015 he called the Paris talks “a total fraud”. Nuclear and Paris are contested positions, but they are arguments about how to cut emissions, not about hurting people.
His biggest stoush lately is over the science. His 2025 study in the journal Environment argued warming has accelerated, and Kevin Trenberth, Ken Caldeira and Michael Mann pushed back, with Mann saying exaggeration helps polluters. Hansen's reply was blunt: he prefers not to spend time on “scientific illogic”, and said “the real world is the judge”. Where you land depends on whether you read him as the early-warning guy who keeps being proved right, or as someone overreaching on short-term data.
Earlier this year he was back in print, arguing in the Boston Globe that wildfire thinning could be a way to expand logging on public lands, and that it may raise forest carbon emissions. It fits the pattern: a man who keeps taking unpopular positions on behalf of forests and the climate, rather than selling anything.