In this panel presentation, speakers present on the Effects of Climate Change on Oceans focusing in particular on Africa in the global context, also in conjunction with the IPCC-AR5 Report at COP 22, Marrakech.
Prof. Dr Hans-Otto Pörtner of Alfred Wegener Institute, Bremerhaven (AWI), Ocean biologist, Climate researcher and Co‐Chair IPCC WGII – globally, there is one overarching trend in response to global warming with fish-stocks and invertebrate diversity being displaced and reduced at low latitudes, especially in Africa. The general trend is that in the low latitudes there is a reduction in the fisheries catch potential in a world that is 2 degrees warmer by mid-century, with the ocean on average being 0.7 degrees warmer – the system is responding very sensitively. On average, the globe will lose biodiversity, productivity and also accordingly, the fish catch.
The Mediterranean observations are reflecting the global situation as well, with there being no increase in the fisheries catch years so far, and the only increase in marine production achieved is by aquaculture, which is now being exposed to the climate drivers as well, and needs to be considered in the future management strategies thereof.
In terms of the unabated global ocean acidification trend, focusing specifically on African system in terms of information obtained from calcifier locations, the sensitivities of both molluscs and cold and warm water corals are being affected by the increase of CO2 levels, and these risks are being exacerbated by warming extremes. Also, Sea level rise beyond 2100 may challenge natural and human systems, affecting habitat, freshwater resources, human society through flooding events, etc. – High ambition mitigation is needed to address a global mean temperature change of between 1.5° to 2° celsius.
Prof. Dr Ulf Riebesell, Head of Biological Oceanography research unit at Geomar Helmholtz Centre for Ocean Research, and Prof. of Marine Biology and Chemistry at Christian Albrechts University in Kiel. In taking an African perspective, he focuses on the Eastern Boundary Upwelling system (EBUS) which is of high economic importance, of which Africa has two, i.e. the Benguela and Canary systems. The oceans are under immense pressure from three main stressors simultaneously, ie. Heating up (Ocean warming) – low to intermediate latitudes affected, Sour (Ocean acidification) – strongest impacts in the high latitudes and Breathless (Deoxygenation) – plays out in regions with already low oxygen at low latitudes, these stressors are playing out worldwide, but they don’t affect ecosystems equally. Where these three stressors meet, it’s called ‘hotspots for ocean change’ (EBUS), being the regions where warming, acidification and deoxygenation play out strongest in combination. We need a better understanding of the impacts of multiple stressors on EBUS!
Ass. Prof. Nayrah Shaltout, (National Institute of Oceanography and Fisheries, Egypt) talks about Ocean currents around Africa, i.e. Agulhas current – East coast, Canary current – West coast, Benguela cold water current from the south, including the Mediterranean and Red Sea gyres and current systems and rapid increases in ocean surface acidity. She also covers the Canary and Equatorial Upwelling systems, which are the most biologically productive systems in the oceans of the world.
Dr Phil Williamson, Natural Environment Research Council (NERC) and UEA (University of East Anglia), speaks on Climate Geoengineering from an ocean perspective – problem or solution to climate change?
Climate change scenarios that limit temperature increase to 2 degree celsius rely on net zero emissions by 2070 and thereafter net ‘negative emissions’. Greenhouse gas emissions (GHG’s) in today’s world consist of natural land and ocean uptake, but the greater portion is released as net addition to the atmosphere, some possible solutions, e.g. Carbon Capture and Storage (CCS) at power stations and removal of existing gases from the atmosphere by various methods, viz; Direct Air Capture (Chemical), Biochar and BECCS (Biology) or Enhanced Ocean Uptake.
In his opinion, our three safest solutions to reducing emissions and warming would be Marine renewable energy, Safeguarding Natural coastal carbon sinks, and using Direct Air Capture for negative emissions.
awi.de/en.html Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Research
geomar.de/en/ Helmholtz Centre for Ocean Research, Kiel
niof.sci.eg/ National Institute of Oceanography and Fisheries
nerc.ac.uk/ Natural Environment Research Council