The 21st Century climate challenge

Note to Table 1: about this year’shuman development indexThe human development index (HDI) is acomposite index that measures the averageachievements in a country in three basic dimensionsof human development: a long andhealthy life; access to knowledge; and a decentstandard of living. These basic dimensions aremeasured by life expectancy at birth, adult literacyand combined gross enrolment in primary,secondary and tertiary level education,and gross domestic product (GDP) per capitain Purchasing Power Parity US dollars (PPPUS$), respectively. The index is constructedfrom indicators that are available globallyusing a methodology that is simple and transparent(see Technical note 1).While the concept of human development ismuch broader than any single composite indexcan measure, the HDI offers a powerful alternativeto GDP per capita as a summary measureof human well-being. It provides a useful entrypoint into the rich information contained inthe subsequent indicator tables on different aspectsof human development.Data availability determines HDIcountry coverageThe HDI in this Report refers to 2005. It covers175 UN member countries, along with HongKong Special Administrative Region of China,and the Occupied Palestinian Territories.To enable cross-country comparisons,the HDI is, to the extent possible, calculatedbased on data from leading international dataagencies available at the time the Report wasprepared (see Primary international datasources below). But, for a number of countries,data are missing from these agencies for oneor more of the four HDI components. Forthis reason, 17 UN member countries cannotbe included in the HDI ranking this year. Insteada set of basic HDIs for these countriesis presented in Table 1a.In very rare cases, HDRO has made specialefforts to obtain estimates from other international,regional or national sources when theprimary international data agencies lack datafor one or two HDI components of a country.In a very few cases HDRO has produced an estimate.These estimates from sources other thanthe primary international agencies are clearlydocumented in the footnotes to Table 1. Theyare of varying quality and reliability and arenot presented in other indicator tables showingsimilar data.Primary international data sourcesLife expectancy at birth. The life expectancy atbirth estimates are taken from World PopulationProspects 1950–2050: The 2006 Revision(UN 2007e) the official source of UNpopulation estimates and projections. Theyare prepared biennially by the United NationsDepartment of Economic and Social AffairsPopulation Division (UNPD) using data fromnational vital registration systems, populationcensuses and surveys.In The 2006 Revision UNPD incorporatedavailable national data through the end of2006. For assessing the impact of HIV/AIDS,the latest HIV prevalence estimates prepared bythe Joint United Nations Programme on HIV/AIDS (UNAIDS) are combined with a series ofassumptions about the demographic trends andmortality of both infected and non-infectedpeople in each of the 62 countries for which theimpact of the disease is explicitly modelled.The availability of new empirical evidenceon the HIV/AIDS epidemic and demographictrends often requires adjustments to earlier estimates.Recent UNAIDS estimates indicatea decline in the rate of transition of new individualsinto the high risk group. Based on theseand other factors, World Population Prospects1950–2050: The 2006 Revision made severalmethodological changes, which resulted in significantincreases in estimates of life expectancyat birth for some of the countries. Firstly, The2006 Revision incorporates a longer survivalfor infected persons receiving treatment. Secondly,the rate of mother to child transmissionis also projected to decline at varying rates dependingon the progress made by each countryin increasing access to treatment. The lifeHUMAN DEVELOPMENT REPORT 2007/2008 225