Saturday, May 28, 2016

What Does the Paris Agreement Mean for the Oceans?

The world’s oceans absorb about a quarter of the CO2 and more than 90% of the heat that accumulates in the atmosphere because of human activity, modulating the climate changes we see at the surface.  But they do so at huge cost.

The excess heat and CO2 alters the physics, chemistry and ecology of the oceans, as well as affecting valuable ecosystem services such as fisheries, coastal tourism and coastal protection.

Some impacts are already visible, with reef-building corals and bivalves in mid-latitudes at particularly high risk.  How serious will the impacts of climate change be on the oceans by the end of the century?  The answer to this question strongly depends on the pathway we choose for our greenhouse gas emissions between now and then.

In our new study, published Monday in Nature Climate Change with colleagues from The Oceans 2015 Initiative, we examine what the world’s current level of commitment to tackling climate change is likely to mean for the oceans.

On current pledges alone, our work suggests that present day risks to the ocean and society posed by climate change will more than double by 2100.
Risks to the ocean and society from climate change: present day (black solid line), RCP2.6 (white solid line), 2.7C warming above preindustrial by 2100 (long dashes), same for 3.5C (medium dashes) and RCP8.5C (short dashes). Colours denote very high risk (purple) through to white (undetectable). [Source Credit: Magnan et al., (2016)] Click to Enlarge.
Moving from a 2C scenario (RCP2.6) to 2.7C of warming sees the risk to mangroves increase from undetectable to moderate, as you can see in the graph ... taken from our paper.  The risk to mid-latitude seagrass, bivalve fisheries and aquaculture moves from moderate to high, and the risk to warm water corals rises from high to very high, for example.

Read more at What Does the Paris Agreement Mean for the Oceans?

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