The ozone layer protects the crops and fisheries that we all rely on for food. The phase-out of ozone-depleting substances has protected global food security. By protecting the ozone layer, the Montreal protocol continues to contribute to an estimated US$460 billion (not accounting for inflation) in global benefits between 1987 and 2060 due to avoided damages to agriculture and fisheries.
SDG2 aims to ‘nourish the 815 million people who are hungry today and the additional 2 billion people expected to be undernourished by 2050.’ The Montreal Protocol helps to achieve those aims in several ways, but in particular by contributing to SDG Target 2.4 to ‘ensure sustainable food production systems and implement resilient agricultural practices that strengthen capacity for adaptation to climate change, extreme weather, drought, flooding and other disasters.’
There is little doubt that uncontrolled emissions of ozone-depleting substances (ODSs) would have been a major ‘other disaster’ for many food production systems. Without the Montreal Protocol to control ODSs, run-away ozone depletion would have led to very large increases in UV radiation around the world. Uncontrolled increases in UV radiation would have damaged aquatic ecosystems that are the basis of commercial fisheries, a vital source of food around the world. In addition, extreme levels of UV would have disrupted aquatic food webs and damaged the larval stages of commercially important fish species.
Crops are also vulnerable to damage by excessive UV radiation. Different crops and even different varieties of the same crop would have been more or less sensitive to this damage. This includes crops grown in the tropics, where increased UV radiation reduces the growth of some species and changes the growth form or chemical composition of others. As an overall ball-park figure, the Protocol’s Environmental Effects Assessment Panel concluded that an increase in UV radiation equivalent to a 10 per cent reduction in stratospheric ozone reduces the growth of many crops by around 6 per cent. For comparison, models indicate that without the Montreal Protocol to control ozone-depleting substances (ODSs), ozone depletion would have exceeded 50 per cent by the end of this century.
There have been some assessments of the potential socioeconomic impact of reduced food production due to the unprecedented increase in UV radiation caused by such large ozone depletion. For example, The Montreal Protocol and the Green Economy report cites estimates of global economic losses between 1987 and 2060 of US$238 billion from damage to fisheries and US$191 billion from damage to agriculture. Note that these figures are based on values in US$ in 1997.
Many ODSs, such as chlorofluorocarbons, are very potent greenhouse gases, so by phasing out their use the Montreal Protocol has protected climate as well as the ozone layer. The reduction in ODS emissions achieved by the Protocol is already equivalent to around 135 billion tonnes of CO2. Looking to the future, modelling studies suggest that by controlling ODS emissions, the Montreal Protocol will have prevented temperature increases of 4-6°C at the poles and over 2°C in the tropics by 2070. Building on that success, the Kigali Amendment to the Protocol is set to avoid another 0.4°C by controlling high global warming hydrofluorocarbons (HFCs).
The reports of the Intergovernmental Panel on Climate Change (IPCC), although focused on the continuing challenge of CO2 emissions, gives some insight to how such temperature increases due to ODSs would have affected SDG2. For example, IPCC conclude that temperature increases over 2°C would bring a high risk of severe impacts to small-scale low latitude fisheries and a moderate risk to crop yield. The same report concludes that ‘increasing global temperature poses large risks to food security globally and regionally, especially in low latitude areas.’ These climate-related benefits of the Montreal Protocol on SDG2 seem likely to be substantial, although at present they are less well studied than benefits related to avoiding increased UV radiation.
The Montreal Protocol also contributes to SDG2 by stimulating research and technical innovations that contribute to Target 2.4. For example, the Kigali Amendment of the Montreal Protocol is encouraging access to high-energy efficient, ozone-safe cooling systems. Improving access to affordable refrigeration will contribute to SDG2 by reducing food waste, which currently results in the loss of about 30 per cent of food produced every year. The Montreal Protocol has phased out methyl bromide, a potent ODS previously used for pest control during crop production and storage, resulting in new approaches to sustainable crop production, including pest and disease control.
Research stimulated by the Protocol has greatly improved our understanding of how crops respond to the levels of UV radiation that are always present in sunlight. We now understand that these natural levels of UV radiation may benefit crops by protecting them from pest and disease attack, and this understanding is beginning to be applied in crop production around the world.