Climate tipping points have been the subject of much debate and confusion. Now Professor Tim Lenton of the University of East Anglia has published a very good piece, “Tipping points in the Earth System,” giving some intellectual substance to the notion.

Not surprisingly, the tipping point Prof. Lenton worries about most is the disintegration of Greenland’s ice sheet. He told The Guardian:

We know that ice sheets in the last ice age collapsed faster than any current models can capture, so our models are known to be too sluggish.

His paper examines where Greenland’s tipping point is:

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A new website has launched today:

Cleantech COLLECTIVE is a moderated online business community for clean tech investors, entrepreneurs, policymakers and concerned citizens. If that’s you, sign up and start building a personal network with your peers and leading environmental experts…create a profile and promote your business…submit your own content, rate posts and leave comments…get advice you can use from the web’s leading experts on clean technology.

And yes, I am a featured blogger — they are basically reprinting all my ClimateProgress posts — but I’d recommended it even if I weren’t. If you look around you’ll see some very good writers and some very good information. It features experts like Joel Makower and both of the authors of my favorite book on green technology, The Clean Tech Revolution, by Pernick and Wilder.

People interested in the CleanTech business will probably find the greatest use for this new website.

The carbon capture and storage (CCS) discussion has focused on pre-combustion capture of CO2, since it has long been assumed that is easier and cheaper than trying to capture the CO2 post-combustion from the flue gas (exhaust stream). The problem is 1) that approach limits CCS to new coal plants and 2) that requires utilities to build integrated gasification combined cycle (IGCC) plants, which are more expensive to build and more expensive to maintain.

Post-combustion capture would allow CCS to be retrofitted on existing coal plants. If it proves practical and affordable, that would be a major breakthrough in efforts to control greenhouse gas emissions. Last week brought us this announcement:

BP Alternative Energy and Powerspan Corp. today announced their collaborative agreement to develop and commercialize … a post-combustion CO2 capture process for conventional power plants.

More details on this potentially important technology below:

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