Ocean Newsletter

No.393 December 20, 2016

  • The Need for Fighting against Ocean Change Alexandre K. MAGNAN
    Institute for sustainable development and international relations, IDDRI, France
    Jean-Pierre GATTUSO
    IDDRI/ University Pierre and Marie Curie (UPMC), Centre national de la Recherche Scientifique (CNRS), France
  • The Integration of Container-shipping Operations by Three Japanese Shipping Firms and the Start of a New Alliance Takayuki MORI
    Professor, University of Marketing and Distribution Sciences
    Selected Papers No.22
  • Using GPS Location Data of Ships to Measure and Predict "Mega Tsunamis" Daisuke INAZU
    Project Associate Professor, The University of Tokyo Ocean Alliance
    (Currently Associate Professor, Tokyo University of Marine Science and Technology)

The Need for Fighting against Ocean Change

Japan is intrinsically linked to the ocean, if only because its Exclusive Economic Zone and coastline length are about 4.4 million km2 and 35,000 km, respectively. It is also one of the leading countries in global fisheries and probably the first one for the consumption of ocean-related products (fisheries and aquaculture), with a fish consumption per capita being more than four times the world average. As a result, changes that started to occur in the ocean due to climate change are of concern for this country.

At the global scale, the ocean absorbs about a quarter of the CO2 and more than 90% of the heat that accumulate in the atmosphere because of human activity, thus slowing-down climate change. This however happens at a very high cost, i.e. ocean warming, acidification and deoxygenation, as well as sea level rise. Due to cascading effects, moving from ocean’s physics and chemistry, to ecosystems and to ecosystem services (fisheries, aquaculture, coastal protection, etc.), major consequences are expected for human societies around the world. Some nations, such as Japan, are at the frontline of ocean-related changes. Impacts are already detectable on reef-building corals and mid-latitudes bivalves, for example, and the question raises of the risks of impact to be expected by the end of the century depending on the greenhouse gas emission mitigation trajectory the world will follow. Addressing this issue must be a key concern notably for societies that directly depend on ocean-related resources, and a key incentive to make very ambitious efforts to limit climate change and avoid major disruptions of the ecosystem services provided by the ocean.

Prior to the climate negotiations in Paris in 2015 which end up with the Paris Agreement, most of the countries submitted a plan – the so-called Intended Nationally-Determined Contributions (INDCs, now just NDCs) – for how they intended to curb their national emissions in line with the global goal of holding global average atmospheric temperature rise in 2100 to +2℃ above pre-industrial levels. Japan submitted it quite early, in July 2015, compared to the majority of countries, with a target of reducing its greenhouse gas emissions by 26% by 2030 compared to 2013 (2013 emissions being themselves 25.4% below 2005 emissions). Based on these global scale insights, some organisations such as Climate Action Tracker and Climate Initiative aggregated all INDCs to derive an estimate of the induced increase in global mean temperature by 2100. Their results suggest a range from +2.7℃ to +3.5℃, which would imply an increase in sea surface temperature by 2.0 to 2.6℃ and a decrease in pH by 0.26 to 0.34 units (relative to 1870-1899). Also considering analyses for the +2℃ and +4℃ scenarios schematically represented by some IPCC Representative Concentration Pathways (RCPs 2.6 and 8.5, respectively), we analysed the knock-on effects of these various mitigation-related targets for marine and coastal organisms, ecosystems and services to human societies (Gattuso et al. 2015, Magnan et al. 2016). In other words, we examined what the world’s current level of commitment to tackling climate change is likely to mean for the oceans (Figure 1). We found that moving from a +2℃ scenario to +2.7℃ of warming increases the risks to warm water corals from high to very high, the risks to mid-latitude seagrass, bivalve fisheries and aquaculture from moderate to high, and the risks to mangroves from undetectable to moderate. Overall, we show that the current level of global ambition for tackling climate change multiplies the present-day risk of impact to the oceans by a factor of 2.2 to 2.5 by 2100, compared to factors of 1.4 and 2.7 under the RCP2.6 and RCP8.5 scenarios, respectively. A key conclusion is that current pledges allow significant improvement from the IPCC business-as-usual scenario of more than +4℃ but are insufficient to bring us in line with the “well below +2℃” target of the Paris Agreement.

At this point, the question for Japan and other countries is: what to do now? The scientific and grey literature describes four generic types of options (Billé et al. 2013): (1) Mitigate CO2 emissions to limit the underlying drivers of ocean changes (e.g. emissions reduction, CO2 removing from the ocean, etc.); (2) Protect marine and coastal ecosystems from non-climate/ocean stressors to build or maintain their natural resilience (e.g. protected areas, regulation of natural resources exploitation, reduction in land-based pollution, etc.); (3) Adapt societies (e.g. relocate activities and people, develop more ocean change-compatible economic activities and abandon threatened ones, build coastal defences only in relevant places, etc.); and (4) Repair ecosystems already damaged (e.g. coral farming, mangroves replanting, beach nourishment, etc.). All are useful by themselves, depending on the local-to-national context-specificities, and some synergies can be expected. However, there are serious concerns that these solutions will become fewer and less effective as climate and ocean changes intensify, suggesting that although global mitigation is not a self-sufficient solution, it is the overarching one. This provides further compelling arguments for rapid and ambitious CO2 emission reductions at the international level, which will require countries, and particularly the top emitters, to play a full part in the five-year NDCs revision process established by the Paris Agreement that will start in 2020.

References

Billé R., Kelly R., Biastoch A., Harrould-Kolieb E., Herr D., Joos F., Kroeker K., Laffoley D., Oschlies A., Gattuso J.-P., 2013. Taking action against ocean acidication: a review of management and policy options. Environmental Management 52 (4) : 761-779.
Gattuso J.-P., Magnan A., Billé R., Cheung W.W.L., Howes E.L., Joos F., Allemand D., Bopp L., Cooley S., Eakin M., Hoegh-Guldberg O., Kelly R.P., Pörtner H.-O., Rogers A., Baxter J.M., Lafolley D., Osborn D., Rankovic A., Rochette J., Sumaila U.R., Treyer S., Turley C., 2015. Contrasting Futures for Ocean and Society from Different Anthropogenic CO2 Emissions Scenarios. Science, 349 (6243). DOI: 10.1126/science.aac4722.
Magnan A.K, Colombier M., Billé R., Joos F., Hoegh-Guldberg O., Pörtner H.-O., Waisman H., Spencer T., Gattuso J.-P. 2016. Implications of the Paris agreement for the ocean. Nature Climate Change 16(8): 732-734. DOI: 10.1038/nclimate3038.

Figure 1. 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: Magnan et al. 2016.

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