Are national HFC emissions reports suitable for global policy negotiation?

目前正在进行谈判，以确定氢氟碳化合物(HFC)的使用是否应受到旨在保护平流层臭氧层的国际条约《蒙特利尔议定书》的监管。虽然氢氟碳化物不会消耗平流层臭氧，但它们是强有力的温室气体(GHG)，其全球变暖潜力是二氧化碳的数百至数千倍。因此，议定书拟议修正案的支持者认为，由于氢氟碳化合物在大气中的快速增长是全球逐步减少臭氧消耗物质的直接结果，氢氟碳化合物是其替代品，因此其对全球气候的影响现在应在同一框架下加以管制。正在进行的讨论的一个主要限制是，目前氢氟碳化合物的排放限制很差，2012年通过大气测量确定的全球排放量的60%以上没有报告。这可能是由于报告做法不佳，和/或《联合国气候变化框架公约》(《气候公约》)规定的全球排放报告不完整，只要求一小部分国家详细报告其排放量。最近对大气测量得出的氢氟碳化物和其他合成温室气体排放量的估计表明，这两个因素都可能起到作用。然而，尚未对主要报告国的这种“自上而下”的排放估计数进行全面评估。此外，我们认为，用于推导氢氟碳化合物(和所有其他温室气体)排放的“逆”模型框架中的不确定性量化方法必须得到极大的改进，如果它们要稳健并与政策制定者相关的话。这项建议旨在开发利用大气观测和化学传输模型估计国家温室气体排放的新方法。特别是，我们将率先使用分层贝叶斯建模和高斯过程仿真。这些技术将使我们第一次能够明确地包括大气模拟过程中的一些关键不确定因素对“自上而下”排放估计的影响。这将使我们能够比以往更全面地估计主要氢氟碳化合物的国家排放量。我们将详细审查这些排放量估计数与国家清单之间的差异，并关键地确定目前提交给《气候公约》的报告是否适合为关于《蒙特利尔议定书》未来的辩论提供信息。

Negotiations are underway to determine whether the use of hydrofluorocarbons (HFCs) should be regulated under the Montreal Protocol, the international treaty that is designed to protect the stratospheric ozone layer. Whilst HFCs do not deplete stratospheric ozone, they are potent greenhouse gases (GHG), with global warming potentials hundreds to thousands of times that of carbon dioxide. Therefore, proponents of the proposed amendments to the Protocol argue that, because their rapid growth in the atmosphere is a direct result of the global phase-down of ozone depleting substances, for which HFCs are replacements, their resulting impact on global climate should now be regulated under the same framework. A major limitation of the on-going discussions is that emissions of HFCs are very poorly constrained at present, with more than 60% of the global emissions, as determined using atmospheric measurements, being un-reported in 2012. This could be due to poor reporting practices, and/or the incomplete nature of global emissions reports under the United Nations Framework Convention on Climate Change (UNFCCC), in which only a subset of countries are required to report their emissions in detail. Recent estimates of the emissions of HFCs and other synthetic GHGs derived from atmospheric measurements indicate that both factors are likely to contribute. However, a comprehensive evaluation of such "top-down" emissions estimates for the major reporting countries has not yet been carried out. Furthermore, we argue that the uncertainty quantification methods in the "inverse" modelling frameworks that are used to derive emissions of HFCs (and all other GHGs) must be dramatically improved if they are to be robust and relevant to policy makers.This proposal aims to develop new methods for estimating national GHG emissions using atmospheric observations and chemical transport models. In particular, we will pioneer the use of hierarchical Bayesian modelling and Gaussian process emulation. These techniques will allow us, for the first time, to explicitly include the influence of some critical uncertainties in the atmospheric modelling process on "top-down" emissions estimates. This will allow us to estimate national emissions of the major HFCs with a more complete estimate of the uncertainty than has previously been possible. We will examine in detail the differences between these emissions estimates and the national inventories, and determine critically whether the current reports submitted to the UNFCCC are appropriate for informing the debate on the future of the Montreal Protocol.