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Each year, one-third of the total food for human consumption is either lost or wasted even as millions worldwide experience food insecurity. Similarly, over 25 percent of vaccines are wasted each year while millions die from vaccine-preventable illnesses Sustainable cold chain infrastructure can significantly reduce post-harvest food loss and vaccine wastage and deliver social and climate benefits. However, acknowledging the need for cold storage alone does not ensure food security or access to vaccines, and must be supported by policies and resources, including technologies. Cooperation among G20 countries on cold chains can help coordinate the policies and resources necessary to advance food security, public health, and climate change mitigation.

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.

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.

This chapter provides open-access teaching materials for COP 26 — the Glasgow Climate Summit — held in November 2021. It was written as a supplement to the 6th edition of the casebook, International Environmental Law and Policy, but can be used as a stand-alone assignment for any environmental law course. It contains separate sections on Finishing Paris, NDC Commitments, The Glasgow Climate Pact, Working Toward a Just Transition, Sectoral Commitments Outside NDCs, and Non-State Commitments, followed by a Questions and Discussion section.

The Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) can be further strengthened to control ozone-depleting substances and hydrofluorocarbons used as feedstocks to provide additional protection of the stratospheric ozone layer and the climate system while also mitigating plastics pollution. The feedstock exemptions were premised on the assumption that feedstocks presented an insignificant threat to the environment; experience has shown that this is incorrect. Through its adjustment procedures, the Montreal Protocol can narrow the scope of feedstock exemptions to reduce inadvertent and unauthorized emissions while continuing to exempt production of feedstocks for time-limited, essential uses. This upstream approach can be an effective and efficient complement to other efforts to reduce plastic pollution. Existing mechanisms in the Montreal Protocol such as the Assessment Panels and national implementation strategies can guide the choice of environmentally superior substitutes for feedstock-derived plastics. This paper provides a framework for policy makers, industries, and civil society to consider how stronger actions under the Montreal Protocol can complement other chemical and environmental treaties.

The International Energy Agency expects the global stock of room air conditioners (RACs) to triple between today and 2050, with critical implications for energy use and greenhouse gas emissions. Because China produces approximately 70% of the world’s RACs, it is in a unique position to lead a global transition to higher-efficiency RACs with substantially lower environmental impact. To date, however, Chinese policies have targeted relatively modest RAC efficiency increases. We recommend that China target production of RACs that use low global warming potential (GWP) refrigerants and are at least as efficient as the most efficient RACs produced today in China or on the global market. Specifically, we recommend that China set minimum energy performance standards for RACs at China annual performance factor (APF) 5.4 in 2025 and China APF 6.9 in 2030. This leadership would provide a longer-term policy signal to RAC manufacturers in China, enabling them to meet the efficiency targets cost-effectively by providing adequate time for investment planning. We project that full implementation of our recommended policy could result in global electricity consumption savings of 74 petawatt-hours, CO2 reductions of 49 billion metric tons, and bill savings of 6 trillion U.S. dollars (cumulative benefits 2020–2050). The policy is viable in China because of its provision of long-term certainty for manufacturers and their demonstrated ability to produce low-GWP RACs with the required efficiencies. Exploiting the parallel transition away from high-GWP refrigerants under the Kigali Amendment to the Montreal Protocol would provide manufacturing efficiencies and substantial savings opportunities.

Chapter 25 in Health of People, Health of Planet and Our Responsibility: Climate Change, Air Pollution and Health (Al-Delaimy, W. K., Ramanathan, & V., Sorondo, M. S. eds). Springer, Cham. Pages 321-331.

Climate change is becoming an existential threat with warming in excess of 2 °C within the next three decades and 4–6 °C within the next several decades. Warming of such magnitudes will expose as many as 75% of the world’s population to deadly heat stress in addition to disrupting the climate and weather worldwide. Climate change is an urgent problem requiring urgent solutions. This chapter lays out urgent and practical solutions that are ready for implementation now, will deliver benefits in the next few critical decades, and place the world on a path to achieving the long-term targets of the Paris Agreement. The approach consists of four building blocks and three levers to implement ten scalable solutions described in this chapter. These solutions will enable society to decarbonize the global energy system by 2050 through efficiency and renewables, drastically reduce short-lived climate pollutants, and stabilize the warming well below 2 °C both in the near term (before 2050) and in the long term (after 2050). The solutions include an atmospheric carbon extraction lever to remove CO2 from the air. The amount of CO2 that must be removed ranges from negligible (if the emissions of CO2 from the energy system and short-lived climate pollutants have started to decrease by 2020 and carbon neutrality is achieved by 2050) to a staggering one trillion tons (if the carbon lever is not pulled and emissions of climate pollutants continue to increase until 2030).

Chapter 15: Technologies for Super Pollutant Mitigation 

The chapter explore a complementary climate solution to CO2 reductions: reducing a key group of warming agents knows as super pollutants or short-lived climate pollutants (SLCPs) to bend the warming curve quickly (over a few decades) while we pursue CO2 mitigation to bend the curve in the long term (over several decades to centuries). Combined, these efforts, if enacted by 2020, give us a significant chance (about 90% probability) of keeping warming well below 2°C (aiming for 1.5°C) in this century and beyond. Mitigation of SLCPs, if completed by 2030, can bend the warming curve by up to 0.6°C by 2050 (about 0.4°C from methane mitigation, 0.1°C from black carbon, and 0.1°C from HFCs), cutting the rate of projected warming by about half compared with “business as usual” and reducing the projected sea level rise between 2020 and 2050 by 20%.