For those who don't know, James Hansen, one of the world's most famous climate change scientists, is currently touring New Zealand (FaceSpy here). Yesterday I went to see him in Palmerston North. The lecture theatre was packed, with people sitting in the aisles; I'd estimate three hundred people, mostly Massey staff and scientists from the local CRIs.
The topic was "Human-made climate change: A scientific, moral and legal issue". After running us through the evidence for climate change - that it is happening, that its our fault, and that its going to get worse if we don't stop doing what we're doing, Hansen pointed out some of the problems in dealing with it. The key one IMHO is inertia in the climate system, which both hides the fact that there is a crisis, and commits us to more climate change even if we stopped burning fossil fuels today. Because of this inertia, there's every chance that we could push the climate system beyond its tipping points before we realise it.
This is a huge problem. Human civilisation is dependent on a particular climate (which, for example, allows us to grow enough food to feed 6.8 billion people). If we want to protect that climate, then we need to keep atmospheric CO2 levels below 350 parts per million. We're already at 393 ppm (and going up by ~2 ppm a year), so that means we not only need to stop burning fossil fuels and switch to a greener energy system, but we also need to soak up that excess carbon in the atmosphere as well. Hansen thinks this can be done if we plant enough trees, but its a big ask.
As for why, Hansen's reason was simple: he showed us pictures of his grandchildren. He doesn't want to leave them a radically worse world than the one he inherited, one where his generation has burned all the fossil fuels and fucked the climate, and left their generation to suffer the consequences. Its a powerful moral argument. The question is whether coal company executives love their granschildren too.
Naturally, the lecture attracted the obligatory grumpy old denier, whose sole purpose there seemed to be to witness to the environmentalists (seriously, he didn't even ask a question, just made a statement about recognising people's "sincere beliefs", as if this was a fact-free zone where everything was simply a matter of opinion. Religious people are so amusing). Hansen's answer was simple: real sceptics change their minds in response to the evidence. Climate change deniers don't. They are neither good sceptics or good scientists.
Hansen's next talk is in Wellington on Monday evening. After that, he's hitting Dunedin, Gore, Christchurch, and Auckland (again). I recommend going.
