A new international report on the effects of climate change on our oceans has served as a serious warning of the need for drastic cuts in CO2 in advance of the COP21 climate talks in Paris in November.

The report, from an international team led by Dr Jean-Peirre Gattuso was released in the July edition of the journal Science, and contrasts the possible futures for ocean ecosystems under different levels of global warming and increased carbon dioxide levels. The results make for alarming reading, predicting that under business as usual, there would be enormous and “effectively irreversible” impacts on ocean habitats and the services they provide by 2100. Even a dramatic cut in emissions to stabilise at 2 degrees of warming would still have severe impacts on many marine ecosystems.

The threat comes not only from the many effects of increased temperatures, but also the immediate effects of higher levels of CO2 in the seas water – higher ocean acidification. Already the decrease in pH levels of the oceans have caused some localised problems such as weaker shell development, depressed metabolic rates and immune responses in some organisms. The ocean absorbs between 30 and 40% of global CO2 emissions and is thus very sensitive to increases. The ocean also absorbs a disproportionate amount of the world’s excess heat, which can cause mass ‘die-offs’ of coral and the destruction of fish breeding and feeding grounds. This in turn poses serious threats to the economic activities of coastal communities, who are already bearing a disproportionate burden of the early effects climate change.

The report should act as a wake-up call in advance of UN climate talks in Paris in November. Little progress has been made to date in including emissions from shipping in any agreement. This represents a significant failure by the International Maritime Organisation in the face of evidence that the growth in shipping threatens to expand its share of emissions to 14% by 2050 unless something is done. Seas At Risk has shown that new ships are already exceeding supposedly efficient new design specifications and that this sector must be included in any deal if we are not merely to replace savings in the energy and agriculture sectors with an increase in emissions in this area.

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