A number of important characteristics of the global atmospheric circulation and climate changed in a near monotonic fashion over the decade, or less, centred on the late 1960s. These changes were largest or commonest in tropical regions, the Southern Hemisphere and the Atlantic sector of the Northern Hemisphere. Some, such as the decrease in rainfall in the African Sahel, are well known. Others appear to be new, but their combined extent is global, and dynamical linkages between them are evident. The list of affected variables includes patterns of SST; tropical rainfall in the African Sahel and Soudan, the Amazon basin and North East Brazil, pressure and SST in the tropical North Atlantic and the West and Central Pacific; various branches of the southern Hadley circulation and the southern subtropical jet stream; the summer North Atlantic Oscillation; south Greenland temperature and the Southern Hemisphere storm track. These changes are often strongest in June-August; changes are also seen in December-February, but are generally smaller. In Greenland, annual mean temperature seems to be affected strongly, reflecting similar changes in SST throughout the year in the higher latitudes of the North Atlantic. Possible causes for these coordinated changes appear to include a likely reduction in the northward oceanic heat flux associated with the North Atlantic thermohaline circulation in the 1950s to 1970s. This was nearly in phase with a second likely cause affecting the sea surface temperatures, a rapid increase in anthropogenic aerosol emissions during the 1950s and 1960s, particularly over Europe and North America.