Anthropogenic aerosol depositions of nitrogen and phosphorus reduces the sensitivity of oceanic productivity to warming

Feng Zhou1, Rong Wang1,2, Yves Balkanski2, Laurent Bopp2, Philippe Ciais2

1 Sino-France Institute of Earth Systems Science, Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, P.R. China, Email: [email protected]

2 Laboratoire des Sciences du Climat et de l’Environnement, CEA CNRS UVSQ, 91191 Gif-sur-Yvette, France

Abstract

Satellite data reveal a strong link between contemporary oceanic productivity and climate. Models suggest oceanic productivity is reduced in response to enhanced water stratification induced by warming, but do not include the effect of increasing anthropogenic aerosol depositions of nitrogen and phosphorus (AAD). We model the response of oceanic productivity and chlorophyll to AAD, supported by in situ nutrient and chlorophyll measurements. As a result, AAD reduces the sensitivity of oceanic productivity to sea-surface temperature from -15.2±1.8 to -13.3±1.6 Pg C y-1°C-1 in the stratified ocean during 1948-2007. The reduction over the North Atlantic, North Pacific and Indian oceans reaches 40, 24 and 25%, respectively. We hypothesize that future reduction of aerosol emissions in response to higher air-quality standards will accelerate the decline of oceanic productivity per unit warming.