Call them "Tipping Elements"

This Science Daily article seems to unveil a climate change twist on "tipping points."

"Society may be lulled into a false sense of security by smooth projections of global change," the researchers around Timothy Lenton from the British University of East Anglia in Norwich and Hans Joachim Schellnhuber from the Potsdam Institute for Climate Impact Research report. Global change may appear to be a slow and gradual process on human scales. However, in some regions anthropogenic forcing on the climate system could kick start abrupt and potentially irreversible changes. For these sub-systems of the Earth system the researchers introduce the term "tipping element".

Here's the short list from the UK-based team of researchers with their calculated tipping times:

• Melting of Arctic sea-ice (approx 10 years)
• Decay of the Greenland ice sheet (more than 300 years)
• Collapse of the West Antarctic ice sheet (more than 300 years)
• Collapse of the Atlantic thermohaline circulation (approx 100 years)
• Increase in the El Nino Southern Oscillation (approx 100 years)
• Collapse of the Indian summer monsoon (approx 1 year)
• Greening of the Sahara/Sahel and disruption of the West African monsoon (approx 10 years)
• Dieback of the Amazon rainforest (approx 50 years)
• Dieback of the Boreal Forest (approx 50 years)

And this interesting description of their projections for the Greenland ice cap, which I'd been getting the impression lately losing ice at an accelerated rate. Total melt-off will take at least 300 years and a 7-meter contribution to sea level rise:

Warming over the ice sheet accelerates ice loss from outlet glaciers and lowers ice altitude at the periphery, which further increases surface temperature and ablation. The exact tipping point for disintegration of the ice sheet is unknown, since current models cannot capture the observed dynamic deglaciation processes accurately. But in a worst case scenario local warming of more than three degrees Celsius could cause the ice sheet to disappear within 300 years. This would result in a rise of sea level of up to seven meters.