evidence of positive feedbacks

This column is amazing:

http://climateprogress.org/2009/05/20/mit-doubles-global-warming-projections-2/

I am almost finished reading Fred Pearce's "With Speed and Violence, Why Scientists Fear Tipping Points" which is a superb summation of the pernicious cumulative potential of positive feedbacks. Anyone who reads it will be persuaded that the common predictions are grotesquely overoptimistic.

I saw this map this morning over at survivalacres.com

http://soils.usda.gov/use/worldsoils/mapindex/desert.html

which is scary enough all by itself but here's the thing: From what I can observe personally in New Jersey, and up and down the Eastern Seaboard, this spring it's ever more obvious that the climate here is no longer hospitable to the trees that evolved to inhabit the niche they occupied the past millennia.

Whether in private yards, landscapes around commercial buildings, along roadsides or deep in untended woods, many trees are lifeless standing timber and the rest virtually universally exhibit signs of decline. It is quite difficult to even locate a tree that does have ugly bare branches sticking out above a thinning crown. Most bizarrely, among many of those that have struggled to leaf out, the leaves are not just fewer in number but actually stunted in dimension as well. It's especially notable in the sycamores, who currently have leaves one or two inches wide while they should have great plates 8 or 10 inches across! This shrinking biomass is how the vegetation transitions from being a carbon sink to a carbon source.

Fred Pearce has many examples from the undisputed geological record of the inexorable trend of this process.

Ultimately all these trees will die which will in turn affect all the dependent plants that normally live under their canopy, and all the animals and birds that rely on their shade will perish. The sun will penetrate the soils, depleting and drying them, rains will wash them away diminishing their fertility, wildfires will rage. It remains to be seen how viable they will be for agriculture.

The map begs the question, if the *experts* are so oblivious to this process on the Eastern Seaboard, how much are they ignoring or glossing over the consequences of climate change in areas which they DO identify as at risk?