In 2015 the countries of the world will hopefully agree on a binding climate treaty in Paris. The outcome should stop climate change, which is currently threatening the wellbeing of the inhabitants of this planet.
What are the threats facing the coastal area and the marine systems? The answer to this question was presented in the Summary for policymakers of the Intergovernmental Panel on Climate Change (IPCC) in 2014.
Coastal systems and low-lying areas
Due to sea level rise projected throughout the 21st century and beyond, coastal systems and low-lying areas will increasingly experience adverse impacts such as submergence, coastal flooding, and coastal erosion (very high confidence).
The population and assets projected to be exposed to coastal risks as well as human pressures on coastal ecosystems will increase significantly in the coming decades due to population growth, economic development, and urbanization (high confidence).
The relative costs of coastal adaptation vary strongly among and within regions and countries for the 21st century. Some low-lying developing countries and small island states are expected to face very high impacts that, in some cases, could have associated damage and adaptation costs of several percentage points of GDP.
Healthy mangroves and sea grass beds will be needed for well-functioning coastal ecology and storm protection in Utila, Honduras, also in the future. Photo copyright (c) 2015 Erkki Siirila.
Due to projected climate change by the mid 21st century and beyond, global marine-species redistribution and marine-biodiversity reduction in sensitive regions will challenge the sustained provision of fisheries productivity and other ecosystem services (high confidence).
Spatial shifts of marine species due to projected warming will cause high-latitude invasions and high local-extinction rates in the tropics and semi-enclosed seas (medium confidence).
Species richness and fisheries catch potential are projected to increase, on average, at mid and high latitudes (high confidence) and decrease at tropical latitudes (medium confidence).
The progressive expansion of oxygen minimum zones and anoxic “dead zones” is projected to further constrain fish habitat.
Open-ocean net primary production is projected to redistribute and, by 2100, fall globally under all scenarios.
Climate change adds to the threats of over-fishing and other nonclimatic stressors, thus complicating marine management regimes (high confidence).
For medium- to high-emission scenarios, ocean acidification poses substantial risks to marine ecosystems, especially polar ecosystems and coral reefs, associated with impacts on the physiology, behavior, and population dynamics of individual species from phytoplankton to animals (medium to high confidence).
Ocean acidification poses substantial risks to the health of reef-building corals. Photo from Utila, Honduras. Copyright (c) 2015 Erkki Siirila.
Highly calcified mollusks, echinoderms, and reef-building corals are more sensitive than crustaceans (high confidence) and fishes (low confidence), with potentially detrimental consequences for fisheries and livelihoods.
Ocean acidification acts together with other global changes (e.g., warming, decreasing oxygen levels) and with local changes (e.g., pollution, eutrophication) (high confidence). Simultaneous drivers, such as warming and ocean acidification, can lead to interactive, complex, and amplified impacts for species and ecosystems.
Source: IPCC, 2014: Summary for policymakers. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1-32.