The 21st Century climate challenge

1The 21 st Century climate challengePolicies for mitigatinggreenhouse gas emissionswill require far-reachingchanges in energypolicy and behaviour1.6 Why we should act to avoid dangerousclimate changeWe live in a deeply divided world. Extremesof poverty and prosperity retain the power toshock. Differences in religious and culturalidentification are a source of tension betweencountries and people. Competing nationalismspose threats to collective security. Againstthis backdrop, climate change provides a hardlesson in a basic fact of human life: we sharethe same planet.Wherever people live and whatever theirbelief systems, they are part of an ecologicallyinterdependent world. Just as flows of tradeand finance are linking people together in anintegrated global economy, so climate changedraws our attention to the environmental tiesthat bind us in a shared future.Climate change is evidence that we aremismanaging that future. Climate securityis the ultimate public good: the world’satmosphere is shared by all in the obvioussense that nobody can be ‘excluded’ from it.By contrast, dangerous climate change is theultimate public bad. While some people (theworld’s poor) and some countries stand to losefaster than others, everybody stands to lose inthe long run, with future generations facingincreased catastrophic risks.Writing in the 4 th Century BC, Aristotleobserved that “what is common to the greatestnumber has the least care bestowed uponit”. He could have been commenting on theEarth’s atmosphere and the absence of carebestowed on our planet’s capacity to absorbcarbon. Creating the conditions for changewill require new ways of thinking abouthuman interdependence in a world headingfor dangerous climate change outcomes.Climate stewardship in aninterdependent worldTackling climate change confronts governmentswith difficult choices. Complex issues involvingethics, distributional equity across generationsand countries, economics, technology andpersonal behaviour are at stake. Policies formitigating greenhouse gas emissions willrequire far-reaching changes in energy policyand behaviour.In this chapter we have looked at a rangeof issues that are important in framing theresponse to climate change. Four themes meritspecial emphasis because they go to the heart ofthe ethics and economics of any public policyframework for mitigation:• Irreversibility. Emissions of CO 2andother greenhouse gases are, for all practicalpurposes, irreversible. The duration oftheir residence in the Earth’s atmosphereis measured in centuries. Similar logicapplies to climate system impacts. Unlikemany other environmental issues, wheredamage can be cleaned up relativelyswiftly, the damage wrought by climatechange has the potential to extend fromvulnerable populations today acrossgenerations to the whole of humanity inthe distant future.• Global scale. The climate forcing generatedthrough a build-up of greenhouse gasesdoes not distinguish between nations,even if the effects differ. When a countryemits CO 2the gas flows into a stock thataffects the whole world. Greenhousegas emissions are not the only form oftransboundary environmental pollution:acid rain, oil spillages and river pollutionalso create externalities that cross nationalborders. What is different with climatechange is the scale and the consequence:that no nation state acting alone can solvethe problem (even though some countriescan do more than others).• Uncertainty and catastrophe. Climatechange models deal in probabilities—andprobabilities imply uncertainties. Thecombination of uncertainty and catastrophicrisk for future generations is a powerful58 HUMAN DEVELOPMENT REPORT 2007/2008