Pathway and Cost-Benefit Analysis to Achieve China's Zero Hydrofluorocarbon Emissions.

Global hydrofluorocarbon (HFC) cumulative emissions will be more than 20 Gt CO2-equiv during 2020-2060 and have a non-negligible impact on global warming even in full compliance with the Kigali Amendment (KA). Fluorochemical manufacturers (including multinationals) in China have accounted for about 70% of global HFC production since 2015, of which about 60% is emitted outside China. This study built an integrated model (i.e., DECAF) to estimate both territorial and exported emissions of China under three scenarios and assess the corresponding climate effects as well as abatement costs. Achieving near-zero territorial emissions by 2060 could avoid 23 ± 4 Gt CO2-equiv of cumulative territorial emissions (compared to the 2019 Baseline scenario) during 2020-2060 at an average abatement cost of 9 ± 6 USD/t CO2-equiv. Under the near-zero emission (including territorial and abroad) pathway, radiative forcing from HFCs will peak in 2037 (60 ± 6 mW/m2) with a 33% peak reduction and 8 years in advance compared to the path regulated by the KA, and the radiative forcing by 2060 will be lower than that in 2019. Accelerated phase-out of HFC production in China could provide a possibility for rapid global HFC abatement and achieve greater climate benefits.

A review of bottom-up and top-down emission estimates of hydrofluorocarbons (HFCs) in different parts of the world.

Hydrofluorocarbons (HFCs) are widespread alternatives for the ozone-depleting substances chlorofluorocarbons and hydrochlorofluorocarbons. They are used mainly as refrigerants or as foam-blowing agents. HFCs do not deplete the ozone layer, but they are very potent greenhouse gases, already contributing to global warming. Since 2019 HFCs are regulated under the Kigali Amendment to the Montreal Protocol, which demands reliable emission estimates to monitor the phase-down. Quantification of emissions is performed with two methods: bottom-up from product inventories or data on chemical sales; or top-down, inferred from atmospheric measurements by inverse modelling or interspecies correlation. Here, we review and compare the two methods and give an overview of HFC emissions from different parts of the world. Emission estimates reported by the different methods vary considerably. HFC emissions of developed countries (Annex I) are reported to the United Nations Framework Convention on Climate Change. These bottom-up estimates add up to only half of global emissions estimated from atmospheric data. Several studies with regional top-down estimates have shown that this gap is not owed to large-scale underreporting of emissions from developed countries, but mostly due to emissions from developing countries (non-Annex I). China accounts for a large fraction of the emissions causing the gap, but not entirely. Bottom-up and top-down estimations of emissions from other developing countries that could identify other large emitters are largely unavailable. Especially South America, West-, Central- and East-Africa, India, the Arabian Peninsula and Northern Australia are not well covered by measurement stations that could provide atmospheric data for top-down estimates.