Read here. Map source here. Wet, cold, stormy, miserable, severe weather can be an indicator of a global cooling climate phase. As past empirical evidence well documents, the climate makes swings from warmer to cooler phases, which impacts local and regional weather patterns.
New research (Griessinger et al.) from China confirms that global cooling can cause weather to become wetter and soggier even in semi-arid areas during the hot summer months of the Northern Hemisphere. (click on images to enlarge)
"Based on correlations they exhibited with climate data, tree-ring δ18O measurements of high-elevation Tibetan junipertrees...state that the 800-year annually-resolved oxygen isotope series they developed reflects long-term variations in Asian summer monsoon (ASM) activity in that part of the world. And this history, as they describe it, reveals an "ASM minimum during the Medieval Warm Period (around 1200-1400) and moister conditions during the Little Ice Age (1400-1900),"...This close but inverse correspondence between centennial-scale precipitation anomalies and similar well-known global temperature anomalies (the MWP, LIA and CWP) provides further evidence for the historical reality of the MWP on the Tibetan Plateau,..." [Jussi Grissinger, Achim Bräuning, Gerd Helle, Axel Thomas, Gerhard Schleser 2011: Geophysical Research Letters]