Climate change is on a precipice of unsustainability and instability that risks abrupt climatic disasters, which overhang the entire planet, e.g., an abrupt crash of the Pine Island Glacier (a 37-mile ice tongue) in West Antarctica, raising sea level one-half inch, which, in turn, could ripple-effect a major destabilization of the entire Western Antarctic Ice Sheet, equivalent to 10-13 feet of sea level rise. (Source: G. Durand, et at, Retreat of Pine Island Glacier Controlled by Marine Ice-Sheet Instability, Nature Climate Change, doi: 10.1038/nclimagte2094, Jan. 12, 2014.) [emphasis mine]
According to Robert Hunziker, if when the Pine Island Glacier in West Antarctica disintegrates, it could destabilize the entire Western Antarctic Ice Sheet. I guess an abrupt half inch rise causes a much stress as a very gradual 13 foot rise.
"A major Antarctic ice mass, the Pine Island Glacier, is melting irreversibly and could add as much as a centimeter to global sea level rise over the next 20 years alone, according to new research published in Nature Climate Change. Calculations show that the Pine Island Glacier's "grounding line" — where land-based ice meets a floating ice shelf that is an extension of the glacier — has retreated roughly 10 kilometers in the past decade. Scientists say that the grounding line is in the process of a 40-kilometer retreat that could push it beyond an important tipping point. Pine Island Glacier is a major contributor to global sea level rise and has been losing massive amounts of ice for decades, accounting for 20 percent of the West Antarctic Ice Sheet's total ice loss. An international research team says that the Pine Island Glacier has been losing 20 billion tons of ice annually for the past two decades and could lose 100 billion tons annually over the next 20 years. The glacier "has started a phase of self-sustained retreat and will irreversibly continue its decline," says Gael Durand, a glaciologist with France's Grenoble Alps University."
It seems pretty clear to me that climate change is real, human caused, and at the tipping point.