What is credible evidence that we are experiencing man-made global warming?  This is the question broached previously on Uncommon Descent.  Again, I found this CNS article, A Bit of History for Global Warmers: Look at 1930, interesting:

People sweltering from a heat wave in the Mid-Atlantic region of the U.S. might find cold comfort in the fact that the temperatures of the past few days are not the hottest on record. That "honor" belongs to a summer 76 years ago — decades before the controversy over "man-made global warming" began.