Read here. This peer-reviewed Gulf of California research uses temperature proxy evidence (sediment core diatoms and silicoflagellate assemblages) that reveals modern global warming not to be very global, nor very robust. Actual, but inconvenient thermometer evidence corroborates both conditions.
Additional temperature proxies, such as tree-rings, also indicated that modern global warming was mild to non-existent. In fact, the weak tree-ring data used by the infamous Climategate scientists is what eventually led to the fraudulent 'hide-the-decline' fiasco, which then resulted in this famous, entertaining and toe-tapping video (new version of video here).
Back to the science....below is Gulf of California data. (click on image to enlarge)
"Barron and Bukry developed high-resolution records of diatoms and silicoflagellate assemblages spanning the past 2000 years from analyses of a sediment core extracted from Guaymas Basin in the Gulf of California. Results indicated that the relative abundance of Azpeitia nodulifera (a tropical diatom whose presence suggests the occurrence of higher sea surface temperatures), was found to be far greater during the Medieval Warm Period than at any other time over the 2000-year period studied, while during the Modern Warm Period its relative abundance was actually lower than the 2000-year mean." [Barron, J.A. and Bukry, D. 2007, Marine Micropaleontology 62: 115-139]