The 21st Century climate challenge

1The 21 st Century climate challengeTable 1.2Global carbon footprints at OECD levelswould require more than one planet aachieve its prosperity. How many planets willIndia require for development?”We ask the same question for a world edgingtowards the brink of dangerous climate change.Using the annual ceiling of 14.5 Gt CO 2, ifemissions were frozen at the current level of 29Gt CO 2we would need two planets. However,some countries are running a less sustainableaccount than others. With 15 percent of theworld population, rich countries are using 90percent of the sustainable budget. How manyplanets would we need if developing countrieswere to follow the example of these countries?If every person living in the developingworld had the same carbon footprint as the averagefor high income countries, global CO 2emissions would rise to 85 Gt CO 2—a levelthat would require six planets. With a globalper capita footprint at Australian levels, wewould need seven planets, rising to nine for aworld with Canada and United States levels ofper capita emissions (table 1.2).The answer to Gandhi’s question raises somewider questions about social justice in climatechange mitigation. As a global community,we are running up a large and unsustainablecarbon debt, but the bulk of that debt has beenaccumulated by the world’s richest countries.CO 2emissionsper capita (t CO 2)2004Equivalent number ofEquivalent global CO 22004 b budgets cemissions (Gt CO 2) sustainable carbonWorld d 4.5 29 2Australia 16.2 104 7Canada 20.0 129 9France 6.0 39 3Germany 9.8 63 4Italy 7.8 50 3Japan 9.9 63 4Netherlands 8.7 56 4Spain 7.6 49 3United Kingdom 9.8 63 4United States 20.6 132 9a. As measured in sustainable carbon budgets.b. Refers to global emissions if every country in the world emitted at the same per capita level as the specifi ed country.c. Based on a sustainable emissions pathway of 14.5 Gt CO 2per year.d. Current global carbon footprint.Source: HDRO calculations based on Indicator Table 24.The challenge is to develop a global carbonbudget that charts an equitable and sustainablecourse away from dangerous climate change.Charting a course away fromdangerous climate changeWe use the PIK model to identify plausiblepathways for keeping within the 2°C threshold.One pathway treats the world as a single country,which for carbon accounting purposes it is,then identifies targets for rationing or ‘burdensharing’. However, the viability of any system ofburden sharing depends on participants in thesystem perceiving the distribution of rationsto be fair. The UNFCCC itself acknowledgesthis through an injunction to “protect theclimate system…on the basis of equity and inaccordance with…common but differentiatedresponsibilities and respective capabilities.”While interpretation of that injunction isa matter for negotiation, we have distinguishedbetween industrialized countries and developingcountries, charting separate pathways forthe two groups. The results are summarized infigure 1.11. The cuts from a 1990 base-yearon our sustainable emissions pathway are asfollows:• The world. Emissions for the world will haveto be reduced by around 50 percent by 2050,with a peak around 2020. Emissions wouldfall towards zero in net terms by the end ofthe 21 st Century.• Developed countries. High-income countrieswould have to target an emissions peakbetween 2012 and 2015, with 30 percent cutsby 2020 and at least 80 percent cuts by 2050.• Developing countries. While there would belarge variations, major emitters in the developingworld would maintain a trajectory ofrising emissions to 2020, peaking at around80 percent above current levels, with cuts of20 percent against 1990 levels by 2050.Contraction and convergence—sustainability with equityWe emphasize that these are feasible pathways.They are not specific proposals for individualcountries. Yet the pathways do serve animportant purpose. Governments are embarking48 HUMAN DEVELOPMENT REPORT 2007/2008