The only skeptic, I'm aware, to have a decent criticisms of the temperature rise (as exaggerated rather than claiming there's no overall rise) comes from Ross McKitrick and Stephen McIntyre, of which many issues have been addressed, and some are still up for debate. In other respects, an overall rise is kind of a red herring: urban temperature rise killed 35000 in Europe in 2003, agricultural zones are changing with exceptional rapidity (wine regions are moving Northward, for example. There are even successful vineyards in Nova Scotia, in Canada, where I come from, now.)
In any case, regardless of global warming, we are making huge changes in the atmospheric composition. Sudden changes in atmospheric composition have been implicated is most of the mass extinction events throughout Earth's history. How can calling the wisdom of these drivers in to question be politically motivated bullshit rather than a genuine concern for sustainability/survival?
http://www.ted.com/talks/peter_ward_on_mass_extinctions.html