We are going to see more images like the one on the left, it seems. I picked up the news from a Google feed to this article at mother nature network. Climate scientist James Hansen has retired at the age of 72 from NASA GISS in order to concentrate on activism. The scoop was claimed by the New York Times. Climate Progress quickly picked up on the story.

Hansen first made a splash with an article with six other scientists in 1981. After his testimony to Congress in 1988 he retired from public advocacy and communication for about 15 years, concentrating on the science and his administrative role at NASA GISS, to become publicly active again from about 2003.

NASA’s press release on his retirement emphasises that his research was closely aligned with:

the development of increasingly sophisticated satellite platform measurements, such as the terrestrial radiation budget, ozone and weather-related data, and the need for increasingly sophisticated atmospheric models to assess and evaluate the information content and utility of these measurements.

Also the use of models to make climate change predictions for the future. To some he had the uncanny knack of being a bit ahead of the science. From the NY Times article:

“Jim has a real track record of being right before you can actually prove he’s right with statistics,” said Raymond T. Pierrehumbert, a planetary scientist at the University of Chicago.

Personally I think it’s because he has the ability to recognise what is important in all the information to hand, to make the appropriate connections and draw appropriate inferences. He’s always had an eye on the bigger picture, the main game.

Climate Progress looked back at Hansen’s 1981 predictions in August 2008, as did Skeptical Science in more detail in May 2012. In 1981 Hansen et al suggested that:

anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980s. Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.

All these things are coming to pass or are on the way. On temperature change Skeptical Science displays this remarkable graph of temperature of Hansen’s 1981 temperature projections:

Hansen tells us in his book Storms of My Grandchildren and in his TED talk last year that after his 1988 Congressional testimony he put his head down and did science for 15 years, leaving public advocacy and communication to others. He was actually by nature reticent and uncomfortable in a public role. He changed his mind because he couldn’t bear his grandchildren later saying, “Opa understood what was happening but didn’t make it clear.”

I first met up with him (I came to climate change late) through his article Can we defuse the global warming time bomb?, or more particularly the shortened version published in the Scientific American in 2004. His book admits that he went public to try to prevent the Bush re-election in 2004. From that time on his public role sat very uncomfortably with his official duties. He became subject to controversy and criticism. There is little doubt that his organisation suffered under the Bush regime.

Back in 2006, as in the Stern Review, it was commonly thought appropriate to aim at stabilising atmospheric CO2 at 550 ppm, or 450 ppm at the least. In response to a question put by Bill McKibbin, in December 2007 at the American Physical Union conference, Hansen nominated a target of 350 ppm as necessary for a safe climate, which means beyond zero emissions as we are currently approaching 400 ppm. Many, like Joe Romm at Climate Progress, nevertheless thought:

My Bottom Line: Let’s start working now toward stabilizing below 450 ppm, while climate scientists figure out if in fact we need to ultimately get below 350.

Hansen is saying, no, it’s imperative that we target 350 ppm while scientists figure out whether we need to go further.

Romm stuck to his guns and there was a debate between them. Romm did say that if you are going for 350 ppm, it’s not viable to just adopt an emissions trading scheme. A price on carbon would be pointless and irrelevant:

We need to go straight to the government-led WWII-style effort for the whole planet that is sustained for decades. You need to go for a WW2 style direct action.

Meanwhile in October 2007 David Spratt and Philip Sutton (see the publication the big melt), later incorporated into Climate Code Red had recommended going further, 320 ppm from memory. Hansen says the planet had changed since pre-industrial times, especially wrt to vegetation cover and reflectivity, so 350 ppm remains appropriate as an initial target.

Hansen is totally opposed to the exploitation of Canada’s tar sands, as he made clear in his NYT piece last year Game Over for the Climate:

The concentration of carbon dioxide in the atmosphere has risen from 280 parts per million to 393 p.p.m. over the last 150 years. The tar sands contain enough carbon — 240 gigatons — to add 120 p.p.m. Tar shale, a close cousin of tar sands found mainly in the United States, contains at least an additional 300 gigatons of carbon. If we turn to these dirtiest of fuels, instead of finding ways to phase out our addiction to fossil fuels, there is no hope of keeping carbon concentrations below 500 p.p.m. — a level that would, as earth’s history shows, leave our children a climate system that is out of their control.

In his book and elsewhere he has said that if we exploit all conventional and unconventional sources of fossil carbon we’ll cook the planet to the point of the Venus Syndrome, where the possibility of life is lost forever.

Last year in a Washington Post op ed Hansen told us that climate change is here, and it’s hot. Why we experience more heat extremes is very easily conveyed in the following diagram from a recent Climate Commission report:

That conveys the overall concept. Hansen has a figure that is more accurate:

The link came from Climate Progress where Hansen is quoted thus:

When we plotted the world’s changing temperatures on a bell curve, the extremes of unusually cool and, even more, the extremes of unusually hot are being altered so they are becoming both more common and more severe.

The change is so dramatic that one face of the die must now represent extreme weather to illustrate the greater frequency of extremely hot weather events.

Such events used to be exceedingly rare. Extremely hot temperatures covered about 0.1 percent to 0.2 percent of the globe in the base period of our study, from 1951 to 1980. In the last three decades, while the average temperature has slowly risen, the extremes have soared and now cover about 10 percent of the globe.

This is the world we have changed, and now we have to live in it…

In the TED talk he points out that the increase they found is by a factor of 25 to 50. Nearly 80% of Americans have been hit by extreme weather disaster since 2007 and even Republicans are starting to wise up.

In the past Hansen has not been pleased with Obama’s record on climate change. It’s extremely unlikely that anything has changed.

In a way Hansen has reached sufficient certainty on the major questions relating to climate change to the degree where he finds the case for urgent action is compelling. At 72 he has chosen the spend the rest of his time on the planet pushing for such action. Part of his time will be spent as an advisor to the National Center for Science Education (NCSE). More power to his arm!