3. Long Range Forcast
"We explore the risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a “Hothouse Earth” pathway even as human emissions are reduced.
"Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene. We examine the evidence that such a threshold might exist and where it might be. If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies.
"Collective human action is required to steer the Earth System away from a potential threshold and stabilize it in a habitable interglacial-like state. Such action entails stewardship of the entire Earth System—biosphere, climate, and societies—and could include decarbonization of the global economy, enhancement of biosphere carbon sinks, behavioral changes, technological innovations, new governance arrangements, and transformed social values."
Problem: what is a "serious disruption to ecosystems, society and economies."
We already have this so what is next? Here are a few early risers. How about this one. Scientists are always cautious so they guess low. This is not low. In the fifteen years I have been studying global warming, almost invaribly the estimate of future warming has been overly conservative. In the particular case of Greenland, one of the first measureents was set up ande when the sientist came back a year later his "jaw dropped." Part of the problem is that if the strategy was "best guess" then there would be more overestimates, and given the attitudes of conservatives, a single miss would count as loosing the World Series.