• The burning of fossil fuels is one of the many sources of mercury pollution.

    The burning of fossil fuels is one of the many sources of mercury pollution.

    Photo: Wikimedia Commons

    Full Screen

Will the new global mercury treaty be effective?

The burning of fossil fuels is one of the many sources of mercury pollution.

MIT researcher Noelle Selin assesses the challenges of implementing the first global mercury treaty.

After four years of negotiations, delegates from more than 140 countries met last January to finalize the first global treaty to mitigate and prevent mercury pollution, the Minamata Convention. Now, as delegates reconvene in October to sign the treaty, an MIT researcher analyzes its potential effectiveness.

"This is the first global treaty to tackle this major public health and environmental pollutant," says Noelle Selin, an assistant professor of engineering systems and atmospheric chemistry and a researcher with MIT's Joint Program on the Science and Policy of Global Change. "While the treaty may not be perfect, it's a step in the right direction."

Selin, who participated in the January meeting and plans to attend the October signing, evaluated the impact of the treaty in a study published this week in Environmental Toxicology and Chemistry. Her analysis finds that, once fully implemented, the greatest environmental benefits of the treaty will be from avoided increases in emissions.

The treaty addresses almost all mercury sources worldwide. But the actions required differ depending on the source of emissions, which include chemical and industrial processes such as the burning of fossil fuels, cement production, waste incineration and gold mining. For example, one provision of the treaty requires countries to devise national action plans to help limit and control artisanal and small-scale gold mining, one of the largest sources of mercury pollution at about 37 percent of emissions. Selin's assessment will help policymakers focus their attention on where they can make the most impact in reducing this harmful pollutant.

Selin calculates that once the treaty is fully implemented emissions will decrease slightly or stay at about today's levels. Because mercury takes decades to centuries to cycle through the environment, it will take a while before changes come into effect on a global scale. That explains why Selin's projections through 2050 show only a small decrease in environmental mercury levels, about 1-2 percent a year.

"Since mercury remains in the environment long after it is released, any decrease in mercury emissions will be slow to affect global mercury levels. This means that actions, or inactions, today will ultimately influence global levels long into the future," Selin says, stressing the significance of the treaty's progress, however limited.

"Without policy measures, mercury emissions are likely to increase dramatically and preventing these emissions today will benefit the environment in the long term. It's clear that the Minamata Convention will help countries prevent future emissions," Selin says. "But we shouldn't expect an immediate change in mercury pollution levels."

Selin also notes that because the immediate drops in mercury levels over the next few decades are expected to be minor, "such a small decrease is less than we can confidently quantify using existing methods."

The treaty, however, does include provisions to enhance monitoring capabilities. Selin makes several suggestions in her analysis of how to best make these enhancements. For example, she encourages different measurement techniques for organic and inorganic forms of mercury since they behave in unique ways in the global environment. In addition, because much of the benefit of the treaty will involve avoided emissions, comparison between models that project future emissions will be critical.

"There are major gaps in researchers' ability to measure mercury pollution," Selin says. "The Minamata Convention works to address these gaps. I look forward to seeing increased monitoring and research as the treaty is implemented around the globe. It's a strong step, but must be just the first of many."

Topics: Climate, Climate change, Environment, Joint Program on the Science and Policy of Global Change, Mercury, Policy


Hi Alli - Thank you for presenting Noelle Selin's contribution to the Minamata Mercury Treaty. It is extraordinary how a first-world economy such as Australia has adopted a blindfold and ignore mentality to mercury leakage into the natural environment. This includes all levels of government as well as the lighting, dental and chemical industries totally avoiding the M word in their legislation, codes of practice and environmental policies.

Tonnes of mercury are being released every year - and NO ONE in the broader community knows. The lack of data on mercury capture (or release) from local, State and federal governments is the first indicator of widespread ignorance. No facts means no issue means no action. Based on European metrics, the 23 million people of Australia release over 3 tonnes of dental mercury each year. Yet this information is not collected or made known.

The Minamata Convention on Mercury Treaty, first ratified by the USA - and now open for 140 other countries to follow is a once-in-a-generation opportunity to cap mercury leakage, make the wider community aware of the issue and change behaviours. This heavy metal is nasty stuff, very nasty. To quote the EU Environment Agency "High doses can be fatal to humans, but even relatively low doses can seriously affect the nervous system and have been linked with possible harmful effects on the cardiovascular, immune and reproductive systems. Methylmercury readily passes through both the placenta and the blood-brain barrier, so exposure of women of child-bearing age and of children is of greatest concern." We owe it to our children's grandchildren to raise awareness and take action to capture mercury before it is released to the natural environment.

Back to the top