The finches on the Galapagos Islands have been observed closely over a long period, and seen to change from year to year in response to climate (and therefore food supply) variations: http://en.wikipedia.org/wiki/Peter_and_Rosemary_Grant .
I think you're seriously overestimating the time needed for ecosystems to adapt, and for lineages of organisms to change significantly.
For each of your examples which show successful adaption, I believe that there are others that show that species have been dying out because they cannot adapt or evolve because of the rapid changes occurring in the ecosystem or because the niche to which they adapted is no longer there.
I would prefer not to see humanity bet the ranch on the ability of the global ecosystem to adapt rapidly when there is scant evidence that such an adaption will happen at all, much less, happen quickly and painlessly. I think we need to gather more data and learn more about the way our global ecosystem functions. I thin it is prudent to work hard to minimize the quantities of greenhouse gas dumped into the atmosphere, move to renewable energy sources, and generally try to not perturb the system until we understand it.
In a stable environment a large greedy specialist often does better then a lean thrifty generalist. In a more dynamic environment a lean thrifty generalist does better then a larger greedy specialist.
The problem is our methods of food production: Specialized, concentrated and resource hungry. We might have to become more generalized, distributed and efficient.
[Note: Currently "efficiency" is often mistake to mean "externalizing the cost", "doing less", etc. Here it means "more productive with less resources" and "working smarter not harder"]
Our food lacks any real bio-diversity, it all requires nearly the same conditions to grow. For every joule of food we are currently using more then 10 joule of energy, basically we are turning oil into food. And it's not very mobile.
After 20 years of observing E. Coli in a medium that had lots of citrate, one (of twelve) population became able to digest citrate: http://en.wikipedia.org/wiki/E._coli_long-term_evolution_exp... .
There were only about 400 years between the Medieval Warm Period http://en.wikipedia.org/wiki/Medieval_Warm_Period and the Little Ice Age http://en.wikipedia.org/wiki/Little_Ice_Age , but Europe still has a perfectly good ecosystem.
The finches on the Galapagos Islands have been observed closely over a long period, and seen to change from year to year in response to climate (and therefore food supply) variations: http://en.wikipedia.org/wiki/Peter_and_Rosemary_Grant .
I think you're seriously overestimating the time needed for ecosystems to adapt, and for lineages of organisms to change significantly.