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.

Uncertainty, Science and the Press

I rely on RealClimate to untangle much of the confusion around reports of global warming and climate change. This confusion - as described in this classic case concerning the melting of the Greenland ice cap - is often generated by the biases and ignorance inherent in press coverage.

As my preceding article explained, there is alway uncertainty in forecasting, and there is definitely uncertainty in any attempt to predict the weather - whether it be for the next decade or this afternoon. But misinterpretation of scientific findings introduces even more uncertainty in the minds of citizens, who read or hear conflicting reports and then decide not to trust any of them.

A deep core sample of the ice in Greenland found the "oldest pure DNA ever" and the reports published in Science magazine included some mentions of historic ice cap melting some 125,000 years ago when the sea level was some 6 meters above what it is today. Some press accounts of the Science article interpreted those mentions as meaning that forecasts of the impact of current Greenland meltoff were overblown, exaggerated.

RealClimate provides a more accurate explanation of the original study, which is consistent with the IPCC findings regarding the ice cap. So we're back to considering the possibility that a Greenland meltoff, combined with similar melting of the Antarctic ice cap, the melting of many smaller mountain glaciers around the world and the expansion of the ocean itself due to warming may - MAY - still result in at least a 6 meter rise in sea level.

Europe: New Ice Age Cancelled?

It wasn't too long ago that one of the major fears of the looming ice melt-off in the Arctic was the cut-off of the Gulf Stream's feed of warm water to Europe. A new ice age decending on the continent was something to be considering, if not preparing for. But continued study and computer modelling have apparently put the kobosh to that future. Indeed, as we've been witnessing in Europe, the future seems to be consistent with the overall warming effect. It's been getting hotter and drier for more and more of the year.

Preparing for a cold future has never been high on the political agenda. Perhaps understandably, European leaders have been more preoccupied with responding to the 2003 summer heat wave that killed 15,000 people across France and the need for new dike technology to keep the Netherlands from being inundated by rising seas associated with melting ice caps.

Richard Seager, a senior research scientist at the Lamont-Doherty Earth Observatory of Columbia University in Palisades, N.Y., said thatEuropeans should trust what they feel in the air. “Britain and western Europe have had one heat wave after another so far this century,” Dr. Seager said. “It’s phenomenal. The idea that anyone is worried about a new ice age I find rather odd.”