Biogeochemical response of the Mediterranean Sea to the transient SRES-A2 climate change scenario - Département de mécanique Accéder directement au contenu
Article Dans Une Revue Biogeosciences Année : 2019

Biogeochemical response of the Mediterranean Sea to the transient SRES-A2 climate change scenario

Résumé

The Mediterranean region is a climate change hotspot. Increasing greenhouse gas emissions are projected to lead to a substantial warming of the Mediterranean Sea as well as major changes in its circulation, but the subsequent effects of such changes on marine biogeochemistry are poorly understood. Here, our aim is to investigate how climate change will affect nutrient concentrations and biological productivity in the Mediterranean Sea. To do so, we perform transient simulations with the coupled high-resolution model NEMOMED8-PISCES using the high-emission IPCC Special Report on Emissions Scenarios (SRES) A2 socioeconomic scenario and corresponding Atlantic, Black Sea, and riverine nutrient inputs. Our results indicate that nitrate is accumulating in the Mediterranean Sea over the 21st century , while phosphorus shows no tendency. These contrasting changes result from an unbalanced nitrogen-to-phosphorus input from riverine discharge and fluxes via the Strait of Gibraltar, which lead to an expansion of phosphorus-limited regions across the Mediterranean. In addition, phytoplankton net primary productivity is reduced by 10 % in the 2090s in comparison to the present state, with reductions of up to 50 % in some regions such as the Aegean Sea as a result of nutrient limitation and vertical stratification. We also perform sensitivity tests to separately study the effects of climate and bio-geochemical input changes on the future state of the Mediter-ranean Sea. Our results show that changes in nutrient supply from the Strait of Gibraltar and from rivers and circulation changes linked to climate change may have antagonistic or synergistic effects on nutrient concentrations and surface primary productivity. In some regions such as the Adriatic Sea, half of the biogeochemical changes simulated during the 21st century are linked with external changes in nutrient input, while the other half are linked to climate change. This study is the first to simulate future transient climate change effects on Mediterranean Sea biogeochemistry but calls for further work to characterize effects from atmospheric deposition and to assess the various sources of uncertainty.

Mots clés

Fichier principal
Vignette du fichier
bg-16-135-2019.pdf (15.86 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-02903069 , version 1 (16-09-2020)

Licence

Paternité

Identifiants

Citer

Camille Richon, Jean-Claude Dutay, Laurent Bopp, Briac Le Vu, James Orr, et al.. Biogeochemical response of the Mediterranean Sea to the transient SRES-A2 climate change scenario. Biogeosciences, 2019, 16 (1), pp.135-165. ⟨10.5194/bg-16-135-2019⟩. ⟨hal-02903069⟩
60 Consultations
14 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More