imber_banner

Theme 2. Sensitivity to Global change

What are the responses of key marine biogeochemical cycles, ecosystems and their interactions, to global change?

Theme 2 is the core of IMBER research. IMBER will investigate how large-scale climate phenomena that alter the physical forcing on seasonal to inter-decadal time scales affect the ocean, and how these oceanic changes can directly alter the temperature and light environment and distribution of carbon and nutrients in the upper ocean. This theme will also consider how changes in pH and carbon system parameters can alter biogeochemical cycles and ecosystems. Further, an other challenge will be to understand how global change affects the controls on biological growth which are exerted by oceanic distributions of macro- and micronutrients, and by the complex roles of iron and other nutrients from continental sources. Fishing pressure is heavily impacting marine food webs – and possibly biogeochemical cycles – although our understanding of potentially complex feedback effects like trophic cascades is rudimentary. IMBER will focus on observation and analysis of current marine biogeochemical cycles and ecosystems that may respond most directly to global change, and also on understanding and predicting how these will respond to the complex forcings associated with global change.

 

Surface seawater pHT values and atmospheric CO2 concentrations. Surface seawater pHT values include 3000 values for 1990-2002 (from the upper 25m across all oceans) calcultaed from measured DIC and alkalinity; typical values for glacial times (blue), pre-industrial times (green) and the present (orange); and predicted future values (red). Future values are based on predicted atmospheric CO2. Atmospheric CO2 values are based on historic measurements and an exponential future increase from simple scenario calculations. Prepared by Arne Körtzinger on the basis of WOCE data (Schlitzer, 2000).

Four key issues have been identified within this theme (for further details, download the SPIS or its summary).

Issue 2.1 Impacts of Climate-Induced Changes Through Physical Forcing and Variability

  • What are the impacts of changes in circulation, ventilation and stratification?
  • What are the direct effects of changes in ocean temperature and light environment?
  • What are the impacts of changes in the frequency and intensity of extreme and episodic events?

Issue 2.2 Effects of Increasing Anthropogenic CO2 and Changing pH on Marine Biogeochemical Cycles, Ecosystems and their Interactions

  • What are the effects of CO2-driven changes in carbonate chemistry?
  • What are the effects of pH-driven changes in nutrient and trace metal speciation?
  • Which organisms and biologial processes are most sensitive to pH and CO2 changes, what are the consequences and to what extent can organisms adapt in reponse to these changes?

Issue 2.3 Effects of Changing Supplies of Macro- and Micronutrients

  • How will changes in macro- and micronutrient inputs to the ocean affect the cycles of these elements?
  • How will changes in the abundance, distribution and stoichiometry of nutrient elements affect food web structure and function?
  • How will increases in hypoxia and anoxia affect food webs and cycles of key macro- and micronutrients?

Issue 2.4 Impacts of Harvesting on End-to-End Food Webs and Biogeochemical Cycles

  • How do harvesting-induced changes in food web structure impact biogeochemical cycles?
  • What are the impacts of harvesting living marine reources on end-to-end food webs?

Last Updated: 2006-07-07 10:27 AM / DHTML Web Menu by OpenCube