For ice sheets - huge refrigerators that slow down the warming of the planet - the tipping point has probably already been passed, Steffen said. The West Antarctic ice sheet has shrunk over the last decade and the Greenland ice sheet has lost around 200 cubic km (48 cubic miles) a year since the 1990s.
Most climate estimates agree the Amazon rainforest will get drier as the planet warms. Mass tree deaths caused by drought have raised fears it is on the verge of a tipping point, when it will stop absorbing emissions and add to them instead.
Around 1.6 billion tonnes of carbon were lost in 2005 from the rainforest and 2.2 billion tonnes in 2010, which has undone about 10 years of carbon sink activity, Steffen said.
One of the most worrying and unknown thresholds is the Siberian permafrost, which stores frozen carbon in the soil away from the atmosphere.
In other words, with the ice sheets screwed, the rest of the planet goes into a positive feedback temperature loop. The more ice melts, the more carbon goes into the atmosphere and the hotter things get...melting more ice and releasing more carbon. And the earliest that anything might begin to happen on the side of carbon reduction is 2020.
In other words, extreme tornado seasons and summer temps in March are just the beginning. It's like a wobbly wheel on an axle, soon the wobble gets so bad that the wheel falls off.
And we're about to get rolled. Our kids? Resource wars and in serious trouble. Our grandkids? Maybe they'll survive the wars. Dunno.
But we're about to pay the price for dong nothing and letting the climate deniers win. We all will lose as a result.