Climate actions can advance sustainable development

The post-2015 development agenda is dominated by a set of Sustainable Development Goals (SDGs) which arose from the 2012 Rio+20 UN Conference on Sustainable Development. The agreed 17 goals and 169 targets address diverse and intersecting aspects of human and environmental needs and challenges. Achieving the SDGs by 2030 requires implementing coordinated and concerted strategies and actions that minimize potential trade-offs and conflicts and maximize synergies to contribute to multiple SDGs 1. Measures to mitigate emissions of short-lived climate pollutants (SLCP) are an example of actions that contribute to multiple outcomes relevant to development 2,3. This paper highlights the interlinkages between SLCPs and the SDGs and shows that implementing SLCP emissions reduction measures will contribute to achieving many of the SDGs. 1.0. Mitigating SLCPs SLCPs are agents that contribute to warming but have relatively short lifetimes in the atmosphere-a few days to a few decades-consequently harmful concentrations of SLCPs can be reduced in a matter of weeks to years, resulting in near-term benefits. Many SLCPs are also powerful air pollutants which are significant contributors to premature death and chronic illness globally and harm the environment. The main SLCPs are black carbon, methane, tropospheric ozone, and hydrofluorocarbons (HFCs) (Figure 1).

In 1974, Mario Molina and F. Sherwood Rowland warned that chlorofluorocarbons (CFCs) could destroy the stratospheric ozone layer that protects Earth from harmful ultraviolet radiation. In the decade after, scientists documented the buildup and long lifetime of CFCs in the atmosphere; found the proof that CFCs chemically decomposed in the stratosphere and catalyzed the depletion of ozone; quantified the adverse effects; and motivated the public and policymakers to take action. In 1987, 24 nations plus the European Community signed the Montreal Protocol. Today, 25 years after the Montreal Protocol was agreed, every United Nations state is a party (universal ratification of 196 governments); all parties are in compliance with the stringent controls; 98% of almost 100 ozone-depleting chemicals have been phased out worldwide; and the stratospheric ozone layer is on its way to recovery by 2065. A growing coalition of nations supports using the Montreal Protocol to phase down hydrofluorocarbons, which are ozone safe but potent greenhouse gases. Without rigorous science and international consensus, emissions of CFCs and related ozone-depleting substances (ODSs) could have destroyed up to two-thirds of the ozone layer by 2065, increasing the risk of causing millions of cancer cases and the potential loss of half of global agricultural production. Furthermore, because most ODSs are also greenhouse gases, CFCs and related ODSs could have had the effect of the equivalent of 24-76 gigatons per year of carbon dioxide. This critical review describes the history of the science of stratospheric ozone depletion, summarizes the evolution of control measures and compliance under the Montreal Protocol and national legislation, presents a review of six separate transformations over the last 100 years in refrigeration and air conditioning (A/C) technology, and illustrates government-industry cooperation in continually improving the environmental performance of motor vehicle A/C. Implications: The comforts and conveniences of modern life are largely taken for granted. When purchasing a product, consumers are usually not concerned with how or why it works, often assuming the product is safe to use and safe for the environment. This critical review addresses why such general public acceptance and complacency is not always the best policy. The paper explains how early warnings given by vigilant scientists highlighted the dangers of ODS and calls for action and boycotts by concerned citizens 35 years ago and regulatory actions taken by governments worldwide 25 years ago successfully phased out ODSs and avoided global catastrophe. It also highlights new opportunities for the Montreal Protocol to further protect against climate change. The implication is that scientific vigilance, public policy, and citizen action have protected and can protect Earth for future generations.

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We assess that full global compliance with the Kigali Amendment to the Montreal Protocol will not provide emission reductions consistent with the 1.5 o C target of the Paris Agreement. Following the Montreal Protocol's start-and-strengthen approach to refrigerant management, fast-tracking hydro uorocarbon phase-down under the Kigali Amendment would result in additional reductions vital for achieving the Paris climate goals. This would also increase chances of staying below 1.5 o C additional warming throughout this century. MainHydro uorocarbon (HFC) refrigerants are factory-made chemicals produced for use in refrigeration, air conditioning, insulating foams, re extinguishers, solvents and aerosol propellants. Since their introduction emissions of HFCs have grown rapidly as they are the primary replacement for ozonedepleting substances (ODSs) currently managed under the Montreal Protocol 1,2,3 . HFCs are not ODSs but powerful greenhouse gases (GHGs) and account for about 1.5% of global anthropogenic GHG emissions 2 . Without any controls, HFC emissions are expected to double by 2030 and nearly quadruple by 2050 over the 2015 level 3,4 .