The Physical Vulnerability to Climate Change Index: An Index to Be Used for International Policy

Abstract

Recent years have seen a sharp increase in the production of indices of vulnerability to climate change. Most of these indices of vulnerability to climate change have been primarily used for awareness-raising purposes rather than for guiding international policy. The Physical Vulnerability to Climate Change Index (PVCCI) proposed in this paper has been designed as an index of exogenous vulnerability, not influenced by the present policy of the countries concerned. As such it can be used as a criterion for guiding the international allocation of concessional resources (in particular those devoted to adaptation), as well as for the identification of the countries that are most vulnerable for structural or physical reasons. The index has been calculated for 191 countries. LDCs, SIDS, and African countries have a higher average score. However, there is a wide disparity in PVCCI scores within these three groups of countries, implying that a country-by-country allocation of resources should be used rather than an allocation by country group. The findings appear to be robust after comparison of various options.

Introduction

Financing adaptation, and allocating adaptation resources, have remained major issues to be adressed after the 2015 COP 21 Summit in Paris. For ethical reasons, it seems fair that the allocation of financial support to developing countries for adaptation should take into account their vulnerability to climate change. For this purpose indices of vulnerability to climate change are needed. However, the broad concept of vulnerability leaves room for a wide range of approaches in the construction of indicators.

Over recent years, a proliferation of indices of vulnerability to climate change has developed. A majority of them are based on the IPCC's three key aspects of vulnerability: exposure, magnitude, and adaptive capacity.¹ Among the most prominent indices are the indices produced by institutions such as the UNDP's Disaster Risk Index, GAIN's Index of Vulnerability and Readiness, Maplecroft's Climate Vulnerability Index, DARA's Climate Vulnerability Monitor, and ICRISAT's Quantitative Assessment of Vulnerability to Climate Change Index, as well as indices authored by academic researchers, such as Yohe et al. (2006), Buys et al. (2009), Barr et al. (2010), Wheeler (2011). These indices, whose rankings are sometimes contraditory, have been primarily created for awareness-raising purposes and are not designed to guide the allocation of adaptation resources.

A suitable indicator for permitting a fair allocation of adaptation funds should only reflect a vulnerability to climate change that is independent of the countries present policies. It should be a structural vulnerability and should be estimated from the physical exogenous shocks faced by the countries, for which they are not responsible (Guillaumont, 2015). Of course, it cannot be the only allocation criterion, and is to be used alongside the more traditional allocation criteria of income per capita and performance of countries. This paper presents the first comprehensive attempt to build an index of vulnerability to climate change meeting the requirements to be used in this allocation framework.

Keeping in mind that an index's objectives influence its content, the search for an appropriate indicator of vulnerability to climate change can draw lessons from the Economic Vulnerability Index (EVI), which was designed for the identification of the Least Developed Countries (LDCs). These are poor countries facing the most severe structural handicaps to development. The EVI has been built so that its components reflect only exogenous factors, independent of the present will of countries (UNCDP, 2018). It is now considered not only as a criterion for the identification of the LDCs, but also as a relevant criterion for the allocation of development assistance (United Nations, 2012; Guillaumont, 2009, Guillaumont, 2013). However, the Economic Vulnerability Index is not focused on vulnerability to climate change and cannot be used for the allocation of adaptation resources.

In this paper, we propose an index of vulnerability to climate change that captures a “physical” vulnerabilty to climate change and can be considered as exogenous. Such a vulnerabilty to climate change index, independent of the present political will of countries, is aimed to be used, as a criterion for the allocation of adaptation ressources. It could then be combined with other indicators to determine an optimal allocation of these resources (Guillaumont, 2015), or to analyse the extent to which donors actually take into account structural vulnerability to climate change in the allocation of adaptation resources (Guillaumont and Simonet, 2011; Fransen et al., 2013; Weiler et al., 2018). The general literature on the allocation of development assistance traditionnally refers to two kinds of criteria: the “needs” and the “performance” of receiving countries (see for instance McGillivray and Guillaumont, 2017. in particular Guillaumont et al., 2017). In the case of allocation of adaptation resources, the vulnerability to climate change (which does not depend on the present will or policies of the countries), clearly reflects a need, while the dampening of vulnerability due to these policies reflects their performance. This is why it is necessary to distinguish in the vulnerability to climate change what is exogenous from what is not.

This “Physical Vulnerability to Climate Change Index” (PVCCI), which captures the vulnerability that results from risks in geophysical conditions, differs from the other existing indices of vulnerability to climate change. It indeed considers only the vulnerability which does not depend on the present will of the countries, but has also several features generally not found in current indices.

First, because it does not have socioeconomic components, the PVCCI helps guard against the difficulty of measuring the socioeconomic impact of climatic shocks, which often undermines the ex ante assessment of vulnerability.

Second, the structure of the index reflects two types of risk related to climate change: the risks of an increase in the intensity of recurrent shocks (in temperature, rainfall, and storms), and the long-term risks of progressive shocks (such as flooding due to higher sea level, or desertification).

Third, the way by which the components are aggregated within the index is an important issue. While the index is a composite index covering the main major sources of vulnerability to climate change, it highlights the specific way by which climate change hits each country, thanks to the use of quadratic mean.

Fourth, since the physical impact of shocks related to climate change depends on the initial situation, the components of the PVCCI are weighted by an index of each country's exposure to the corresponding shocks.

Although in view of allocation of concessional funds the index is mainly needed for poor countries, it has also been calculated for 191 countries members of the United Nations to fit the framework of the Sustainable Development Goals (SDGs).

The remainder of this paper is organized as follows: Section 2 explains why the proposed index differs from the existing indices. Section 3 presents the structure of the PVCCI, the methodology for calculating and agregating its compoents. Section 4 gives results of the PVCCI and assesses its robustness. Section 5 concludes.