A PROPOSED MECHANISTIC MODEL FOR CLIMATE EFFECTS OF LOBE SHIFTS IN THE MISSISSIPPI RIVER DELTA

There is a fairly close correlation between the timing of shifts in location of Mississippi delta lobes and Holocene climate shifts in Europe, with western lobe locations correlating with warm periods and eastern lobe locations correlating with cool periods. Nevertheless, this temporal correlation may be coincidental because it is difficult to see how river flow into the northern Gulf of Mexico can significantly alter the heat flow in Europe, especially since the Mississippi River system flow is only about 0.1% of the Florida Strait flow.

However, altering the direction of the river input can be expected to alter the smaller gyres within the Gulf, which in turn can affect the path of the through-flow from the western Caribbean (the real source of Florida current heat) to the Florida Strait. If so, an eastward river input could decrease the amplitude of the northern meander of the current, thereby speeding the drainage of warm water from the western Caribbean and reducing the heat buildup in that source area. Conversely, a western river input could enhance the amplitude of the northern meander of the Caribbean-Florida Strait current, thereby slowing the drainage and allowing a greater buildup of heat in the source area. If this connection is real, we could postulate a potential climate response to the increasing diversions of Mississippi River water into the Atchafalaya basin.