Extensive CO2 emissions from shallow coastal waters during passage of Hurricane Irene (August 2011) over the Mid-Atlantic Coast of the U.S.A.

Shallow coastal waters serve an important role as long-term carbon (C) sinks because they capture terrestrial C and retain internally produced C in wetlands and sediments. We show that tropical cyclones (TCs) can lead to rapid CO2 efflux from estuaries, driven by physical and biogeochemical perturbation of these coastal C reservoirs, and that the magnitude of TC-driven CO2 emissions may offset C that accumulates over much longer timescales. In August 2011, Hurricane Irene passed over North Carolina's Neuse River Estuary-Pamlico Sound (NRE-PS), which is part of the second largest estuarine system in the U.S., the Albemarle-Pamlico Sound. Irene rapidly changed the NRE-PS system from a small CO2 sink to a large CO2 source. Irene-induced CO2 efflux from the NRE alone was at least four times the annual riverine C input and seven times the annual atmospheric CO2 uptake. The magnitude and duration of ecosystem disturbance from TCs vary with storm intensity and frequency but likely are qualitatively similar across many terrestrial and coastal systems. Consequently, altered TC activity under future climate scenarios may shift the balance between C accumulation in, and release from, coastal C reservoirs.