How quickly should methyl bromide be phased out?

Montreal Protocol, methyl bromide

There had already been controversy about the possible effects of chlorofluorocarbons (CFCs) for a decade when a hole the size of the USA was discovered over Antarctica by British scientists. In spite of the fact that the link between CFCs and damage to the environment or humans had not been proven, the Montreal Protocol was signed in 1987 by 57 (initially 24) countries. This was the first international agreement concerned with ozone layer depletion. 183 countries had ratified it by September 2002. Under it, developed countries have ceased production of a list of ozone depleting chemicals and are phasing out others. Developing countries have longer to phase the chemicals out. They need industrial development and their production and use of ozone depleting substances (ODS) is relatively small.

A $250m adjustment fund was set up in 1990 to help some nations. After new scientific evidence showed in 1992 that speeding up the phasing out would save approximately 1m deaths from skin cancer per year, it was raised to $500m.

CFCs were not the only chemicals of concern. Others include methyl bromide (see below), halons (used in fire extinguishers - also banned), carbon tetrachloride and methyl chloroform. See the table below for details of their phasing out

The framework for ozone agreements was laid down in the Vienna Convention on the Protection of the Ozone Layer in 1985. Since 1987, the Montreal Protocol has been added to in London (1990), Copenhagen (1992), Montreal (1997) and Beijing (1999) as knowledge about the threats to the ozone layer increased.

The Montreal Protocol was also the first international agreement that incorporated the "precautionary principle" - the assumption that any action which might cause environmental change will actually cause damage, until proven otherwise. In the case of CFCs, etc, it was just as well that it was applied, as the scientific evidence of damage has been mounting up.

As well as governments, organizations such as the World Meteorological Organization and the United Nations Environmental Programme were involved. NGOs represented business and science. The Protocol is unusual in that it puts environmental concerns above free trade.

As research into alternatives to CFCs had been underway for some time prior to the Protocol, and some countries already had bans in place, the ratio of benefits to costs of implementation was relatively high. The fact that CFCs were only produced in a few places meant that policing costs were relatively low.

Control Measures of the Montreal Protocol (courtesy of UNDP)

Methyl bromide

The pesticide and agricultural fumigant methyl bromide (BrCH₃), or bromomethane, is used to control insects, weeds, rodents, and pathogens. The USA Environmental Protection Agency (EPA) also uses it against anthrax. It is colorless, odorless, nonflammable gas at room temperature, but is stored as a liquid under pressure. It is an organic halogen. It is manufactured by a reaction of methanol with hydrobromic acid. It has been particularly important to the seed industry as a soil sterilant, where selective herbicides cannot be used.

Methyl bromide can be found in oceans, where it may be formed by algae and kelp. It also results from biomass burning, leaded fuel combustion, and plant and marsh emissions. It is 45 times more destructive to ozone than chlorine, and therefore highly damaging to the ozone layer. It can be dangerous to human health. It can break down naturally.

Methyl bromide is currently being phased out under the Montreal Protocol.

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How quickly should methyl bromide be phased out?

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