Side event presented on behalf of UN-Oceans at COP 23: Ocean and climate: A resilient ocean for future generations
11 Nov 2017
COP23, Bonn
Increasing greenhouse gases concentration in the atmosphere cause both anthropogenic climate change and anthropogenic ocean acidification. The induced changes are wide ranging and significant. One fourth of the carbon dioxide released into the atmosphere from anthropogenic activities is taken up by the ocean, considerably helping to limit climate change. But this vital service to humanity is not without consequence: when carbon dioxide enters the ocean it changes seawater chemistry, resulting, among other changes, in increased seawater acidity (decreased pH). Studies around the world have revealed that current levels of marine acidity have increased by about 26 per cent since the start of the Industrial Revolution. In addition, most of the heat excess caused by increases in atmospheric greenhouse gases is absorbed by oceans. This led to a 0.7oC increase in global mean sea surface temperature over the last century, with effects on many temperature-dependent biological processes. Among the most visible and destructive is coral bleaching, which is projected to become more frequent and more severe with climate change, threatening the many coral reef ecosystem services on which hundreds of millions coastal dwellers depend.

The most notable effects on the oceans are ocean warming and acidification which cause, inter alia, rising sea levels, changes in ecosystems and biodiversity loss, extreme weather events and the loss of polar ice. These impacts result in loss of life, destruction of property, erosion of coastlines, loss or degradation of coastal habitats, changes in the range, distribution and productivity of marine species including migration of fish stocks, coral bleaching and loss of related ecosystem services, as well as other ecosystem degradation with corresponding socioeconomic impacts. In particular, ocean acidification has emerged as one of the most worrying global threats to marine organisms, ecosystems, services, and resources. However, ocean acidification and ocean warming do not impact marine ecosystems in isolation. They also act as threat multipliers by combining with other anthropogenic impacts, such as land-based pollution, unsustainable fishing practices and coastal development, causing serious cumulative effects, which are diverse, widespread and profound, not only affecting the ecology of the oceans, but also producing significant socioeconomic consequences for all States and exacerbating challenges relating to food security, livelihoods and the development of communities. This in turn undermines the ability of States, in particular least developed countries and small island developing States, to achieve sustainable development and in some cases threatens the viability and survival of communities, in particular in low-lying coastal countries, which are particularly affected by sea-level rise.

These impacts are progressive and expected to worsen, even under low-emission scenarios. There is an urgent need for additional integrated research and assessments to better understand their nature, scale, interactions and future trends. Such information would support the planning and implementation of successful action to tackle these global challenges in regional, national and local contexts.
The proposed side event will present actions that countries are taking, with the support of the UN system, to address climate related multi-stressors on the ocean through improved scientific capacity to understand ocean change, the development of CO2 mitigation strategies and new innovative adaption approaches. Mr. Peter Thomson, UN Special Envoy for the Ocean, will make the closing remarks.
United Nations