Are national HFC emissions reports suitable for global policy negotiation?

目前正在进行谈判，以确定是否应根据旨在保护平流层臭氧层的国际条约《蒙特利尔议定书》对氢氟碳化合物（HFCs）的使用进行监管。虽然氢氟碳化合物不会消耗平流层臭氧，但它们是强效温室气体，其全球变暖潜能值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，由于这些物质在大气中的迅速增加是全球逐步减少臭氧消耗物质的直接结果，而氢氟碳化合物是这些物质的替代品，因此，现在应在同一框架下对这些物质对全球气候造成的影响进行监管。正在进行的讨论的一个主要局限性是，目前氢氟碳化合物的排放受到的限制非常少，根据大气测量结果，2012年全球排放量的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》）下的全球排放报告不完整，其中只要求一小部分国家详细报告其排放量。最近对氢氟碳化合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作用。然而，尚未对主要报告国的这种“自上而下”的排放量估计进行全面评价。此外，我们认为，不确定性量化方法的“逆”模型框架，用于推导排放量的氢氟碳化合物（和所有其他温室气体）必须显着改善，如果他们是强大的，相关的决策者。本提案旨在开发新的方法，估计国家温室气体排放量使用大气观测和化学运输模型。特别是，我们将率先使用分层贝叶斯建模和高斯过程仿真。这些技术将使我们能够第一次明确地包括大气模拟过程中某些关键不确定性对“自上而下”排放估计的影响。这将使我们能够对主要氢氟碳化合物的国家排放量进行估计，并对不确定性进行比以前更全面的估计。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，并严格确定目前提交给UNFCCC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.