A potential interaction between sea-level rise and global warming: implications for coastal stability on the Mississippi River Deltaic Plain

Abstract

A portion of the southeastern United States is currently experiencing the most severe drought on record. Rainfall deficits accumulated since 1998 have led to a twofold increase in mean annual salinity in the study area, a wetland landbridge located in the Lake Pontchartrain Estuary in southeastern Louisiana. Global circulation models have predicted a rise in both the frequency and amplitude of extreme weather if global warming continues. This indicates a threat to the stability of deltaic plains, particularly those with altered hydrologies. Throughout the Mississippi River Deltaic Plain, river control structures have eliminated freshwater inputs. Generally, this should lead to increases in salinity that can become particularly acute during drought events. Such conditions have been shown to play a decisive role in plant community ecology, an important force in deltaic plain stability. Beyond certain thresholds, these conditions can have detrimental effects upon primary production. The accumulation of primary production deficits may lead to increases in the rate of relative sea-level rise. Though the drought is not proven to be the result of global warming, this event shows that coastal ecology is sensitive to drought conditions and any increase will be detrimental to floodplain stability.