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By phasing out production and consumption of most ozone-depleting substances (ODSs), the Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) has avoided consequences of increased ultraviolet (UV) radiation and will restore stratospheric ozone to pre-1980 conditions by mid-century, assuming compliance with the phaseout. However, several studies have documented an unexpected increase in emissions and suggested unreported production of trichlorofluoromethane (CFC-11) and potentially other ODSs after 2012 despite production phaseouts under the Montreal Protocol. Furthermore, because most ODSs are powerful greenhouse gases (GHGs), there are significant climate protection benefits in collecting and destroying the substantial quantities of historically allowed production of chemicals under the Montreal Protocol that are contained in existing equipment and products and referred to as ODS “banks”. This technical note presents a framework for considering offsets to ozone depletion, climate forcing, and other environmental impacts arising from occurrences of unexpected emissions and unreported production of Montreal Protocol controlled substances, as recently experienced and likely to be experienced again. We also show how this methodology could be applied to the destruction of banks of controlled ODSs and GHGs or to halon or other production allowed under a Montreal Protocol Essential Use Exemption or Critical Use Exemption. Further, we roughly estimate the magnitude of offset each type of action could provide for ozone depletion, climate, and other environmental impacts that Montreal Protocol Parties agree warrant remedial action.

Fast action to mitigate non-CO2 climate pollutants, such as methane, including through implementing methane intensity requirements (such as via procurement specifications) for domestic and imported oil and gas, can have a significant role in reducing the likelihood of triggering catastrophic climate impacts as countries pursue carbon-neutrality goals. Without robust monitoring, reporting, and verification (MRV) of methane emissions, we will not be able to know the efficacy of methane mitigation policies and programs or whether we are meeting methane mitigation targets. Acting quickly to ensure that new investments in oil and gas infrastructure are built with enhanced MRV systems and methane intensity requirements in mind is essential to limiting risks of stranded assets and aligning with carbon-neutrality goals.

The transition away from the production and consumption of high global warming potential (GWP) hydrofluorocarbons (HFCs) under the 2016 Kigali Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer has prompted air conditioning, refrigeration, and heat pump equipment manufacturers to seek alternative refrigerants with lower direct climate impacts. Additional factors affecting alternative refrigerant choice include safety (i.e., flammability and toxicity), environmental, and thermodynamic constraints. At the same time, manufacturers are incentivized to seek refrigerants with higher energy efficiency, which saves on electricity costs and reduces indirect greenhouse gas emissions from electricity generation. The life cycle climate performance (LCCP) metric is commonly used to assess the combined direct and indirect climate impacts of refrigerant-use equipment. Here, we consider an additional impact on climate performance: the degradation of refrigerant in equipment, i.e., the direct climate impacts of high-GWP byproducts that can form as the result of adding trifluoroiodomethane (CF3I) to refrigerant blends to reduce flammability. Such a production of high-GWP gases could change the acceptability of CF3I-containing refrigerants. Further, it highlights the need to understand refrigerant degradation within equipment in calculations of the environmental acceptability of new cooling technology.

Heating and cooling demand for space conditioning and refrigeration accounts for around a fifth of global final energy consumption. Climate change, urbanization, and economic development have tripled electricity demand for cooling alone since the 1990s, with the majority coming from the use of inefficient cooling equipment, which burdens electricity grids, especially during peak hours. It is imperative to address the energy required to provide cooling. The Kigali Amendment to the Montreal Protocol addresses these needs by setting ambitious global targets to phase down refrigerants with high global warming potential while improving energy efficiency. Integrating energy efficiency and the refrigerant transition will contribute to economic security, well-being, energy access and security, and sustainability among the G20 countries.

Burning trees for energy delivers a one-two punch against climate change mitigation efforts. Harvesting woody biomass reduces the sequestration potential of forest carbon sinks, while the combustion of woody biomass releases large quantities of carbon into the air. Forest regrowth may not offset these emissions for many decades —well beyond the time the world has left to slow warming to avoid catastrophic impacts from climate change. With little time left to achieve a sustainable and inclusive future, burning forests for energy contributes to warming in the near-term and is not a viable climate solution

This article begins with an overview of the scientific background of why harvesting and burning forests for energy is not a viable solution to climate change or related challenges. This background section includes an explanation of key terminology used in the article. The next section presents the European Union (EU)’s Renewable Energy Directive as a case study on the consequences of including bioenergy in renewable energy policies. Following the case study, the article examines bioenergy policies in the United States and China—the world’s two largest greenhouse gas emitters. The article concludes with policy recommendations to focus government action towards reducing reliance on energy from forest biomass. These recommendations are that governments: (1) re-evaluate their bioenergy policies and ensure lifecycle accounting of forest bioenergy’s climate emissions associated with harvesting and burning forest biomass; (2) end incentives for harvesting forests for fuel and invest in forest preservation, low-emission energy, and low energy demand pathways; and (3) advance international consensus on the harms from forest bioenergy, specifically the impact on climate and biodiversity.

Environmentally harmful product dumping (“environmental dumping”) of new and used low-efficiency cooling appliances with obsolete ozone-depleting and greenhouse gas refrigerants in African countries impoverishes communities, hinders economic development, threatens ecological systems, and harms public health. The use of lowefficiency cooling appliances increases energy demand, leading to higher power plant emissions and limiting affordable energy access in African countries. These low-efficiency appliances and products contain ozone-depleting refrigerants with high global-warming potential (GWP) or ozone-safe refrigerants with high GWP. Environmental dumping of these appliances and products makes it more difficult for countries to meet their international climate obligations and for the world to meet the Paris Agreement’s climate change mitigation targets. Ghana faces high levels of environmental dumping, despite a national ban on importing used cooling appliances and established efficiency standards for new air conditioners and refrigerators. Through the Energy Commission’s Office of Renewable Energy, Energy Efficiency, & Climate Change (REEECC), the government of Ghana is partnering with the Institute for Governance & Sustainable Development (IGSD) to stop environmental dumping. This article provides a list of interventions that can be implemented by Ghana, by governments in countries that export to Ghana, and by industry and other stakeholders. Notably, these actions focus on the shared responsibility of exporting countries and manufacturers by calling on exporting countries to update and enhance enforcement of their laws, and on global manufacturers to stop exporting inefficient products with obsolete refrigerants to Ghana and other African countries.

The ongoing and projected impacts from human-induced climate change highlight the need for mitigation approaches to limit warming in both the near term (<2050) and the long term (>2050). We clarify the role of non-CO2 greenhouse gases and aerosols in the context of near-term and long-term climate mitigation, as well as the net effect of decarbonization strategies targeting fossil fuel (FF) phaseout by 2050. Relying on Intergovernmental Panel on Climate Change radiative forcing, we show that the net historical (2019 to 1750) radiative forcing effect of CO2 and non-CO2 climate forcers emitted by FF sources plus the CO2 emitted by land-use changes is comparable to the net from non-CO2 climate forcers emitted by non-FF sources. We find that mitigation measures that target only decarbonization are essential for strong long-term cooling but can result in weak near-term warming (due to unmasking the cooling effect of coemitted aerosols) and lead to temperatures exceeding 2 °C before 2050. In contrast, pairing decarbonization with additional mitigation measures targeting short-lived climate pollutants and N2O, slows the rate of warming a decade or two earlier than decarbonization alone and avoids the 2 °C threshold altogether. These non-CO2 targeted measures when combined with decarbonization can provide net cooling by 2030 and reduce the rate of warming from 2030 to 2050 by about 50%, roughly half of which comes from methane, significantly larger than decarbonization alone over this time frame. Our analysis demonstrates the need for a comprehensive CO2 and targeted non-CO2 mitigation approach to address both the near-term and long-term impacts of climate disruption.

Scientific studies show that fast actions to reduce near-term warming are essential to slowing self-reinforcing climate feedbacks and avoiding irreversible tipping points. Yet cutting CO2 emissions only marginally impacts near-term warming. This study identifies two of the most effective mitigation strategies to limit near-term warming beyond CO2 mitigation, namely reducing short-lived climate pollutants (SLCPs) and promoting targeted nature-based solutions (NbS), and comprehensively reviews the latest scientific progress in these fields. Studies show that quickly reducing SLCP emissions, particularly hydrofluorocarbons (HFCs), methane, and black carbon, from all relevant sectors can avoid up to 0.6 °C of warming by 2050. Additionally, promoting targeted NbS that protect and enhance natural carbon sinks, including in forests, wetlands, grasslands, and agricultural lands, can avoid emissions of 23.8 Gt of CO2e per year in 2030, without jeopardizing food security and biodiversity. Based on the scientific evidence, the paper provided a series of policy recommendations on SLCPs and NbS.

The global phasedown of hydrofluorocarbon (HFC) refrigerants under the Kigali Amendment to the Montreal Protocol will make a crucial contribution to slowing climate change and meeting the goals of the 2015 Paris Agreement. An even faster phasedown could be achieved with a more extensive replacement of high-GWP HFCs with commercially available low-GWP alternatives in refrigeration and air conditioning equipment. Climate emissions also can be reduced by collecting HFCs at the end of the useful life of cooling equipment and either recycling or destroying them. Such strategies could avoid up to 0.5°C of warming by 2100. 

This report is a comprehensive assessment of the climate and development benefits of efficient and climate-friendly cooling.