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A new treaty to control mercury…could be good for climate too

Laurent Granier's picture

courtesy: UNEP

Early in the morning on Saturday, January 19, 2013, negotiators from around 140 countries completed negotiations for the Mercury Treaty that will be adopted later this year in Japan. It will be known as the Minamata Convention, in deference to the victims of mercury poisoning from industrial pollution that occurred when residents of the Minamata Bay ingested contaminated fish and shellfish in the 1950s.

The Convention that took four years to negotiate under the auspices of the United Nations Environment Programme (UNEP) joins the ranks of a number of treaties that address chemicals and wastes. It is the first treaty to specifically address heavy metals.

Why is the international community concerned about mercury? Mercury is typically released into the environment in metallic, or “elemental”, form, or as an inorganic salt. In elemental form, it easily vaporises and can be transported great distances worldwide.  When deposited in the environment, mercury eventually can be transformed to its organic forms, including Methylmercury, which is highly toxic and readily accumulates and bioconcentrates in animals and humans. Eventually, mercury settles in cold climates and bioconcentrates up the food chains to the point that Indigenous Peoples in the North that rely on traditional foods are exposed to damaging high levels.

One of the reasons heavy metals are difficult to address is that they are mobilised through human activities, but they are also released in the environment through natural processes, for example through volcanic eruptions or in deep-sea vents. Nevertheless, estimates are that at any given time, 90% of the mercury cycling in the environment is linked to human activities – hence the need for action. The recently released UNEP Global Mercury Assessment 2013 outlines major sources of emissions, geographic and temporal trends, and behaviour in the environment. 

Moreover, international action is warranted because of the transboundary dimension of the issue. In the United States for example, it is estimated that half the mercury in fish caught in rivers comes from anthropogenic Continental sources – predominantly from coal burning – whilst the other half represents emissions from Asia. At the same time, by some estimates, approximately 50% of US releases are deposited beyond the country’s border. This is textbook justification for international action.

Fast forward to a cooler world

Richard Hosier's picture

At the C40 Summit in Sao Paolo last week, former President Clinton urged participating cities and the World Bank to make a dramatic reduction in methane and black carbon. He said it would help the earth buy some time on climate change. He has reasons to be worried: In Cancun last year, parties agreed to stabilize average global temperatures at a level not exceeding 2 degree C above pre-industrial levels. This looks difficult as 0.8 degree C warming has already taken place and GHG emissions continue to grow. 

Developed countries collectively reduced greenhouse gas (GHG) emissions by a mere 6.1% from 1990-2008. Compared to the fast track for warming, humanity is on the slow train to reducing carbon dioxide (CO2) emission reductions.

President Clinton’s statement follows two recent reports that point to emerging scientific awareness that a climate change strategy focusing exclusively on carbon dioxide (CO2) is neither the quickest nor the most effective way to achieve long-term climate stabilization. These reports focus on non-CO2 emissions that stay in the atmosphere for a shorter period of time than CO2. As a result, reducing emissions of these non-CO2 gases will result in a slowing of temperature rise over the first half of the 21st century, buying time both to adapt and to transition away from carbon. 

The first report, produced by UNEP and WMO, assesses black carbon and tropospheric ozone. Black carbon—basically soot—is produced by incomplete combustion of carbon fuels, particularly diesel, wood, and coal. It is a dark suspended particle or aerosol, technically not a GHG. It is frequently emitted together with light-colored aerosols (sulfates and organic carbon) which cool the climate. The latest research indicates that, on balance, the warming effect of black carbon overpowers the cooling effect of its companions. It stays in the atmosphere for only a few weeks before falling to earth. Its warming contribution comes from its black color, making it absorb heat while in the air. If it falls onto mountain or polar snow, it accelerates glacial melt.