It's based on the deviation from the average temperature from 1961-1990. Lots of flaws applyng that over a 22,000 year time series where you have vast differences in data resolution. Especially when you pick and choose your resolutions to prove your point.
Are we contributing? Yes. Not as much as a supervolcano though, and I saw no high temporal resolution pullouts of any of those. You could easily move temps a couple of degrees over 50 years with one, but it would smooth out over a 500 year line. Of course we also are using analogs for all prehistoric dates, since there were no met stations around circa 15000BC. Good enough for +-100 years (probably), but then you can't make direct comparisons to <100 year temperature datasets that were collected with high resolution equipment.
Also, there is absolutely no natural reason that the Earth couldn't get down to <1% global ice over the next 10,000 years, or rebuild ice over the same timeframe. Talking about <100 year climatological changes is simply ridiculous unless you're a conceited human who has only been on the planet a minute or so in geologic timescales.
Also, 97% of "climate scientists" is not actually 97% of climate experts, like planetary climatologists and astrophysicists. I knew lots of people who called themselves "climate scientists" at the old job, including in published papers. Yet they actually were biologists or had degrees in environmental science. They were simply encouraged by bosses and grants to add AGW components to their research. Kind of a circle thing.
Also, yes - nuclear. I find that to be an excellent delineator between people who actually want to do something and the people who drive Priuseses and create giant carbon footprints flying to their eco-vacations.
