Klima-scenario med blot 1º temperaturstigning

18. januar 2009

Worldwatch Institute er netop udkommet med sin 26. årlige rapport om klodens tilstand, og med State of the World 2009. Into a Warming World, er temaet i år direkte klimaudfordringen.

Om end det sjældent er opmuntrende læsning, har disse tilstandsrapporter gennem årene givet en række uvurderlige analyser af den globale tilstand. Og årets fokus på klimaproblematikken giver et fornemt, om end næsten knugende billede af det enorme svælg mellem klimaforskernes forståelse af, hvilke tiltag, der er nødvendige for at stabilisere klimaet, og den manglende forståelse hos de politikere og erhvervsfolk, som med deres beslutninger og mangel på samme kommer til at tegne udviklingen i de kommende årtier.

W.L. Hare fra Potsdam Institute giver i kapitel 2, A Safe Landing for the Climate (pdf), et godt perspektiv på klimasituationen. Hvor IPCC nu prøver at opstille en afløser for Kyoto-aftalen, som kan sikre, at vi maksimalt får en global temperaturstigning på 2º, vurderer hare på baggrund af en række nyere resultater, at vi nærmere skal sigte mod 1,7 º eller 1,5º grader global stigning, og ideelt set burde sigte mod et 1º-scenario for med høj sandsynlighed at kunne stabilisere klimaet.

Kapitel 2 afrundes med en skitse til et 1º-scenario, som vil kræve CO2-neutralitet i 2050 og en hurtig udvikling videre frem mod en CO2-’negativitet’, hvor vi globalt set bliver i stand til at absorbere mere CO2 end vi udleder. Noget i den stil vil blive nødvendigt for at bringe atmosfærens koncentration af CO2 tilbage under 350 ppm – den grænse mange klimaforskere i dag sætter som den maksimale for at langtidsstabilisere klimaet. CO2-koncentrationen, som før industrialiseringen lå på omkring 280 ppm, er i dag på 387 ppm og stiger omkring 2 ppm pr. år. De globale temperaturstigning siden industrialiseringen er i dag på omkring 0,7.

På lidt længere sigt må vi ifølge Hare sigte mod en fjernelse af CO2 i et omfang på linje med de samlede udledninger fra fossile brændstoffer siden industrialiseringens begyndelse for fuldt ud at restabilisere klimaet med en koncentration på omkring 300 ppm.

For at have stor sikkerhed for, at klimaet ikke når såkaldte ‘tipping points’ konkluderer Hare, at vi må sigte på en stigning på max. 1º. på kurverne herover, som stammer fra kapitel 2, kan man se, at IPCCs ‘high’ scenario, hvor vi kun i lille grad formår at bremse CO2-udledningerne, frem mod år 2100 vil medføre CO2-koncentrationer på over 1.000 ppm og en globale opvarmning i størrelsesordenen 4-5ºC.

State of the World 2009. Into a Warming World, giver et prisværdigt overblik over klimasituationen og er yderst anbefalelsesværdig læsning. De enkelte kapitler kan downloades i pdf-format, se links nedenfor. Der er et eksemplar at State of the World 2009 på vej til vores Agenda 21-bibliotek på Rådhuspladsen 77.

Kapitel 1 rummer en sammenfatning med 10 punkter, som vil kunne give en CO2-neutral verden i 2050. De er medtaget nedenfor i en forkortet udgave, som stammer fra Leo Hickmanns omtale af State of the World 2009 i The Guardian i torsdags.¹

indlæg oprettet af Jens Hvass

State of the World 2009: Into a Warming World, Worldwatch Institute 2009.

Deborah Zabarenko: Halt all carbon emissions by 2050, says Worldwatch, Scientific American 13.01.2009.

Tanya Syed, World ‘needs radical cuts’ on CO2, BBC News 14.01.2009.

Leo Hickmann: Emission impossible, The Guardian 15.01.2009.¹

 

 

De enkelte kapitler:

State of the World: A Year in Review – A timeline of significant environmental news events from October 2007 to September 2008 (pdf).
1) The Perfect Storm – The climate dilemma, in a nutshell (pdf).
2) A Safe Landing for the Climate – Current climate science and the emissions path needed to glide toward a safe landing (pdf).
3) Farming and Land Use to Cool the Planet – The needed transition to carbon-absorbing forestry and food production (pdf).
4) An Enduring Energy Future – The opportunity and the imperative for building a low-carbon energy future (pdf).
5) Building Resilience – The importance of building resilience to climate change (pdf).
6) Sealing the Deal to Save the Climate – The agreement that nations must reach to begin stabilizing the climate while adapting to a warming world (pdf).
Climate Connections – 22 essays by experts around the world on wide-ranging topics relevant to climate change.
Climate Change Reference Guide and Glossary – A primer for following the developments on climate change that will unfold in 2009 (pdf).

1) Thinking long-term – At the core of the climate problem is the likelihood that future generations will pay with a deteriorating global environment for the refusal of current generations to live in balance with the atmosphere. Visionary leaders will need to marshal the public to take responsibility for the impacts of today’s behaviour on the future and to act accordingly.

2) Innovation – The emissions shift will require technologies that break the carbon link to energy consumption with as little sacrifice of price and convenience as possible. A range of renewable technologies can produce electricity and meet heating and cooling needs. Such technologies include buildings that produce more energy than they consume and “smart grids” that use information technology to match renewably produced electricity precisely to demand.

3) PopulationRarely addressed in the context of climate change, future population trends could make the difference between success and failure in the long-term balance of human activities, atmosphere, and climate. The world’s population is likely to stop growing and then gradually decline for a period when women gain the full capacity to decide for themselves whether and when to have children.

4) Changing lifestyles – The assumption that the “good life” requires ever more individual consumption, more meat-eating, ever larger homes and vehicles, and disposable everything will need to fade. A spirit of shared and equitable material sacrifice can replace it – with no loss of what really matters, such as active good health, strong communities, and time with family.

5) Healing land – Managed for the task, the Earth’s soil and vegetation can remove billions of tons of carbon from the atmosphere. Agricultural landscapes can accomplish this while improving food and fibre production and minimising the need for artificial fertiliser and fossil-fuel-driven tilling and raising farmer incomes.

6) Strong institutions – As with the deteriorating global economy, the global nature of climate change demands international cooperation and sound governance. The strength and effectiveness of the United Nations, multilateral banks, and major national governments are essential to addressing global climate change. These institutions – and those emerging from the hoped-for Copenhagen climate agreement in 2009 – require strong public support for their critical work.

7) The Equity imperative – No climate agreement will succeed without support from those countries that have so far contributed little to human-induced climate change, have low per-capita emissions, and stand to face the biggest challenges in adapting to the coming changes. A pact that is fair to developing and industrialised countries alike is essential.

8) Economic stability – With the world now fixated on the sputtering global economy, addressing climate change will demand attention to costs and the promise of improving rather than undermining long-term economic prospects. A climate agreement will have to operate effectively during anaemic as well as booming economic periods, facing squarely the challenges of poverty and unemployment while continually reducing emissions of carbon dioxide and other greenhouse gases.

9) Political stability – A world beset by conflict and terrorism is far less likely to prevent dangerous climate disruption than one at peace. Security and climate must be addressed simultaneously. On the positive side, negotiating an effective and fair climate agreement offers countries a needed opportunity to practice peace and re-frame international relations along cooperative rather than competitive lines.

10) Mobilising for change – The way to deal with climate change we ourselves are causing is to see the opportunity for a new global economy and new ways of living in the effort to bring net greenhouse gas emissions to an end. There’s no guarantee such a transition will be easy – or even possible. But a global movement to make the effort is needed now, and could yield new jobs, new opportunities for peace, and global cooperation beyond what humanity has ever achieved.

De 10 punkter herover er en forkortet udgave fra The Guardian.¹

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  1. Peter kommentarer:

    En meget interessant rapport, der sætter tingene lidt i perspektiv.

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